Title of Invention

A METHOD FOR OPERATING A VAPOR COMPRESSION REFRIGERATION SYSTEM AND A VAPOR COMPRESSION REFRIGERATION SYSTEM

Abstract

A method for operating a vapor compression refrigeration system, wherein an evaporator removes heat from a medium which is circulated through said evaporator in heat exchange relation with an evaporator coil in said evaporator, said evaporator coil comprising an inlet which is in flow communication with an expansion device and an outlet which is in flow communication with a compressor, the method comprising the steps of. compressing a refrigerant fluid in said compressor; condensing said refrigerant fluid in a condenser to form a condensed refrigerant fluid; expanding said condensed refrigerant fluid in said expansion device to form an expanded refrigerant fluid, wherein said expanded refrigerant fluid is in a liquid form or substantially in said liquid form with a small vapor fraction; supplying said expanded refrigerant to an evaporator feed line connecting said expansion device to said evaporator coil inlet; converting a significant amount of said liquid form to a liquid and vapor mixture within said evaporator feed line, wherein the diameter and length of said evaporator feed line facilitates said conversion; supplying said mixture of refrigerant vapor and liquid to said evaporator coil inlet, said mixture comprising a substantial vapor portion; and converting substantially all of said liquid to vapor as said mixture passes through said evaporator coil, whereby efficient heat transfer is provided between said mixture and said medium along substantially the entire length of said coil, and whereby the build-up of frost on said evaporator coil is substantially reduced. A vapor compression refrigeration system comprising a compressor, a condenser, an expansion device, an evaporator, an evaporator feed line and a suction line.

Full Text

FIELD OF THE INVENTION The present invention relates to a method for operating a vapor compression refrigeration system and a vapor compression refrigeration system and, more particularly, to vapor compression refrigeration, freezer and air conditioning systems. In this regard, an important aspect of the present invention concerns improvements in the efficiency of vapor compression refrigeration systems which are advantageously suited for use in commercial medium and low temperature refrigeration/freezer applications. BACKGROUND OF THE INVENTION Vapor compression refrigeration systems typically employ a fluid refrigerant medium that is directed through various phases or states to attain successive heat exchange functions. These systems generally employ a compressor which receives refrigerant in a vapor state (typically in the form of a super heated vapor) and compresses that vapor to a higher pressure which is then supplied to a condenser wherein a cooling medium comes into indirect contact with the incoming high pressure vapor, removing latent heat from the refrigerant and issuing liquid refrigerant at or below its boiling point corresponding to the condensing pressure. This refrigerant liquid is then fed to an expansion device, for example, an expansion valve or capillary tube, which effects a controlled reduction Another object of the present invention is to provide a vapor compression refrigeration method and apparatus characterized by reduced power consumption and cost of operation. Another object of the present invention is to provide a vapor compression refrigeration method and apparatus having improved heat transfer efficiency and reduced refrigerant charge requirements, enabling in many applications the elimination of traditional components such as, for example, a receiver in the refrigeration circuit. Another object of the present invention is to provide a vapor compression refrigeration method and apparatus wherein the temperature differential between the cooling coils and air circulated in heat exchange relationship therewith is minimized, resulting in substantially reduced extraction of the water content in that air and the maintenance of more uniform humidity levels in refrigeration cases and freezer compartments associated therewith. Another object of the present invention is to provide a commercial refrigeration system wherein the compressor, expansion device and condenser can be remotely located from the refrigeration or freezer compartment associated therewith, thereby facilitating the servicing of those components without interference with customer traffic and the like. Another object of the present invention is to provide a vapor compression refrigeration system wherein the compressor, expansion device and condenser, together with their associated controls, are contained as a group in a compact housing which can be easily installed in a refrigeration circuit. Accordingly, the present invention provides a method for operating a vapor compression refrigeration system, wherein an evaporator removes heat from a medium which is circulated through said evaporator in heat exchange relation with an evaporator coil in said evaporator, said evaporator coil comprising an inlet which is in flow communication with an expansion device and an outlet which is in flow communication with a compressor, the method comprising the steps of: compressing a refrigerant fluid in said compressor; condensing said refrigerant fluid in a condenser to form a condensed refrigerant fluid; expanding said condensed refrigerant fluid in said expansion device to form an expanded refrigerant fluid, wherein said expanded refrigerant fluid is in a liquid form or substantially in said liquid form with a small vapor fraction; supplying said expanded refrigerant to an evaporator feed line connecting said expansion device to said evaporator coil inlet; converting a significant amount of said liquid form to a liquid and vapor mixture within said evaporator feed line, wherein the diameter and length of said evaporator feed line facilitates said conversion; supplying said mixture of refrigerant vapor and liquid to said evaporator coil inlet, said mixture comprising a substantial vapor portion; and converting substantially all of said liquid to vapor as said mixture passes through said evaporator coil, whereby efficient heat transfer is provided between said mixture and said medium along substantially the entire length of said coil, and whereby the build-up of frost on said evaporator coil is substantially reduced. Accordingly, the present invention also provides a vapor compression refrigeration system, comprising: a compressor for increasing the pressure and temperature of a refrigerant vapor, said compressor having an inlet and an outlet; a condenser having an inlet in flow communication with the outlet of said compressor for liquefying pressurized refrigerant vapor received from said compressor; an expansion device having a first inlet which, during a cooling mode of operation of said refrigeration system, is in flow communication with an outlet of said condenser for receiving liquid refrigerant from said condenser and vaporizing a substantial portion of the same, and wherein said first inlet of said expansion device is in proximity with said outlet of said condenser; an evaporator comprising an evaporating coil having an inlet and an outlet, said evaporating coil being in heat exchange relation with a medium along substantially the entire length of said coil; an evaporator feed line providing flow communication of said expansion device with said evaporating coil inlet; a suction line providing flow communication of said evaporating coil outlet with said compressor inlet; said expansion device and said evaporator feed line, during a cooling mode of operation of said vapor compression refrigeration system, being sized to provide said evaporating coil inlet with a refrigerant liquid and vapor mixture that comprises a substantial vapor portion; and said evaporating coil being sized to provide said refrigerant liquid and vapor mixture with a linear velocity sufficient to provide efficient heat transfer along substantially the entire length of said coil. These and other objects of the present invention will be apparent to those skilled in this art from the following detailed description of the accompanying drawings and charts wherein like reference numerals indicate corresponding parts and which: WE CLAIM; 1. A method for operating a vapor compression refrigeration system, wherein an evaporator removes heat from a medium which is circulated through said evaporator in heat exchange relation with an evaporator coil in said evaporator, said evaporator coil comprising an inlet which is in flow communication with an expansion device and an outlet which is in flow communication with a compressor, the method comprising the steps of: compressing a refrigerant fluid in said compressor; condensing said refrigerant fluid in a condenser to form a condensed refrigerant fluid; expanding said condensed refrigerant fluid in said expansion device to form an expanded refrigerant fluid, wherein said expanded refrigerant fluid is in a liquid form or substantially in said liquid form with a small vapor fraction; supplying said expanded refrigerant to an evaporator feed line connecting said expansion device to said evaporator coil inlet; converting a significant amount of said liquid form to a liquid and vapor mixture within said evaporator feed line, wherein the diameter and length of said evaporator feed line facilitates said conversion; supplying said mixture of refrigerant vapor and liquid to said evaporator coil inlet, said mixture comprising a substantial vapor portion; and converting substantially all of said liquid to vapor as said mixture passes through said evaporator coil, whereby efficient heat transfer is provided between said mixture and said medium along substantially the entire length of said coil, and whereby the build-up of frost on said evaporator coil is substantially reduced. 2. The method as claimed in claim 1, wherein the build-up of frost on said evaporator coil is substantially reduced such that said vapor compression refrigeration system can be operated without requiring a defrosting cycle over a substantially increased number of refrigeration cycles as compared to a second vapor compression refrigeration system having a second expansion device located in close proximity to a second evaporator inlet of a second evaporator; wherein said second evaporator coil has the same cooling load and evaporating temperature conditions as said evaporator. 3. The method as claimed in claim 1, wherein the supplying of a mixture of refrigerant vapor and liquid is at a given mass flow rate and at a given volumetric flow velocity sufficient to provide efficient heat transfer between said mixture and said medium along substantially the entire length of said coil. 4. The method as claimed in claim 1, wherein at least 2% of the mass of refrigerant liquid/vapor mixture is in a liquid state at said outlet of said evaporator coil during the portion of each refrigeration cycle when said expansion device is actively supplying said mixture of said refrigerant vapor and liquid to said evaporating coil inlet. 5. The method as claimed in claim 1, wherein the volumetric velocity of said refrigerant vapor and liquid mixture at said evaporator coil inlet is at least 10% greater than the volumetric velocity of refrigerant fluid feed to a second evaporator inlet of a second evaporator coil in a second refrigeration system having a second expansion device located in close proximity to said second evaporator inlet, wherein said second evaporator coil has the same size, flow rate of said medium circulated therethrough, and same cooling load as said evaporator coil. 6. The method as claimed in claim 5, wherein the volumetric velocity of said refrigerant vapor and liquid mixture at said evaporator coil inlet is from 10% to 25% greater than the volumetric velocity of the refrigerant feed to the evaporator inlet of said second refrigeration system. 7. The method as claimed in claim 5, wherein the volumetric velocity of said refrigerant vapor and liquid mixture at said evaporator coil inlet is at least 18% greater than the volumetric velocity of the refrigerant feed to the evaporator inlet of said second refrigeration system having a second expansion device located in close proximity to a second evaporator inlet of a second evaporator coil, wherein said second evaporator coil has the same size, flow rate of said medium circulated therethrough, and same cooling load as said evaporator coil. 8. The method as claimed in claim 1, wherein the mass flow rate of said refrigerant vapor and liquid mixture at said evaporator coil inlet is at least 5% greater than the mass flow rate of refrigerant fluid feed to an evaporator in a second refrigeration system. 9. The method as claimed in claim 8, wherein the mass flow rate of said refrigerant vapor and liquid mixture at said evaporator coil inlet is from 5 to 20% greater than the mass flow rate of refrigerant feed to the evaporator inlet of said second refrigeration system. 10. The method as claimed in claim 8, wherein the mass flow rate of said refrigerant vapor and liquid mixture at said evaporator coil inlet is at least 12% greater than the mass flow rate of the refrigerant feed to the evaporator inlet of said second refrigeration system. 11. The method as claimed in claim 1, wherein said medium has a given relative humidity and is withdrawn from a refrigerated compartment, circulated through the evaporator in heat exchange relation with the evaporator coil, and returned to the refrigerated compartment. 12. The method as claimed in claim 11, wherein the differential temperature between said coil and said medium adjacent at least a portion of said coil, during at least a portion of a refrigeration cycle, is sufficient to substantially maintain said given relative humidity in said medium. 13. The method as claimed in claim 1, wherein said medium is air. 14. The method as claimed in claim 13, wherein said air medium is circulated in counter-current relation to the flow of refrigerant vapor and liquid particles in said evaporating coil wherein the temperature of the air being supplied to said evaporator from said refrigerated compartment is equal to or lower than the temperature of the evaporating coil inlet during at least the portion of a refrigeration cycle. 15. The method as claimed in claim 1, wherein said mixture of refrigerant vapor and liquid is supplied to the evaporator coil inlet at a linear velocity of at least 400 feet per minute. 16. The method as claimed in claim 15, wherein said linear velocity is from 400 to 750 feet per minute. 17. The method as claimed in claim 1, wherein said expansion device has an outlet which communicates with an inlet to a multi-functional valve which comprises an expansion chamber, and wherein a liquid refrigerant is supplied to said expansion device and undergoes a two-stage series expansion in said expansion chamber to produce said mixture of refrigerant vapor and liquid. 18. The method as claimed in claim 17, wherein one stage in said two-stage series expansion is modulated. 19. The method as claimed in claim 17, wherein the first stage in said two-stage series expansion is modulated. 20. The method as claimed in claim 17, wherein some liquid is present in said mixture at said outlet of said evaporator coil during the portion of each of said refrigeration cycles when said compressor is operating. 21. The method as claimed in claim 1, wherein the compressor and condenser are remote from said evaporator and said expansion device is closer to said condenser than to said evaporator, said method comprising the step of: controlling the flow rate of said refrigerant vapor and liquid mixture in a substantial portion of the refrigerant circuit between said condenser and evaporator so that the refrigerant vapor and liquid mixture has a linear velocity which is at least 20% greater than the linear velocity of a refrigerant feed in a substantial portion of a second refrigeration circuit between a second condenser and a second evaporator in a second refrigeration system having a second expansion device located in close proximity to a second evaporator inlet of a second evaporator, wherein said second evaporator has the same cooling load and evaporating temperature conditions as said evaporator. 22. The method as claimed in claim 21, wherein said expansion device is in flow communication with an inlet to said evaporator via an evaporator feed line and so the linear velocity of said refrigerant vapor and liquid mixture in a substantial portion of the length of said evaporator feed line is at least 400 feet per minute. 23. The method as claimed in claim 21, wherein the linear velocity of said refrigerant vapor and liquid mixture in a substantial portion of said evaporator feed line is from 400 to 750 feet per minute. 24. A vapor compression refrigeration system, comprising: a compressor for increasing the pressure and temperature of a refrigerant vapor, said compressor having an inlet and an outlet; a condenser having an inlet in flow communication with the outlet of said compressor for liquefying pressurized refrigerant vapor received from said compressor; an expansion device having a first inlet which, during a cooling mode of operation of said refrigeration system, is in flow communication with an outlet of said condenser for receiving liquid refrigerant from said condenser and vaporizing a substantial portion of the same, and wherein said first inlet of said expansion device is in proximity with said outlet of said condenser; an evaporator comprising an evaporating coil having an inlet and an outlet, said evaporating coil being in heat exchange relation with a medium along substantially the entire length of said coil; an evaporator feed line providing flow communication of said expansion device with said evaporating coil inlet; a suction line providing flow communication of said evaporating coil outlet with said compressor inlet; said expansion device and said evaporator feed line, during a cooling mode of operation of said vapor compression refrigeration system, being sized to provide said evaporating coil inlet with a refrigerant liquid and vapor mixture that comprises a substantial vapor portion; and said evaporating coil being sized to provide said refrigerant liquid and vapor mixture with a linear velocity sufficient to provide efficient heat transfer along substantially the entire length of said coil. 25. The system as claimed in claim 24, comprising a sensor in said suction line operatively associated with said expansion device for regulating the flow of refrigerant from the inlet of said expansion device to the inlet of said evaporating chamber. 26. The system as claimed in claim 25, wherein said sensor is temperature activated. 27. The system as claimed in claim 24, wherein said expansion device is a multi-functional valve which comprises a second inlet, said second inlet being in flow communication with the outlet of said compressor when said refrigeration system is in a defrost mode of operation during which the pressurized refrigerant vapor which is discharged from said compressor outlet is supplied to said multi-functional valve, through said evaporator feed line and into the inlet of said evaporator coil. 28. The system as claimed in claim 27, wherein said multi-functional valve comprises a second inlet, a first passageway coupled to the first inlet, said first passageway being gated by a first valve, a second passageway coupled to the second inlet, the second passageway being gated by a second valve, and a metering valve positioned in the first passageway which is activated by the sensor in said suction line. 29. The system as claimed in claim 28, wherein each of said first and second valves is a solenoid valve. 30. The system as claimed in claim 24, comprising a unit enclosure and a refrigeration case, wherein the compressor, condenser and expansion device are located within the unit enclosure and wherein the evaporator is located within the refrigeration case. 31. The system as claimed in claim 24, wherein said expansion device comprises a thermostatic expansion valve. 32. The system as claimed in claim 24, wherein said expansion device comprises an automatic expansion valve. 33. The system as claimed in claim 24, wherein said expansion device comprises a capillary tube. 34. The system as claimed in claim 24, wherein said expansion device is closer to the outlet of said condenser than to the inlet to said evaporating coil. 35. The system as claimed in claim 24, wherein said expansion device is adjacent the outlet of said condenser. i ! i 36. The system as claimed in claim 24, wherein said expansion device comprises a thermostatic expansion valve having an inlet and an outlet, the outlet of said thermostatic expansion valve being in series flow communication with an inlet to a multifunctional valve which comprises an expansion chamber whereby liquid refrigerant supplied to said expansion device undergoes a two-stage expansion. 37. A method for operating a vapor compression refrigeration system, substantially as herein before described with reference to the accompanying drawings. 38. A vapor compression refrigeration system, substantially as herein before described with reference to the accompanying drawings.

Documents:

in-pct-2001-0962-che abstract duplicate.pdf

in-pct-2001-0962-che abstract-duplicate.pdf

in-pct-2001-0962-che abstract.jpg

in-pct-2001-0962-che abstract.pdf

in-pct-2001-0962-che claims-duplicate.pdf

in-pct-2001-0962-che claims.pdf

in-pct-2001-0962-che correspondence others.pdf

in-pct-2001-0962-che correspondence po.pdf

in-pct-2001-0962-che description (complete) duplicate.pdf

in-pct-2001-0962-che description(complete)-duplicate.pdf

in-pct-2001-0962-che drawings-duplicate.pdf

in-pct-2001-0962-che drawings.pdf

in-pct-2001-0962-che form-1.pdf

in-pct-2001-0962-che form-13.pdf

in-pct-2001-0962-che form-19.pdf

in-pct-2001-0962-che form-26.pdf

in-pct-2001-0962-che form-3.pdf

in-pct-2001-0962-che form-5.pdf

in-pct-2001-0962-che form-6.pdf

in-pct-2001-0962-che others.pdf

in-pct-2001-0962-che pct.pdf

in-pct-2001-0962-che petition.pdf