US20090277196A1

US20090277196A1 - Apparatus and method for modulating cooling

Info

Publication number: US20090277196A1
Application number: US12/434,469
Authority: US
Inventors: Dennis S. Gambiana; Bradford L. Blankenship; Dennis R. Maniello; Michael J. Dimunation
Original assignee: Varidigm Corp
Current assignee: HVAC MODULATION TECHNOLOGIES LLC; Varidigm Corp
Priority date: 2008-05-01
Filing date: 2009-05-01
Publication date: 2009-11-12
Also published as: US20090277197A1

Abstract

This invention relates to a method and an apparatus for a modulating air conditioning system having increased energy efficiency and greater turndown capabilities. A modulating air conditioning system includes modulating at least one of the following components: a compressor, a compressor driver, a condenser fan, an evaporator fan, an effective evaporator surface area, an effective condenser surface area and/or an expansion device.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. application Ser. No. 61/049,457, filed on 1 May 2008. The co-pending provisional application is hereby incorporated by reference herein in its entirety and is made a part hereof, including but not limited to those portions which specifically appear hereinafter.

BACKGROUND OF THE INVENTION

1. Field of the Invention
This present invention is directed to a method and an apparatus for modulating cooling in air conditioning and cooling systems, particularly for residential and commercial buildings.
2. Discussion of the Related Art
There is a general desire for a modulating air conditioning system with increased energy efficiency and greater turndown capabilities.
In a typical closed-loop vapor compression cycle, a heat transfer fluid (refrigerant) either absorbs or rejects heat to the environment by changing state between a liquid and a vapor. A compressor is used to pump and compress the vapor refrigerant. The refrigerant leaves the compressor as a high pressure, high temperature vapor, and enters the condenser. As the refrigerant passes through the condenser, heat is rejected from the refrigerant into the environment. As heat is rejected, the refrigerant condenses from a vapor into a liquid. Refrigerant leaves the condenser as a subcooled liquid, and enters an expansion device, where it undergoes a volumetric expansion. The expanded low temperature liquid refrigerant enters the evaporator coil, where it undergoes a vaporization process as it absorbs heat from the environment. The refrigerant exits the evaporator as a superheated low-pressure vapor, then flows through a suction line back to the compressor.
An evaporator in a typical air conditioning application serves a dual purpose of dehumidification as well as temperature control. A circulator fan forces air over the evaporator coil surface. As the evaporator coil absorbs heat from the air passing over its surface, the air is cooled, and exits the evaporator at a lower temperature than that of the entering air. As the air is cooled, it loses its ability to hold moisture. If the coil surface is cooled to a temperature below the dew point temperature of the passing air, then water will begin to condense on the evaporator coil surface, thereby reducing the moisture contained in the air. This reduction in moisture serves to dehumidify the controlled space.
Evaporator coil temperature is primarily controlled by the saturation vapor pressure of the refrigerant, and its corresponding temperature. As the refrigerant undergoes a state change from a liquid to vapor, it maintains a constant temperature until the process has completed. After the change in state of the refrigerant has completed, the additional absorption of heat will cause the refrigerant vapor to increase in temperature while remaining at a constant pressure. This additional temperature rise is a thermodynamic property known as superheat, and can be used as a control feedback to regulate the expansion process of the refrigerant before entering the evaporator coil.
The time required for the refrigerant to change state is dependent upon both the rate of heat transfer from the evaporator to the surrounding air, and the flow rate of the refrigerant through the closed-loop system. Furthermore, the rate of heat transfer, after incorporating several system constants, is largely dependent upon the flow rate of the air passing over the evaporator coil, the surface area of the evaporator exposed to the moving air, and the temperature differential between the evaporator surface and the moving air. An increase of air flow, evaporator surface area, or temperature differential will increase the rate of heat transfer between the moving air and the evaporator. Conversely, a reduction in air flow, evaporator surface area or temperature differential will reduce the rate of heat transfer.
Accordingly, the heat transfer between the refrigerant and the evaporator surface is governed by a similar relationship, involving the flow rate of the refrigerant through the evaporator, the surface area of the evaporator exposed to the refrigerant, and the temperature differential between the refrigerant and the coil surface. As it pertains to this discussion, the thermal mass of the evaporator itself is assumed to be negligible, and therefore the heat transfer rate between the refrigerant and the evaporator shall be assumed equal to the heat transfer rate between the evaporator and the moving air.
The refrigerant expansion device provides a restriction in the refrigerant loop, causing the refrigerant to undergo a volumetric expansion process as it passes through the restriction. Typically, the expansion device will incorporate a feedback system to properly regulate the superheat of refrigerant exiting the evaporator. This feedback system may consist of a mechanical thermostatic valve assembly, an electronic temperature sensor, pressure sensor and corresponding control for an electronically controlled valve, or various other means. Regardless of the feedback mechanism incorporated into the system, regulation of refrigerant superheat is the primary purpose of this device.
When the refrigerant state change in the evaporator has completed, the refrigerant is no longer capable of effectively facilitating heat transfer between itself and the evaporator surface. Therefore, refrigerant superheat, which begins to occur immediately after this state change has completed, can be used to indicate that it is no longer advantageous to allow that specific quantity of refrigerant to remain in the evaporator.
Assuming all other temperatures and flow rates remain constant, the expansion device can be used to regulate the superheat of the refrigerant exiting the evaporator coil by either restricting or increasing the flow of refrigerant through the device. As the refrigerant flow is restricted, the refrigerant flow rate through the evaporator decreases. The heat capacity of the refrigerant has not changed, and therefore completion of the vaporization process of the refrigerant occurs at a point closer to the inlet of the evaporator. After this point, the refrigerant begins to absorb heat as superheat until it either exits the coil or reaches the same temperature as the ambient air, preventing further heat transfer. Conversely, as the refrigerant flow restriction is relaxed, the refrigerant flow rate is increased, and the vaporization process is completed at a point further away from the inlet. As a result, less evaporator surface area is used to superheat the refrigerant vapor, and the superheat of the refrigerant at the exit of the coil is reduced. Through this process of relaxing and restricting the flow of refrigerant through the expansion device, the refrigerant superheat can be controlled, and peak heat transfer efficiency is maintained while correcting for outside influences.
A consequence of this flow restriction is a pressure differential between the refrigerant entering and exiting the expansion device. As the flow is restricted, the pressure differential increases, and therefore the pressure of the refrigerant exiting the expansion device is reduced. This pressure reduction causes a corresponding temperature reduction, as dictated by the saturation vapor pressure-temperature relationship.
In a typical residential or commercial system, the evaporator fan serves to both transfer heat from the air to the evaporator, and to distribute the conditioned air throughout the controlled space. Vapor compression systems with variable fan control have the ability to reduce the flow of moving air across the evaporator to better match the operating conditions of the system. As the fan speed is reduced, heat transfer across the evaporator is also reduced. Assuming all other factors remain constant, as the fan speed is reduced, the expansion device must further restrict the flow of refrigerant in order to ensure that the vaporization process can be completed before the refrigerant leaves the evaporator coil.
Conventional residential air conditioning systems do not modulate based on cooling requirements, but cycle between an on state and an off state. Two stage residential air conditioning systems cycle between a high output, a low output and an off state, such as utilizing two compressors, de-energizing an unloader valve or using other capacity reduction devices. Single stage air conditioning systems are sized only for peak cooling requirements and operate less efficiently when under partial load. Two stage air conditioning systems are also sized for peak load when operated at full capacity, but are typically more efficient when operated at their second, reduced capacity state.
Known modulating air conditioning systems available for the residential and commercial air conditioning marketplace undesirably make use of an inverter-driven three phase motor with variable-frequency control to increase and/or decrease a rotational speed of the attached compressor. Inverter-driven compressors require the use of specialized and costly electronics to control the output frequency of the three phase power supplied to the motor. Furthermore, additional phase conversion hardware is needed since three phase power is not generally available in most residential and light commercial installations.
Known modulating air conditioning systems use proprietary hardware and/or propriety control systems to allow modulation. The design of known modulating air conditioning systems cannot be used with conventional furnaces, evaporator coils and/or thermostat controls. In a typical installation of a known “ductless mini-split” modulating air conditioning system, a condenser coil and a compressor assembly feeds one or more wall-mounted evaporator coils, each evaporator coil includes a separate control system, a thermostat and a refrigeration line set.
Conventional compressor designs available for use in residential and/or commercial cooling applications include reciprocating compressors, rotary compressors, rotary vanes, or scroll compressors. In conventional cooling systems, a reciprocating compressor uses a crank shaft, connecting rods, pistons and valves to draw vapor refrigerant into a cylinder and compress the refrigerant into a condensing coil. In the condensing coil, the refrigerant transfers heat and/or enthalpy absorbed from a building as the refrigerant condenses back into a liquid through a phase change.
An electric motor drives the crank shaft and a motor speed controller varies a speed the compressor for modulated capacity. Undesirably, the motor speed controller is expensive and efficiency gains are limited by frictional losses from the piston moving throughout a stroke during turndown. The frictional losses increase as a percentage of output power when the compressor is slowed, necessitating a significant increase in heat exchanger surface area. The net result is a modest efficiency gain at much higher capital and/or equipment cost.
In other conventional cooling systems, a scroll compressor utilizes two interleaved spiral-like vanes to compress a refrigerant. Typically, scroll compressors can be more efficient than reciprocating compressors and are the industry standard for residential and light commercial cooling applications. The scroll compressor includes limitations for turndown. The vanes of the scroll compressor generate heat due to the compression process and are constantly lubricated to prevent premature damage to compressor components. When the motor is turned down, heat of compression is still high but the lubricating oil pump in the compressor also slows down, so the heat of compression is not removed resulting in premature compressor failure. Other methods and/or attempts for modulating the scroll compressor, such as dynamically off-setting the vanes, has proved effective for capacity control, but does not result in higher efficiency ratings.
Conventional compressor designs include electric motor windings imbedded in a compressor housing and cooled by the same refrigerant used to cool the structure. Heat generated by the motor is added to the refrigerant cooling load and removed in the refrigeration cycle resulting in more work for the compressor, more energy usage by the system and a lower system efficiency. Known hermetic and semi-hermetic compressor designs result in increased heat load on the cooling system.

SUMMARY OF THE INVENTION

A general object of the invention is met at least in part by a modulating air conditioning system having increased energy efficiency and greater turndown capabilities than conventional air conditioning systems. The improved air conditioning system may include control based on actual and/or real time cooling loads and/or demands.
A more specific object of the invention is to overcome one or more of the problems described above.
The general object of the invention can be attained, at least in part by a modulating air conditioning system, where at least one of the following components includes modulating capabilities: a compressor, a compressor driver, a condenser fan, an evaporator fan, an effective evaporator surface area, an effective condenser surface area and/or an expansion device.
The invention includes an air conditioning apparatus for a residential or commercial building that includes as components a compressor, a condenser coil, an expansion device, and an evaporator coil. The apparatus further includes a modulating refrigerant distribution and/or expansion device selected from a group consisting of a variable displacement compressor device, a modulating expansion device, a modulating evaporator device, and combinations thereof. A controller for modulating the at least one modulating refrigerant distribution and/or expansion device is also included.
The invention further includes an air conditioning apparatus for a residential or commercial building that includes a compressor device for receiving and compressing a refrigerant and a motor for operating the compressor device, wherein the motor is air-cooled and the compressor device has a capacity of less than six tons or the motor has a power output of about 5,222 watts or less.
The invention further includes a method of conditioning air for a residential or commercial building including the steps of: modulating a compressing of a refrigerant in a compressor; condensing the compressed refrigerant within a condenser; running the condensed refrigerant through an expansion device to cool the refrigerant; absorbing heat from the residential or commercial building with the cooled refrigerant within an evaporator device; modulating a flow of the refrigerant through the expansion device and/or the evaporator device; and returning the heated refrigerant gas to the compressor.
The invention further includes an air conditioning apparatus for a residential or commercial building. The apparatus includes an expansion device for reducing a pressure of a refrigerant and an evaporating device for receiving the refrigerant from the expansion device. The evaporator device includes two refrigerant distribution assemblies and the apparatus includes a means for alternating a flow of the refrigerant between though only one of the two refrigerant distribution assemblies and through both of the two refrigerant distribution assemblies.
The invention further comprehends an air conditioning apparatus for a residential or commercial building including an evaporating device including two refrigerant distribution assemblies, a valve assembly in combination the evaporating device for modulating refrigerant through the evaporating device, and a controller in communication with the valve assembly for alternating the valve assembly between delivering the refrigerant to only one of the two refrigerant distribution assemblies and delivering the refrigerant to both of the two refrigerant distribution assemblies.
A method of conditioning air according to this invention includes: compressing a refrigerant; condensing the compressed refrigerant; introducing the compressed refrigerant into an evaporating device; modulating a flow of the refrigerant within the evaporating device; moving air over at least a portion of the evaporating device; and absorbing heat from the air with the refrigerant within an evaporator device.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of this invention will be better understood from the following detailed description taken in conjunction with the drawings.

FIG. 1 schematically illustrates an air conditioning apparatus for a residential or commercial building according to one embodiment of this invention.

FIG. 2 shows a partial sectional view of a variable displacement compressor, according to one embodiment of this invention.

FIG. 3 shows internal components of a variable displacement compressor.

FIG. 4 shows a view of a compressor input shaft adapter according to one embodiment of this invention.

FIG. 5 shows a partial sectional view of a modulating condensing unit, according to one embodiment of this invention.

FIGS. 6-13 are schematic illustrations of modulating air conditioning systems according to embodiments of this invention.

FIGS. 14 and 15 are schematic illustrations of modulating evaporator devices according to embodiments of this invention.

FIG. 16 is a modulating evaporator device according to one embodiment of this invention.

FIGS. 17-19 are schematic illustrations of modulating evaporator devices according to embodiments of this invention.

FIG. 20 shows a graph of power consumption and SEER versus compressor modulation level.

FIG. 21 shows a compressor input shaft adapter according to another embodiment of this invention.

DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS

This invention provides increased efficiency for air conditioners and/or dehumidification units of fixed structures by using modulating techniques and/or designs. Modulating techniques of this invention may also be applied to refrigeration storage systems and/or applications. Alternately, the modulating techniques of the invention may also be applied to and/or adapted for heat pump operations.
Conventional air conditioning systems do not modulate and/or have turndown ratios, but provide a constant rate of heat removal when operated regardless of actual cooling demand. Conventional air conditioning systems include a fixed speed compressor motor, a fixed volume compressor, a fixed surface area evaporator coil, a fixed surface area condenser coil, a fixed speed evaporator fan and a fixed speed condenser fan.
Conventional air conditioning systems are sized based on maximum cooling requirements, such as a peak summer day with high humidity, but are often inefficient during cooler days requiring less cooling. Conventional air conditioning systems undesirably cycle on and off while allowing a temperature inside a building to fluctuate between feeling hot and cold. Cycling and/or swinging of the conventional air conditioning system further increases inefficiencies and/or energy consumption.
In some embodiments of this invention, the modulating air conditioning system includes at least one of a variable displacement compressor, a variable volume compressor, a variable speed compressor driver, a variable surface area evaporator coil, a variable surface area condenser coil, a variable speed evaporator fan driver, a variable volume evaporator fan, a variable speed condenser fan driver and/or a variable volume condenser fan. The modulating air conditioning system of this invention may operate with any suitable refrigerant, such as R-11, R-12, R-14, R-22, R-32, R-125, R-134a, R-407c, R-410a, R-744, carbon dioxide, ammonia, propane, hydrogen and/or any other substance with a phase change.
By utilizing at least one component with modulating and/or variable capabilities, the improved air conditioning system operates to supply an amount of cooling that is needed in real time, for example. Additional modulating components provide additional degrees of freedom in an air conditioning system and may provide a wider operating range, an increased number of operating points and/or a higher energy efficiency.
The compressor of this invention may include any suitable devices, such as reciprocating compressors, swashplate compressors, variable swashplate compressors, scroll compressors, variable scroll compressors, rotary compressors, variable rotary compressors, rotary lobe (Roots-type) compressors, axial compressors, centrifugal compressors, screw compressors and/or any apparatus increasing pressure from an inlet and/or suction to an outlet and/or discharge. Suitable compressors may include multiple units and/or stages in series and/or in parallel configurations.
FIG. 1 schematically illustrates an air conditioning apparatus for a residential or commercial building according to one embodiment of this invention. The apparatus 40 includes as components a compressor 42, a condenser coil 44, an expansion device 46, an evaporator 48, and an accumulator 50, all connected by refrigerant lines suitable for passing a refrigerant to and between the components. It is also common for such systems to include other components, such as mufflers, liquid line receivers, filters or dryers in the refrigerant lines.
In some embodiments of this invention, and as shown in FIG. 1, the compressor 42 is a variable displacement compressor. The variable displacement compressor of this invention is capable of modulating the compression of refrigerant by varying the amount and/or rate of compressed refrigerant for a given period of time. A variable displacement compressor allows for modulation of compression output even while using a single speed motor. The variable displacement compressor can be a variable stroke compressor that has piston with modulating strokes. Exemplary variable stoke compressors include swashplate or wobbleplate compressors.
One suitable variable stoke compressor can be the swashplate compressor 60 shown in FIG. 2. Compressor 60 includes a multi-cylinder reciprocating design utilizing a rotating plate 62 instead of a connecting rod and a crankshaft linkage. The plate 62 is connected to pistons 66 by a bearing plate 65 attached to the driveshaft 64. The embodiment of FIG. 3 shows a plate 63, a bearing plate 65, and a driveshaft 64. At no-load conditions, the plate 62 spins on a perpendicular plane and/or axis to the drive shaft 64, so the pistons 66 remain idle. As an angle of the rotating plate 62 is varied, such as by an external controller function, the pistons 66 are driven up and/or in and down and/or out within corresponding bores and/or cylinders 68. Desirably, an increased plate angle results in an increased output of the system.
Capacity control of modulating air conditioning apparatus with swashplate compressors can be achieved by, for example, varying a length of a piston stroke inside the compressor with the rotating plate 62. The swashplate 62 shifts from near perpendicular to the drive shaft for low capacity to, for example, about 45 degrees to the drive shaft for high capacity. As the angle of the swashplate 62 decreases, the stroke of each piston 66 is reduced, reducing the amount of refrigerant cycled with each corresponding stroke. Desirably, frictional losses associated with each piston 66 are reduced nearly proportionally with the system capacity for optimum system efficiency throughout the modulated range of the swashplate compressor.
The modulating air conditioning apparatus of this invention may operate with any suitable lubricant and/or lubrication system, such as mineral oil, synthetic oil, semi-synthetic blend, polyalphaolefin (PAO), polyolester (POE), polyalkalene glycol (PAG) and/or any other substance reducing friction. Desirably, compatibility of a selected refrigerant and/or a lubricant package provides desired reliability and/or operability of the system.
The compressors and/or turbomachinery of this invention may include any suitable sealing design between a rotating shaft and a refrigerant-containing zone and/or chamber, such as packing glands, dry packing glands, lubricated packing glands, stuffing boxes, bellows seals, mechanical seals, double mechanical seals, wet mechanical seals, labyrinth seals, gas seals, dry gas seals, hermetic seals, semi-hermetic seals, welded enclosures, bolted enclosures, gasketed enclosures and/or any other suitable isolating design. Suitable packing materials may include polymers, elastomers, fluoropolymers, polyaramids, carbon materials and/or any other inert relatively flexible materials.
In one embodiment of this invention, the angle of the plate 62 is controlled by a high pressure refrigerant throttled through a control valve 70. As the control valve 70 is opened, a force applied by the high pressure refrigerant on the plate 62 is increased and the plate angle increases. The control valve 70 can be electronically controlled by a pulse-width modulated (PWM) signal, for example. This technique is in common use in modulating furnaces as the variable furnace control (VFC) may also include utilize PWM signals with control valves for natural gas flow applications, for example. Some features of the modulating cooling system of this invention are similar to features taught by Sigafus et al., U.S. Pat. No. 6,866,202, and by Sigafus et al., U.S. Pat. No. 7,293,718, the entire teachings of both commonly assigned patents are incorporated by reference into this specification.
Swashplate-type compressors are commonly used in automotive applications, such as available from several manufacturers including Denso, Toyota, Visteon, and Delphi. However, for use in the residential and commercial building applications of this invention, automobile swashplate compressors are insufficiently mechanically and fluidically efficient, and are thus unsuitable. The variable stroke compressors of this invention that incorporate swashplates have modified structures that include improved valve mechanisms, piston fit, coatings, oil return mechanisms, seals, reduced machined parting lines and gaskets; and drive connection and mounting changes, such as to facilitate mounting, and/or a fixed speed operation without a clutch mechanism, such as by a motor driver.
The variable stroke compressor of this invention may include any suitable number of cylinders, such as two, three, four, five, six, seven, eight, nine, ten, twelve and/or fifteen. In one embodiment, suitable variable displacement compressors of this invention have a capacity of six tons or less and may include an output from about 1 to about 225 cubic centimeters per revolution at operating speeds from about 500 to about 9000 rpm, for example. Fluid and/or refrigerant contamination may damage swashplate compressors and/or other compressors, so an optional refrigerant filter may also be desired.
As shown in FIG. 1, a compressor drive motor 52 is used for operating the compressor device 42. The compressor 42 of this invention may be driven, turned and/or rotated by any suitable devices, such as electric motors, AC motors, DC motors, synchronous motors, induction motors, single phase motors, 3-phase motors, multiphase motors, permanent split capacitor (PSC) motors, brushless DC motors, electrically commutated motors (ECM), switched reluctance motors (SRM), variable frequency drive (VFD) controlled motors, turbines, hydraulic turbines, gas turbines, expanders, engines, internal combustion engines and/or any other mechanical driver.
In one embodiment of this invention, the variable displacement compressor can be driven by a cost effective, efficient single-phase PSC motor with a fixed operating speed. Modulation can be achieved by the variable stroke design of a variable displacement compressor, allowing the motor run at an optimal operating state over the entire range of cooling output. Alternately, an inverter-driven three phase motor system, such as a VFD, can be used to drive the compressor.
The compressor drive motor of the modulating air conditioning system of this invention may include any suitable fixed and/or variable speed, such as about 1800 revolutions per minute (rpm), about 3250 rpm, about 3600 rpm, between about 0 rpm and about 10,000 rpm, between about 0 rpm and about 5,000 rpm and/or any other suitable value or range. Desirably, the compressor drive motor has a power output of about 5,222 watts (i.e., about seven horsepower) or less.
The compressor of this invention may be directly and/or indirectly coupled and/or combined with the drive motor by any suitable devices, such as unitary common drive shafts, rigid couplings, flexible couplings, fluid couplings, magnetic couplings, gearboxes, speed increasers, speed decreasers, belts with pulleys or sheaves and/or any other apparatus. In one embodiment of this invention and as shown in FIG. 4, the coupling includes a compressor input shaft adapter.
As shown in FIG. 1, the apparatus 40 also includes a condenser fan 54 and an evaporator fan 56. The condenser fan 54 and evaporator fan 56 of this invention may include any suitable air moving device, such as a fixed pitch fan, a variable pitch fan, a damper controlled fan, a multi-ducted fan assembly, a constant speed fan, a variable speed fan, a propeller, an impeller, a blower, an axial blower, a radial blower, a rotary lobe blower, an eductor, an ejector and/or any other suitable motive force. Forced draft, induced draft and/or combined draft configurations are possible. Desirably, the condenser fan 54 and/or the evaporator fan 56 is a modulating fan able to be varied in speed and/or blade pitch by a controller.
The condenser coil 44 shown in FIG. 1 may include any suitable heat transfer media and/or configurations, such as pipes, tubing, coils, extended surface heat transfer materials, finned tubing and/or any other thermally conducting and/or pressure containing equipment. In some embodiments of this invention, the tubing internally includes baffles or twisted ribbons, such as to create turbulent flow and/or improve heated transfer coefficients.
The condenser coil 44 of this invention may be fabricated by any suitable method, such as by welding, brazing, soldering, fusing, stamping, rolling, crimping, gasketing, gluing and/or any other technique to form and/or make a pressure containing conduit. The condenser coil 44 of this invention may include any suitable material of construction, such as metal, steel, copper, aluminum, alloy material, engineered plastic and/or any other thermally conducting material. Joints and/or connections may be permanent, semi-permanent and/or removable. Fittings, flanges, valves and/or any other suitable items may be included in the modulating air conditioning system, such as to facilitate start up, shut down, repair and/or operation. The evaporator coil 48 may include any of the characteristics and/or designs discussed above with respect to the condenser coil, and can be a modulating evaporator as discussed further below.
In some embodiments of this invention, the improved air conditioning system includes a variable displacement modulating compressor and/or fan control technology for variable cooling output levels. The modulating cooling apparatus of this invention can be a semi-hermetic electronically controlled variable stroke compressor. A controller and/or logic processor may regulate both an output of a variable stroke compressor and/or a speed of a condenser fan, for example. The controller may also interface with a variable furnace control, for example. The controller regulates the variable displacement compressor and/or regulates the blower or fan speed in relation to changing cooling demands of the heating ventilation and air conditioning (HVAC) system in real time, for example.
Benefits of this invention can include reducing and/or eliminating cycling of the compressor, dramatically reducing fan and/or compressor noise during partial load operation, eliminating hard starts of the air conditioner, providing continuous dehumidification, increasing system efficiency and/or increasing a seasonal effective energy efficiency ratio (SEER) rating of the system at all levels of operation.
In some embodiments of this invention, the modulating air conditioning system allows equivalent SEER and cooling output ratings, while reducing coil size. Reduced coil size lowers material costs and manufacturing labor charges.
The improved air conditioner of this invention desirably provides transparent and/or simple operation for HVAC installations by an end user, such as by utilizing one stage thermostats, two stage thermostats, available condenser coils, and/or available evaporator coils.
The modulating air conditioning apparatus of this invention includes any suitable capacity, such as a capacity of at least about one ton of refrigeration capacity, and more desirably between about 2-6 tons of refrigeration capacity, but can be used in applications having a capacity greater than 6 tons of refrigeration capacity. Series and/or parallel configurations are also possible to provide increased capacity, for example. As discussed above, the variable displacement compressor can operate at industry standard motor speeds, such as 1800 rpm, 3250 rpm, 3600 rpm and/or any other suitable rotational velocity.
The modulating air conditioning system of this invention may cool any residential or commercial building structure, such as residential buildings, industrial buildings, commercial buildings, tents, temporary structures, localized outside settings and/or any other suitable fixed edifice or stationary location.
In some embodiments of this invention, the modulating capabilities of the air conditioning system can be used interchangeably among an entire line of refrigeration equipment without any modification, such as for cooling a two-bedroom townhouse, a five-bedroom home and/or a restaurant. A soft limit and/or a value in the controller may regulate the compressor output to match and/or not exceed a coupled motor and/or driver rated output.
In some embodiments of this invention, the modulating air conditioning system meets and/or exceeds requirements and/or standards from the Department of Energy (DOE) for residential and/or commercial air conditioning equipment. A higher or increased SEER rating number indicates a more efficient system. The modulating air conditioner may have a SEER rating of at least about 13, desirably at least about 15, desirably at least about 20, more desirably at least about 25 and even more desirably at least about 30.
Improved SEER ratings may be achieved by replacing the conventional compressor and motor assembly with a more efficient unit. Conventional compressor and motor assemblies are a hermetically sealed as an integrated unit, undesirably requiring cutting and/or breaking refrigerant lines to change and/or replace the assembly, the compressor and/or the motor. There is significant cost and labor associated with compressor and/or motor replacement of a conventional system. In some embodiments of this invention, the motor can be replaced without cutting of the refrigerant lines, such as to allow replacement with a higher efficiency motor.
Another option to increase SEER rating is to replace the condenser coil with a larger sized coil, effectively reducing the size of the compressor relative to the coil. However, replacing the coil can be cost prohibitive and involve extensive retooling and/or manufacturing changes.
Alternately and in some embodiments of this invention, an improved SEER rating can be achieved by modulating the compressor and matching the cooling requirements of a space and/or a volume in real time and/or with minimal delay. If immediate cooling needs do not include the full system capacity, then modulating the compressor to reduce output results in a more efficient operating state and/or mode. In some embodiments of this invention, the variable displacement compressor and the corresponding driver assembly mount directly into an existing condensing unit to utilize existing thermostatic controls with modulation algorithms. Additional controls may be included, but desirably are not necessary for improved operation.
In some embodiments of this invention, the modulating air conditioning system provides constant dehumidification, even in low load conditions. Fan and/or compressor noise may be reduced in partial load states. Alternately, the condensing fan may shut off when outside conditions provide sufficient convective heat transfer, such as by a cool breeze. This convective heat transfer may also sometimes be referred to as gravity flow.
In some embodiments of this invention, the modulating air conditioning system provides a simple, transparent upgrade which is compatible with standard furnaces, existing evaporator coils, one-stage thermostats, two-stage thermostats, original equipment manufacturer (OEM) condenser coils and/or conventional fans. Furthermore, combining a modulating air conditioning system and a modulating furnace provides additional synergies, functionality and/or control.
In some embodiments of this invention, the modulating air conditioning system includes a compressor designed specifically for high efficiency cooling modulation in the HVAC industry. Benefits of a modulating cooling system may be considerably greater than those available in a modulating heating system. For example, modulating cooling offers the potential to double the efficiency over known state of the art systems for residential air conditioners with a SEER of 13. The high efficiency modulating air conditioning system of this invention may approach and/or exceed a SEER of 30.
In some embodiments of this invention, the modulating air conditioning and/or cooling system utilizes smaller and/or quieter equipment, while providing superior temperature and/or humidity control for the consumer and/or end user.
During past energy crisis situations some consumers removed inefficient but still operating and/or functioning cooling equipment to replace it with newer technology, if the energy saving benefits were sufficient. Additionally, growing “Green” legislation focused on energy efficient technology may further prompt equipment replacements. Modulating air conditioning and/or cooling systems can be inherently “Green” compared to conventional state of the art systems.
Modulating cooling systems of this invention can cut and/or reduce energy usage in half during the critical summer part of the year, for example. Modulating cooling systems of this invention may reduce greenhouse gases affecting climate change by using less electricity during peak load times and allowing carbon control and/or capture at central power plants.
In some embodiments of this invention, the modulating air conditioning system includes a reciprocating design without fixed frictional losses and an air-cooled motor. In some further embodiments of this invention, the electric motor for the compressor can be removed from the refrigerant path and utilize ambient air to cool the motor windings.
In some embodiments of the invention, the compressor drive motor is an air-cooled electric motor. The air-cooled electric motor is useful in the modulating air conditioning systems of this invention, but also can be used in conventional non-modulating systems to increase efficiency. The compressor motor can be any motor described herein, but is preferably a brushless DC motor or an electrically commutated motor. Likewise, the compressor can be a conventional compressor of a variable displacement compressor of this invention.
In the embodiment of FIG. 1, the compressor drive motor 52 is separate from and in operating combination with the compressor driveshaft 64. The motor 52 includes a motor driveshaft 55 that is detachably connected to the compressor driveshaft 64 to turn the compressor driveshaft 64. Conventional compressors include an integrated motor, that can be contained in a single sealed housing but more importantly is cooled by the refrigerant in the compressor and/or adjacent refrigerant line. In one embodiment of this invention, the separate, non-integrated compressor motor of this invention is not cooled by the refrigerant, and is instead cooled by air being moved over the motor.
The air-cooled compressor motor can be included in a single housing with the compressor, only separate from the refrigerant and including a mechanism, such as vent holes, to allow air to pass over the motor. However, more desirably, the motor is not housed with the compressor, such as shown in FIG. 5. FIG. 5 is a sectional view from above that illustrates a common conventional condensing unit modified to include the compressor and separate motor of this invention. As shown in FIG. 5, a compressor 80 is mounted with respect to a separate compressor drive motor 82 on a frame 84. A drive shaft 86 of the motor 82 is connected to a compressor drive shaft 88 by a shaft adapter 90, such as shown in FIG. 4.
A refrigerant flows through a refrigerant line 92, through accumulator 94, and to compressor 80. The refrigerant is compressed into the condenser 96. The condenser 96 includes a condenser fan, generally positioned at a top of the condensing unit, that draws air over the condenser coils 96. In this embodiment, the condenser fan also draws air over the motor 82, which in turn cools the motor.
Alternately, the condenser fan draws ambient air over the motor 96 that is at least partially separated from air passing through the condenser coils 96. A separate and/or alternate air path maybe provided, and can include a separate inlet, ductwork and/or shroud. The compressor motor may additionally or alternatively include an integral fan for cooling. In some embodiments of this invention, a separate fan and driver intermittently cool the compressor motor based on a temperature of the motor windings, such as detected by a thermocouple and/or a suitable device.
Open drive compressors, i.e., shaft or pulley driven compressors with the motor entirely separate from the refrigerant compressor assembly, with integrated air-cooled motors of this invention may replace conventional designs and eliminate system efficiency losses associated with conventional refrigerant-cooled motor windings, for example.
The air conditioning apparatus of this invention includes a controller for modulating the one or more modulating components such as the variable displacement compressor device, the compressor motor, a modulating expansion device, and/or a modulating evaporator device. In some embodiments of this invention, the compressor control assembly provides modulation with a combination of a variable speed motor control and a dynamically variable compressor control in an air-cooled system. The condenser and/or evaporator heat exchanger surface areas do not need to be grossly over-sized to achieve the improved efficiencies over conventional designs. The modulating design of this invention allows a reduced product size, lower material costs, lower production costs and/or reduced shipping charges.
FIGS. 6-13 each illustrate a modulating air conditioning apparatuses of this invention including a controller. As shown in FIG. 6 and in some embodiments of this invention, the modulating cooling system controller includes a logic and control board with a microprocessor memory, a compressor motor control and a compressor output control. The apparatus of FIG. 6 also includes a condensing unit with a semi-hermetic modulating compressor, an external motor, a condenser fan and a condensing heat exchanger. The apparatus of FIG. 6 also includes an evaporating unit with an evaporator and/or circulator fan and an evaporating heat exchanger. The apparatus of FIG. 6 also includes a mechanical expansion device, a contactor and the corresponding connections to the above identified items. The apparatus of FIG. 6 provides modulation by varying the compressor output.
As shown in FIG. 7 and in some embodiments of this invention, the modulating cooling system further includes condenser fan control based on liquid line subcooling. The apparatus of FIG. 7 includes components described with respect to FIG. 6 and further includes a condenser fan modulation control with a condenser fan output and a subcooling input, a liquid line temperature sensor, a liquid line pressure sensor and the corresponding connections to the above identified items. The apparatus of FIG. 7 provides modulation by both varying the compressor output and the condenser fan output. Desirably, the condenser fan control utilizes all the available surface area of the condensing heat exchanger, such as the last vapor bubble collapses at the exit of the condensing heat exchanger. Alternately, the apparatus of FIG. 7 subcools the refrigerant below the temperature for condensation.
As shown in FIG. 8 and in some embodiments of this invention, the modulating cooling system further includes evaporator fan control based on discharge air temperature. The apparatus of FIG. 8 includes components described with respect to FIG. 7 and further includes an evaporator fan control with an evaporator fan output and a temperature input, an evaporator discharge air temperature sensor and the corresponding connections to the above identified items. The apparatus of FIG. 8 provides modulation by varying the compressor output, the condenser fan output and the evaporator fan output. Desirably, the evaporator fan control maximizes and/or minimizes the evaporator discharge air temperature. Alternately, the apparatus of FIG. 8 maintains an evaporator discharge temperature at a set point by varying the evaporator fan output.
As shown in FIG. 9 and in some embodiments of this invention, the modulating cooling system includes expansion valve control and evaporator fan control based on a combination of suction line superheat and evaporator discharge temperature. The apparatus of FIG. 9 includes components described with respect to FIG. 7 and further includes an expansion valve and evaporator fan control with an evaporator fan output, a temperature input and an expansion valve output, an evaporator discharge air temperature sensor, a suction line temperature sensor, a suction line pressure sensor and the corresponding connections to the above identified items. The apparatus of FIG. 9 provides modulation by varying the compressor output, the condenser fan output, the evaporator fan output and the expansion valve output. Desirably, the expansion valve and evaporator fan control optimizes the pressure drop across the expansion valve, such as with respect to controlling a refrigerant phase change, and/or while controlling a discharge air temperature. Alternately, the apparatus of FIG. 9 seeks to utilize all the available surface area of the evaporating heat exchanger, such as the last liquid drop vaporizes at the exit of the evaporating heat exchanger.
As shown in FIG. 10 and in some embodiments of this invention, the modulating cooling system includes a multi-outlet and/or multi-path expansion valve connected with respect to a plurality of evaporating heat exchanger pathways. The apparatus of FIG. 10 provides modulation by varying the compressor output, the condenser fan output, the evaporator fan output, the expansion valve output and the different paths from the expansion valve. Desirably, the multi-outlet expansion valve allows use of less than all the evaporator coils and/or allows uses of different zones for increased efficiency and/or cooling of different areas. FIG. 11 illustrates an alternative embodiment, where the electronically controlled expansion valve of FIG. 9 is coupled with an electronically controlled distribution valve connected with respect to a plurality of evaporating heat exchanger pathways.
This invention also includes the refrigerant connections, electrical connections, control connections and/or other connections and/or relationships as shown in FIGS. 6-11. Other embodiments and/or arrangements of equipment are possible without departing from the scope of this invention. For example, FIG. 12 illustrates the apparatus of FIG. 11, only including a variable speed hermetically sealed compressor with an integrated motor. FIG. 13 illustrates another alternative of the apparatus of FIG. 11, including a single or two-stage hermetically sealed compressor and a mechanical expansion valve.
As discussed in FIGS. 10-13, the air conditioning apparatus of this invention can include a modulating evaporating device. FIGS. 14-18 illustrate exemplary modulating evaporating devices according to this invention.
FIG. 14 includes an evaporating device 100 for receiving the refrigerant from an expansion device. The evaporator device 100 includes an evaporator assembly 102 including a plurality of refrigerant distribution assemblies 104. The number, size and configuration of the refrigeration distribution assemblies can vary depending on need. Each of the refrigerant distribution assemblies includes a refrigerant distribution inlet 106 at a first end for receiving the refrigerant from the expansion device and a refrigerant distribution outlet 108 at a second end opposite the refrigeration distribution inlet 106. A manifold 110, such as a suction manifold line, can be used to connect the refrigerant distribution outlets 108 of each of the refrigerant distribution assemblies 104 to a means, such as a one or more suction refrigerant line, for transferring the refrigerant to a compressor of the air conditioning apparatus. In one embodiment of this invention, each of the refrigerant distribution assemblies 104 includes one or more evaporator coils 112 extending from the refrigerant distribution inlet 106 and to the refrigerant distribution outlet 108. Each assembly 104 is independent and not interconnected with other adjacent assemblies 104, thereby providing separate and independent evaporator coil zones.
In one embodiment of this invention, the modulation of the evaporator device 100 is provided by alternating a flow of the refrigerant between various combinations of the refrigerant distribution assemblies 104. For example, when a reduced cooling or humidity removal is needed, refrigerant flow through one or more of the assemblies 104 can be reduced or stopped, thereby effectively reducing the effective cooling surface area of the evaporator device 100 when evaporator fan 125 is operated to force ambient air, water, or a secondary refrigerant across evaporator assembly 102 to facilitate heat transfer.
In one embodiment of this invention, a restriction device is used to control the distribution of refrigerant between the evaporator coils zones. The restriction device can include a distribution valve in combination with a refrigerant distribution inlet 106. In FIG. 14, the restriction device is embodied as a distribution valve assembly 116 including a plurality of distribution valves 118 each in refrigerant delivering combination with one inlet 106. An electromechanical valve control assembly 120, such as or in combination with the system controller described above, can be used to open and close each valve 118 to increase or decrease the number of refrigeration distribution assemblies 104 receiving refrigerant. Each of the valves 118 operates independently of the other valves 118.
Distribution valve assembly 116 can be any type of device or assembly known by those skilled in the art designed to modify, restrict, or regulate flow of a heat transfer fluid, such as one or more needle valves, ball valves, solenoid plunger valves, or any other type of valve or combination of valves which can be used to regulate, redirect, or restrict the flow of a heat transfer fluid. For instance, distribution valve assembly 116 could be a series of rotary needle valves with a common shaft connecting to valve control assembly 120. Aforementioned valves may be positioned with varying offsets designed to reduce refrigerant flow to one or more discrete evaporator assemblies 104, while allowing other sections to maintain nominal flow. Valve assembly 116 may also include one or more ball valves, each controlled through a common linkage, or a rotating column or sphere with one or more inlet and outlet passages which align with one or more inlet and outlet ports in the valve body.
In one embodiment of this invention, as shown in FIG. 14, the restriction device can be a multi-outlet and/or multi-path expansion valve. Referring to FIG. 14, each of the valves 118 can be an expansion valve controlled by the electromechanical valve control assembly 120. FIG. 15 illustrates an alternative embodiment of the invention where a separate expansion device, embodied as expansion valve 122 is disposed upstream from the distribution valve assembly 116. The expansion valves of this invention can be a thermostatic expansion valve, an automatic expansion valve, a single orifice valve, or electronic expansion valve.
FIG. 16 illustrates an exemplary evaporator device 100 according to one embodiment of this invention. The evaporator device 100 includes a triangular evaporator assembly 102 including six refrigerant distribution assemblies or zones. A valve assembly 116 including three valves 118, with each valve 118 feeding two zones, is in combination the evaporator assembly 102 for modulating refrigerant through the evaporator assembly 102. A control assembly 120 is in communication with the valve assembly 116 for alternating the valve assembly between delivering the refrigerant to all or less than all of the evaporator coils 112.
FIG. 17 illustrates another embodiment of a restriction device according to this invention. In FIG. 17, two expansion valves are used in combination with the evaporator assembly 102. A first expansion valve 122 is in refrigerant delivering combination with a first one or plurality of refrigerant distribution assemblies 104. A second expansion valve 122′ is in refrigerant delivering combination with a second one or plurality of refrigerant distribution assemblies 104. Each of the expansion valves 122 and 122′ is preferably controlled by a dedicated electromechanical valve control assembly 120. FIG. 18 illustrates an alternative variation of the embodiment in FIG. 17. In FIG. 18, one of the two expansion valves, e.g., valve 122, is a primary mechanical expansion valve, such as a conventional expansion valve, and the other expansion valve 122′ is an electromechanical expansion valve, as shown in FIG. 17.
The modulating evaporator device of this invention, such as shown in FIGS. 14-18, allows for a modulating conditioning of air by modulating the flow of the refrigerant within the evaporating device. In this manner, only the portion of the air moving over the portion of the evaporator device including refrigerant is cooled. In another embodiment of this invention, the modulation can be obtained or assisted by reducing or stopping an air flow over a portion of the evaporator coils. The moving air can be isolated from portions of the evaporator coil by a damper, cover, or other method to restrict air flow, and preferably the refrigerant flow to those portions is halted, or redirected to other portions of the evaporator coil.
As discussed above, the modulating evaporator of this invention can also be used in combination with other modulating components discussed herein, such as the variable displacement compressor, which can be used to provide more or less compressed refrigerant depending on the number of evaporator coil zones to be used.
In some embodiments of this invention with a multi-outlet valve, different zones of the evaporator coil include a check valve and/or other suitable backflow preventing device. Alternately, individual control valves may be included on the inlet and/or outlet of the evaporator zone coils.
In some embodiments of this invention, a home and/or a building heat pump system, air conditioning system, dehumidification system and/or cooling system includes an apparatus for controlling refrigerant distribution and/or expansion, the apparatus includes a compressor, a condenser coil, an expansion and distribution device, an evaporator coil, and corresponding and/or applicable wiring, tubing and/or piping adapted to connect the components and provide communication between the components. The apparatus of this invention can include refrigerant distribution tubes, pipes, channels, conduits, headers, and/or manifolds connected to discrete sections of the evaporator coil, such as to allow modulating based on refrigeration load. Each refrigerant distribution tube can include a restriction device installed to restrict and/or regulate a flow of refrigerant through the corresponding refrigerant distribution tube. Suitable restriction devices include valves, control valves, thermostatic valves, expansion valves, orifices, multiple hole orifices, variable open area orifices, multiple-outlet valves and/or any other flow controlling device. The orifice may include a plate and/or a part with one or more bores, holes and/or passages.
In some embodiments of this invention, the orifices and/or passages of the restriction device may provide both refrigerant direction and expansion characteristics and/or features using one assembly. In other embodiments of this invention, a first device provides expansion of the refrigerant, such as by Joule-Thomson effect and a second device and/or devices provide direction and/or distribution of refrigerant flow. The second device may be after and/or downstream of the first device, for example.
Joule-Thomson effect and/or Joule-Kelvin effect describes the increase and/or decrease in the temperature of a real gas when it is allowed to expand freely at constant enthalpy, such as that no heat transfers to and/or from the gas and no external work is extracted. Alternately, a turbo expander may recover work from the refrigerant while lowering a pressure from an inlet pressure to an outlet pressure, for example.
The air conditioning apparatus may include an expansion valve to expose one or more evaporator tubes to an input side and/or upstream side of the expansion valve. In some embodiments of this invention, the input side of the expansion valve connects through a tube and/or a fitting to a refrigerant circuit and/or loop. The expansion valve may include two or more fittings attached to the evaporator coil for supplying refrigerant to the evaporator coil and/or corresponding bank or sections of the evaporator coil.
In some embodiments of this invention, the refrigerant distributes to corresponding discrete sections of the evaporator coil by controlling the restriction exposure, such as with a multi-outlet valve. Desirably, but not necessarily, the multi-outlet valve simultaneously controls expansion of the refrigerant and/or flow of the refrigerant through the evaporator coils and/or sections of the evaporator coils. Alternately, the multi-outlet valve includes flow direction and flow throttling features.
In some embodiments of this invention, control of the refrigerant flow maintains a sufficient velocity and/or mass flow with respect to an effective cross sectional area of a utilized section of the evaporator coils and/or condenser coils, such as to provide sufficient oil return and/or improve heat transfer by reducing oil film. Desirably, the refrigerant flow is controlled in a way to increase refrigerant velocity through the coil so an oil return process remains consistent with the other levels of operation regardless of turndown, for example. According to another embodiment of this invention, a separate lubrication unit with a separate oil pump and/or driver operates to supply adequate lubrication to the air conditioning system and/or the compressor independent of operating rate.
In some embodiments of this invention, the modulating cooling system includes selective evaporator coil defrosting and de-icing, such as allowing one bank to warm to ambient conditions with and/or without a condenser fan circulating air, while a second evaporator bank provides and/or meets a needed refrigeration load capacity. Additional heat sources may assist in deicing procedures. The above features of a zoned evaporator may also be applied to a zoned condenser, such as to allow for deicing and/or thawing of frosted coils.
In some embodiments of this invention, a thermostatic expansion valve, an automatic expansion valve, a single orifice and/or an electronic expansion valve controls refrigerant expansion and a separate multi-outlet valve assembly serves as a distribution device, such as to multiple evaporator coils.
In one embodiments of this invention, such as shown in FIG. 19, a expansion valve 122, such as a thermostatic expansion valve, an automatic expansion valve, a single orifice and/or an electronic expansion valve controls refrigerant expansion, while a valve or series of valves 124, connected by a saturated vapor line manifold 126 in FIG. 19, are used to selectively distribute refrigerant to one or more areas or banks of the evaporator device. Suitable valves 124 include solenoid valves, ball valves, needle valves, diverter valves, or any other valve or device which may be used to redirect, restrict or stop the flow of refrigerant. Furthermore, these valves may be operated in such a way as to alternate or cycle between different areas and/or banks of the evaporator coil on a timed, controlled, or random basis. This cycling process can be used to control the latent and sensible heat loads on the evaporator or specific areas of the evaporator.
A method of operating the air conditioning system of this invention may include diverting refrigerant to one and/or more discrete areas and/or banks of the evaporator coil, leaving other areas and/or banks of the evaporator coil free of refrigerant flow and/or essentially free of refrigerant. Alternately, non-flowing areas and/or banks of the evaporator coils remain filled with refrigerant, such as in a liquid and/or a vapor state.
The method of operating the air conditioning system of this invention may further include isolating portions of the evaporator coil from a circulator and/or evaporator fan air flow by a damper, a cover, and/or any other suitable device to restrict air flow. Desirably, the refrigerant flow to isolated portions of the evaporator coil stops, halts and/or redirects to other portions of the evaporator coil. The evaporator coil can by made up of several discrete coils and each coil can include one or more refrigerant paths.
In some embodiments of this invention, a home and/or building heat pump and/or air conditioning system provides modulation of the air conditioning system by controlling refrigerant distribution and/or expansion. The air conditioning system includes a compressor, a condenser coil, an expansion and/or distribution device, an evaporator coil and/or applicable and/or corresponding wiring, tubing and/or piping to connect components of the air conditioning system. The modulating air conditioning system may include a motor that is physically separated from the compressor, such as including a separate motor shaft and a separate compressor shaft. Desirably, the compressor is directly coupled the motor, such as without any change in speed and/or gearing. The air conditioning system may further include a device for receiving a modulating signal, such as from a controller to modulate the motor and/or the compressor while providing variable refrigeration capacity and/or output for the air conditioning system.
The modulation of the air conditioning system may include any suitable continuous and/or discrete amounts and/or increments over suitable operating ranges and/or parameters. In some embodiments of this invention, modulation includes and/or is defined as three or more distinct and/or discrete operating levels and/or speeds other than zero. Any suitable number of operating levels is possible.
In some embodiments of this invention, the compressor includes a variable displacement compressor, such as a variable swashplate compressor and/or a scroll compressor. The motor driver for the compressor may include a brushless DC motor and/or an electrically commutated motor. In some other embodiments of this invention, a single speed motor drives the variable displacement compressor and modulation can be achieved with the variable displacement compressor. Desirably, the compressor motor can be cooled by outside air, such as to remove a motor coil heat loading from the refrigeration loading and the SEER calculation. Alternately, the compressor includes a swashplate compressor with an external motor and/or a scroll compressor with an external motor.
Desirably, a method of controlling the modulating air conditioning system of this invention includes a control scheme and/or system to maximize dehumidification during the air conditioning cycle, for example.
In some embodiments of this invention, a control scheme uses pre-defined and/or preset values and/or functions for a compressor output, an expansion valve pressure drop and/or an orifice open area. The compressor output may be controlled in response to and/or based on a thermostat algorithm and/or a separate controller. The expansion valve may be controlled to provide the most efficient operating mode of the system, such as for system dehumidification at an evaporator coil by regulating the evaporator coil temperature based on a combination of compressor output and/or expansion pressure drop. Desirably, a relationship between the temperature of the evaporator coil, the compressor output and the expansion valve pressure drop can be used to determine and/or control the evaporator coil temperature.
In some embodiments of this invention, the air conditioning system regulates evaporator coil superheat so liquid refrigerant does not escape and/or exit the evaporator coil before a change in state, such as to a vapor and/or a gas. Alternately, the air conditioning system regulates evaporator coil superheat so the evaporator coil remains filled with liquid refrigerant.
In some embodiments of this invention, a system temperature is controlled by a dew point and/or humidity sensor and/or probe. Alternately, other psychrometric parameters and/or measures can be used to control the air conditioning system. Psychrometrics and/or psychrometry includes the field of engineering concerned with the determination of physical and thermodynamic properties of gas-vapor mixtures. Alternately, the air conditioning system can be controlled by a temperature sensor configured to identify a dew point temperature, such as in a living space.
In some embodiments of this invention, the air conditioning system includes a shell and/or a cover welded and/or sealed around the compressor to prevent refrigerant leaks. The shell may include two or more pieces to at least partially surround the compressor and/or the driver.
The compressor and the motor may be mechanically connected and/or coupled in any suitable manner. The compressor and the motor may be sealed in any suitable manner, such as to prevent refrigerant leaks. In some embodiments of this invention, an adapter connects the motor to the compressor.
Any suitable control system may modulate the compressor, such as a hard wired circuit, an integrated circuit, a programmable logic controller (PLC) with ladder logic, a central processor unit with software instructions and/or any other comparator or decision making device.
In some embodiments of this invention, a sequence and/or order of modulation includes any suitable order, such as optimizing the expansion device, the compressor, the condenser fan and the evaporator fan, for example.

EXAMPLES

Example 1

A computer simulation showed the benefits of a modulating compressor design in an air conditioning system. A simulation was written in the Engineer Equation Solver compiler to accurately model the operation of a reciprocating compressor at different speeds and compression ratios. In the simulation, the compressor powered a refrigeration cycle with a variety of refrigerant types, air temperatures, coil heat transfer coefficients, coil sizes, fan speeds and/or expansion pressure drops. This simulation was developed to test and/or compare modulating air conditioning system designs to conventional systems.
A set of experimental parameters were refined to include air conditioning systems ranging from 2.5 to 3 tons of refrigeration capacity, with an indoor temperature of 70 degrees Fahrenheit (21.1 degrees Celsius) and an outdoor temperature of 80 degrees Fahrenheit (26.7 degrees Celsius). The coil sizes, heat transfer coefficients, compressor speed, compression ratio, physical geometry and air flow velocity were derived from a standard model conventional air conditioning system with a SEER of 12. During the simulation, the compressor modulation level was adjusted from 10 percent to 100 percent capacity and the results were charted versus the instantaneous SEER and the power consumption of the system, as shown in FIG. 20. The simulation showed at a 30 percent modulation level, the air conditioning system achieved its highest efficiency and a SEER increase of over three points. The SEER increased from 11 to 14.3 for an increase of 30 percent over a conventional air conditioning system.

Example 2

A variable displacement modulating air conditioner was fabricated and used for testing. A Denso 7SEU16C swashplate compressor was mounted on a test platform and was driven by a 5 HP Dayton motor with a variable speed pulley drive. The compressor was controlled by a Labview console developed specifically for the modulating air conditioner test. The test included refrigerant compatibility, oil compatibility, power requirements, system state temperatures, system state pressures and/or control response.
Initial testing was performed on an R-22 based system, with a mineral oil lubricant having a light viscosity. The test was conducted with rubber quick-disconnect hose and suction line filters. After satisfactory results were achieved on the variable speed test platform, a direct coupling from the motor to the compressor was engineered and machined. The compressor utilized a screw-on pulley with a set screw on the attaching hub. A converting shaft replaced the pulley with a ⅝″ keyed shaft attached directly to the motor by a rubberized power coupling. The direct drive provided nearly silent operation at no-load conditions. Further testing utilized a customized compressor driveshaft as shown in FIG. 21, designed to replace the existing internal driveshaft while providing a keyed drive suitable for mounting of a pulley sheave, or direct drive coupling.
Further testing includes using a smaller welded base to allow the entire motor-compressor assembly to be mounted inside an existing condenser cabinet and both R-22 and R-410 refrigerant varieties. Additional and/or expanded experimental variables may include mass flow, crankcase pressures, condenser fan mass air flow, blower fan mass air flow, water removal volume and/or dehumidification percentage. Particularly, test procedures may include SEER ratings and efficiency over comparable conventional units and/or compressor types.
It will be appreciated that details of the foregoing embodiments, given for purposes of illustration, are not to be construed as limiting the scope of this invention. Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible based at least in part on the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention, which is defined in this specification and all equivalents thereto. Further, it is recognized that many embodiments may be conceived that do not achieve all of the advantages of some embodiments, particularly of the preferred embodiments, yet the absence of a particular advantage shall not be construed to necessarily mean that such an embodiment is outside the scope of the present invention.

Claims

1. An air conditioning apparatus for a residential or commercial building and including as components a compressor, a condenser coil, an expansion device, and an evaporator coil, the apparatus comprising:

a modulating refrigerant distribution and/or expansion device selected from a group consisting of a variable displacement compressor device, a modulating expansion device, a modulating evaporator device, and combinations thereof; and

a controller for modulating the at least one modulating refrigerant distribution and/or expansion device.

2. The apparatus according to claim 1, further comprising at least one of a modulating condenser fan or a modulating evaporator fan.

3. The apparatus according to claim 1, further comprising a variable stroke compressor as the variable displacement compressor device.

4. The apparatus according to claim 3, wherein the variable displacement compressor device has a capacity of less than six tons.

5. The apparatus according to claim 3, further comprising a motor for operating the compressor device, wherein the motor is cooled by air moving over the motor.

6. The apparatus according to claim 5, wherein the motor is detachably connected to the compressor unit and not cooled by the refrigerant.

7. The apparatus according to claim 1, further comprising the modulating evaporator device including more than one evaporator coil zone and a restriction device for each of the more than one evaporator coil zone, wherein each restriction device restricts and/or regulates a flow of refrigerant to a corresponding evaporator coil zone.

8. The apparatus according to claim 7, wherein the controller operates the restriction device of each of the more than one evaporator coil zone.

9. The apparatus according to claim 1, further comprising the modulating expansion device including more than one expansion valve.

10. An air conditioning apparatus for a residential or commercial building, the apparatus comprising:

a compressor device for receiving and compressing a refrigerant; and

a motor for operating the compressor device, wherein the motor is air-cooled;

wherein the compressor device has a capacity of less than six tons or the motor has a power output of about 5,222 watts or less.

11. The device according to claim 10, wherein the motor is detachably connected to the compressor unit and not cooled by the refrigerant.

12. The device according to claim 11, wherein the motor comprises a motor driveshaft, the compressor device comprises a compressor driveshaft, and the motor driveshaft is separate from and in operating combination with the compressor driveshaft.

13. The device according to claim 10, wherein the motor comprises a brushless DC motor or an electrically commutated motor.

14. The device according to claim 10, wherein the compressor comprises a variable displacement compressor.

15. The device according to claim 14, wherein the motor comprises a single speed motor.

16. The device according to claim 14, further comprising a controller for modulating at least one of the variable displacement compressor or a speed of the motor.

17. A method of conditioning air for a residential or commercial building, the method comprising:

modulating a compressing of a refrigerant in a compressor;

condensing the compressed refrigerant within a condenser;

running the condensed refrigerant through an expansion device to cool the refrigerant;

absorbing heat from the residential or commercial building with the cooled refrigerant within an evaporator device;

modulating a flow of the refrigerant through the expansion device and/or the evaporator device; and

returning the heated refrigerant gas to the compressor.

18. The method according to claim 17, wherein the compressor comprises a variable displacement compressor.

19. The method according to claim 17, further comprising modulating a pressure drop of the refrigerant at the expansion device.

20. The method according to claim 17, wherein the evaporator device comprises more than one evaporator coil zone and further comprising reducing or stopping for a time period a flow of refrigerant from one of the more than one evaporator coil zone.

21. The method according to claim 17, further comprising reducing or stopping an air flow over a portion of the evaporator device.