US20060191675A1

US20060191675A1 - Apparatus and methods for warming and cooling bodies

Info

Publication number: US20060191675A1
Application number: US11/277,078
Authority: US
Inventors: R. Fletcher; John Fletcher; Katie Au; Christopher Clarke; Yunquan Chen
Original assignee: Coolhead Tech Inc
Current assignee: Coolhead Tech Inc
Priority date: 2003-09-22
Filing date: 2006-03-21
Publication date: 2006-08-31

Abstract

A flexible heat exchanger is suitable for heating or cooling living subjects or objects. The heat exchanger has a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. A flexible heat exchange plate that is essentially impermeable to the heat exchange fluid is penetrated by substantially rigid thermally-conductive members. The members provide paths of high thermal conductivity through the plate. The heat exchange fluid may be water.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of PCT patent application No. PCT/CA2004/001660 filed on 22 Sep. 2004 which is a continuation-in-part of U.S. application Ser. No. 10/665,073 filed on 22 Sep., 2003 and entitled FLEXIBLE HEAT EXCHANGERS FOR MEDICAL COOLING AND WARMING APPLICATIONS, Ser. No. 10/665,074 filed on 22 Sep., 2003 and entitled FLEXIBLE HEAT EXCHANGERS pursuant to 35 U.S.C. § 120. PCT patent application No. PCT/CA2004/001660 also claims the benefit of U.S. patent application 60/565,517 filed on 27 Apr. 2004 and entitled FLEXIBLE HEAT EXCHANGERS, 60/565,537 filed on 27 Apr. 2004 and entitled FLEXIBLE HEAT EXCHANGERS FOR MEDICAL COOLING AND WARMING APPLICATIONS, and 60/580,356 filed on 18 Jun. 2004 and entitled METHOD AND APPARATUS FOR AFFIXING THROUGH MEMBER IN MEMBRANE, all of which are hereby incorporated by reference herein. This application claims the benefit of U.S. application No. 60/663,267 filed on 21 Mar. 2005 pursuant to 35 U.S.C. § 119.

TECHNICAL FIELD

The invention relates to heat exchangers. The invention has particular application to heat exchangers for use in warming or cooling living subjects. The invention may be applied to cooling the brains or other body parts of living subjects. The apparatus and methods generally provide a heat exchange fluid, which is a liquid in some embodiments and a gas in other embodiments, that passes through a heat exchanger to exchange heat with a body to be warmed or cooled.

BACKGROUND

It has been discovered that quickly inducing hypothermia can significantly improve the recovery prospects of patients who suffer global ischemic brain injury secondary to cardiac arrest and probably focal ischemic brain injury from thrombotic or embolic causes. The latter is referred to as an ischemic stroke. Some trials have placed global and focal ischemic brain damaged victims in whole-body cooling chambers or devices. Intra vascular devices are used for whole body cooling and, secondarily, brain cooling. Such chambers or devices are unwieldy and can be intimidating for the patient. Fletcher, U.S. Pat. No. 6,511,502 discloses methods for cooling a subject's brain by applying heat exchangers to the neck of the subject adjacent the subject's carotid arteries. The heat exchangers cool blood flowing to the subject's brain.
In various other areas of medicine it is desirable to cool or warm body parts. For example, U.S. Pat. Nos. 4,138,743; 5,916,242; 4,566,455; 4,750,493; 4,763,866; 4,020,963; 5,190,032; 5,486,204; 5,643,336; 5,897,581; 5,913,855; 5,057,964; and 6,030,412 relate to cooling or warming body.
Various types of heat exchanger exist. Air cooled heat sinks are structures which take heat from an object and dissipate the heat into ambient air. Such heat sinks typically consist of a finned piece of thermally-conductive material having a face which can be placed in thermal contact with an object, such as an electronic component, to be cooled. Some heat sinks are equipped with fans located to flow air past the fins to improve the rate at which heat is dissipated.
U.S. Pat. No. 6,549,411 B1 discloses a flexible heat sink that can be attached to a generally flat surface of an object. The heat sink can flex to conform to the surface of the object to achieve improved contact with the object, and hence increase the efficiency of heat transfer between the heat sink and the object. U.S. Pat. No. 6,367,541 B2 discloses a heat sink that can be attached to multiple electronic chips which have different heights. The heat sink dissipates heat from the chips into ambient air. The devices disclosed in these patents are not suitable for heating or cooling living subjects.
U.S. Pat. No. 5,368,093 discloses a flexible bag filled with thermal transfer fluid useful for thawing frozen foods. U.S. Pat. No. 4,910,978 discloses a flexible pack containing a gel. The pack can be cooled and applied to a patient for cold therapy. The pack conforms to surface contours of the patient's body. These devices have limited cooling capacities.
More sophisticated heat exchangers use a heat exchange fluid such as a cooling or heating liquid instead of ambient air to carry heat away from or provide heat to an object to be cooled or heated. Golden, U.S. Pat. No. 4,864,176 discloses a thermal bandage. The bandage includes a conforming member adapted to be placed against the skin. A thermal pack includes a chamber through which fluid can be circulated. The thermal pack is separated from the conforming member by a thermally-conductive surface. U.S. Pat. No. 5,757,615 discloses a flexible heat exchanger with circulating water as coolant for cooling a notebook computer. U.S. Pat. No. 5,643,336 discloses a flexible heating or cooling pad with circulating fluid for therapeutically treating the orbital, frontal, nasal and peri-oral regions of a patient's head. U.S. Pat. No. 6,551,347 B1 discloses a flexible heat exchange structure having fluid-conducting channels formed between two layers of flexible material for heat/cold and pressure therapy. U.S. Pat. Nos. 6,197,045 B1 and 6,375,674 B1 disclose a flexible medical pad with an adhesive surface for adhering the pad to the skin of a patient. U.S. Pat. No. 6,030,412 discloses a flexible enveloping member for enveloping a head, neck, and upper back of a mammal for cooling the brain of the mammal suffering a brain injury. All of these heat exchangers require heat to pass through a layer of some flexible material such as rubber, a thermoplastic, or a flexible plastic such as polyurethane. In addition, heat is exchanged between the surface of the flexible material and circulating fluid. Water is the most commonly used circulating fluid.
Rubber and flexible plastics are poor conductors of heat. To provide a high heat transfer efficiency in a flexible heat exchanger in which heat is transferred across a layer of rubber or plastic the layer must be very thin. This makes such heat exchangers prone to damage. In addition, water is a poor heat conductor. Heat exchange between the flexible material and water is largely dependent on convection. Water flowing over a relatively flat surface will often not result in efficient heat exchange.
U.S. Pat. No. 3,825,063 discloses a heat exchanger having metal screens of fine mesh with internal plastic barriers that at least partly penetrate the screens. The screens are stacked to provide transverse heat conduction relative to longitudinal flow paths. U.S. Pat. No. 4,403,653 discloses a heat transfer panel comprising a woven wire mesh core embedded in a layer of plastic material. The mesh and closure layer extend in the same longitudinal direction. U.S. Pat. No. 5,660,917 discloses a sheet with electrically insulating thermal conductors embedded in it. The apparatus disclosed in those patents is not adapted for warming or cooling living subjects.
There remains a need for heat exchangers suitable for warming or cooling living subjects via the surface of the subjects' skin. There is a particular need for such heat exchangers that provide a high ratio of heat-transfer capacity to skin contact area. There is also a need for heat exchangers which can be used in practising the methods described in Fletcher, U.S. Pat. No. 6,511,502 and which avoid at least some disadvantages of prior heat exchangers. In some fields there remains a need for heat exchangers capable of providing high heat transfer rates between the heat exchangers and objects that are not flat, are vibrating or are otherwise difficult to interface to. There is a particular need for such heat exchangers which have high ratio of heat-transfer capacity to contact area.

SUMMARY OF THE INVENTION

The invention relates to heat exchangers and has many aspects which may be combined or, in some cases, exploited individually. One aspect of the invention provides a flexible heat exchanger comprising a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet and a flexible sheet essentially impermeable to the heat exchange fluid. The sheet carries a plurality of substantially-rigid members. Each of the members comprises an exposed thermally-conductive surface on a thermally-conductive first body on an outside of the sheet and having a thermally-conductive portion extending from the thermally-conductive first body, through the sheet, and into the volume. Each of the plurality of members comprising opposed gripping surfaces held firmly against opposed sides of the sheet.
Another aspect of the invention provides a flexible heat exchanger comprising a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. The volume has a flexible wall essentially impermeable to the heat exchange fluid. The wall carries a plurality of substantially-rigid members. Each of the members comprising a thermally-conductive surface on an outside of the wall and has a thermally-conductive portion extending from the thermally-conductive surface, through the wall and into the volume. The thermally-conducting surface is supported at a location spaced outwardly apart from an outside surface of the wall.
Another aspect of the invention provides a flexible heat exchange surface for use in a heat exchanger. The flexible heat exchange surface comprises a flexible sheet essentially impermeable to the heat exchange fluid. The sheet carries a plurality of substantially-rigid members sealed to the sheet. Each of the members comprises first and second thermally-conductive bodies exposed on first and second sides of the sheet. The first and second thermally-conductive bodies are connected by a narrowed thermally-conductive portion having a cross sectional area smaller than a cross sectional area of either of the first and second bodies. The thermally-conductive portion extends through an aperture in the sheet.
Another aspect of the invention provides a flexible heat exchanger comprising a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. The volume has a flexible wall essentially impermeable to the heat exchange fluid. The wall carries a plurality of substantially-rigid members. Each of the members comprises a thermally-conductive surface on an outside of the wall and has a thermally-conductive portion extending from the pad, through the wall and into the volume. The thermally-conducting surface is either flush with or projects outwardly from an outside surface of the wall.
Another aspect of the invention provides a method for making a heat exchange surface for use in a heat exchanger. The method comprises providing a sheet, the sheet being essentially impervious to a heat exchange fluid to be used in the heat exchanger; inserting thermally-conductive members through the sheet; and, deforming at least one end of each of the thermally-conductive members to cause the thermally-conductive member to sealingly engage the sheet.
Another aspect of the invention provides a method for cooling or warming a plurality of thermally-conductive heat exchange surfaces suitable for placement against the skin of a living subject to cool or warm the living subject. The method comprises: establishing a turbulent flow of a heat exchange fluid through a volume; allowing the heat exchange fluid to contact and exchange heat with a plurality of thermally-conductive members projecting into the volume through a flexible wall of the volume, the thermally-conductive members each in direct thermal contact with at least one of the heat exchange surfaces by way of an unbroken path of a material or materials having a thermal conductivity of at least 50 Wm⁻¹K⁻¹; and, allowing heat to flow between the heat exchange surfaces and the thermally-conductive members along the paths.
Another aspect of the invention provides a flexible heat exchanger for warming or cooling a living subject. The heat exchanger comprises a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet; and, a flexible heat exchange plate essentially impermeable to the heat exchange fluid, the plate comprising a plurality of substantially rigid thermally-conductive members extending through a flexible material of the plate from an outside surface of the plate into the volume, the thermally-conductive members each projecting into a volume by a distance of at least 2 mm.
Another aspect of the invention provides a flexible heat exchanger comprising a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet; and, a flexible plate essentially impermeable to the heat exchange fluid. The plate comprises an array of closely-spaced apart substantially rigid metal thermally-conductive members extending through a flexible material of the plate, substantially at right angles to inner and outer surfaces of the plate, from an outside surface of the plate into the volume wherein a total area of the thermally-conductive members exposed on the outer surface of the plate exceeds a total cross sectional area of the thermally-conductive members at a point where the cross sectional members are extending through the flexible material.
Another aspect of the invention provides apparatus for warming or cooling a living subject, the apparatus comprising a plurality of heat exchangers and a mechanism for independently regulating a supply of cooling or warming fluid circulated through each of the heat exchangers. One aspect of the invention provides a flexible heat exchanger for warming or cooling a living subject. The heat exchanger comprises a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. A heat exchange fluid may be circulated through the volume. The heat exchanger comprises a flexible heat exchange plate essentially impermeable to the heat exchange fluid. The plate comprises a flexible fluid-impervious membrane supporting a plurality of substantially rigid thermally-conductive members. The thermally-conductive members extend through the membrane from an outside surface of the plate into the volume. Each of the thermally-conductive members comprises a body, a portion extending through the membrane from the body and a retainer member on a side of the membrane opposite to the body. The membrane is gripped between the body and the retainer member.
Another aspect of the invention provides a flexible heat exchanger. The heat exchanger comprises a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. A heat exchange fluid, for example, water, can flow through the volume. A flexible heat exchange plate essentially impermeable to the heat exchange fluid has a plurality of substantially rigid thermally-conductive members. The thermally-conductive members extend through a flexible material of the plate from an outside surface of the plate into the volume. The thermally-conductive members conduct heat between a subject and the heat exchange fluid.
Another aspect of the invention provides systems for heating or cooling a subject. The systems have a reservoir holding heat exchange fluid and a pair of feed pumps. One feed pump is connected to deliver the heat exchange fluid to a heat exchanger. Another feed pump is connected to withdraw the heat exchange fluid from the heat exchanger. The rate at which the heat exchange fluid is introduced into the heat exchanger by the first feed pump is balanced with the rate at which fluid is withdrawn from the heat exchanger by the second feed pump to maintain a pressure within a volume in the heat exchanger within a desired range of an ambient pressure.
One aspect of the invention provides a flexible heat exchanger. The heat exchanger comprises a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. A heat exchange fluid may be circulated through the volume. The heat exchanger comprises a flexible heat exchange plate essentially impermeable to the heat exchange fluid. The plate comprises a flexible fluid-impervious membrane supporting a plurality of substantially rigid thermally-conductive members. The thermally-conductive members extend through the membrane from an outside surface of the plate into the volume. Each of the thermally-conductive members comprises a body, a portion extending through the membrane from the body and a retainer member on a side of the membrane opposite to the body. The membrane is gripped between the body and the retainer member.
Another aspect of the invention provides a flexible heat exchanger. The heat exchanger comprises a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. A heat exchange fluid, for example, water, can flow through the volume. A flexible heat exchange plate essentially impermeable to the heat exchange fluid has a plurality of substantially rigid thermally-conductive members. The thermally-conductive members extend through a flexible material of the plate from an outside surface of the plate into the volume. The thermally-conductive members conduct heat between a subject and the heat exchange fluid.
Another aspect of the invention provides systems for heating or cooling an object. The systems have a reservoir holding heat exchange fluid and a pair of feed pumps. One feed pump is connected to deliver the heat exchange fluid to a heat exchanger. Another feed pump is connected to withdraw the heat exchange fluid from the heat exchanger. The rate at which the heat exchange fluid is introduced into the heat exchanger by the first feed pump is balanced with the rate at which fluid is withdrawn from the heat exchanger by the second feed pump to maintain a pressure within a volume in the heat exchanger within a desired range of an ambient pressure.
Another aspect of the invention provides a heat exchanger comprising front and rear sheet portions substantially impermeable to a heat exchange fluid. The front sheet portion supports a plurality of substantially rigid thermally-conductive members extending through the front sheet portion and having inner portions projecting into a volume between the front sheet portion and the rear sheet portion. The thermally-conducting members have exposed thermally-conducting surfaces on a front side of the front sheet portion. The rear sheet portion is formed with indentations receiving each of the inner portions of the plurality of thermally-conductive members.
Other aspects of the invention provides flexible heat exchange interfaces. The interfaces have plates or membranes penetrated by substantially rigid thermally-conductive members. The thermally-conductive members have enlarged pads on at least one side of the plate or membrane. The flexible material allows the interfaces to flex while the thermally-conductive members are operative to channel heat from a higher-temperature side of the interface to a lower-temperature side of the interface.
Another aspect of the invention provides a flexible heat exchanger comprising a volume having an inlet and an outlet. The volume can receive a heat exchange fluid, for example, water or a water-based coolant. The heat exchanger includes a flexible plate. Substantially rigid thermally-conductive members extend through a flexible material of the flexible plate from an outside surface of the flexible plate into the volume.
In preferred embodiments the thermally-conductive members each have a thermal conductivity of at least 50 Wm¹K¹and preferably at least 100 Wm¹K¹. The thermally-conductive elements may be made of materials such as aluminum, copper, gold, silver, alloys of two or more of aluminum, copper, gold, or silver with one another, alloys of one or more of aluminum, copper, gold, or silver with one or more other metals, carbon, graphite, diamond, or sapphire.
The thermally-conductive members may cover a substantial portion of the outer surface of the flexible heat exchange plate in some embodiments. For example, the thermally-conductive members may be exposed in an area of 30% or 40% or more of an area of the flexible heat exchange plate. In some embodiments, at least 50%, at least 70% or even at least 80% of an area of the flexible heat exchange plate is covered by the thermally-conductive members. Because of the very high rate at which heat can be carried through a thermally- conductive member, in some cases a coverage of 20% or even less by the thermally-conductive members is sufficient.
The flexible material of the plate sheet or membrane may comprise, for example, a suitable grade of polyurethane or other suitable thermoplastic polymer. Examples of other materials that may be suitable for use as the plate of membrane include: styrenic copolymers; suitable grades of: polyvinyl chloride (PVC); polyolefins such as polyethylene or polypropylene; styrenics such as polystyrene; polyesters such as polyethylene terephthalate (PET); polyethers such as polyetheretherketone (PEEK); polyamides (e.g. NYLON™); silicone; cellophane; cellulose acetates; natural or synthetic rubbers; ethylene-vinyl acetate; neoprene; polytetrafluoroethylene (PTFE e.g. TEFLON™); plasticized metallic films; a combination of two or more of these materials; coated or impregnated fabrics; and the like. In some embodiments the flexible material has a thermal conductivity not exceeding 5 Wm⁻¹K⁻¹.
A further aspect of the invention provides a temperature control system comprising a heat exchanger according to the invention, a reservoir containing a heat exchange fluid; a first feed pump connected to feed heat exchange fluid from the reservoir into the heat exchanger and a second feed pump connected to withdraw the heat exchange fluid from the heat exchanger.
Further aspects of the invention and features of specific embodiments of the invention are described below.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate non-limiting embodiments of the invention:
FIGS. 1A, 1B and 1C are respectively a longitudinal elevational cross-section view; a top plan view and a bottom plan view of a flexible heat exchanger configured as a cooling/warming pad for a subject's neck;
FIGS. 2A, 2B and 2C are respectively a cross-section view; a bottom view; and a top view of the flexible heat exchange plate of a heat exchanger according to an alternative embodiment of the invention;
FIG. 2D is a partial view of the outside surface of a heat exchanger having thermally-conductive members arranged in a triangular array;
FIG. 2E is a partial view of the outside surface of a heat exchanger having thermally-conductive members arranged to provide converging lines of flexible material;
FIG. 2F is a view of the outside surface of a heat exchanger having thermally-conductive members arranged in a rectangular array oriented at an angle to a long axis of the heat exchanger;
FIGS. 3A, 3B and 3C are respectively a cross-section view; a bottom view; and a top view of the flexible heat exchange plate of a heat exchanger according to one embodiment of the invention;
FIGS. 4A through 4L are views of different heat conductors that can be used in heat exchangers according to different embodiments of the invention;
FIGS. 5A and 5B are respectively sectional and bottom views of a flexible plate of a heat exchanger according to another embodiment of the invention;
FIG. 6 is a section through a heat exchanger according to another embodiment of the invention. FIGS. 6A, 6B and 6C are respectively a cross section in the plane 6A-6A, a bottom plan view, and a horizontal section through the heat exchanger of FIG. 6 (with the rear membrane removed);
FIGS. 6D, and 6E illustrate a heat exchanger in which a pattern of seams provides a U-shaped channel; FIG. 6F shows another heat exchanger in which a pattern of seams provides two separate fluid paths through the heat exchanger;
FIGS. 7A through 7P illustrate some alternative constructions for thermally-conductive members;
FIG. 8A illustrates a number of alternative configurations for a pin in a thermally-conductive member; FIG. 8B illustrates a number of alternative configurations for a base in a thermally-conductive member; FIG. 8C illustrates a number of alternative configurations for a retention member; FIG. 8D illustrates a thermally-conductive member having a projecting sealing ring; FIG. 8E shows some possible surface configurations for bases of thermally-conductive members; FIG. 8F shows a construction which includes a compliant washer;
FIGS. 9A through 9F illustrate some alternative constructions for thermally-conductive members;
FIG. 10A shows a few possible alternative configurations for a pin in a thermally-conductive member; FIG. 10B shows a few possible shapes for a pin in a thermally-conductive member; FIG. 10C shows a few possible configurations for retainers for thermally-conductive members of the types shown in FIGS. 10A and 10B;
FIGS. 11A through 11E illustrate extensions which may be attached to thermally-conductive members to provide enhanced thermal contact with a circulating fluid;
FIGS. 12A through 12C illustrate thermal conduction members according to other alternative embodiments of the invention;
FIG. 13 is a cross section through a pin passing through a membrane before the pin is deformed to seal to the membrane;
FIG. 13A is a top plan view of the pin of FIG. 13;
FIG. 14 is a cross section through the pin of FIG. 13 while the pin is being deformed and the membrane is being carried into a groove on the pin;
FIG. 15 is a cross section through the pin of FIG. 13 after the pin has been deformed to seal to the membrane;
FIG. 15A is an enlarged view of one of the grooves shown in FIG. 15;
FIGS. 16A, 16B, 16C, 16D, 16E and 16F are detailed views of alternative configurations for the edge of a membrane retention groove;
FIG. 17 illustrates a two-part through member according to an alternative embodiment of the invention;
FIGS. 18A, 18B and 15C are cross sectional views of three through members according to alternative embodiments of the invention;
FIGS. 19A, 19B and 19C demonstrate the use of a through member according to the invention to join together two or more thin flexible sheets;
FIGS. 20A, 20B, 20C, 20D and 20E show a through member according to an alternative embodiment of the invention; and, FIG. 21 shows a through member according to another alternative embodiment of the invention.
FIGS. 22, 22A and 22B illustrate heat exchangers having rear sheets affixed to thermally-conductive members;
FIGS. 23A and 23B illustrate embodiments of the invention in which inner and outer surfaces of a membrane have different characteristics;
FIGS. 24, 25, and 26 are schematic views of cooling systems according to the invention;
FIG. 27 shows a heat exchanger adapted for cooling or warming the neck of a subject;
FIGS. 28A, 28B and 28C show a heat exchanger like that of FIG. 27 in position on the neck of a subject;
FIGS. 29A, 29B and 29C illustrate a heat exchanger system comprising a heat exchanger configured to fit a subject's neck and another heat exchanger configured to fit the subject's face;
FIGS. 30A, 30B and 30C illustrate a heat exchanger system comprising a heat exchanger configured to fit a subject's neck, another heat exchanger configured to fit the subject's face and another heat exchanger configured to fit the subject's scalp;
FIG. 31 illustrates a heat exchanger system having heat exchangers for warming or cooling a patient's head, torso and thighs;
FIGS. 32A, 32B and 32C illustrate various heat exchangers and fluid flow paths of the heat exchanger system of FIG. 31;
FIGS. 33A, 33B, 33C and 33D are schematic views of heat exchangers according to embodiments of the invention being applied to cooling various objects;
FIGS. 33E and 33F show heat exchangers having thermally conductive members shaped to conform with a surface of an object to be cooled;
FIG. 33G shows thermally-conductive members having ends shaped in various ways;
FIG. 34 illustrates a heat exchanger according to an embodiment of the invention being used to cool a high-temperature object;
FIGS. 35A and 35B show heat exchangers according to alternative embodiments of the invention
FIG. 36A is a top plan view of a heat exchange pad according to an embodiment of the invention;
FIG. 36B is a bottom plan view of the heat exchange pad of FIG. 36A;
FIG. 37A is a longitudinal section through the heat exchange pad of FIG. 36A;
FIG. 37B is an enlarged portion of FIG. 37A;
FIG. 37C is an enlarged portion of FIG. 36A;
FIG. 37D is a transverse section through the heat exchange pad of FIG. 36A;
FIG. 37E is an enlarged portion of FIG. 37D;
FIG. 37F is an enlarged top plan view of a heat exchanger according to an alternative embodiment of the invention;
FIG. 37G is a top plan view of a heat exchange pad according to another alternative embodiment of the invention;
FIGS. 38A, 38B and 38C are respectively a side elevation view, an elevational cross section view, and a transverse cross section view through a heat exchange pad according to the invention wrapped around an outer surface of a cylindrical object;
FIGS. 39A, 39B and 39C are isometric views of three different thermal reservoirs having integrated heat exchangers;
FIGS. 39D, 39E and 39F are respectively a top plan view, a longitudinal elevational section, and a transverse elevational section of a thermal reservoir according to another embodiment of the invention;
FIGS. 39G and 39H are respectively a longitudinal elevational section, and a transverse elevational section of a thermal reservoir according to another embodiment of the invention;
FIG. 40A through 40E are schematic views illustrating cooling and heating systems according to various embodiments of the invention;
FIG. 41 is a schematic view illustrating a cooling system that uses a gaseous heat exchange fluid; and, FIGS. 42A, 42B and 42C are respectively a longitudinal section, a transverse section and an enlarged view of a portion of a transverse section of a heat exchange pad according to an alternative embodiment of the invention.

DESCRIPTION

Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practised without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense.
One aspect of this invention relates to pads useful for transferring heat between a body and a heat exchange fluid. Where the heat exchange fluid is warmer than the body, the pad facilitates heat flow from the heat exchange fluid into the body and the pad serves to warm the body. When the heat exchange fluid is cooler than the body then the pad facilitates heat flow from the body into the heat exchange fluid and the pad serves to cool the body.
The heat exchange fluid may comprise a liquid, of which water is an example, or a gas, of which air is an example. The heat exchange fluid is provided at a suitable temperature by a suitable temperature control system.
Some embodiments of this invention provide flexible heat exchangers suitable for use in warming or cooling living subjects. Heat exchangers according to the invention have a flexible heat exchange plate. A plurality of thermal channels pass through the flexible heat exchange plate. The flexible heat exchange plate has a plurality of thermally-conductive members projecting through a flexible medium that is essentially fluid-impermeable. The thermally-conductive members provide effective means to accept heat from a higher-temperature side of the medium, channel the heat through the medium, and release the heat on a lower-temperature side of the medium.
An outer side of the flexible heat exchange plate can be brought into contact with a living subject. The thermally-conductive members contact the skin of the subject. In preferred embodiments, an inner side of the flexible heat exchange plate forms one side of a channel which carries a heat exchange fluid. Heat can be exchanged between the heat exchange fluid and the subject's skin at a high rate by way of the thermally-conductive members which extend directly from the subject's skin into the heat exchange fluid.
The thermally-conductive members may be made of any suitable thermally-conductive materials including thermally-conductive metals, for example, aluminum, copper, gold, silver, or alloys of these metals with one another and with other metals. The thermally-conductive members may also be made of non-metals which have high thermal conductivities such as carbon, suitable grades of graphite, diamond, sapphire or the like. Preferably the thermally-conductive members are made from materials having thermal conductivities, k, of at least 50 Wm⁻¹K⁻¹and preferably at least 100 Wm⁻¹K⁻¹. All other factors being equal, it is desirable that the material from which the thermally-conductive members is made be relatively low in density to reduce the weight of heat exchangers according to the invention. Where a heat exchanger is made in a way that involves deforming the thermally-conductive members, the material of the thermally-conductive members is chosen to be malleable. For many applications, aluminum is a good choice for the material of thermally-conductive members. For many embodiments, soft 1300 series aluminum is a good choice of material for the thermally-conductive members.
The thermally-conductive members are sized and located to permit the thermally-conductive plate to be flexed sufficiently to conform substantially to a part of a body of a living subject. The thermally-conductive members are dimensioned and distributed in a manner so that the thermally-conductive members cover a large proportion of the area of the outer side of the flexible heat exchange plate. In certain embodiments of the invention a plurality of the thermally-conductive members cover more than 30% of an area of the outer side of the flexible heat exchange plate. In some embodiments 50% or more of an area of the outer side of the flexible heat exchange plate is covered by the thermally-conductive members.
In preferred embodiments of the invention a plurality of the thermally-conductive members have thermally-conductive pins, fins, bars or the like that project into the volume of a heat exchanger to form an efficient heat exchange interface with heat exchange fluid in the volume. The projecting pins, fins, bars, plates or the like that form a heat exchange interface with the fluid inside the volume of a heat exchanger may or may not be similar in shape or other physical characteristics to the pins, fins, bars, plates or the like that extend through the flexible medium to form a thermal channel through the medium.
The following example embodiments of the invention will be described in the context of cooling a living subject. Embodiments of the invention could also be applied to warming a subject. As noted below, embodiments of the invention could also be applied to heating or cooling objects in other fields.
FIGS. 1A through 1C show a heat exchanger 10 according to an embodiment of the invention. Heat exchanger 10 has a flexible heat exchange plate 12 penetrated by a number of thermally-conductive members 14. Plate 12 has an outer face 16 and an inner face 18. Heat exchanger 10 has an inside volume 20 and ports 22, 23 by way of which a heat exchange fluid can flow through volume 20. Volume 20 is defined on a front side by plate 12 and on a rear side by a rear wall 24. Side walls 25 extend between plate 12 and rear wall 24. Plate 12, rear wall 24 and side walls 25 are all flexible so that the outer surface 16 of heat exchanger 10 can conform to the local contours of a portion of a subject's body to be cooled or heated.
Thermally-conductive members 14 pass through the material 30 of plate 12. Inside ends 26 of thermally-conductive members 14 project into volume 20. Ends 26 preferably project significantly into volume 20. In the illustrated embodiment, ends 26 are cut away to provide increased surface area for heat transfer with fluid in volume 20. Each inner end 26 comprises a number of prongs 27. Outer faces 28 of thermally-conductive members can be placed against the skin of a subject. Outer faces 28 may be outer faces of thermally-conductive bodies (which may be called “bases”) 29. Bases 29 are separated sufficiently to permit heat exchanger 10 to flex in a desired degree but are preferably closely spaced to maximize the area of outer faces 28 that can be placed against a desired region on a subject. For example, in some embodiments, bases 29 are spaced apart from one another by spacings in the range of 0.5 mm to 5.0 mm.
In some embodiments, each base 29 has a thickness in the range of 0.5 mm to 5 mm. For example, in some embodiments base 29 has a thickness in the range of 1 mm to 2.5 mm. The size and dimensions of base 29 in the plane of plate 12 may be chosen to suit the application, and particularly depends on the contour of the object to be cooled or heated. Thermally-conductive members 14 according to some embodiments of the invention for use in cooling/warming pads for human subjects, have bases 29 having areas in the range of 1 mm²to 400 mm². For such cooling/heating pads the area is preferably in the range of 10 mm²to 100 mm².
Thermally-conductive members 14 may have reduced cross sectional areas in their portions inward from bases 29. The cross-sectional area of thermally-conductive members 14 at the point that thermally-conductive members 14 emerge from material 30 on the inside face of plate 12 may, for example, be in the range of 20% to 100%, and preferably 35% to 65%, of the area of base 29.
Plate 12 comprises a flexible sheet or membrane through which thermally-conductive members 14 project. The membrane may be made of a flexible material or materials 30. Thermally-conductive members 14 have lengths sufficient to pass through material 30. In preferred embodiments, members 14 project into volume 20. Thermally-conductive members 14 may, for example, project into volume 20 for a distance in the range of 0 mm to 20 mm. In some embodiments intended for warming or cooling a living subject, thermally-conductive members 14 project into volume 20 for a distance in the range of 2 mm to 10 mm. In some embodiments members 14 project past material 30 by at least 3 mm. The portions of members 14 which project into volume 20 may also function as supports to maintain a minimum spacing between rear wall 24 and plate 12.
It is not necessary that all thermally-conductive members 14 be identical or that all thermally-conductive members 14 have equal-sized bases 29 although it is convenient to make heat exchanger 10 with thermally-conductive members 14 substantially the same as one another.
Material 30 constitutes a flexible membrane through which thermally-conductive members 14 extend. In some embodiments, rear wall 24 is made of material 30. Substantially all of heat exchanger 10, except for thermally-conductive members 14, may be made of the same material or materials 30. Material 30 is preferably flexible and/or elastically stretchable. Material 30 may, for example, comprise any of a variety of suitable flexible polymers such as natural rubber, polyurethane, polypropylene, polyethylene, ethylene-vinyl acetate, polyvinyl chloride, silicone, a combination of these materials, a coated fabric, or the like. Material 30, or portions of material 30 may optionally be loaded with particles of one or more thermally-conductive materials such as metal or graphite. However, since material 30 is not required to play a significant role in conducting heat, material 30 may be a material having a low thermal conductivity not exceeding 5 Wm⁻¹K⁻¹without significantly impairing the function of heat exchanger 10. In some embodiments, material 30 has a hardness in the range of 10 to 80 on the Shore A hardness scale.
One specific example embodiment of the invention is constructed as shown in FIGS. 1A to 1C and is designed to be applied to the neck of a human subject to cool the subject's brain. This embodiment of heat exchanger 10 has approximately 50 thermally-conductive members 14 arranged in a rectangular array. Each member 14 has nine pins which project into volume 20. Bases 29 have areas of about 10 mm×10 mm and thicknesses of about 2 mm. Each of the pins has a diameter of about 1.8 mm. The total length of each of the pins is about 10 mm. The thickness of material 30 in the walls of heat exchanger 10 is about 4 mm. Two short tubes of approximately 10 mm inner diameter provide inlet and outlet ports 22 and 23. A heat exchange fluid 65 such as cold water may be circulated through volume 20.
Two such heat exchangers may be dimensioned so that they can be applied to a subject's neck respectively over the left and right carotid arteries to cool the subject's brain by cooling blood flowing to the subject's brain. The heat exchangers are sufficiently flexible to conform substantially to the curvature of the subject's neck without causing unacceptable pressure spots. The heat exchangers may be held in place under a collar, such as a foam collar.
Plate 12 may be fabricated using any suitable process. For example, plate 12 may be made by making holes in a sheet of material 30 and inserting thermally-conductive members 14 through the holes. The holes may initially have dimensions smaller than corresponding dimensions of thermally-conductive members 14 so that material 30 seals around thermally-conductive members 14 sufficiently to prevent any significant loss of heat exchange fluid from volume 20. Additionally, or in the alternative, a sealant, such as a suitable glue may be provided to enhance the seal between thermally-conductive members 14 and material 30. Plate 12 may also be made by a suitable plastic manufacturing process such as thermal injection molding, reaction injection molding, compression molding, vacuum forming or casting. In this case, thermally-conductive members 14 may be molded into plate 12.
The thickness of material 30 in plate 12 can be selected to provide a desired compromise between flexibility and durability. Since heat exchanger 10 does not rely on material 30 to conduct heat, it is not necessary to make material 30 extremely thin to improve heat conduction. Material 30 may, for example, have a thickness in the range of about 0.1 mm to 20 mm. In some embodiments of the invention, material 30 has a thickness in the range of 4 mm to 7 mm in plate 12. When thermally-conductive members of types which grip material 30 from either side (as shown for example in FIG. 4I to FIG. 4L or 7A to 7P) are used, the thickness of material 30 may be smaller, for example, as little as about 1 mm in plate 12.
Projections of material 30 or some other material may optionally extend into volume 20. Such projections may be positioned to support wall 24 relative to plate 12, to direct the flow of fluid 65 within volume 20 and/or to induce turbulence at selected locations in the flow of fluid 65 in order to provide enhanced thermal contact between thermally-conductive members 14 and fluid 65.
Thermally-conductive members 14 may be arranged in a wide range of patterns. For example, as shown in FIGS. 1A to 1C and 3A to 3C, members 14 may be arranged in a number of rows and columns to form a rectangular array, which could be a square array. In some embodiments, members 14 are arranged in rows or columns which are shifted relative to one another as shown in FIGS. 2B and 2C. This arrangement creates increased turbulence in fluid 65 flowing through volume 20 and hence increases the efficiency of heat transfer between the inside ends of thermally-conductive members 14 and fluid 65. In some embodiments, bases 29 of members 14 are arranged in a rectangular array as illustrated, for example, in FIG. 1, while portions of members 14 which project into volume 20 are arranged in rows or columns which are shifted relative to one another as shown in FIGS. 2B and 2C. In some embodiments, members 14 are arranged in a triangular array, as shown in FIG. 2D.
Flexing of plate 12 may be facilitated by arranging members 14 to provide substantially unbroken lines 31 of material 30 extending generally parallel to one or more axes about which a user may wish to flex heat exchanger 10. The embodiment shown in FIG. 1B shows two sets of lines 31 of material 30 which extend between adjacent rows and columns of members 14. The embodiment illustrated in FIG. 2B has one set of parallel lines 31. Lines 31 are not necessarily parallel to one another. For example, FIG. 2E illustrates an arrangement of members 14 which facilitates flexing in such a way as to conform to a portion of the surface of a cone. The array of members 14 is not necessarily aligned with any axis of heat exchanger 10. For example, FIG. 2F shows the outside face of a heat exchanger wherein thermally-conductive members 14 are arranged in a rectangular array oriented at an angle, φ, to a long axis of the heat exchanger.
FIGS. 1A to 1C and 2A to 2F illustrate heat exchangers in which faces 28 are substantially flush with material 30 on outer face 16. This arrangement facilitates cleaning, as outer face 16 is substantially smooth. FIGS. 3A to 3C illustrate an alternative embodiment of the invention wherein base 29 is not embedded in material 30. In this embodiment faces 28 are spaced outwardly from material 30. The embodiments illustrated in these Figures can be fabricated, for example, by inserting thermally-conductive members 14 though holes formed in a sheet of material 30.
Thermally-conductive members 14 may take any of a wide variety of forms which provide the function of carrying heat in either direction between a subject on one side of the flexible plate and a heat exchange fluid 65 or other matter on an opposed side as the flexible plate that is warmer or cooler than the subject. Ideally, members 14 provide:

- good thermal interfaces between the thermally-conductive members and the subject to be cooled or warmed;
- good thermal channels across flexible material 30; and
- good thermal interfaces between the thermally-conductive members and the fluid in volume 20 of the thermal exchanger.
  Some possible forms for members 14 are illustrated in FIGS. 4A through 4L. It is understood that these are possible forms and are included only as examples. Modifications to these examples can be made to obtain a much larger list of examples. In addition, features illustrated in these examples can be exchanged or combined partially or fully to obtain an even larger list of examples.

FIG. 4A shows a thermally-conductive member 14A having a square base 29 and cylindrical pin 32. Pin 32 can carry heat through material 30 and constitutes a means for channelling heat through flexible material 30 and releasing heat into (or taking heat from) fluid in volume 20 of a heat exchanger. FIG. 4B shows a thermally-conductive member 14B having a circular base 29 instead of a square base. It is generally preferable that the thermally-conductive surfaces that contact a subject's skin be rounded and not have sharp corners.
FIG. 4C shows a thermally-conductive member 14C wherein both base 29 and the pin 32 are square in cross-section (like the thermally-conductive members of FIGS. 2A to 2C). FIG. 4D shows a thermally-conductive member 14D similar to member 14A except that pin 32 has a circumferential groove 33 in its part close to base 29. Groove 33 receives extra material 30 in an injection molding or casting process to better seal member 14D to material 30. FIG. 4E shows a thermally-conductive member 14E wherein a tip of pin 32 is tapered to facilitate insertion into a hole in a sheet of material 30.
FIG. 4F shows a thermally-conductive member 14F having a pair of platelike rectangular conductors 34 which serve both as thermal channels through material 30 and as structures for releasing heat into (or taking heat from) volume 20. Conductors 34 may be arranged in a V-shape to better transfer heat to fluid flowing past plates 34. Plate-like conductors could also be arranged in other manners such as being parallel with each other. Thermally-conductive member 14F has the advantage in manufacturing that it can be made by cutting and folding thermally-conductive sheet material.
FIG. 4G shows a thermally-conductive element 14G having a thermal channel portion provided by a tubular pin 36. FIG. 4H shows a thermally-conductive member 14H having multiple pins 38 extending from base 29. Pins 38 provide multiple thermal channels extending from the same base 29 and projecting into the volume 30. Conductive member 14H advantageously provides increased contact area between conductive member 14H and a heat transfer fluid 65 in volume 20. FIGS. 41 and 4J show a thermally-conductive member 14I that is designed to reduce the possibility of fluid leaking between material 30 and member 14I. Member 14I may be fabricated in two-pieces 14I-1 and 14I-2 that can be assembled together in a manner that provides good thermal contact between pieces 14I-1 and 14I-2.
In the illustrated embodiment, one of the pieces of member 14I has a pin 39 which is received in a corresponding socket 40 (see FIG. 4J) in the other piece. Pin 39 may have an interference fit in socket 40 to keep the two pieces tightly together and to provide good heat transfer between the pieces. A circumferentially extending groove 41 is defined between pieces 14I-1 and 14I-2. Groove 41 receives material 30. The faces of pieces 14I-1 and 14I-2 which contact material 30 may be undercut to provide ridges 42 which help to prevent fluid from leaking past member 14I. The pieces of multi-piece thermally-conductive members may be fastened together in other ways which provide thermal contact between the pieces. For example, fastening means such as screws, rivets, or the like may be provided. FIGS. 4K and 4L show a thermally-conductive member 14K that is similar to member 14I but is an integral part. Member 14K is designed to be cramped onto material 30. Material 30 projects into a groove 43. The sides of the groove 43 may be cramped together to hold material 30 around the edges of member 14K as shown in FIG. 4L.
FIGS. 5A and 5B show a flexible fluid heat exchanger 50 which is normally curved in the absence of applied forces. Heat exchanger 50 may be used to apply heat to or to cool a substantially cylindrical object such as a subject's limb. Apart from being curved, heat exchanger 50 is similar to heat exchanger 10 of FIGS. 1A through 1C.
FIGS. 6 through 14B illustrate various embodiments of heat exchanger according to the invention in which thermally-conductive members extend through apertures in a fluid impermeable membrane and are held in place by retention members. FIG. 6 shows a heat exchanger 110 having a volume 120 defined within a membrane 130. Membrane 130 comprises a layer of a suitable flexible fluid-impermeable material. Membrane 130 has a thickness adequate to provide a desired strength. Membrane 130 may be thin. For example, in some embodiments, membrane 130 has a thickness of 0.010 inches or less.
Membrane 130 may comprise, for example, a suitable grade of polyurethane or other suitable thermoplastic polymer. Examples of other materials that may be suitable for use as membrane 130 include: styrenic copolymers; suitable grades of: polyvinyl chloride (PVC); polyolefins such as polyethylene or polypropylene; styrenics such as polystyrene; polyesters such as polyethylene terephthalate (PET); polyethers such as polyetheretherketone (PEEK); polyamides (e.g. NYLON™); silicone; cellophane; cellulose acetates; natural or synthetic rubbers; ethylene-vinyl acetate; neoprene; polytetrafluoroethylene (PTFE e.g. TEFLON™); plasticized metallic films; combinations of two or more of these materials; coated or impregnated fabrics; and the like.
Thermally-conductive members 114 penetrate membrane 130. Each thermally-conductive member 114 has a pad (which may also be called a base) 129 on an outer side of membrane 130 and a pin portion 132 which projects into volume 120 and is in thermal contact with a fluid 65 in volume 120. Base 129 may be a body formed in or attached to thermally-conductive member 114. Thermally-conductive members 114 are held in place by retention members 115.
As shown in FIGS. 6A, 6B and 6C, membrane 130 may be affixed to itself, for example by adhesive bonding or by welding at seams 117, to form channels 119. In the embodiment illustrated in FIGS. 6 through 6C, front and rear sheets 130A and 130B of membrane 130 of heat exchanger 110 are joined together in a pattern which provides a single sinuous channel 119 which extends between ports 122 and 123. Ports 122 and 123 are attached to membrane 130 with a suitable fluid-impermeable attachment means such as welding, suitable adhesive, stitching, taping, or the like. Front and rear sheets 130A and 130B are not necessarily equal in thickness. In some embodiments, front sheet 130A is thicker than rear sheet 130B.
In a currently preferred embodiment of the invention, rear sheet 130B is vacuum formed, or otherwise shaped, to provide a dimple corresponding to each of the thermally-conductive members (e.g. 114). Thermally-conductive members 114 project into the corresponding dimples. This can yield a structure which remains highly flexible and resistant to “ballooning” as heat exchange fluid 65 is pumped through it. With this construction the volume surrounding thermally conductive members 114 can be made small, thereby reducing the weight of the fluid-filled heat exchanger. Front and rear sheets 130A and 130B may be affixed together at locations which define one or channels which each have a single row of thermally-conductive members extending along the channels. The locations at which front and rear sheets 130A and 130B are affixed together may be just far enough apart to be on either side of the thermally-conductive members 114. The channels may be straight, serpentine, U-shaped, or follow alternative paths as convenient for the application at hand. One can appreciate that as one moves along the centerline of one of the channels the rear sheet 130B bumps away from the front sheet 130A in each dimpled portion and is close to, even touching or almost touching front sheet 130A in its portions between thermally-conductive members 114.
In some embodiments of the invention, the heat exchanger has “drape”. This means that when the heat exchanger is placed over a horizontal member, such as a thin horizontal dowel or a pencil, the overhanging parts of the heat exchanger hang down substantially vertically from the horizontal member. A heat exchanger which has drape can conform readily to the surface contours of a person or object against which it is brought.
FIGS. 6D and 6E illustrate a heat exchanger in which the pattern of seams 117 provides a U-shaped channel 119. By comparing FIGS. 6A through 6C to FIGS. 6D and 6E it can be seen that the width of channel 119 may be varied. In some embodiments channel 119 is narrow and accommodates only a single row of thermally-conductive members 114. In other embodiments, channel 119 is wider and can accommodate several thermally-conductive members 114 side-by-side. As described above, there are many variations in the placement of thermally-conductive members 114. FIG. 6F shows another heat exchanger in which a pattern of seams 117 provides two separate paths through the heat exchanger. Each path has ports which provide an inlet and outlet for the path.
FIGS. 7A and 7B illustrate a thermally-conductive member 114A. As shown in FIG. 7A, thermally-conductive member 114A has a shoulder 121 which projects through membrane 130 and through an aperture 115A in retention member 115. As shown in FIG. 7B, shoulder 121 is deformed, for example by pressing, to firmly engage retention member 115 and to compress membrane 130 between retention member 115 and base 129. In some embodiments, shoulder 121 initially projects past retention member 115 just far enough that it provides a good seal when pressed flush with retention member 115. Aperture 115A may have various profiles, for example, it may be tapered, as shown in FIGS. 7A and 7B or straight-sided, as shown in FIGS. 7A-1, 7B-1, 7A-2 and 7B-2.
FIGS. 7C and 7D show a thermally-conductive member 114B. Pin 132 of thermally-conductive member 114B has a sharp end 132A and a cross sectional profile which matches the cross sectional profile of retention member 115B. Thermally-conductive member 114B does not require a pre-existing aperture in membrane 130. Pin 132 and retention member 115B cooperate as a punch and die. As pin 132 is pressed into the aperture in retention member 115B through membrane 130, the end of pin 132 punches an aperture in membrane 130 which matches the cross sectional shape of pin 132. Pin 132 is a friction fit in the aperture of retention member 115B.
FIGS. 7E and 7F illustrate an alternative thermally-conductive member 114C wherein pin 132 is threaded and the retention member comprises a washer 115C which is compressed against membrane 130 by a nut 115D.
FIGS. 7G and 7H illustrate an alternative thermally-conductive member 114D which is adhered to membrane 130 by a suitable adhesive. Thermally-conductive member 114D may be used with or without a retention member as shown in FIGS. 7G and 7H or with a retention member as shown in FIGS. 7I and 7J. In some embodiments, a retention member 115 is secured to membrane 130 with a suitable adhesive.
FIGS. 7K, 7L, 7K-1, 7L-1, 7K-2 and 7L-2 illustrate alternative constructions wherein pin 132 of a thermally-conductive member 114E is deformed and shaped into a head 132B which bears against membrane 130. A washer may be provided between head 132B and membrane 130. This configuration is the basis for a currently preferred embodiment of the invention.
In other embodiments of the invention (not shown), a part of thermally-conductive member 114 projects from an enlarged body in volume 120 through an aperture in membrane 130. The projecting part of thermally-conductive member 114 is subsequently deformed, for example by pressing, to form an enlarged base on the outside of membrane 130. The membrane is held between the body in volume 120 and the enlarged base.
FIGS. 7M and 7N illustrate a construction in which a thermally-conductive member 114F is held against membrane 130 by a spring clip 115-2.
FIGS. 7O and 7P illustrate a construction wherein a retaining member 115 is deformed, for example by pressing, to seal against pin 132 and membrane 130.
Many variations in the design of a thermally-conductive member 114 and retention member 115 are possible within the scope of the invention. Thermally-conductive member 114 and retention member 115 may be made of the same material. If they are made from different materials then it is desirable that the coefficients of thermal expansion of the materials of thermally-conductive member 114 and retention member 115 be such that retention member 115 does not tend to loosen as a heat exchanger is used. For example, where a heat exchanger is to be used for cooling applications it is desirable that retention member 115 have a coefficient of thermal expansion that is the same as or greater than that of pin 132.
FIG. 8A shows a few possible forms for pin 132. Pin 132 may have any of a wide range of cross-sectional shapes. FIG. 8B shows a few possible shapes for base 129. FIG. 8C shows a few possible configurations for retention member 115. Retention members 115-1 and 115-2 are spring clips, sometimes known as push retainers. Retention members 115-1 and 115-2 have inner edge portions 118 which tightly engage pin 132. The retention member used to retain a thermally-conductive member 114 typically has an outer profile which matches that of the base 129 of the thermally-conductive member 114 although this is not necessary. In some embodiments of the invention a compliant member, such as an 0-ring or compliant washer is provided between retention member 115 and membrane 130, between base 129 and membrane 130, or both. FIG. 8F shows a construction which includes a compliant washer.
In some embodiments of the invention, retention member 115, base 129, or both have one or more narrow projecting rings 131 or grooves (FIG. 8D) to provide an enhanced seal with membrane 130. FIG. 8E shows some possible surface configurations for bases 129. Bases 129 may be roughened or profiled to provide increased surface area and consequentially improved thermal conductivity between bases 129 and an adjacent compliant surface, such as the surface of a subject's skin.
FIGS. 9A through 9F show some alternative embodiments of the invention in which thermally-conductive members have an enlarged portion within volume 120 and are held to membrane 130 by a retainer located on the outer side of membrane 130. FIGS. 9A and 9B show a thermally-conductive member 114G which comprises a pin 132 which projects into volume 120 from an enlarged portion 133. A pin 135 extends from enlarged portion 133 through membrane 130. Pins 132, 135 and enlarged portion 133 are conveniently integral with one another. A retainer 137 engages pin 135 to hold thermally-conductive member 114G in place and sealed to membrane 130. Pin 132 may project through retainer 137, as shown in FIGS. 9A and 9B. In some embodiments retainer 137 covers the end of pin 132.
FIGS. 9C and 9D illustrate another thermally-conductive member 114H in which pin 135 is threaded and retainer 137 is in the form of a nut that screws onto pin 135. In the illustrated embodiment, the portion of retainer 137 that contacts membrane 130 is smaller than the body-contacting end of retainer 137. This enhances the flexibility of the heat exchanger.
FIGS. 9E and 9F show another thermally-conductive member 114I wherein retainer 137 is a press fit onto pin 135.
Many variations are possible in the embodiments of the invention illustrated in FIGS. 9A through 9F. Pins 132 and 135 may have the same cross sectional shape, as shown in FIGS. 9E and 9F or may have different cross sectional shapes, as shown in FIGS. 9A and 9B.
FIGS. 10A through 10C show thermally-conductive members that may be used in embodiments like those of FIGS. 9A through 9F. FIG. 10A shows a few possible forms for pin 135. In the embodiments of FIG. 10A, enlarged portion and pin 132 have the same diameter. Pin 132 may have any of a wide range of cross-sectional shapes. FIG. 10B shows a few possible shapes for pin 132 in thermally-conductive members which also have a pin 135. FIG. 10C shows a few possible configurations for retainers 137.
Some embodiments of the invention provide an extension on one or more of pins 132 which provides additional surface area for thermal contact with fluid 65. The extension may be in the form of a cap affixed to the end of pin 132. Various forms of extension are shown in FIGS. 11A through 11E. FIG. 11A shows an extension 141A shaped generally like a mushroom cap. FIG. 11B shows an extension 141B in the form of a cylinder. FIG. 11C shows an extension 141C shaped generally like a football in side elevation and star-shaped in cross section. FIG. 11D shows a fin-shaped extension 141D. FIG. 11E shows a tear-drop-shaped extension 141A. The extensions may be made of the same class of materials as pins 132 and are in good thermal contact with pins 132. In some embodiments, extensions are formed integrally with pins 132.
FIGS. 12A through 12C illustrate some further alternative embodiments of the invention. As shown in FIG. 12A, a single base 129 may have multiple pins 132 which extend through membrane 130 and are held in place by a single retainer member 115-3. As shown in FIG. 12B, multiple thermally-conductive members 114 may be held in place by a single retainer member 115-4. As shown in FIG. 12C, a single base 129 having multiple pins 132 passing through membrane 130 may be held in place by multiple retainer members 115-5.
FIGS. 13 to 21 show members adapted to be sealed to a membrane or other flexible material and methods for installing such members. A number of the embodiments of FIGS. 13 to 21 are suitable for use as thermally-conductive members in heat exchangers according to the invention. FIG. 13 shows a pin 210 passing through an aperture 212 in a membrane 214. Pin 210 has a head 220 on a first side 214A of membrane 214. Pin 210 has a shaft 222 which extends through aperture 212 and projects on a second side 214B of membrane 214. A groove 224 in head 220 extends around the base of shaft 222. Groove 224 is wide enough to receive an edge portion 214C of membrane 214.
As shown in FIG. 14, shaft 222 can be deformed, for example, by compressing shaft 222 toward head 220 with a press 228. As the deformation occurs, the material on the outside of shaft 222 in its lower portion 222A near head 222 tends to move outwardly and downwardly as indicated by arrows 230.
Edge portion 214C of membrane 214 fits closely to shaft 222. The deformation of lower portion 222A of shaft 222 carries edge portion 214C of membrane 214 into groove 224. Continued deformation of shaft 222 moves edge portion 214C deeper into groove 224. Eventually the continued deformation of shaft 222 moves inner wall 224A of groove 224 toward outer wall 224B of groove 224 so that edge portion 214C of membrane 214 becomes gripped between inner wall 224A and at least a portion of outer wall 224B as shown in FIG. 15. Typically membrane 214 is gripped first between inner wall 224A and corner 224C at which outer wall 224B meets surface 220A of head 220 which surrounds groove 224.
It is thought that providing a smooth or even polished surface on the portion of shaft 222 contacted by the edge of a sheet 214 during deformation of shaft 222 will help the edge of sheet 214 to slide down shaft 222 into groove 224. It is also thought that the edges of sheet 214 will be drawn most effectively into groove 224 if the edges of sheet 214 is at least somewhat elastic.
In some embodiments of the invention, membrane 214 is impervious to fluids and pin 210 makes a fluid-tight seal to membrane 214. Membrane may be of any suitable flexible material. In some embodiments of the invention, membrane 214 comprises an elastic material, such as urethane. Membrane 214 could comprise any of a variety of suitable flexible sheet like materials. Some examples are polymers such as natural rubber, polyurethane, polypropylene, polyethylene, ethylene-vinyl acetate, polyvinyl chloride, silicone, a combination of these materials, fabrics, or the like.
Pin 222 may be of any suitable material which is sufficiently ductile to be plastically deformed by pressing, as described above. Where pin 222 is to operate as a thermally-conductive member in a heat exchanger then the material of pin 222 should be highly thermally-conductive. For example, pin 222 may be made of aluminum, copper, or another plastically deformable metal having good thermal conductivity. Other metals or materials commonly used to make blind or solid rivets could be used. Some examples of such metals include suitable steels, stainless steels; brasses; bronzes; monel (a nickel-copper alloy); and inconel (a nickel-chromium alloy). Some successful prototypes have used 1100 series aluminum having a hardness of about 32 on the Brinell hardness scale for shaft 222. The other materials listed above typically have hardnesses in the range of about 20 and about 200 on the Brinell hardness scale. In applications in which pin 222 is not required to conduct heat, deformable plastics such as suitable grades of polyurethane, polyethylene, polypropylene, PVC or poly carbonate could also be used for shaft 222.
As shown in FIGS. 16A to 16F, the profile of groove 224 may be varied. It may be desirable to provide a relieved corner or “lip” 224C where outer wall 224B of groove 224 intersects surface 220A of head 220. In some embodiments of the invention the main seal between pin 210 and membrane 214 occurs at the nip 232 (FIG. 15) between corner 224C and the deformed shaft 222. Providing a relieved corner 224C provides increased surface area in the seal and also facilitates membrane 214 being moved into groove 224.
FIG. 16A shows a groove 224 having a sharp outside corner 214C. FIG. 16B shows a groove 224 having a bevelled outside corner 214C-1. FIG. 16C shows a groove 224 having a rounded outside corner 224C-2. FIG. 16D shows a groove 224 wherein outside corner 224C-3 is elevated above the surrounding surface of face 220A of head 220. FIG. 16F shows a groove 224 having an outer wall 224B which is inclined away from shaft 222.
It is convenient, although not mandatory, to make head 220 and shaft 222 integral with one another. Head 220, including the outer wall 224B of groove 224 does not need to be deformable as does shaft 222. In some embodiments, shaft 222 and head 220 could comprise separate parts which are suitably affixed to one another. An example of such a construction is depicted in FIG. 17.
FIG. 17 shows a through-member 240 having a first part 242 which includes a plastically deformable shaft 243 having an enlarged head 244 at one end. A second part 245 has an aperture 246. Shaft 243 projects through aperture 246. A groove 248 is defined between shaft 243 and a wall 249 of a counterbored part 246A of aperture 246. Second part 245 may be made of a harder material than first part 242.
FIG. 18A illustrates a through member 260 according to an alternative embodiment of the invention in which shaft 262 is tubular. FIG. 18B illustrates a through member 264 according to another alternative embodiment of the invention in which shaft 266 is semi-tubular. A tubular or semi-tubular shaft can be deformed with the application of less force than would be required to deform a solid shaft made out of the same material.
A through member may be configured as a blind rivet. FIG. 18C shows a through member 270 configured as one type of blind rivet. Through member 270 has an actuating stud 272 passing through a hollow shaft 274. Actuating stud 272 has an enlarged head 276 and a weakened portion 278. Through member 270 can be installed by pulling on the projecting shank 279 of actuating stud 272. This causes head 276 to compress shaft 274 and to deform shaft 274 outwardly. As shaft 274 is deformed, a membrane 214 is drawn into and becomes affixed within a groove 224 as described above. Eventually enough tension can be applied to shank 279 to cause actuating stud 272 to break off at weakened portion 278. In typical embodiments, shaft 274 is a soft deformable material such as aluminum or a suitable grade of stainless steel while stud 272 is of a harder material such as steel.
The invention could also be embodied in blind rivets of other types which have a shaft which in deforms outwardly when the blind rivet installed in a manner such that a membrane 214 or other material through which the blind rivet passes is moved into and retained in a groove by the deformation of the shaft.
A through member according to the invention may be used to join together two or more sheets of material. FIGS. 19A, 19B and 19C, show the application of a through member 280 to join together two or more sheets of material. Through member 280 may be constructed and used as described above. Through member 280 is similar to the through member 210 of FIG. 13 except that groove 224 has been made wider. In this embodiment, groove 224 is wide enough to receive edges 214-1C and 214-2C of each of the sheets 214-1 and 214-2 of material being joined together. Even where the sheets of material are flexible it is not necessary to provide a washer or other separate fastening component on the side of the material sheets away from head 220. Through members according to other embodiments of the invention described herein, including the blind rivet embodiments, could also be used to attach multiple sheets of material together.
FIGS. 20A through 20E depict stages in the installation of a though member 290 according to an alternative embodiment of the invention. Through member 290 has a square shaft 291 extending from a head 292. An aperture 293 extends through shaft 291. A groove 294 extends around the base of shaft 291. Shaft 291 passes through an aperture in a sheet 214 of a flexible material.
As shown in FIG. 20C, deformation of shaft 291 causes the outward faces of shaft 291 to be tapering toward groove 294. This urges the edges of sheet 214 into groove 294. Continued deformation of shaft 291 results in the edges of sheet 214 being captured in groove 294 between the outer face of shaft 291 and the outside corner (or “lip”) of groove 294.
Another aspect of the invention provides a method for securing a through member in a membrane. The method begins with providing a through member having a head, a shaft extending from the head and a groove surrounding the shaft. The shaft is inserted through an aperture in a membrane to which the through member is to be secured. The method continues by compressing the shaft of the through member longitudinally and thereby deforming the shaft such that an initial deformation of the shaft moves an edge portion of the membrane into the groove of the through member. The method continues by continuing to compress the shaft longitudinally until the shaft deforms sufficiently to cause the edge portion of the membrane to be gripped between an outer surface of the deformed shaft and an outer wall of the groove.
This method may be used to secure a one-piece through member securely, and in some embodiments sealingly, to a membrane or to multiple membranes or other sheet-like materials in a single operation. It is not necessary to assemble multiple pieces to provide the through member or to perform multiple operations (although the invention could be applied to through members assembled from more than one part or to methods involving additional steps). The through member may be introduced from one side of the membrane (or other sheet like material(s)) to which the through member is being affixed. It is not necessary to introduce different parts of the through member from different sides of the membrane.
Head 220 may carry or be attached to some structure which is to be attached to membrane 214. For example, head 220 may carry a snap and membrane 214 may comprise a cover for something, an article of clothing, or the like. A through member according to the invention may be apertured. A valve, stopper or orifice for allowing air, another gas or a liquid to flow through the aperture may be provided in the aperture. A through member may have a threaded aperture capable of receiving a screw or may have a projecting stud. A through member could carry alternative structures such as electrical connectors. In some embodiments of the invention the through member is electrically conductive or has one or more electrical conductors which join electrical connectors on opposing sides of membrane 214.
Various alterations and modifications are possible in the construction and installation of through-members as illustrated in FIGS. 13 to 20 without departing from the invention. For example:

- shaft 222 is not necessarily circular, as illustrated, but could have another cross sectional shape, such as slightly elliptical or square.
- where a shaft has an aperture passing all or part way through it, as shown in FIGS. 20A through 20E, for example, then the installation method may include pressing outwardly from within the aperture. for example, the method may include pressing a tapered pin into the aperture.
- the outer surface of shaft 222 is not necessarily perpendicular to the head. For example, FIG. 21 illustrates an embodiment wherein a lower portion 299 of a shaft 222 is tapered toward groove 224. In this embodiment, the thickness of shaft 222 increases in the direction away from head 222. However, if membrane 214 is elastic then membrane 214 can be pulled over shaft 222 and still contact portion 299 closely enough to be urged into groove 224 as shaft 222 is deformed.
- A through member according to the invention may be attached to sheet like materials of a wide range of types including fabrics, membranes, leather, thin metal sheets (e.g. metal foils, shim stock), plastic sheets, rubberized sheets and the like.

As shown in FIG. 22, rear sheet 130B of membrane 130 may be affixed to some or all of thermally-conductive members 114. This helps to prevent “ballooning” of the heat exchanger, especially where volume 120 is large. Any suitable means may be provided to affix rear sheet 130B to thermally-conductive members 114. For example:

- rear sheet 130B may be glued to thermally-conductive members 114 using a suitable adhesive;
- a piece of material to which rear sheet 130B may be welded may be affixed in any suitable manner at the inner ends of thermally-conductive members 114 and rear sheet 130B may be welded to that piece of material; or
- rear sheet 130B may be mechanically attached to thermally-conductive members 114, for example: a screw, part of the thermally-conductive member 114 or the like may pass through an aperture in rear sheet 130B to hold rear sheet 130B against thermally-conductive member 114; a portion of rear sheet 130B may be pressed into an aperture on the end of thermally-conductive member 114; or, a retaining member behind rear sheet 130B may be held in place by deforming a portion of thermally-conductive member 114 in a manner similar to that illustrated in FIGS. 7K and 7L. FIGS. 22A and 22B show one example of a mechanical means for holding rear sheet 130B to thermally-conductive member 114.

In some embodiments of the invention it is desirable that the outer surface of membrane 130 have different properties than the surface of membrane 130 which faces into volume 120. For example, where a heat exchanger is intended to warm or cool a living subject it may be desirable that the outer surface of membrane 130 be absorbent to absorb any sweat, dirt or condensation from the subject's skin. As shown in FIG. 23A, membrane 130 may be a two-ply membrane having different surface characteristics on its inner and outer faces.
In the embodiment of FIG. 23B, membrane 130 is made up of an inner fluid-impermeable layer 130-1 and an outer absorbent layer 130-2. With this construction, it is unnecessary to make fluid-impermeable layer 130-1 of a material that is approved for contact with a subject or other item to be heated or cooled because only thermally-conductive members and outer absorbent layer 130-2 can come into contact with the subject. As an example, layer 130-2 may comprise SOFTESSE™ material available from DuPont.
Where a membrane has multiple layers, the materials of the layers may be chosen to have characteristics under compression and/or elastic characteristics which differ from one layer to the other. Such membranes may be included to advantage in embodiments of the invention in which the membrane is compressed between parts of a thermally-conductive member (as shown, for example, in FIG. 6A or 13 to 21). In such embodiments of the invention, it can be desirable for the membrane to include a relatively soft fluid impermeable layer which can seal well to the thermally-conductive member. However, a single-ply membrane that is highly compressible and/or greatly compressed by a thermally-conductive member may take on a shape which is somewhat distorted in the vicinity of the thermally-conductive member. By providing a two-ply or two-layer membrane this problem can be avoided. The membrane can combine a sealing layer having good properties for sealing with a control layer. The sealing layer may be highly compressible and relatively easily stretchable. The control layer may be significantly less stretchy and less compressible than the sealing layer.
For example, the sealing layer may comprise a sheet of suitable plastic material, such as urethane, while the control layer may comprise a sheet of a woven or unwoven fabric. The fabric may be significantly less elastic than the sealing layer and, in some cases may be substantially non-elastic under the expected conditions of use of the heat exchanger. The sealing layer may be on the inside of membrane 130 facing into volume 120 in which case the sealing layer may be welded to a layer making up the back side of volume 120.
In some embodiments of the invention the membrane has three layers, for example, a compressible elastomer sealing layer; a fabric control layer; and an outer layer of a soft absorbent material that is approved for skin contact.
A suitable circulation system may be used to circulate a heat exchange fluid through the volume 20 of one or more heat exchangers as described herein. For cooling purposes it is desirable that the temperature of circulating fluid 65 be greater than 0° C. to avoid freezing the subject's skin. The desired temperature of the circulating fluid will depend to some degree on the application and the portion of the subject's body to be treated. The desired temperature for cold therapy ranges between 0° C. and 15° C. Water has properties which make it good for use as a circulating fluid 65.
It is generally desirable to maintain the pressure of fluid 65 in volume 20 approximately equal to the air pressure surrounding heat exchanger 10. If the pressure within volume 20 is significantly smaller than the ambient air pressure then pressure differences across the walls of volume 20 will tend to collapse volume 20 although the projecting inside ends 26 of thermally-conductive members 14 may prevent the walls from complete collapse. If the pressure within volume 20 is significantly larger than the ambient air pressure then heat exchanger 10 will tend to balloon.
FIG. 24 is a schematic view of a cooling system which includes a heat exchanger 10 and a fluid circulating system 60. Circulation system 60 has an insulated reservoir 62 containing a volume of ice 64. System 60 contains a suitable heat exchange fluid 65, which may be liquid water. System 60 delivers fluid 65 to heat exchanger 10 through delivery conduit 66 and returns coolant to reservoir 62 through a return conduit 67.
A first feed pump 70 upstream from heat exchanger 10 delivers fluid 65 from reservoir 62 to heat exchanger 10. A second feed pump 72 is located downstream from heat exchanger 10. Second feed pump 72 draws fluid 65 from heat exchanger 10 and returns the fluid to reservoir 62. First and second feed pumps 70 and 72 are balanced so that within volume 20 of heat exchanger 10 the pressure of fluid 65 is substantially equal to the ambient air pressure.
One or more bypass valves may be provided to provide better control over fluid pressure within volume 20. In system 60, an adjustable bypass valve 74 is connected between the output of first feed pump 70 and reservoir 62. Bypass valve 74 indirectly regulates the pressure within volume 20. When bypass valve 74 is opened, a larger proportion of fluid 65 is returned to reservoir 62 by way of bypass conduit 75 and the amount of fluid 65 flowing into heat exchanger 10 is reduced. Bypass valve 74 may be pressure-operated.
System 60 has a second bypass valve 76 connected in parallel with second feed pump 72. When second bypass valve 76 is open, second feed pump 72 can draw fluid 65 from reservoir 62 by way of conduit 77. Opening second bypass valve 76 increases pressure at the input of second feed pump 72 and consequently increases the pressure within volume 20.
Many variations of system 60 are possible. Although two bypass valves are shown in FIG. 24 for maximum flexibility, one bypass valve connected parallel with either one of pumps 70 or 72 or in parallel with heat exchanger 10 may be sufficient to permit pressure inside heat exchanger 10 to be maintained within a desired range. In addition, depending upon the construction of pumps 70 and 72 and the fluid flow properties of the circuit which includes conduits 66, 67 and heat exchanger 10 it may be possible to maintain the fluid pressure in volume 20 within the desired range without the need for bypass valves 74 and 76. Where bypass valves are provided it is not necessary that they be connected directly to reservoir 62 as illustrated. Other connections may be provided which have the result of maintaining pressures upstream and/or downstream from heat exchanger 10 at values which keep the pressure within volume 20 at a desired level while maintaining fluid flow through volume 20.
In some cases it may be convenient to provide a single reservoir 62 for providing heat exchange fluid for multiple heat exchangers 10. In such cases it is best to provide upstream and downstream pumps 70 and 72 for each heat exchanger 10. In the alternative, suitable manifolds, such as T-connectors, could be provided to allow a number of heat exchangers 10 to be connected in parallel between a single upstream pump system and a single downstream pump system.
FIG. 25 illustrates another fluid circulating system 60A. In system 60A, a first flow regulator 78 comprising a restrictor 80 and a bypass valve 82 is provided between first feed pump 70 and heat exchanger 10. Bypass valve 82 is connected in parallel with restrictor 80. When fluid 65 is flowing through flow regulator 78 then a pressure drop across flow regulator 78 depends upon the fluid flow rate and upon the degree to which bypass valve 82 is open.
System 60A has a second flow regulator 79 which includes a second flow restrictor 84 and a bypass valve 86. Bypass valve 86 is connected in parallel with restrictor 84.
In system 60A, bypass valves 82 and 86 are adjustable. The fluid pressure within volume 20 can be controlled by adjusting one or both of bypass valves 82 and 86.
Some alternative embodiments of the invention lack one of flow regulators 78 and 79. When system 60A is connected to supply fluid 65 to a plurality of heat exchangers 10 it is preferable to provide for each heat exchanger 10 at least one adjustable flow regulator 78 or 79 located where only fluid going to or from that heat exchanger passes through the flow regulator. This permits the pressure within each heat exchanger 10 to be individually regulated. In the alternative, as described above, suitable manifolds may be provided to split the flow of fluid 65 between a number of heat exchangers 10 connected in parallel.
FIG. 26 illustrates another fluid circulating system 60B. In system 60B the pressure within volume 20 of heat exchanger 10 is controlled by adjusting the rate of operation of one or both of upstream and downstream feed pumps 70 and 72. In some embodiments of the invention a control system simultaneously increases the rate of operation of feed pump 70 and decreases the rate of operation of feed pump 72 or vice versa. The rate of operation of pumps 70 and 72 may be controlled by adjusting the rate of rotation of motors which drive the pumps, by adjusting displacements of the pumps, or the like.
In the illustrated embodiment, control is accomplished by operating a power splitter 88 (illustrated schematically by a potentiometer). Power splitter 88 can be operated to increase the speed of a motor driving pump 70 and to decrease the speed of a motor driving pump 72 or vice versa.
Systems 60, 60A and 60C may be automatically controlled using any suitable control system. For example, a controller may be provided to operate bypass valves and/or control pump speeds or displacements by way of suitable actuators (not shown) as necessary to control pressure within volume 20 to stay within a desired range. Those skilled in the art are familiar with suitable controllers. The controller may, for example, comprise a suitable programmed programmable controller or a hardware controller. One or more pressure sensors and/or flow sensors (not shown) may be included to provide feedback to the controller.
Any of cooling systems 60, 60A and 60B could be adapted for warming by replacing ice 64 with a suitable heating element which can be operated to raise fluid 65 in reservoir 62 to a desired temperature. Instead of ice 64, any of systems 60, 60A or 60B could cool fluid 65 by way of a refrigeration system. However, a refrigeration system large enough to provide high-rate cooling of a living person is expensive, consumes a large amount of power and is not readily portable. Ice has the advantage that melting a block of ice takes a large amount of heat. A reservoir 62 containing enough ice to apply high rate cooling to a human subject for a significant period can be small enough to be readily portable.
FIGS. 27 through 32C show heat exchangers incorporating thermally- conductive members 14 or 114 as described above. The heat exchangers may be used to cool or warm various body parts of a living subject. FIG. 27 shows a heat exchanger 310 adapted for cooling or warming the neck of a subject adjacent the subject's carotid arteries. Such a heat exchanger may be used to cool blood flowing to the subject's brain. Heat exchanger 310 comprises two pads 310A and 310B. The pads may be attached around a subject's neck with fasteners 313A and 313B which may, for example, comprise complementary hook and loop fasteners such as VELCRO™. A layer of thermally-conductive gel may be provided on the pad to improve heat transfer between the subject's skin and thermally-conductive members 114. Cooling fluid may be introduced through an inlet port 322. The cooling fluid circulates through both of pads 310A and 310B before exiting at outlet port 323. A tube 311 carries fluid from pad 310A to pad 310B and a return tube 312 returns fluid from pad 310B to pad 310A.
FIGS. 28A, 28B and 28C show a heat exchanger 310 like that of FIG. 27 in position on the neck of a subject.
As shown in FIGS. 29A through 30C, additional heat exchanger pads may be connected in series with heat exchanger 310 to cool or warm a larger area of the subject. FIGS. 29A, 29B and 29C show a system 318 which includes a pad 310C configured to be applied over a subject's face. Pad 310C receives fluid from pad 310A through tube 311A and returns fluid to pad 310B through tube 312A. Pad 310C is held in place by a head strap 314 and a chin strap 315.
FIGS. 30A, 30B and 30C show a head cooling and/or warming system 320 which includes a scalp pad 310D in addition to the pads 310A, 310B and 310C of the system of FIGS. 29A through 29C. Scalp pad 310D is configured to conform substantially with the scalp of a subject. In the illustrated embodiment, scalp pad 310D receives fluid from face pad 310C by way of tube 311B and returns fluid to face pad 310C by way of tube 312B.
FIG. 31 illustrates a system 340 for cooling or warming multiple regions of a subject. System 340 includes a head cooling and/or warming system 320 as shown in FIGS. 30A through 30C, a torso cooling and/or warming system 342 and a thigh cooling and/or warming system 344. Each of systems 320, 342 and 344 are connected to a source 60 of a cooled (or warmed) fluid. The rate of flow of fluid through each of systems 320, 342 and 344 may be independently regulated. In some embodiments of the invention, a controller associated with source 60 regulates the rate of fluid flow through systems 320, 342 and 344 in response to measurements of the subject's core temperature or equivalent measurements and a target value for the subject's core temperature.
FIG. 32A illustrates a possible arrangement of fluid passages in head cooling and/or warming system 320. FIG. 32B illustrates a possible arrangement of fluid passages in torso cooling and/or warming system 342. FIG. 32C illustrates a possible arrangement of fluid passages in thigh cooling and/or warming system 344. Thermally-conductive members 114 have been omitted from FIGS. 32A through 32C for clarity.
As noted above, heat exchangers according to alternative embodiments of the invention may be applied to heating or cooling objects of diverse types. For example, FIG. 33A shows a heat exchanger 10 being used to cool an electric motor 52. Bases 29 of thermally-conductive members 14 contact the curved outer surface 53 of motor 52. FIG. 33B shows a heat exchanger 10 being applied to cool a compressor 54 having an outer housing 55 which has a profile having compound curvature. Bases 29 contact the surface of housing 55. Compressors having compound curves are frequently used in refrigeration and air conditioning systems. FIG. 33C and 33D show a heat exchanger 10 being applied to cool a pipe 56. Bases 29 contact an outer cylindrical surface 57 of pipe 56. Pipe 56 could be an exhaust pipe, for example.
Bases 29 or 129 of thermally-conductive members of heat exchangers as described herein may be shaped to better conform with a surface of an object to be warmed or cooled. For example, FIG. 33E shows a heat exchanger in which bases 129 of thermally-conductive members 114 are machined or otherwise shaped to provide concave faces 129A. Faces 129A each have a radius of curvature to match that of the cylindrical surface of a housing 55 of an object to be heated or cooled. On other embodiments (not shown), thermally- conductive members 14 or 114 may have faces shaped to provide convex surfaces of surfaces having more complex shapes to match the profile of a surface of an object to be cooled or heated. In some cases, ends of thermally- conductive members 14 or 114 may be affixed, for example, with bolts or studs, to a surface of an object to be cooled or heated.
An object to be heated or cooled may be specially configured to match a heat exchanger according to this invention. FIG. 33F shows an object to be cooled which has sockets 55A in an outer housing 55. A heat exchanger has thermally-conductive members 114 having bases 129 with ends 129B inserted into and shaped to conform with sockets 55A. A suitable thermally-conductive paste may be used to enhance thermal contact between thermally-conductive members 114 and housing 55. FIG. 33G shows thermally-conductive members having ends shaped in various ways.
FIG. 34 illustrates schematically a heat exchanger 58 being used to cool an object 59 having a temperature high enough that it could cause degradation of material 30. Heat exchanger 58 is similar to heat exchanger 10 except that bases 29 are elongated so that they contact object 59 at a location spaced away from material 30. A heat shield 360 is provided between object 59 and material 30. Thermally-conductive members 14 pass through the heat shield. Each of thermally-conductive members 14 extends through a thermally insulating sleeve 59A. Sleeves 59A protect material 30 from becoming overheated through contact with members 14. Shield 360 protects material 30 from heat radiated by object 59.
Heat exchangers may also be used to transfer heat between fluids and/or between solid objects. FIG. 35A shows a heat exchanger 61 comprising a membrane of a material 30 penetrated by thermally-conductive members 62. Members 62 have bodies 29 on both sides of material 30. As shown in FIG. 35B, bodies 29 can optionally comprise fins, pins or other thermally-conductive elements disposed to provide improved thermal contact between the body 29 and a surrounding fluid. The heat exchanger 61A illustrated in FIG. 35B has pins 32 projecting from each body 29. Bodies 29 are larger in area than the central portions of members 14 which pass through material 30. The edges of the bodies press against the membrane to seal any gap between the member and the membrane so that fluid will not leak from one side to the other.
FIGS. 36A through 37F show a pad 510 according to one embodiment of the invention. Pad 510 has an inlet 512 for receiving a heat exchange fluid 513, a path 514 along which heat exchange fluid 513 can flow, and an outlet 516. In some embodiments, heat exchange fluid 513 is recirculated along a fluidic circuit extending between a temperature controller and one or more pads 510. For example, pad 510 may be used in one of the systems for heating or cooling a body disclosed in PCT patent application No. PCT/CA2004/001660.
Path 514 of pad 510 is defined in a chamber 518 between a back sheet 520 and a front sheet 522 that are bonded together along connection lines 523. Connection lines 523 comprise locations along which back sheet 520 and front sheet 522 are affixed to one another by welding, a suitable adhesive, or other suitable affixation means. Thermally-conductive members 524 are disposed along path 514. Each thermally-conductive member 524 penetrates and is sealed to front sheet 522 to prevent heat exchange fluid 513 from leaking around thermally-conductive members 524.
Each thermally-conductive member 524 has an outer face 524A on a front face of pad 510 and an inner face 524B on a part of member 524 that projects into chamber 518. Inner faces 524B of thermally-conductive members 524 are in contact with heat exchange fluid 513. Thermally-conductive members 524 may have, for example, any of the constructions described in the above-noted PCT application.
Rear sheet 520 is formed to provide a cup 530 coinciding with each thermally-conductive member 524. As seen best in FIGS. 37B and 37C, the cross-sectional area of path 514 alternates between cups 530 in which the cross-sectional area is relatively large and constricted areas 532 between thermally-conductive members in which the cross-sectional area of path 514 is relatively small. In embodiments illustrated by FIG. 37B, the clearance 535 between inner face 524B of the thermally-conductive member 524 and rear sheet 520 is greater than the clearance between rear sheet 520 and front sheet 522 in constricted area 532. In the embodiments illustrated by FIG. 37C, the width of path 514 is greater in portions of path 514 adjacent a thermally-conductive member 524 than it is in its constricted portions 532.
In some preferred embodiments front sheet 522 and rear sheet 520 are very flexible fluid-impermeable sheets such as thin sheets of polyether thermoplastic polyurethane. This material has a temperature range from −60 C to 140 C. Front sheet 522 and rear sheet 520 may also be made of other suitable materials, such as urethane, polyurethane, polyvinylchloride (PVC), rubber, silicone, or the like. Various materials suitable for use as front sheet 522 and rear sheet 520 are described in the above-noted PCT application. The material of rear sheet 520 is preferably somewhat elastic. Urethane having a thickness of approximately 0.015 inches has been found to be a satisfactory material to use for rear sheet 520.
For some applications, the thermal characteristics of the materials are important. For example, some polyvinylchloride materials become quite brittle at temperatures below 5° C. Ethylvinylacetate can also become undesirably rigid at low temperatures. Such materials would not be optimum choices for front sheet 522 and rear sheet 520 in applications where a pad 510 is operated at lower temperatures.
Fluid flowing along path 514 encounters a pattern of alternating constrictions 532 and enlarged areas corresponding to cups 530. Although the inventors do not wish to be bound by any particular theory of operation, this alternating pattern of areas of greater and lesser cross-sectional area is thought to help to prevent chamber 518 from becoming overly inflated and overly rigid as heat exchange fluid 513 flows through pad 510. This pattern may also assist heat transfer between thermally-conductive members 524 and heat exchange fluid 513.
In some embodiments of the invention the cross-sectional area of path 514 in constricted areas 532 is about 50% or less, (in some embodiments 25% or less, or even 10% or less) of the cross-sectional area of path 514 in the vicinity of a thermally-conductive member 524. In all such embodiments, the cross-sectional area in constricted areas 532 can be said to be “substantially less” than the cross sectional areas adjacent thermally-conductive members 524.
The configuration of path 514 can be adjusted by altering the manner in which rear sheet 520 is formed. For example, making cups 530 deeper increases the cross-sectional areas of path 514 in its parts adjacent to thermally-conductive members 524. The configuration of path 514 can also be adjusted by altering the paths of connecting lines 523. For example, the cross-sectional area of constricted portions 532 can be made smaller by making the opposing connecting lines 523 closer to one another. Similarly, the cross-sectional area of constricted portions 532 can be made larger by making the opposing connecting lines 523 farther apart from one another.
FIG. 37F shows an alternative embodiment of the invention wherein connecting lines 523 are straight and constricted portions 532 are defined, in part, between opposing spot connections 523A and 523B. FIG. 37G shows a pad 510A which is similar to pad 510. In pad 510A the pattern of cupped areas 530 and back sheet 520 and connecting lines 523 and spot connections 523A and 523B is such that path 514 follows a zig-zag course.
FIGS. 38A to 38C illustrate the fact that a pad according to the invention can be very flexible and can be made to conform with a surface of a body such as the cylindrical body 540. Body 540 can be anything that it is desired to heat or cool with a pad 510 according to the invention. Body 540 may be a portion of a body of a living being, such as a human or animal, or may be a part of a device, machine or the like.
FIGS. 39A through 39C show thermal reservoirs 550A, 550B and 550C (collectively thermal reservoirs 550) as provided by another aspect of the invention. Each thermal reservoir 550 comprises a bladder 552 containing a heat storage material, which is preferably a liquid, such as water, that has a phase transition (e.g. freezing/melting) at a temperature in a range of interest. The heat storage material can either take in or give out heat.
A number of thermally-conductive members 524 penetrate the material of bladder 552 on at least one face thereof. Thermally-conductive members 524 provide paths of very high thermal conductivity between their outer faces 524A and the heat storage material contained within bladder 552. Thermal reservoirs 550 may be used as ice packs, or may be used to warm or cool a heat exchange fluid, or the like.
Each bladder 552 is made of a suitable material (which may be a material of the same type as used for the pads 510 described above). While bladders 552 are preferably flexible, in some embodiments of the invention, bladders 552 are of a stiffer material, such as a plastic, that holds its shape.
Thermally-conductive members 524 may be arranged in any suitable patterns on thermal reservoirs 550. Thermally-conductive members 524 may be disposed on one or more sides of a thermal reservoir 550.
FIGS. 39D, 39E and 39F show a thermal reservoir 555 that combines structural features of a pad 556 that is like pad 510 of FIGS. 36A and 36B, and a bladder 557 filled with a heat storage material 558. Bladder 557 may, for example, be filled with water. The water may be frozen. A heat exchange fluid may subsequently be cooled by circulating it through pad 556.
As shown in FIGS. 39E and 39F the front sheet 522 of pad 556 forms a portion of one wall of bladder 557. Faces 524A of thermally- conductive members 524 are in contact with heat storage material 558. Faces 524B of thermally-conductive members 524 are in contact with heat exchange fluid 513 in pad 556. As heat exchange fluid 513 is circulated through pad 556 it is either warmed or cooled. Whether heat exchange fluid is warmed or cooled depends upon the relative temperatures of the heat storage material 558 and the incoming heat exchange fluid 513.
In the embodiment illustrated in FIGS. 39D to 39F, bladder 557 is formed by affixing a sheet 559 to pad 556 in any suitable way. For example, sheet 559 may be welded to pad 556 to provide fluid-tight bladder 557. In the illustrated embodiment, sheet 559 has been formed (for example by vacuum forming) to allow a relatively large volume of heat storage material 558 to be contained in bladder 557 without distortion of front sheet 522 of pad 556.
One or more drain ports (not shown) may optionally be provided to allow heat storage material 558 to be added or changed. In some embodiments, a hole is punched through the walls of bladder 557. Heat storage fluid 558 is introduced through the punched hole. The hole is then sealed by a rivet and washer as described in the appended PCT application.
FIGS. 39G and 39H show a thermal reservoir according to a further embodiment of the invention in which bladder 557 is roughly lenticular in cross section when filled with thermal storage material 558.
FIGS. 40A to 40E show systems for heating or cooling a living being (a “subject”) or an object which incorporate one or more heat exchange pads, as described above and/or one or more thermal reservoirs as described above. FIG. 40A shows a system 560 that has a pad 510 connected in a fluid circuit 562 through which a heat exchange fluid 513 is circulated by a pump 564. Outer faces 524A of the thermally-conductive members 524 of pad 510 are in thermal contact with an ice pack 565. System 560 includes a heat exchanger 566, which could comprise another pad 510, a pad as described in PCT patent application No. PCT/CA2004/001660, or some other heat exchanger. Heat exchanger 566 is in contact with a body to be cooled. For example, heat exchanger 566 may be in contact with a portion of a human or animal body to be cooled.
Fluid 513 passes out of pad 510 at outlet 516, along tube 567A to heat exchanger 566. Fluid 513 returns to pad 510 by way of tube 567B, pump 564 and tube 567C. A controller 568 (which may comprise any suitable programmable controller or control circuitry, for example) senses a temperature of heat exchange fluid 513 circulating past a temperature sensor 569 and controls pump 564 to adjust a rate of flow of the heat exchange fluid 513 to maintain a desired temperature. Additional temperature sensors (not shown) may be provided in other parts of fluid circuit 562 (for example at heat exchanger 566) to provide additional inputs to controller 568.
The provision of a pad 510 equipped with thermally- conductive members 524 helps to facilitate transfer of heat from circulating heat exchange fluid 513 into ice pack 565. Apparatus 560 could use a pad of one of the types described in PCT patent application No. PCT/CA2004/001660 in place of pad 510.
FIG. 40B shows a system 570 for heating or cooling that is similar to system 560 of FIG. 40A but differs in two respects. In system 570 temperature sensor 569 senses the temperature of heat exchange fluid 513 returning to pad 510 from heat exchanger 566 instead of the temperature of heat exchange fluid being carried from pad 510 to heat exchanger 566. Also, system 570 has a thermal reservoir 555 which may be like that shown in FIGS. 39D, 39E and 39F, for example. Thermally-conductive members 524 of pad 10 are in contact with thermally-conductive members 524 of thermal reservoir 555.
In some embodiments of the invention, thermally-conductive members 524 are arranged in complementary patterns on pad 510 and thermal reservoir 555. In some embodiments of the invention, the faces of thermally-conductive members 524 of pad 510 have shapes that are complementary to the shapes of the faces that they contact of thermally-conductive members 524 of thermal reservoir 555. For example, the faces of both sets of thermally-conductive members may be flat so that a large area of contact is made between the thermally-conductive members 524 of pad 510 and the thermally-conductive members 524 of thermal reservoir 555. In some embodiments, magnets or other means may be provided to urge the thermally-conductive members 524 of pad 510 into contact with the thermally-conductive members 524 of thermal reservoir 555 to ensure maximum surface area contact between the thermally-conductive members 524 of pad 510 and the thermally-conductive members of thermal reservoir 555. For example, a small rare-earth magnet may be embedded in a thermally-conductive member 524 of pad 510 and another small magnet of opposite orientation or a piece of ferromagnetic material may be embedded in the corresponding thermally-conductive member of heat reservoir 555.
FIG. 40C shows a cooling system 572 which is similar to system 560 except for the locations in circuit 562 of pump 564 and temperature sensor 569 and the arrangement of pad 510. System 572 uses a larger pad 510 than is shown in system 560. In system 572, pad 510 is wrapped around ice pack 565. Another feature of system 572 is that heat exchanger 566 is expressly indicated as being equipped with thermally- conductive members 524.
FIG. 40D shows a heating or cooling system 574 in which heat exchange fluid circulating in pad 510 is in contact with a thermal reservoir 575 having thermally-conductive members 524 on multiple faces. Thermal reservoir 575 has a first group 577 of thermally-conductive members 524 on its top surface and a second group 578 of thermally-conductive members 524 on its bottom surface. Thermally-conductive members of pad 510 are in contact with both sets of thermally-conductive members of thermal reservoir 575 to enable a relatively high rate of heat transfer between heat exchange fluid 513 circulating in pad 510 and the heat exchange material 558 in thermal reservoir 575.
FIG. 40E shows a system 580 for warming or cooling a person, animal or object having an integrated thermal reservoir 555 like that shown in FIGS. 39D through 39F. A heat exchange fluid 513 is heated or cooled as it circulates through integrated thermal reservoir 555. The fluid passes through a heat exchanger 566 which is in thermal contact with a person, animal or object to be heated or cooled.
In alternative systems like those of FIGS. 40A to 40E, a pad 510 containing a heat exchange fluid 513 could be immersed in or in contact with a liquid that acts as a thermal reservoir. The liquid of the thermal reservoir may be at a temperature suitable to take up or give heat to the heat exchange fluid 513 circulating in the pad 510. for example, in some embodiments, the liquid of the thermal reservoir may comprise a volume of cold water or ice water.
Another embodiment of the invention is illustrated by FIG. 41 which shows a system 590 for cooling a person or object. System 590 comprises a source 592 of compressed heat exchange fluid 593, which may comprise compressed air, for example. An air compressor (not shown) may be provided to fill source 592 with compressed air. Heat exchange fluid is allowed to pass through a control valve 594 into an expansion chamber 596. Expansion of heat exchange fluid 593 causes heat exchange fluid 593 to become cooler. The cooled heat exchange fluid 593 passes from expansion chamber 596 into a heat exchanger 598. Heat exchanger 598 is in contact with a person or animal or object to be cooled. After passing through heat exchanger 598, the heat exchange fluid may be vented as indicated at 599.
Heat exchanger 598 may comprise a pad (for example a pad 510) as described herein or a heat exchanger as described in PCT patent application No. PCT/CA2004/001660. The heat exchanger 598 of FIG. 41 has thermally-conductive members 524 that are in contact with heat exchange fluid 593 inside heat exchanger 598 and extend through a wall of heat exchange 598 to contact a body to be cooled.
A controller 600, which may comprise a programmable controller or another suitable control circuit or mechanism operates control valve 594 in response to a temperature sensed at temperature sensor 602.
System 590 could be used in any of many ways including to cool a subject's body in a case where cooling is required for some medical purpose or to provide comfort for a person in a hot environment, for example.
In lieu of, or in addition to an expansion chamber, system 590 could include a suitable “metering” device to decrease the pressure of the heat exchange fluid without the use of an expansion chamber. For example, system 590 may comprise an expansion valve, capillary line, etc. Such devices are known to those skilled in the fields of air conditioning and refrigeration.
FIGS. 42A, 42B and 42C are views of a pad 610 according to an alternative embodiment of the invention. Pad 610 is substantially similar to pad 510 shown in FIG. 37A except that, in addition to thermally-conductive members 524 passing through front sheet 522, pad 610 includes additional thermally-conductive members 624 that pass through rear sheet 520. Pad 610 can exchange heat with thermal reservoirs or other heat sources or sinks on both of its sides. For example, when used in a system like system 560 or 570 (see FIGS. 40A and 40B) a pad 610 could be in thermal contact with ice packs, or thermal reservoirs 555 on both sides of the pad 610. In the alternative, pad 610 may be immersed in a bath of liquid, in which case, the addition of thermally-conductive members 624 provides for a higher rate of heat transfer between the liquid and a heat exchange fluid 513 circulating in the pad 610.
Where a component (e.g. a member, pump, valve, sensor, controller, assembly, element, device, circuit, etc.) is referred to above, unless otherwise indicated, reference to that component (including a reference to a “means”) should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention.
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. For example:

- Thermally- conductive members 14 or 114 may have any suitable shapes and arrangements. Those illustrated herein are but examples.
- Flexible material 30 may have different compositions in different parts of a heat exchanger according to the invention. Different suitable flexible materials 30 may be used for material 30 in different parts of a heat exchanger.
- A heat exchanger according to the invention is not necessarily rectangular or parallel-sided. A heat exchanger according to the invention could have other shapes. Heat exchangers according to some embodiments of the invention are elongated and have fluid inlets and fluid outlets located in areas at opposed ends of a long axis.
- The arrangements of heat exchangers shown in the Figures could be applied to warm a subject instead of to cool a subject.

Claims

1. A flexible heat exchanger comprising:

a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet; and,

a flexible front sheet essentially impermeable to the heat exchange fluid, the front sheet carrying a plurality of substantially-rigid members, each of the members comprising an exposed thermally-conductive surface on a thermally-conductive first body on an outside of the front sheet and having a thermally-conductive portion extending from the thermally-conductive first body, through the front sheet, and into the volume,

each of the plurality of members comprising opposed gripping surfaces held firmly against opposed sides of the front sheet.

2. A flexible heat exchanger according to claim 1 wherein the volume is defined between the front sheet and a flexible rear sheet.

3. A flexible heat exchanger according to claim 2 wherein the rear sheet is shaped to provide indentations at locations that are adjacent to the substantially-rigid members and the thermally-conductive portions of the substantially-rigid members project into the indentations.

4. A flexible heat exchanger according to claim 3 wherein wherein the members are arranged in rows to provide a plurality of substantially unbroken lines of the front sheet extending between the rows of the members.

5. A flexible heat exchanger according to claim 1 wherein wherein the members are arranged in rows to provide a plurality of substantially unbroken lines of the front sheet extending between the rows of the members.

6. A flexible heat exchanger according to claim 4 wherein the members are arranged in an array such that the plurality of substantially unbroken lines of the front sheet includes first and second sets each comprising a plurality of the unbroken lines wherein the unbroken lines of the first set intersect with the unbroken lines of the second set.

7. A flexible heat exchanger according to claim 1 having drape.

8. A flexible heat exchanger according to claim 1 wherein the volume comprises a channel extending from the inlet to the outlet wherein a cross-section of the channel varies periodically along a length of the channel.

9. A flexible heat exchanger according to claim 8 wherein the thermally-conductive members are spaced apart along the channel and the channel includes constricted areas located between the thermally-conductive members.

10. A flexible heat exchanger according to claim 8 wherein the channel is a sinuous channel.

11. A flexible heat exchanger according to claim 1 wherein the thermally-conductive surface of the first body is spaced outwardly from the outside of the front sheet.

12. A flexible heat exchanger according to claim 1 wherein an area of the thermally-conductive surface of the first bodies exceeds a total cross sectional area of the thermally-conductive portions measured where the thermally-conductive portions pass through the front sheet.

13. A flexible heat exchanger according to claim 1 wherein the thermally-conductive portions project into the volume past an inside face of the front sheet by distances of at least 3 mm.

14. A flexible heat exchanger according to claim 1 wherein the thermally-conductive portions each have a thermal conductivity of at least 50 Wm⁻¹K⁻¹.

15. A flexible heat exchanger according to claim 1 wherein the thermally-conductive portions each have a thermal conductivity of at least 100 Wm⁻¹K⁻¹.

16. A flexible heat exchanger according to claim 1 wherein the thermally-conductive portions are made of metal.

17. A flexible heat exchanger according to claim 16 wherein the thermally-conductive portions are made of metals selected from the group consisting of: aluminum, copper, gold, silver, alloys of two or more of aluminum, copper, gold, or silver with one another and alloys of one or more of aluminum, copper, gold, or silver with one or more other metals.

18. A flexible heat exchanger according to claim 1 wherein the outside of the front sheet is faced with an absorbent fabric and the thermally-conductive portions of the members project through the absorbent fabric.

19. A flexible heat exchanger according to claim 1 wherein the plurality of the members covers at least 30% of an area of the outside of the front sheet.

20. A flexible heat exchanger according to claim 2 wherein the front and rear sheets are attached to one another in a pattern of attached areas to provide a sinuous channel in the volume, the sinuous channel and extending between the inlet and outlet.

21. A flexible heat exchanger according to claim 20 wherein the members are spaced apart along the channel, each of the members is located in a wider portion of the channel and the channel has a plurality of narrower portions spaced apart along the channel, the narrower portions each located between an upstream one of the members and a downstream one of the members.

22. A flexible heat exchanger according to claim 1 wherein, for each of the plurality of members, the sheet is received in a groove extending circumferentially around the member.

23. A flexible heat exchanger according to claim 1 wherein each of the plurality of members comprises a rivet having a head on the outside of the front sheet and a washer on an inside of the front sheet, the thermally-conductive body comprises a head of the rivet and the front sheet is gripped between the head of the rivet and the washer.

24. A flexible heat exchanger according to claim 1 wherein the thermally-conducting surface is either flush with or projects outwardly from an outside surface of the wall.