US2934322A - Heat exchanger - Google Patents

Description

F. E. HAZARD HEAT EXCHANGER April 26, 1960 Filed Sept, 1, 1955 FIG.3

FIG.4

INVENTOR. F. E. HAZARD FIG.2

ATTORNEY MAT EXCHANGER Frederick E. Hazard, Chicago, Ill. Application September 1, 1955, Serial No. 531,966

12 Claims. (Cl. 257-256) This invention pertains to the art of heat exchange and, although the inventive embodiments disclosed and claimed herein are intended primarily for the field of refrigerated transport, the principles are applicable to other fields, such as cold storage, and also to instances involving the elevating of temperature.

Gne of the significant improvements wrought by this invention is a panel or like structure for carrying a heatexchange fluid to effect temperature changes and temperature hold in a container, such as a refrigerated transport car or truck. In the refrigeration phase particularly, it is an object of the invention to afford a fluid-carrying structure so designed as to fluid-carrying capacity as to avoid stratification where uniform temperatures are desired. A further object of the invention resides in a principle of design in which the proportions of the structure may be initially varied to provide for temperature differences at different zones of the structure, where desired, all of which is accomplished, generally by maintaining or varying a specific area of heat-exchange surface on the structure or panel. As applied to refrigeration, the improved panel is operative to eliminate temperature differences of substantially over F. between its surface and the space being cooled, whereby condensation is avoided where the required temperature to be maintained is above 32 F.; to avoid exposing perishables to damaging extreme temperatures; and to increase the efficiency of the system at zero or sub-zero conditions.

it is a still further object of the invention to provide the heat exchanger as a double-walled panel having fluid pasages therein for circulating secondary heat transfer fluid in a system in which temperature difierential is produced in the secondary fluid by a master or primary refrigerant or refrigerating means. Further objects reside in the arrangement of the panel in such manner that the length of the passages is inclined at an angle on the order of 45 to 75 to the horizontal, specifically where circulation of the fluid is achieved thermosyphonically; and the use of appropriate manifolding and baffling to achieve a smooth and even flow of fluid.

The foregoing and other important objects and features of the invention will become apparent on the basis of the following disclosure of what are now regarded as preferred embodiments and functions of the invention.

In the drawings:

Figure l is a schematic view, partly in section, of the improved panel as used in a system having a refrigerating means and in which the panel carries the fluid;

Figure 2 is an elevation of the double-wall panel structure, portions of the top or outer wall having been removed to disclose the passages and manifolds;

Figure 3 is an enlarged fragmentary section as seen along the line 3-3 of Figure 2;

Figure 4 is a similar section as seen along the line 44 of Fig. 2;

Figure 5 is an enlarged fragmentary section as seen along the line 5-5 of Figure 2; and

ates Patent Figure 6 is an enlarged fragmentary section as seen along the line 66 of Figure 2.

The heat exchanger is designated as a whole by the numeral 10 and comprises a double-Walled panel, here shown as rectangular but obviously susceptible to other shapes, made up of a pair of symmetrical plates 12 and 14 secured together flat-wise and joined about its edges as at l6, 18, 2t and 22 to provide a peripheral selvage and funther joined at various zones within the edges to afford islands 24 and conduits or passages in the form of channels or tubes 26. In the specific embodiment shown, the islands and passages run lengthwise of the structure and are straight, but serpentine or other configurations are not excluded. Any of the well-known processes for forming cold plates, for example the Wellknown Roll Bond process, may be used to produce the thermopanel just described. In addition to the passages or channels 26, the panel has an upper manifold 28 and a lower manifold 30. The selvage at 22 is omitted in a limited zone to give the upper manifold an outlet port 32 adjacent to one lateral end thereof and the selvage at 13 is similarly designed to give the lower manifold a fluid inlet port 34 adjacent to its opposite lateral end. Each manifold, in a panel of rectangular shape as shown here, runs crosswise or across the short dimension of the panel and the tubes or channels 26 run lengthwise of the panel; although, in a panel of another shape the terms laterally, vertically, lengthwise, crosswise etc. could have a different meaning; hence, the expressions are relative only. The manifold 28 diverges laterally to the outlet 32 and the manifold 30 converges laterally from the inlet 34. Stated otherwise, the upper ends of the channels 26 join the manifold 28 along a. straightline zone relative to which the upper edge or Wall 36 of the manifold is non-parallel. A lower edge or wall 38 of the manifold 30 is non-parallel to the straight-line zone along which the lower ends of the passages join the manifold 30. Heat exchange fluid entering the inlet 34 from a conduit 4d and via a connector 42' is thus evenly distributed among the lower ends of the passages 26, aided by a lower bafile 44. A top bafile 46 expedites distribution of the fluid as it exists from the upper ends of the passages 26 to pass to a return conduit 48 via a connector 50. The shape of each connector includes a compound taper to accommodate the elongated nature of the inlet (or outlet) and the circular section of the associated conduit. The cross-sectional area of the outlet 32 is substantially equal to that of the conduit 48; and the same is true of the inlet 34 and its conduit 40; although, the latter is smaller than the conduit 48, which contributes to the efficiency of the panel particularly when used in a thermosyphon system. The bafiies 44 and 46 are preferably parallel to the respective junction zones between the passages 25 and manifolds.

The panel is sectionalized as to the cross-sectional areas of the passages or channels 26, which sectionalization is designated, in one proportionate arrangement, at A, B and C (Fig. 1). That is to say, each channel has first, second and third consecutive portions 52', 54 and 56 lying respectively in the zones A, B and C, it being understood that portions of the zones A and C are omitted in Fig. 2 in the interests of placing the figure on the sheet. The number, size and shape of the zones could be varied to suit different conditions. In the present case, each passage portion 52 is of uniform cross-sectional area throughout its zone or length; each passage portion 56 is of uniform cross-sectional area throughout its zone or length, but that area is greater than that at 52; and each intermediate passage portion 54 tapers so that its cross-sectional area varies from end to end of its zone, changing from the area of 52 to that of 56. Hence, for a given length or height of any one of the passages, a certain volume of heat transfer fluid will be contained. In a preferred structure as shown, the volume in each zone is in excess of that in the next zone below it (with the exception of zone A, of course, which has no lower zone). For example, in the design shown here, the volume of fluid in zone A is less than in zone B; yet, zone A is much higher or longer than zone B; but the volumetric excess in zone B results from the larger passage portions 54. Zone B is somewhat higher or longer than zone C but zone C has a volumetric excess over zone B. The proportions can be adjusted by proper design to eliminate stratification and thereby to obtain uniform temperature from top to bottom of the container. The fluid will pass more rapidly through the smaller passage portions on its way to the top of the structure and will therefore lose less in temperature than if it flowed uniformly as in a conventional structure. Consequently, the top zone. C will be relatively colder, as to plate surface, than the comparable parts of known panels.

Another feature of the invention is the use of the panel for carrying a heat-transfer fluid in a system in which heat is abstracted from or added to said fluid by a refrigerating means of any type, be it natural, mechanical, electrical, chemical or any other type. Exemplary of such system is that shown in Fig. 1, wherein the panel-connected conduits 40 and 48 are connected respectively to the outlet and inlet sides of a fluid chamber 58 in which temperature differentials are produced in the fluid in said chamber by a refrigerating means 60, here shown, for purposes of illustration only, as a compressor-condenserevaporator unit, or any other in which there is heat exchange but no direct fluid exchange between such unit and the panel.

Also, as shown in Figure 1, it is advantageous to arrange the panel so that the length or height of the passages 26 is at an angle on the order of 45 to 75 to the horizontal. The angle shown is 60 and is achieved by tilting the panel in its own plane. It is found that thermosyphonic circulation is expedited to a maximal degree with the passages at this angle, probably because sharp corners and radii are so disposed as to minimize their obstacle effect to the flow of fluid, particularly at the inlet and outlet ends of the panel.

Other features and advantages of the invention, in addition to those enumerated here, will undoubtedly occur to those skilled in the art, as will the adaptation of structural and functional features equivalent to those disclosed here, all of which may be achieved without departure from the spirit and scope of the invention.

What is claimed is:

l. A heat exchanger, comprising: a fluid-carrying panel of the type including a pair of plates secured together about their edges and at various intermediate zones to afford end manifolds and a plurality of passages extending between and interconnecting the manifolds, characterized in that each passage has a first portion leading from one manifold and of uniform cross-sectional area, a second consecutive portion of its length of changing crosssectional area, and a third consecutive portion of its length leading from the second portion to the other manifold and having a uniform cross-sectional area.

2. The invention defined in claim 1, in which: the cross-sectional area of the third passage portion exceeds that of the first and the second passage portion diverges from the first to the third.

' 3. A heat exchanger, comprising: a double-walled panel made up of a pair of plates secured together flatwise to provide symmetrical halves at opposite sides of the median plane of the panel and formed at opposite cndsrespectively with inlet and outlet fluid manifolds, said panel further having a plurality of fluid passage formed therein and extending between and interconnecting the manifolds, said plates being secured together between the passages to separate said passages from each other except at the manifolds, and each passage having first, second and third consecutive portions of its length respectively of different cross-sectional'areas, said diflerences in areas occurring in the direction of the median plane so as to retain the same overall thickness of the panel from top to bottom, said first portion extending a substantial distance from the inlet manifold and being of uniform relatively small cross-section, said second portion extending consecutively from the first portion for a substantial distance and being of divergent shape toward the third portion, and said third portion extending consecutively from the second portion to the outlet manifold and being of uniform relatively large cross-section.

4. A heat exchanger, comprising: a substantially rectangular fluid carrying double-walled panel disposed with its long dimension generally upright and formed of a pair of plates secured together about their edges and at various intermediate zones to afiord upper and lower end manifolds transverse to the long dimension of the'panel and a'plurality of passages spaced laterally of the manifolds and extending lengthwise of the panel between and interconnecting said manifolds, characterized in that the panel is symmetrical at opposite sides of its median plane and that each passage increases in cross-sectional area from the lower manifold to the upper manifold, said lower manifold includes a fluid inlet adjacent to one lower corner of the panel and has an opposite closed end at the opposite lower corner of said panel, said upper manifold includes a fluid outlet adjacent to the upper corner of the panel diagonally opposite to said one lower corner and further has a closed end at the other upper corner of the panel, the lower manifold converges from its inlet to its closed end, and the upper manifold converges from its outlet to its closed end, each passage being of relatively small uniform cross-section throughout a substantial portion of its length adjacent to the lower manifold and changing to upwardly divergent shape throughout a substantial consecutive portion of its length and being thence of relatively large uniform cross-section throughout a further consecutive substantial portion of its length leading to the upper manifold.

5. The invention defined in claim 4, in which: each manifold includes a baffle running lengthwise thereof, the baffle in the lower manifold being located adjacent to the inlet end of said manifold and of such length as to traverse the upper ends of only those passages adjacent to said inlet, and the baffle in the upper manifold being located adjacent to the outlet end of said upper manifold and being of such length as to traverse only those passages adjacent to said outlet end.

6. The invention defined in claim 4, in which: the panel has a top and a. bottom substantially parallel to each other, the converging character of the lower manifold is established by a lower edge at an angle to the bottom of the panel and a junction with the lower ends of the passages in a zone generally parallel with said bottom of the panel, and the converging character of the upper manifold is established by an upper edge at an angle to the top of the panel and a junction with the upper ends of the passages in a zone generally parallel to said top of the panel.

' 7. The invention defined in claim -4, in which the proportions of the lengths of the passages to the respective cross-sectional areas of the passages being such that the volumetric capacity of the third portion is greater than that of the second portion and that of the second portion is greater than that of the first portion.

8. A heat exchanger, comprising: a fluid-carrying panel of the type including'a pair of plates secured together about their edges and at various intermediate zones to afford end manifolds and a plurality of passages extending between and interconnecting the manifolds, characterized in that each passage has a first portion leading from one manifold and of uniform cross-sectional area, a second consecutive portion of its length of changing cross-sectional area, and a third consecutive portion of its length leading from the second portion to the other manifold and having a uniform cross-sectional area, the proportions of the lengths of the passages to the respective crosssectional areas of the passages being such that the volumetric capacity of the third portion is greater than that of the second portion and that of the second portion is greater than that of the first portion.

9. The invention defined in claim 4, in which: the inlet is an elongate opening, an inlet connector of compound tapered shape is connected to said inlet opening and has a circular conduit-receiving opening of a cross-sectional area substantially equal to that of said inlet opening, the outlet is an elongate opening, and an outlet connector of compound tapered shape is connected to said outlet opening and has a circular conduit-receiving opening of a cross-sectional area substantially equal to that of said outlet opening.

10. The invention defined in claim 9, in which: the cross-sectional area of the outlet opening is greater than that of the inlet opening.

11. A heat exchanger for conveying and controlling a relatively non-expansible secondary heat exchange fluid, comprising: a fluid-carrying structure having a lower inlet and an upper outlet end and fluid conduit means extending between and interconnecting said ends, said conduit means having first, second and third consecutive portions of its length respectively of different cross-sectional areas, and said first, second and third portions being so respectively proportioned to said areas that the volumetric capacity of the third portion is greater than that of the second portion and that of the second portion is greater than that of the first portion whereby to improve the siphonic capacity of said structure.

12. A heat exchanger for conveying and controlling a relatively non-expansible secondary heat exchange fluid, comprising: a panel made up of a pair of plates secured together fiatwise and formed at opposite ends respectively with a lower inlet manifold and an upper outlet manifold, said panel further having a plurality of fluid passages formed therein and extending between and interconnecting the manifolds, said plates being secured together between the passages to separate said passages from each other except at the manifolds, and each passage having first, second and third consecutive portions of its length respectively of difierent cross-sectional areas, and said first, second and third portions being so respectively proportioned to said areas that the volumetric capacity of the third portion is greater than that of the secondportion and that of the second portion is greater than that of the first portion whereby to improve the siphonic capacity of said panel.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain June 14, 1934

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