US20060064997A1 - Cooling systems - Google Patents
Cooling systems Download PDFInfo
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- US20060064997A1 US20060064997A1 US10/954,499 US95449904A US2006064997A1 US 20060064997 A1 US20060064997 A1 US 20060064997A1 US 95449904 A US95449904 A US 95449904A US 2006064997 A1 US2006064997 A1 US 2006064997A1
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- Prior art keywords
- evaporator
- expansion device
- heat exchanger
- refrigerant
- flow
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/13—Economisers
Definitions
- the invention relates to cooling systems. More particularly, the invention relates to the control of refrigerant phase in evaporators of air conditioning and refrigeration systems.
- a particular area of emphasis has been the engineering of distributor systems.
- a distributor receives two-phase refrigerant from the expansion device and provides balanced delivery of liquid and gas refrigerant phases among the various coils of an evaporator so as to prevent uneven performance.
- Various types of distributors have been developed. These include capillary-type distributors and impingement/turbulence distributors. Exemplary distributors are shown in U.S. Pat. Nos. 2,148,414, 2,461,876, 3,795,259, 4,543,802, 5,832,744, and 5,842351, EP 0160542, and JP 5-322378 and 10-185363.
- One aspect of the invention involves an apparatus including a compressor having suction and discharge ports, a condenser, first and second expansion devices, an evaporator, and a heat exchanger having first and second portions in heat exchange relation with each other.
- One or more conduits form a main flowpath and a bypass flowpath.
- the main flowpath runs from the discharge port through the condenser, the heat exchanger first portion, the first expansion device, and the evaporator, and returns to the suction port.
- the bypass flowpath bypasses the heat exchanger first portion, the first expansion device, and the evaporator, but passes through the second expansion device and the heat exchanger second portion.
- the evaporator may lack a distributor.
- the second expansion device may be a TXV having a bulb essentially in heat exchange relation with a suction port condition.
- the second expansion device may be an EXV.
- a controller may be coupled to the EXV and programmed to control the EXV responsive to indicated superheat.
- the heat exchanger first portion may be downstream of the condenser and upstream of the evaporator along the main flowpath.
- the heat exchanger second portion may be downstream of the condenser along the bypass flowpath.
- the heat exchanger first portion may be upstream of the first expansion device along the main flowpath.
- the evaporator may be a refrigerant-to-air heat exchanger.
- a bypass flow along the bypass flowpath may enter the heat exchanger second portion in a two-phase gas/liquid condition and exit the heat exchanger second portion in a single-phase superheated gas condition.
- a main flow along the main flowpath may remain essentially a single-phase liquid in said heat exchanger second portion.
- the compressor may be selected from the group consisting of screw compressors and scroll compressors.
- Another aspect of the invention involves a method for operating such an apparatus. At least one operational parameter is detected. Responsive to the detection, at least the second expansion device is operated so as to maintain essentially single-phase liquid refrigerant entering the evaporator along the main flowpath.
- the at least one operational parameter may include at least one of saturated suction temperature and actual suction temperature.
- Another aspect of the invention involves a method for operating a cooling system.
- a main flow of refrigerant is caused to pass through an evaporator.
- the main flow is precooled upstream of the evaporator so as to maintain the main flow essentially as a liquid entering the evaporator.
- the precooling may comprise controlling a bypass flow in heat exchange relation with the main flow.
- the method may further comprise determining whether, absent the precooling, the main flow would enter the evaporator essentially as a two-phase flow.
- Another aspect of the invention involves a system comprising a compressor, a condenser, an expansion device, and an evaporator, a discharge line couples the compressor to the condenser to carry at least a main flow of refrigerant from the compressor to the condenser.
- a suction line couples the evaporator to the compressor to carry refrigerant from the condenser to the compressor.
- the system includes means for precooling refrigerant entering the expansion device so as to maintain the main flow essentially as a liquid while flowing along a flowpath length at least from the expansion device to the evaporator.
- the evaporator may lack a distributor.
- the main flow may transition to a two-phase liquid/gas flow and then to a one-phase superheated gas flow.
- the bypass flow may represent 10 %- 35 %, by weight, of a total refrigerant flow through the compressor.
- FIG. 1 is a schematic representation of a refrigeration or air conditioning system employing the present invention.
- FIG. 2 is a phase diagram for a prior art system.
- FIG. 3 is a phase diagram for the system of FIG. 1 .
- FIG. 1 shows an exemplary closed refrigeration or air conditioning system 10 .
- the system 10 has a hermetic compressor 12 , from which a compressor discharge conduit or line 14 extends downstream to a condenser 16 .
- An intermediate line 18 extends downstream from the condenser 16 to an expansion device 20 and an evaporator 22 .
- a suction line 24 extends downstream from the evaporator 22 to the compressor 12 to complete the main circuit/flowpath 26 .
- a bypass line 30 branches off from the intermediate line 18 and contains an auxiliary expansion device 32 and connects with the suction line 24 .
- a heat exchanger 34 is located such that the bypass line 30 , downstream of the expansion device 32 , and the line 18 , upstream of the main expansion device 20 , are in heat exchange relationship.
- the exemplary evaporator 22 is a cross-flow refrigerant-to-air heat exchanger having a number of parallel refrigerant coils 36 extending from inlet ends at a liquid collector or manifold 38 to outlet ends at a suction collector or manifold 40 .
- a fan 42 drives an airflow 44 across the coils 36 so that the refrigerant passing through the coils may draw heat from the airflow.
- Exemplary expansion devices 20 and 32 are electronic expansion valves (EEVs) and are illustrated as coupled to a monitoring/control system 44 (e.g., a microprocessor-based controller) for receiving control inputs via control lines 45 and 46 , respectively.
- the exemplary control system 44 may receive inputs such as zone inputs from one or more sensors 47 , system condition inputs from one or more sensors (e.g., suction temperature sensor 50 and suction pressure sensor 52 ), and external control inputs from one or more input devices (e.g., thermostats 60 ).
- any of a variety of expansion devices may be used (e.g., a thermal expansion valve (TXV) 32 having a remote bulb 70 , a fixed orifice device, or a capillary tube device).
- TXV thermal expansion valve
- FIG. 2 shows pressure 100 and enthalpy 102 for the refrigerant flow in such a basic system (or the present system with no bypass flow).
- a boundary 104 separates a two-phase gas/liquid mixture domain 106 from a single phase sub-cooled liquid domain 108 and a single phase superheated gas domain 110 .
- Suction conditions are shown as point or condition 120 at enthalpy 122 and pressure 124 . These conditions are essentially present in the flowpath downstream from the suction manifold 40 to the compressor suction port.
- the refrigerant is compressed (plot compression segment 125 ) in the compressor 12 to a compressed point 126 with increased enthalpy 128 and increased pressure 130 .
- the refrigerant may typically remain in the superheated gas domain 110 or may transition thereto from the two-phase domain 106 .
- the refrigerant is condensed (condensing segment 131 ) in the condenser 16 to a condensed point 132 with reduced enthalpy 134 but at the same pressure as the compressed/discharge condition.
- the refrigerant state may transition from the superheated gas domain 110 to the two-phase domain 106 and even into the sub-cooled liquid domain 108 .
- the refrigerant is expanded (expansion segment 135 ) in the expansion device 34 to an expanded point 136 with decreased pressure 138 .
- enthalpy may remain essentially constant at 134 .
- the refrigerant may reenter or remain in the two-phase domain 106 during the expansion 135 .
- This expanded two-phase refrigerant must enter the evaporator.
- the refrigerant is evaporated (evaporation segment 139 ) in the evaporator to return to the suction point 120 with substantially increased enthalpy and slightly decreased pressure relative to the expanded point 136 .
- the presence of the expanded point 136 in the two-phase domain 106 presents substantial problems. With two-phase refrigerant entering the evaporator, it becomes difficult to balance the refrigerant across the evaporator coils. Namely, otherwise similar coils may see different total amounts of refrigerant and/or different ratios of the two phases. This can produce substantially different coil conditions amongst the various coils. The coils with higher amounts of refrigerant and higher relative amounts of liquid may overcool so as to produce excessive frost buildup. Overall efficiency may be reduced. Accordingly, it is known to use complicated distributor arrangements in place of the liquid manifold 38 to balance the ratios among the different coils. Distributors tend to be expensive.
- the point 136 under ambient conditions that would otherwise cause the point 136 to be in the two-phase domain 106 , it would be desirable to shift the point 136 into the single phase liquid domain 108 eliminating the need for a distributor.
- the single-phase liquid inlet flow to the evaporator could readily be separated into similar flows for each coil.
- the coils could be designed/configured for operating with such an input flow.
- FIG. 3 shows how the bypass flow of the present invention may be utilized to achieve advantageous refrigerant conditions entering the evaporator 22 .
- the suction condition/point 220 may be essentially the same as point 120 of FIG. 2 .
- the compressed/discharge/point 226 may be similar to the point 126 of FIG. 2 .
- the condensing 231 brings the combined main flow and bypass flow to a condensed/point 232 which may be similar to point 132 .
- the bypass flow splits from the main flow.
- the bypass flow refrigerant is expanded (segment 233 ) to reach a point 234 which may be essentially at the suction pressure 124 and the enthalpy 134 .
- Heat exchange ( 235 for the bypass flow and 236 for the main flow) from the main flow to the bypass flow in the heat exchanger 34 then returns the bypass flow conditions to point 220 and cools the main flow to a precooled/point 238 with further reduced main flow enthalpy 240 .
- the main flow of refrigerant is expanded (segment 241 ) in the expansion device 20 to a point 242 with decreased pressure 244 (which may be essentially the same as 138 ).
- the main flow of refrigerant is evaporated (segment 245 ) in the evaporator 22 to return the main flow to the initial suction point 220 .
- the heat exchange from the bypass flow to the main flow tends to shift the point 242 to a lower enthalpy condition.
- the required amount of heat exchange may depend upon ambient conditions.
- a basic operation of the expansion device 32 may be responsive to sensed superheat of the refrigerant exiting the evaporator 22 .
- the degree of superheat (actual temperature minus saturated temperature) may be determined based upon the output of the temperature sensor 50 for the actual temperature and the pressure sensor 52 for the saturated temperature (e.g., in view of known refrigerant properties which may be programmed into the control system 44 ).
- the expansion device 32 may be opened either in a binary fashion or a progressive fashion in response to the presence or degree of superheat or superheat parameter (e.g., superheat above a threshold).
- control could be achieved by placing its bulb 70 in heat exchange relation with the refrigerant at suction conditions. Much more complex arrangements are also possible.
- the expansion device 32 and/or other components of the bypass flowpath may be dimensioned in view of main flowpath components to permit an appropriate balance between bypass and non-bypass flows.
- an exemplary balance involves having the bypass flow be approximately 30 % of the total flow through the compressor (i.e., 3/7 of the non-bypass flow) by weight/mass.
- Broader exemplary figures for binary operation are 25%-33%, and 10%-35%.
- Progressive or stepwise operation may permit maximums in such ranges and may, optionally, permit flows smaller than the lower ends of such ranges.
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- Physics & Mathematics (AREA)
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- Air Conditioning Control Device (AREA)
Abstract
An apparatus has a compressor having suction and discharge ports. One or more conduits form a main flowpath from the discharge port through a condenser, a heat exchanger first leg, a first expansion device, and an evaporator to return to the suction port. The conduits also form a bypass flowpath bypassing the heat exchanger first leg, the first expansion device, and the evaporator but passing through a second leg of the heat exchanger in heat exchange relation with the first leg.
Description
- The invention relates to cooling systems. More particularly, the invention relates to the control of refrigerant phase in evaporators of air conditioning and refrigeration systems.
- Many engineering considerations attend the design and operation of closed air conditioning and refrigeration systems. Among these are a variety of efficiency and other considerations attendant to evaporator operation. Proper evaporator operation is important for obtaining efficient and reliable system operation. Considerations include the handling of refrigerant and the management of heat transfer. Among problems that must be managed is excessive icing as this may interfere with heat transfer. Accordingly, much effort has gone into evaporator design and engineering.
- A particular area of emphasis has been the engineering of distributor systems. A distributor receives two-phase refrigerant from the expansion device and provides balanced delivery of liquid and gas refrigerant phases among the various coils of an evaporator so as to prevent uneven performance. Various types of distributors have been developed. These include capillary-type distributors and impingement/turbulence distributors. Exemplary distributors are shown in U.S. Pat. Nos. 2,148,414, 2,461,876, 3,795,259, 4,543,802, 5,832,744, and 5,842351, EP 0160542, and JP 5-322378 and 10-185363.
- Nevertheless there remains room for further improvement in the art.
- One aspect of the invention involves an apparatus including a compressor having suction and discharge ports, a condenser, first and second expansion devices, an evaporator, and a heat exchanger having first and second portions in heat exchange relation with each other. One or more conduits form a main flowpath and a bypass flowpath. The main flowpath runs from the discharge port through the condenser, the heat exchanger first portion, the first expansion device, and the evaporator, and returns to the suction port. The bypass flowpath bypasses the heat exchanger first portion, the first expansion device, and the evaporator, but passes through the second expansion device and the heat exchanger second portion.
- In various implementations, the evaporator may lack a distributor. The second expansion device may be a TXV having a bulb essentially in heat exchange relation with a suction port condition. The second expansion device may be an EXV. A controller may be coupled to the EXV and programmed to control the EXV responsive to indicated superheat. The heat exchanger first portion may be downstream of the condenser and upstream of the evaporator along the main flowpath. The heat exchanger second portion may be downstream of the condenser along the bypass flowpath. The heat exchanger first portion may be upstream of the first expansion device along the main flowpath. The evaporator may be a refrigerant-to-air heat exchanger. In at least a bypass mode, a bypass flow along the bypass flowpath may enter the heat exchanger second portion in a two-phase gas/liquid condition and exit the heat exchanger second portion in a single-phase superheated gas condition. In the bypass mode, a main flow along the main flowpath may remain essentially a single-phase liquid in said heat exchanger second portion. The compressor may be selected from the group consisting of screw compressors and scroll compressors.
- Another aspect of the invention involves a method for operating such an apparatus. At least one operational parameter is detected. Responsive to the detection, at least the second expansion device is operated so as to maintain essentially single-phase liquid refrigerant entering the evaporator along the main flowpath. The at least one operational parameter may include at least one of saturated suction temperature and actual suction temperature.
- Another aspect of the invention involves a method for operating a cooling system. A main flow of refrigerant is caused to pass through an evaporator. The main flow is precooled upstream of the evaporator so as to maintain the main flow essentially as a liquid entering the evaporator. The precooling may comprise controlling a bypass flow in heat exchange relation with the main flow. The method may further comprise determining whether, absent the precooling, the main flow would enter the evaporator essentially as a two-phase flow.
- Another aspect of the invention involves a system comprising a compressor, a condenser, an expansion device, and an evaporator, a discharge line couples the compressor to the condenser to carry at least a main flow of refrigerant from the compressor to the condenser. A suction line couples the evaporator to the compressor to carry refrigerant from the condenser to the compressor. The system includes means for precooling refrigerant entering the expansion device so as to maintain the main flow essentially as a liquid while flowing along a flowpath length at least from the expansion device to the evaporator.
- In various implementations, the evaporator may lack a distributor. Within the evaporator, the main flow may transition to a two-phase liquid/gas flow and then to a one-phase superheated gas flow. The bypass flow may represent 10%-35%, by weight, of a total refrigerant flow through the compressor.
- The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
-
FIG. 1 is a schematic representation of a refrigeration or air conditioning system employing the present invention. -
FIG. 2 is a phase diagram for a prior art system. -
FIG. 3 is a phase diagram for the system ofFIG. 1 . - Like reference numbers and designations in the various drawings indicate like elements.
-
FIG. 1 , shows an exemplary closed refrigeration orair conditioning system 10. Thesystem 10 has ahermetic compressor 12, from which a compressor discharge conduit orline 14 extends downstream to acondenser 16. Anintermediate line 18 extends downstream from thecondenser 16 to anexpansion device 20 and an evaporator 22. Asuction line 24 extends downstream from the evaporator 22 to thecompressor 12 to complete the main circuit/flowpath 26. - To form a bypass circuit/flowpath 28, a
bypass line 30 branches off from theintermediate line 18 and contains anauxiliary expansion device 32 and connects with thesuction line 24. Aheat exchanger 34 is located such that thebypass line 30, downstream of theexpansion device 32, and theline 18, upstream of themain expansion device 20, are in heat exchange relationship. - The exemplary evaporator 22 is a cross-flow refrigerant-to-air heat exchanger having a number of
parallel refrigerant coils 36 extending from inlet ends at a liquid collector ormanifold 38 to outlet ends at a suction collector ormanifold 40. Afan 42 drives anairflow 44 across thecoils 36 so that the refrigerant passing through the coils may draw heat from the airflow. -
Exemplary expansion devices control lines exemplary control system 44 may receive inputs such as zone inputs from one or more sensors 47, system condition inputs from one or more sensors (e.g.,suction temperature sensor 50 and suction pressure sensor 52), and external control inputs from one or more input devices (e.g., thermostats 60). - Alternatively to the EEVs, any of a variety of expansion devices may be used (e.g., a thermal expansion valve (TXV) 32 having a
remote bulb 70, a fixed orifice device, or a capillary tube device). - A basic prior art system would lack the bypass flowpath 28 and
heat exchanger 34.FIG. 2 showspressure 100 andenthalpy 102 for the refrigerant flow in such a basic system (or the present system with no bypass flow). Aboundary 104 separates a two-phase gas/liquid mixture domain 106 from a single phase sub-cooledliquid domain 108 and a single phasesuperheated gas domain 110. Suction conditions are shown as point orcondition 120 atenthalpy 122 andpressure 124. These conditions are essentially present in the flowpath downstream from thesuction manifold 40 to the compressor suction port. The refrigerant is compressed (plot compression segment 125) in thecompressor 12 to acompressed point 126 with increasedenthalpy 128 and increasedpressure 130. During thecompression 125, the refrigerant may typically remain in thesuperheated gas domain 110 or may transition thereto from the two-phase domain 106. The refrigerant is condensed (condensing segment 131) in thecondenser 16 to acondensed point 132 with reducedenthalpy 134 but at the same pressure as the compressed/discharge condition. During the condensing 131, the refrigerant state may transition from thesuperheated gas domain 110 to the two-phase domain 106 and even into the sub-cooledliquid domain 108. The refrigerant is expanded (expansion segment 135) in theexpansion device 34 to an expandedpoint 136 with decreasedpressure 138. During theexpansion 135, enthalpy may remain essentially constant at 134. The refrigerant may reenter or remain in the two-phase domain 106 during theexpansion 135. This expanded two-phase refrigerant must enter the evaporator. The refrigerant is evaporated (evaporation segment 139) in the evaporator to return to thesuction point 120 with substantially increased enthalpy and slightly decreased pressure relative to the expandedpoint 136. - The presence of the expanded
point 136 in the two-phase domain 106 presents substantial problems. With two-phase refrigerant entering the evaporator, it becomes difficult to balance the refrigerant across the evaporator coils. Namely, otherwise similar coils may see different total amounts of refrigerant and/or different ratios of the two phases. This can produce substantially different coil conditions amongst the various coils. The coils with higher amounts of refrigerant and higher relative amounts of liquid may overcool so as to produce excessive frost buildup. Overall efficiency may be reduced. Accordingly, it is known to use complicated distributor arrangements in place of theliquid manifold 38 to balance the ratios among the different coils. Distributors tend to be expensive. Advantageously, under ambient conditions that would otherwise cause thepoint 136 to be in the two-phase domain 106, it would be desirable to shift thepoint 136 into the singlephase liquid domain 108 eliminating the need for a distributor. In such a situation, the single-phase liquid inlet flow to the evaporator could readily be separated into similar flows for each coil. The coils could be designed/configured for operating with such an input flow. -
FIG. 3 shows how the bypass flow of the present invention may be utilized to achieve advantageous refrigerant conditions entering the evaporator 22. The suction condition/point 220 may be essentially the same aspoint 120 ofFIG. 2 . Aftercompression 225, the compressed/discharge/point 226 may be similar to thepoint 126 ofFIG. 2 . The condensing 231 brings the combined main flow and bypass flow to a condensed/point 232 which may be similar topoint 132. - From the condensed condition, the bypass flow splits from the main flow. The bypass flow refrigerant is expanded (segment 233) to reach a
point 234 which may be essentially at thesuction pressure 124 and theenthalpy 134. Heat exchange (235 for the bypass flow and 236 for the main flow) from the main flow to the bypass flow in theheat exchanger 34 then returns the bypass flow conditions to point 220 and cools the main flow to a precooled/point 238 with further reducedmain flow enthalpy 240. The main flow of refrigerant is expanded (segment 241) in theexpansion device 20 to apoint 242 with decreased pressure 244 (which may be essentially the same as 138). The main flow of refrigerant is evaporated (segment 245) in the evaporator 22 to return the main flow to theinitial suction point 220. The heat exchange from the bypass flow to the main flow tends to shift thepoint 242 to a lower enthalpy condition. The required amount of heat exchange may depend upon ambient conditions. - A basic operation of the
expansion device 32 may be responsive to sensed superheat of the refrigerant exiting the evaporator 22. The degree of superheat (actual temperature minus saturated temperature) may be determined based upon the output of thetemperature sensor 50 for the actual temperature and thepressure sensor 52 for the saturated temperature (e.g., in view of known refrigerant properties which may be programmed into the control system 44). Theexpansion device 32 may be opened either in a binary fashion or a progressive fashion in response to the presence or degree of superheat or superheat parameter (e.g., superheat above a threshold). With a TXV as thedevice 32, control could be achieved by placing itsbulb 70 in heat exchange relation with the refrigerant at suction conditions. Much more complex arrangements are also possible. - The
expansion device 32 and/or other components of the bypass flowpath may be dimensioned in view of main flowpath components to permit an appropriate balance between bypass and non-bypass flows. In an exemplary binary configuration (i.e., the binary flow has only off and on conditions) an exemplary balance involves having the bypass flow be approximately 30% of the total flow through the compressor (i.e., 3/7 of the non-bypass flow) by weight/mass. Broader exemplary figures for binary operation are 25%-33%, and 10%-35%. Progressive or stepwise operation may permit maximums in such ranges and may, optionally, permit flows smaller than the lower ends of such ranges. - One or more embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, when implemented as a modification or a reengineering of an existing system, details of the existing system may heavily influence details of the implementation. Although illustrated with regard to a basic system and with simplified conditions, the principles may be applied to more complex system configurations, whether existing or yet-developed. Accordingly, other embodiments are within the scope of the following claims.
Claims (20)
1. An apparatus comprising:
a compressor having suction and discharge ports;
a condenser;
a first expansion device;
a second expansion device;
an evaporator;
a heat exchanger having first and second portions in heat exchange relation with each other; and
one or more conduits forming:
a main flowpath from the discharge port through the condenser, the heat exchanger first portion, the first expansion device, and the evaporator and returning to the suction port; and
a bypass flowpath bypassing the heat exchanger first portion, the first expansion device, and the evaporator, but passing through the second expansion device and the heat exchanger second portion.
2. The apparatus of claim 1 wherein:
the evaporator lacks a distributor.
3. The apparatus of claim 1 wherein:
the second expansion device is a TXV having a bulb essentially in heat exchange relation with a suction port condition.
4. The apparatus of claim 1 wherein:
the second expansion device is an EXV.
5. The apparatus of claim 4 further comprising:
a controller coupled to the EXV and programmed to control the EXV responsive to indicated superheat.
6. The apparatus of claim 1 wherein:
the heat exchanger first portion is downstream of the condenser and upstream of the evaporator along the main flowpath; and
the heat exchanger second portion is downstream of the condenser along the bypass flowpath.
7. The apparatus of claim 6 wherein:
the heat exchanger first portion is upstream of the first expansion device along the main flowpath.
8. The apparatus of claim 1 wherein:
the evaporator is a refrigerant-to-air heat exchanger.
9. The apparatus of claim 1 wherein:
in at least a bypass mode, a bypass flow along the bypass flowpath enters the heat exchanger second portion in a two-phase gas/liquid condition and exits the heat exchanger second portion in a single-phase superheated gas condition; and
in the bypass mode, a main flow along the main flowpath remains essentially a single-phase liquid in said heat exchanger second portion.
10. The apparatus of claim 1 wherein:
the compressor is selected from the group consisting of screw compressors and scroll compressors.
11. A method for operating the apparatus of claim 1 comprising:
detecting at least one operational parameter; and
responsive to the detecting, operating at least the second expansion device so as to maintain essentially single-phase liquid refrigerant entering the evaporator along the main flowpath.
12. The method of claim 11 wherein:
the at least one operational parameter includes at least one of:
saturated suction temperature; and
actual suction temperature.
13. A method for operating a cooling system comprising:
causing a main flow of refrigerant through an evaporator; and
precooling the main flow upstream of the evaporator so as to so as to maintain said main flow essentially as a liquid entering the evaporator.
14. The method of claim 13 wherein:
the precooling comprises controlling a bypass flow in heat exchange relation with the main flow.
15. The method of claim 13 further comprising:
determining whether, absent the precooling, the main flow would enter the evaporator essentially as a two-phase flow.
16. The method of claim 15 wherein:
the determining includes determining that a superheat of refrigerant exiting the evaporator exceeds a threshold.
17. A system comprising:
a compressor;
a condenser;
a discharge line, coupling the compressor to the condenser to carry at least a main flow of refrigerant from the compressor to the condenser;
an expansion device;
an evaporator;
a suction line, coupling the evaporator to the compressor to carry refrigerant from the condenser to the compressor and comprising a first and second parallel segments; and
means for precooling refrigerant entering the expansion device so as to maintain said main flow essentially as a liquid while flowing along a flowpath length at least from the expansion device to the evaporator.
18. The system of claim 17 wherein:
the evaporator lacks a distributor.
19. The system of claim 17 wherein:
within the evaporator, the main flow transitions to a two-phase liquid/gas flow and then to a one-phase superheated gas flow.
20. The system of claim 17 wherein:
the bypass flow represents 10%-35%, by weight, of a total refrigerant flow through the compressor.
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
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US10/954,499 US20060064997A1 (en) | 2004-09-29 | 2004-09-29 | Cooling systems |
CNA2005800331253A CN101031763A (en) | 2004-09-29 | 2005-09-07 | Cooling systems |
EP05794299A EP1800071A2 (en) | 2004-09-29 | 2005-09-07 | Cooling systems |
PCT/US2005/031179 WO2006039042A2 (en) | 2004-09-29 | 2005-09-07 | Cooling systems |
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US10/954,499 US20060064997A1 (en) | 2004-09-29 | 2004-09-29 | Cooling systems |
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US20060064997A1 true US20060064997A1 (en) | 2006-03-30 |
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US10/954,499 Abandoned US20060064997A1 (en) | 2004-09-29 | 2004-09-29 | Cooling systems |
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EP (1) | EP1800071A2 (en) |
CN (1) | CN101031763A (en) |
WO (1) | WO2006039042A2 (en) |
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US20080022706A1 (en) * | 2006-07-31 | 2008-01-31 | Sanyo Electric Co. Ltd. | Two-stage expansion refrigerating device |
US20080307805A1 (en) * | 2005-11-04 | 2008-12-18 | Gupte Neelkanth S | Dual Temperature Refrigeration Circuit |
US20100212342A1 (en) * | 2009-02-25 | 2010-08-26 | Lg Electronics Inc. | Air conditioner and method of controlling the same |
US9644905B2 (en) | 2012-09-27 | 2017-05-09 | Hamilton Sundstrand Corporation | Valve with flow modulation device for heat exchanger |
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Publication number | Priority date | Publication date | Assignee | Title |
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US9982929B2 (en) | 2012-11-20 | 2018-05-29 | Samsung Electronics Co., Ltd. | Air conditioner |
WO2016198258A1 (en) * | 2015-06-08 | 2016-12-15 | Danfoss A/S | A method for operating a vapour compression system with heat recovery |
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US2148414A (en) * | 1934-09-06 | 1939-02-21 | Westinghouse Electric & Mfg Co | Cooling apparatus |
US2461875A (en) * | 1944-02-14 | 1949-02-15 | American Cyanamid Co | Froth flotation of iron ores |
US3795250A (en) * | 1969-07-24 | 1974-03-05 | Amf Inc | Process for making a reconstituted tobacco composition |
US4543802A (en) * | 1983-07-28 | 1985-10-01 | Suddeutsche Kuhlerfabrik Julius Fr. Behr Gmbh & Co. Kg | Evaporating apparatus |
US5390507A (en) * | 1992-09-17 | 1995-02-21 | Nippondenso Co., Ltd. | Refrigerant evaporator |
US5832744A (en) * | 1996-09-16 | 1998-11-10 | Sporlan Valve Company | Distributor for refrigeration system |
US5842351A (en) * | 1997-10-24 | 1998-12-01 | American Standard Inc. | Mixing device for improved distribution of refrigerant to evaporator |
US6474087B1 (en) * | 2001-10-03 | 2002-11-05 | Carrier Corporation | Method and apparatus for the control of economizer circuit flow for optimum performance |
-
2004
- 2004-09-29 US US10/954,499 patent/US20060064997A1/en not_active Abandoned
-
2005
- 2005-09-07 EP EP05794299A patent/EP1800071A2/en not_active Withdrawn
- 2005-09-07 CN CNA2005800331253A patent/CN101031763A/en active Pending
- 2005-09-07 WO PCT/US2005/031179 patent/WO2006039042A2/en not_active Application Discontinuation
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US2148414A (en) * | 1934-09-06 | 1939-02-21 | Westinghouse Electric & Mfg Co | Cooling apparatus |
US2461875A (en) * | 1944-02-14 | 1949-02-15 | American Cyanamid Co | Froth flotation of iron ores |
US3795250A (en) * | 1969-07-24 | 1974-03-05 | Amf Inc | Process for making a reconstituted tobacco composition |
US4543802A (en) * | 1983-07-28 | 1985-10-01 | Suddeutsche Kuhlerfabrik Julius Fr. Behr Gmbh & Co. Kg | Evaporating apparatus |
US5390507A (en) * | 1992-09-17 | 1995-02-21 | Nippondenso Co., Ltd. | Refrigerant evaporator |
US5832744A (en) * | 1996-09-16 | 1998-11-10 | Sporlan Valve Company | Distributor for refrigeration system |
US5842351A (en) * | 1997-10-24 | 1998-12-01 | American Standard Inc. | Mixing device for improved distribution of refrigerant to evaporator |
US6474087B1 (en) * | 2001-10-03 | 2002-11-05 | Carrier Corporation | Method and apparatus for the control of economizer circuit flow for optimum performance |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080307805A1 (en) * | 2005-11-04 | 2008-12-18 | Gupte Neelkanth S | Dual Temperature Refrigeration Circuit |
US20080022706A1 (en) * | 2006-07-31 | 2008-01-31 | Sanyo Electric Co. Ltd. | Two-stage expansion refrigerating device |
US20100212342A1 (en) * | 2009-02-25 | 2010-08-26 | Lg Electronics Inc. | Air conditioner and method of controlling the same |
US8459051B2 (en) * | 2009-02-25 | 2013-06-11 | Lg Electronics Inc. | Air conditioner and method of controlling the same |
US9644905B2 (en) | 2012-09-27 | 2017-05-09 | Hamilton Sundstrand Corporation | Valve with flow modulation device for heat exchanger |
Also Published As
Publication number | Publication date |
---|---|
WO2006039042A2 (en) | 2006-04-13 |
CN101031763A (en) | 2007-09-05 |
EP1800071A2 (en) | 2007-06-27 |
WO2006039042A3 (en) | 2006-11-23 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: CARRIER CORPORATION, NEW YORK Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:GRABON, MICHAL K.;REEL/FRAME:015860/0788 Effective date: 20040928 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |