CA2139020A1 - Heat transfer method using a secondary fluid - Google Patents
Heat transfer method using a secondary fluidInfo
- Publication number
- CA2139020A1 CA2139020A1 CA002139020A CA2139020A CA2139020A1 CA 2139020 A1 CA2139020 A1 CA 2139020A1 CA 002139020 A CA002139020 A CA 002139020A CA 2139020 A CA2139020 A CA 2139020A CA 2139020 A1 CA2139020 A1 CA 2139020A1
- Authority
- CA
- Canada
- Prior art keywords
- refrigerant
- circuit
- air
- heat
- heat exchanger
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F12/00—Use of energy recovery systems in air conditioning, ventilation or screening
- F24F12/001—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air
- F24F12/002—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air using an intermediate heat-transfer fluid
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
- F24F3/12—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling
- F24F3/14—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification
- F24F3/147—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification with both heat and humidity transfer between supplied and exhausted air
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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
- F25B25/00—Machines, plants or systems, using a combination of modes of operation covered by two or more of the groups F25B1/00 - F25B23/00
- F25B25/005—Machines, plants or systems, using a combination of modes of operation covered by two or more of the groups F25B1/00 - F25B23/00 using primary and secondary systems
-
- 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
- F25B29/00—Combined heating and refrigeration systems, e.g. operating alternately or simultaneously
- F25B29/003—Combined heating and refrigeration systems, e.g. operating alternately or simultaneously of the compression type system
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
- Y02B30/56—Heat recovery units
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Central Air Conditioning (AREA)
Abstract
The invention is directed toward an air conditioning system for a building that has a first, compact, refrigeration circuit with high cost vapor/liquid phase, refrigerant therein for dehumidifying air in the building by taking heat out of the air. The system also has a second, longer, refrigeration circuit with a low cost liquid phase, refrigerant therein, and in heat exchange relation with the first circuit, for absorbing the heat picked up by the first circuit The second circuit has two branches with a heat exchanger in each branch for rejecting the heat picked up to outside air. In one branch, used in the wintertime, the heat exchanger in the one branch is used to preheat outside makeup air that is taken in to the system. In another branch, used in the summertime, the heat exchanger in the other branch gives up the heat to outside air outside of the building The use of the two circuits with two different refrigerants reduces the amount of the expensive refrigerant required
Description
HEAT TRANSFER METHOD USING A SECONDARY FLUID
TECHNICAL FIELD
This invention is directed toward an improved refrigerant system.
The invention is also directed toward an improved air conditioning system incorporating the improved refrigerant system.
The invention is further directed toward an improved method for air conditioning a building.
BACKGROUND ART
Refrigerant systems have been using vapor/liquid phase refrigerants, such as CFC refrigerants, for heat transfer purposes. However these CFC
refrigerants are being phased out because of their destructive effect on the ozone layer. The replacement vapor/liquid phase refrigerants however, such as HFC refrigerants, while efficient, are often more costly, less reliable and more subject to regulations with respect to the handling of it than the CFC refrigerants. With the replacement refrigerants operating in both a liquid and vapor phase, a more expensive recovery method operated by a certified refrigeration mechanic is required to service the system. The replacement refrigerants, such as HFC refrigerants, can also lead to liability problems if the vapor phase is accidentally leaked to the atmosphere during installation or servicing. Thus it would be desirable if the amount of these replacement refrigerants in refrigerant systems could be reduced.
Air conditioning systems installed in buildings, which systems incorporate refrigerant systems, often have a heat exchanger mounted outside the building to -remove heat taken out of the building air in the summer time. The heat exchanger passes the heat to outside air. This outside heat exchanger IS usually quite far removed from the main part of the air conditioning system. The heat exchanger can, for example, be mounted on the roof of the building while the remainder of the air conditioning system is mounted in the basement of the building. The piping to carry the refrigerant between the heat exchanger and the remainder of the air conditioning system is quite long and a large amount of expensive, vapor/liquid phase refrigerant is needed. Again, it would be desirable if the amount of refrigerant could be reduced.
Migration of the refrigerant in an air conditioning system with an outside heat exchanger is also a major problem, particularly in the winter, when using refrigerants with a vapor phase such as HFC refrigerants. The outside heat exchanger is normally not used in the winter and a three-way valve is used to divert the refrigerant to the rest of the system. However the vapor phase of the refrigerant in the remainder of the air conditioning system leaks past the three way valve into the piping leading to and from the outside heat exchanger and "migrates" in the piping to the heat exchanger. Because of the length of the piping to the outside heat exchanger, a significant amount of refrigerant can leak out of the main part of the air conditioning system adding to expense. As the refrigerant migrates, it carries lubricating oil with it. The loss of this oil can lead to the compressor or pumps in the system burning out. Additional equipment and servicing is required to avoid these lubrication problems thus making the system more expensive.
DISCLOSURE OF THE INVENTION
It is the purpose of the present invention to provide an improved refrigeration system that is less expensive to install and less expensive to service and to operate than known systems. It is another purpose of the present invention to provide an improved refrigeration system that avoids, or at least minimizes, the problems involved with using vapor/liquid phase refrigerants, such as the "migration" problem. It is another purpose of the present invention to provide an improved air conditioning system that incorporates the improved refrigeration system with all its advantages.
In accordance with the present invention there is provided an improved refrigeration system having two different refrigerant circuits with a vapor/liquid phase refrigerant in one circuit and with a liquid phase refrigerant in the other circuit.
The one circuit with the vapor/liquid phase refrigerant is a compact closed loop having an evaporator therein for taking heat out of a medium, such as building air, and a condenser for transferring the heat from the refrigerant. The other circuit, with the liquid phase refrigerant, is a longer closed loop having the condenser therein so that heat is transferred from the vapor/liquid phase refrigerant to the liquid phase refrigerant and also having heat exchanger means therein to get rid of this heat.
When the refrigeration system is incorporated into an air conditioning system for a building, the evaporator in the one circuit is located in the main air duct of the a/c system within the building to remove humidity from the air. The heat exchanger means in the summer mode of operation of the a/c system can be a heat exchanger located outside the building, well removed from the condenser and the first circuit. The heat exchanger means in the winter mode of operation can be a heat exchanger in an air inlet duct leading to the main air duct for heating up makeup outside air being added to the air in the building.
The use of two separate refrigerant circuits reduces the amount of expensive vapor/liquid phase refrigerants required. The first circuit is quite compact with all the equipment in this circuit near each other. Thus a relatively small amount of vapor/liquid phase refrigerant is required. The longer circuit, using a liquid phase refrigerant, can be easily installed and serviced by a plumber. More expensive servicing, employing a refrigerant recovery method that requires a refrigeration mechanic, is not needed for the liquid phase refrigerant. More importantly, the use of a separate circuit filled with liquid phase refrigerant avoids migration when operating in the winter mode and the problems attendant with migration.
The invention is particularly directed toward an improved refrigerant system having a first refrigerant circuit with an evaporator and a condenser in the circuit and a first refrigerant therein with first means for circulating the first refrigerant through the circuit. The refrigerant system has a second circuit with a heat exchanger and the condenser in the second circuit and a second different refrigerant therein with second means for recirculating the second refrigerant through the circuit. The first refrigerant picks up heat in the evaporator and gives it up to the second refrigerant 2l39020 in the condenser. The second refrigerant picks up the heat in the condenser and gives it up in the heat exchanger.
The invention is also particularly directed toward an air conditioning system for a building having a main air duct with an evaporator in the duct to extract humidity from building air passing through the duct. The system has a first refrigerant circuit connecting the evaporator to a condenser and a second refrigerant circuit connecting the condenser to a heat exchanger in the building. There is a first refrigerant in the first circuit and first means in the first circuit for recirculating the first refrigerant through the first circuit. There is a second refrigerant in the second circuit along with means for circulating the second refrigerant through the second circuit. The first refrigerant takes heat from the building air in the evaporator and gives it up to the second refrigerant in the condenser. The second refrigerant gives up this heat to outside air in the heat exchanger.
The invention is further directed toward a method for operating an air conditioning system in a building comprising the steps of taking heat out of the air in the building while dehumidifying it with a first refrigerant, transferring this heat from the first refrigerant to a second refrigerant in a condenser and transferring the heat out of the second refrigerant to outside air through a heat exchanger.
BRIEF DESCRIPTION OF DRAWINGS
The invention will now be described in detail having reference to the accompanying drawings in which:
FIG. 1 is a schematic view of a simple refrigerant system of the present invention;
213902~
-FIG. 2 is a schematic view of a more complex refrigerant system of the present invention; and FIG. 3 is a schematic of an air conditioning system incorporating the refrigerant system shown in Fig. 2.
DESCRIPTION OF PREFERRED EMBODIMENTS
The improved refrigerant system 1 of the present invention as shown in Fig. 1 has a first circuit 3 that has an evaporator 5, a compressor 7, a condenser g and an expansion valve 11 in series joined by piping 13 in a closed loop. This first circuit 3 is filled by a first refrigerant that operates in vapor/fluid phases. The refrigerant enters the evaporator 5 as a mix of vapor and liquid and picks up heat therein leaving as vapor. The vapor is compressed and heated by the compressor 7 and passes to the condenser 9 where it gives up heat and becomes liquid. The liquid refrigerant then passes to the expansion valve 11 where it is partly vaporized and the vapor/liquid mix passes to the evaporator 5 to repeat the cycle.
The refrigerant system 1 includes a second circuit 17. This second circuit 17 has the condenser 9, a first heat exchanger 23, and a pump 25, all joined in series by piping 31. The second circuit 17 is filled with a second refrigerant that is in a liquid phase.
The second circuit 17 is operated to dissipate heat picked up by the second refrigerant from the first refrigerant in the condenser 9. The first heat exchanger 23 can be located far away from the condenser 9 A more easily handled, less expensive, refrigerant is used in the second circuit making the second circuit, and thus the refrigerant system, 213902~
easier to install and service. The first circuit can be quite compact and requires relatively little of the more efficient but more expensive vapor/liquid phase refrigerant.
The above refrigerant system, slightly modified, - is particularly suited for use in an air conditioning system for buildings, particularly buildings housing swimming pools. As shown in Figs. 2 and 3, the modified refrigerant system 101 has a first circuit 103 with an evaporator 105, a compressor 107, a condenser 109 and an expansion valve 111 all in series connected in a closed loop by piping 113. This circuit is the same as the circuit 3 in the system shown in Fig. 1. The evaporator 105 is mounted within a main air duct 115 in the air conditioning system in a building for removing humidity from the building air drawn through the duct 115 by a fan 117. Heat is taken out of the air to remove humidity by condensation. The first circuit 103 is filled with a first refrigerant that operates in vapor/liquid phases.
The air conditioning system includes a second circuit 121 with two parallel branches 123, 125. The first branch 123 has the condenser 109, a first heat exchanger 127, a pump 131, a check valve 133 and a second heat exchanger 129 all in series connected in a closed loop by piping 135. The first heat exchanger 127 is an air preheater and is located in an air inlet duct 137 connected to the main air duct 115 downstream from the evaporator 105. This first heat exchanger 127 is used to heat outside air being added to the system through the inlet duct 137. The outside air is needed to make up for the loss of some of the warm, humid, building air that is exhausted through an air outlet duct 141 leading to the outside from the main duct 115 just upstream from the evaporator 105 As this air passes to the outside through duct 141, it passes through the second heat exchanger 129 giving up heat to the refrigerant in the line 135 just before the refrigerant returns to the condenser 109 .
Preferably, the first branch 123 employs a third heat exchanger 145 located between the first heat exchanger 127 and the pump 131. This third heat exchanger 145 is an air reheater and is located in the main air duct 115 just downstream from the evaporator 105 and before the air inlet duct 137. The purpose of the air reheater 145 is to reheat the air, if needed, after it has been dehumidified. A bypass line 147 can lead from the piping or line 135 upstream from the reheater 145 to bypass the air reheater 145 if it is not needed. The bypass line joins the main line 135 downstream from the reheater and a diverter valve 149 can control the flow of the refrigerant to the bypass line 147.
The second branch 125 of the second circuit 121 of the a/c system has a second line 155 branching off from the main line 135 just after the main line 135 leaves the condenser 109. The second line 155 has a fourth heat exchanger 157, a second pump 159 and a second check valve 161 in series with the second line 155 rejoining the main line 135 just before it enters the second heat exchanger 129. The fourth heat exchanger 157 is used in the air conditioning system to transfer heat to the outside air. This heat exchanger 157 can be far removed from the main part of the air conditioning system.
The first circuit 103 is quite compact and employs a relatively small amount of expensive, relatively efficient, vapor/liquid phase refrigerant.
g A suitable vapor/liquid phase refrigerant would be an HFC refrigerant. The second circuit 121 can be quite long compared to the first circuit. The refrigerant in the second circuit is a liquid phase refrigerant such as propylene glycol by way of example. This refrigerant is always in the liquid phase and thus is easier to handle, less expensive and avoids any migration problems that may occur with a vapor/liquid phase refrigerant.
In operation, the first refrigerant in the first circuit 103 dehumidifies the warm, humid, building air passing through the main air duct 115 by taking heat out of the air in the evaporator 105. This heat is then transferred from the first refrigerant to the second refrigerant in the second circuit 121 in the condenser 109.
In the winter time, in a heating mode, the first branch 123 of the second circuit 121 alone would operate, with first pump 131 operating and second pump 159 stopped. The second check valve 161 would prevent back flow through the second branch 125 while the first pump 131 is operating. As the second refrigerant is circulated in the first branch 123, it picks up heat from the first refrigerant in the condenser 109 and passes through the first heat exchanger 127 to give up at least some of this heat to reheat the makeup air entering the system through the air inlet duct 137. This first heat exchanger 127 has the capacity to reject all of the heat picked up by the second refrigerant if needed.
If needed, the diverter valve 149 can be operated to direct the second refrigerant through the air reheater 145 to heat up the building air in the main duct 115 which has been cooled during dehumidification. If air reheating is not needed, the diverter valve 149 can be operated to bypass the air reheater 145. The second refrigerant then passes through the second heat exchanger 129 to be reheated to around room temperature by the building air being exhausted from the system through the air outlet duct 141 The first pump 131 keeps the second refrigerant recirculating through the first branch 123 while the second branch 125 is passive. However because the second refrigerant is in the liquid phase, migration is not a similar problem as when using a vapor/liquid phase refrigerant.
In the summer time, in a cooling mode, the first pump 131 is stopped and the second pump 159 is started to move the second refrigerant through the second branch 125. In the second branch 125 the second refrigerant picks up the heat from the primary refrigerant in the condenser 109 and gives it up to the outside air in the fourth heat exchanger 157. The fourth heat exchanger 157 is sized so that it can get rid of all the heat taken out of the building air.
The second refrigerant is recirculated by the second pump 159 through the second heat exchanger 129 to give up more heat to the exhaust air and then back to the condenser 109. The first check valve 133 in the first branch 123 prevents back flow through the first branch 123 while the second pump 159 is operating.
It is within the ambit of the present invention to cover any obvious modifications of the preferred embodiments described herein, provided such modifications fall within the scope of the appended claims. For example, it is conceivable to eliminate the two pumps 131 and 159 and their check valves 133 and 161 respectively and replace them by a three-way valve connected to lines 135 and 155 and also to the second heat exchanger 129. A single pump would then -be connected in the main 135 between the second heat exchanger 129 and the condenser lO9.
TECHNICAL FIELD
This invention is directed toward an improved refrigerant system.
The invention is also directed toward an improved air conditioning system incorporating the improved refrigerant system.
The invention is further directed toward an improved method for air conditioning a building.
BACKGROUND ART
Refrigerant systems have been using vapor/liquid phase refrigerants, such as CFC refrigerants, for heat transfer purposes. However these CFC
refrigerants are being phased out because of their destructive effect on the ozone layer. The replacement vapor/liquid phase refrigerants however, such as HFC refrigerants, while efficient, are often more costly, less reliable and more subject to regulations with respect to the handling of it than the CFC refrigerants. With the replacement refrigerants operating in both a liquid and vapor phase, a more expensive recovery method operated by a certified refrigeration mechanic is required to service the system. The replacement refrigerants, such as HFC refrigerants, can also lead to liability problems if the vapor phase is accidentally leaked to the atmosphere during installation or servicing. Thus it would be desirable if the amount of these replacement refrigerants in refrigerant systems could be reduced.
Air conditioning systems installed in buildings, which systems incorporate refrigerant systems, often have a heat exchanger mounted outside the building to -remove heat taken out of the building air in the summer time. The heat exchanger passes the heat to outside air. This outside heat exchanger IS usually quite far removed from the main part of the air conditioning system. The heat exchanger can, for example, be mounted on the roof of the building while the remainder of the air conditioning system is mounted in the basement of the building. The piping to carry the refrigerant between the heat exchanger and the remainder of the air conditioning system is quite long and a large amount of expensive, vapor/liquid phase refrigerant is needed. Again, it would be desirable if the amount of refrigerant could be reduced.
Migration of the refrigerant in an air conditioning system with an outside heat exchanger is also a major problem, particularly in the winter, when using refrigerants with a vapor phase such as HFC refrigerants. The outside heat exchanger is normally not used in the winter and a three-way valve is used to divert the refrigerant to the rest of the system. However the vapor phase of the refrigerant in the remainder of the air conditioning system leaks past the three way valve into the piping leading to and from the outside heat exchanger and "migrates" in the piping to the heat exchanger. Because of the length of the piping to the outside heat exchanger, a significant amount of refrigerant can leak out of the main part of the air conditioning system adding to expense. As the refrigerant migrates, it carries lubricating oil with it. The loss of this oil can lead to the compressor or pumps in the system burning out. Additional equipment and servicing is required to avoid these lubrication problems thus making the system more expensive.
DISCLOSURE OF THE INVENTION
It is the purpose of the present invention to provide an improved refrigeration system that is less expensive to install and less expensive to service and to operate than known systems. It is another purpose of the present invention to provide an improved refrigeration system that avoids, or at least minimizes, the problems involved with using vapor/liquid phase refrigerants, such as the "migration" problem. It is another purpose of the present invention to provide an improved air conditioning system that incorporates the improved refrigeration system with all its advantages.
In accordance with the present invention there is provided an improved refrigeration system having two different refrigerant circuits with a vapor/liquid phase refrigerant in one circuit and with a liquid phase refrigerant in the other circuit.
The one circuit with the vapor/liquid phase refrigerant is a compact closed loop having an evaporator therein for taking heat out of a medium, such as building air, and a condenser for transferring the heat from the refrigerant. The other circuit, with the liquid phase refrigerant, is a longer closed loop having the condenser therein so that heat is transferred from the vapor/liquid phase refrigerant to the liquid phase refrigerant and also having heat exchanger means therein to get rid of this heat.
When the refrigeration system is incorporated into an air conditioning system for a building, the evaporator in the one circuit is located in the main air duct of the a/c system within the building to remove humidity from the air. The heat exchanger means in the summer mode of operation of the a/c system can be a heat exchanger located outside the building, well removed from the condenser and the first circuit. The heat exchanger means in the winter mode of operation can be a heat exchanger in an air inlet duct leading to the main air duct for heating up makeup outside air being added to the air in the building.
The use of two separate refrigerant circuits reduces the amount of expensive vapor/liquid phase refrigerants required. The first circuit is quite compact with all the equipment in this circuit near each other. Thus a relatively small amount of vapor/liquid phase refrigerant is required. The longer circuit, using a liquid phase refrigerant, can be easily installed and serviced by a plumber. More expensive servicing, employing a refrigerant recovery method that requires a refrigeration mechanic, is not needed for the liquid phase refrigerant. More importantly, the use of a separate circuit filled with liquid phase refrigerant avoids migration when operating in the winter mode and the problems attendant with migration.
The invention is particularly directed toward an improved refrigerant system having a first refrigerant circuit with an evaporator and a condenser in the circuit and a first refrigerant therein with first means for circulating the first refrigerant through the circuit. The refrigerant system has a second circuit with a heat exchanger and the condenser in the second circuit and a second different refrigerant therein with second means for recirculating the second refrigerant through the circuit. The first refrigerant picks up heat in the evaporator and gives it up to the second refrigerant 2l39020 in the condenser. The second refrigerant picks up the heat in the condenser and gives it up in the heat exchanger.
The invention is also particularly directed toward an air conditioning system for a building having a main air duct with an evaporator in the duct to extract humidity from building air passing through the duct. The system has a first refrigerant circuit connecting the evaporator to a condenser and a second refrigerant circuit connecting the condenser to a heat exchanger in the building. There is a first refrigerant in the first circuit and first means in the first circuit for recirculating the first refrigerant through the first circuit. There is a second refrigerant in the second circuit along with means for circulating the second refrigerant through the second circuit. The first refrigerant takes heat from the building air in the evaporator and gives it up to the second refrigerant in the condenser. The second refrigerant gives up this heat to outside air in the heat exchanger.
The invention is further directed toward a method for operating an air conditioning system in a building comprising the steps of taking heat out of the air in the building while dehumidifying it with a first refrigerant, transferring this heat from the first refrigerant to a second refrigerant in a condenser and transferring the heat out of the second refrigerant to outside air through a heat exchanger.
BRIEF DESCRIPTION OF DRAWINGS
The invention will now be described in detail having reference to the accompanying drawings in which:
FIG. 1 is a schematic view of a simple refrigerant system of the present invention;
213902~
-FIG. 2 is a schematic view of a more complex refrigerant system of the present invention; and FIG. 3 is a schematic of an air conditioning system incorporating the refrigerant system shown in Fig. 2.
DESCRIPTION OF PREFERRED EMBODIMENTS
The improved refrigerant system 1 of the present invention as shown in Fig. 1 has a first circuit 3 that has an evaporator 5, a compressor 7, a condenser g and an expansion valve 11 in series joined by piping 13 in a closed loop. This first circuit 3 is filled by a first refrigerant that operates in vapor/fluid phases. The refrigerant enters the evaporator 5 as a mix of vapor and liquid and picks up heat therein leaving as vapor. The vapor is compressed and heated by the compressor 7 and passes to the condenser 9 where it gives up heat and becomes liquid. The liquid refrigerant then passes to the expansion valve 11 where it is partly vaporized and the vapor/liquid mix passes to the evaporator 5 to repeat the cycle.
The refrigerant system 1 includes a second circuit 17. This second circuit 17 has the condenser 9, a first heat exchanger 23, and a pump 25, all joined in series by piping 31. The second circuit 17 is filled with a second refrigerant that is in a liquid phase.
The second circuit 17 is operated to dissipate heat picked up by the second refrigerant from the first refrigerant in the condenser 9. The first heat exchanger 23 can be located far away from the condenser 9 A more easily handled, less expensive, refrigerant is used in the second circuit making the second circuit, and thus the refrigerant system, 213902~
easier to install and service. The first circuit can be quite compact and requires relatively little of the more efficient but more expensive vapor/liquid phase refrigerant.
The above refrigerant system, slightly modified, - is particularly suited for use in an air conditioning system for buildings, particularly buildings housing swimming pools. As shown in Figs. 2 and 3, the modified refrigerant system 101 has a first circuit 103 with an evaporator 105, a compressor 107, a condenser 109 and an expansion valve 111 all in series connected in a closed loop by piping 113. This circuit is the same as the circuit 3 in the system shown in Fig. 1. The evaporator 105 is mounted within a main air duct 115 in the air conditioning system in a building for removing humidity from the building air drawn through the duct 115 by a fan 117. Heat is taken out of the air to remove humidity by condensation. The first circuit 103 is filled with a first refrigerant that operates in vapor/liquid phases.
The air conditioning system includes a second circuit 121 with two parallel branches 123, 125. The first branch 123 has the condenser 109, a first heat exchanger 127, a pump 131, a check valve 133 and a second heat exchanger 129 all in series connected in a closed loop by piping 135. The first heat exchanger 127 is an air preheater and is located in an air inlet duct 137 connected to the main air duct 115 downstream from the evaporator 105. This first heat exchanger 127 is used to heat outside air being added to the system through the inlet duct 137. The outside air is needed to make up for the loss of some of the warm, humid, building air that is exhausted through an air outlet duct 141 leading to the outside from the main duct 115 just upstream from the evaporator 105 As this air passes to the outside through duct 141, it passes through the second heat exchanger 129 giving up heat to the refrigerant in the line 135 just before the refrigerant returns to the condenser 109 .
Preferably, the first branch 123 employs a third heat exchanger 145 located between the first heat exchanger 127 and the pump 131. This third heat exchanger 145 is an air reheater and is located in the main air duct 115 just downstream from the evaporator 105 and before the air inlet duct 137. The purpose of the air reheater 145 is to reheat the air, if needed, after it has been dehumidified. A bypass line 147 can lead from the piping or line 135 upstream from the reheater 145 to bypass the air reheater 145 if it is not needed. The bypass line joins the main line 135 downstream from the reheater and a diverter valve 149 can control the flow of the refrigerant to the bypass line 147.
The second branch 125 of the second circuit 121 of the a/c system has a second line 155 branching off from the main line 135 just after the main line 135 leaves the condenser 109. The second line 155 has a fourth heat exchanger 157, a second pump 159 and a second check valve 161 in series with the second line 155 rejoining the main line 135 just before it enters the second heat exchanger 129. The fourth heat exchanger 157 is used in the air conditioning system to transfer heat to the outside air. This heat exchanger 157 can be far removed from the main part of the air conditioning system.
The first circuit 103 is quite compact and employs a relatively small amount of expensive, relatively efficient, vapor/liquid phase refrigerant.
g A suitable vapor/liquid phase refrigerant would be an HFC refrigerant. The second circuit 121 can be quite long compared to the first circuit. The refrigerant in the second circuit is a liquid phase refrigerant such as propylene glycol by way of example. This refrigerant is always in the liquid phase and thus is easier to handle, less expensive and avoids any migration problems that may occur with a vapor/liquid phase refrigerant.
In operation, the first refrigerant in the first circuit 103 dehumidifies the warm, humid, building air passing through the main air duct 115 by taking heat out of the air in the evaporator 105. This heat is then transferred from the first refrigerant to the second refrigerant in the second circuit 121 in the condenser 109.
In the winter time, in a heating mode, the first branch 123 of the second circuit 121 alone would operate, with first pump 131 operating and second pump 159 stopped. The second check valve 161 would prevent back flow through the second branch 125 while the first pump 131 is operating. As the second refrigerant is circulated in the first branch 123, it picks up heat from the first refrigerant in the condenser 109 and passes through the first heat exchanger 127 to give up at least some of this heat to reheat the makeup air entering the system through the air inlet duct 137. This first heat exchanger 127 has the capacity to reject all of the heat picked up by the second refrigerant if needed.
If needed, the diverter valve 149 can be operated to direct the second refrigerant through the air reheater 145 to heat up the building air in the main duct 115 which has been cooled during dehumidification. If air reheating is not needed, the diverter valve 149 can be operated to bypass the air reheater 145. The second refrigerant then passes through the second heat exchanger 129 to be reheated to around room temperature by the building air being exhausted from the system through the air outlet duct 141 The first pump 131 keeps the second refrigerant recirculating through the first branch 123 while the second branch 125 is passive. However because the second refrigerant is in the liquid phase, migration is not a similar problem as when using a vapor/liquid phase refrigerant.
In the summer time, in a cooling mode, the first pump 131 is stopped and the second pump 159 is started to move the second refrigerant through the second branch 125. In the second branch 125 the second refrigerant picks up the heat from the primary refrigerant in the condenser 109 and gives it up to the outside air in the fourth heat exchanger 157. The fourth heat exchanger 157 is sized so that it can get rid of all the heat taken out of the building air.
The second refrigerant is recirculated by the second pump 159 through the second heat exchanger 129 to give up more heat to the exhaust air and then back to the condenser 109. The first check valve 133 in the first branch 123 prevents back flow through the first branch 123 while the second pump 159 is operating.
It is within the ambit of the present invention to cover any obvious modifications of the preferred embodiments described herein, provided such modifications fall within the scope of the appended claims. For example, it is conceivable to eliminate the two pumps 131 and 159 and their check valves 133 and 161 respectively and replace them by a three-way valve connected to lines 135 and 155 and also to the second heat exchanger 129. A single pump would then -be connected in the main 135 between the second heat exchanger 129 and the condenser lO9.
Claims (17)
1. A refrigerant system having:
a first refrigerant circuit with an evaporator and a condenser in the circuit, the first circuit having a first refrigerant therein and first means for circulating the first refrigerant through the circuit;
a second refrigerant circuit with a heat exchanger and the condenser in the circuit, the second circuit having a second refrigerant therein and second means for circulating the second refrigerant through the circuit;
the first refrigerant picking up heat from the evaporator and giving it up to the second refrigerant in the condenser, the second refrigerant picking up the heat in the condenser and giving it up in the heat exchanger.
a first refrigerant circuit with an evaporator and a condenser in the circuit, the first circuit having a first refrigerant therein and first means for circulating the first refrigerant through the circuit;
a second refrigerant circuit with a heat exchanger and the condenser in the circuit, the second circuit having a second refrigerant therein and second means for circulating the second refrigerant through the circuit;
the first refrigerant picking up heat from the evaporator and giving it up to the second refrigerant in the condenser, the second refrigerant picking up the heat in the condenser and giving it up in the heat exchanger.
2. A refrigerant system as claimed in claim wherein the first refrigerant is a vapor/liquid phase refrigerant and the second refrigerant is a liquid phase refrigerant.
3. A refrigerant system as claimed in claim 2 wherein the first circuit has a relatively short path and the second circuit can have a relatively long path.
4. A refrigerant system as claimed in claim wherein the second circuit has two branches with a heat exchanger and separate recirculating means in each branch, the second circuit operating one branch or the other.
5. An air conditioning system for a building having:
a main air duct; an evaporator in the duct to extract humidity from building air passing through the duct;
a first refrigerant circuit connecting the evaporator to a condenser; a second refrigerant circuit connecting the condenser to a heat exchanger;
a first refrigerant in the first circuit and first means in the first circuit for recirculating the first refrigerant through the first circuit;
a second refrigerant in the second circuit and second means for recirculating the second refrigerant through the second circuit;
the first refrigerant taking heat from the building air in the evaporator and giving it up to the second refrigerant in the condenser, the second refrigerant giving up the heat to outside air in the heat exchanger.
a main air duct; an evaporator in the duct to extract humidity from building air passing through the duct;
a first refrigerant circuit connecting the evaporator to a condenser; a second refrigerant circuit connecting the condenser to a heat exchanger;
a first refrigerant in the first circuit and first means in the first circuit for recirculating the first refrigerant through the first circuit;
a second refrigerant in the second circuit and second means for recirculating the second refrigerant through the second circuit;
the first refrigerant taking heat from the building air in the evaporator and giving it up to the second refrigerant in the condenser, the second refrigerant giving up the heat to outside air in the heat exchanger.
6. An air conditioning system as claimed in claim 5 wherein the first refrigerant is a vapor/liquid phase refrigerant and the second refrigerant is a liquid phase refrigerant.
7. An air conditioning system as claimed in claim 6 wherein the second circuit has two branches with a heat exchanger in each branch to give up heat to outside air, the second recirculating means comprising a pump in each branch, and means for operating one branch only at a time.
8. An air conditioning system as claimed in claim 7 wherein one of the branches is operated in the wintertime and the heat exchanger in the one branch is located in an air inlet duct leading into the main duct to heat up outside air being drawn into the main duct as makeup air.
9. An air conditioning system as claimed in claim 8 including a second heat exchanger in the one branch located in an air outlet duct leading from the main air duct to heat up the second refrigerant by building air being exhausted outside from the main duct.
10. An air conditioning system as claimed in claim 8 including a third heat exchanger in the one branch located in the main duct downstream from the evaporator which reheats the building air after it has been dehumidified, and including means for selectively connecting the third heat exchanger to the one branch.
11. An air conditioning system as claimed in claim 8 wherein the other branch is operated in the summertime and the heat exchanger in the other branch is located outside the building to give up heat to outside air outside the building.
12. An air conditioning system as claimed in claim 6 wherein the first circuit follows a relatively short path and the second circuit follows a relatively long path.
13. A method of air conditioning a building comprising the steps of: removing humidity from the air in the building with a first refrigerant;
transferring the heat removed by the first refrigerant to a second refrigerant; and removing the heat transferred to the second refrigerant by outside air.
transferring the heat removed by the first refrigerant to a second refrigerant; and removing the heat transferred to the second refrigerant by outside air.
14 A method as claimed in claim 13 wherein the first refrigerant is a vapor/liquid phase refrigerant and the second refrigerant is a liquid phase refrigerant.
15. A method as claimed in claim 14 wherein the heat from the second refrigerant is transferred to outside air entering the building as makeup air during the wintertime
16 A method as claimed in claim 14 wherein the heat from the second refrigerant is transferred to outside air outside the building during the summertime.
17. A method as claimed in claim 14 wherein the second refrigerant is used to reheat the dehumidified air
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002139020A CA2139020A1 (en) | 1994-12-23 | 1994-12-23 | Heat transfer method using a secondary fluid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002139020A CA2139020A1 (en) | 1994-12-23 | 1994-12-23 | Heat transfer method using a secondary fluid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2139020A1 true CA2139020A1 (en) | 1996-06-24 |
Family
ID=4154919
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002139020A Abandoned CA2139020A1 (en) | 1994-12-23 | 1994-12-23 | Heat transfer method using a secondary fluid |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2139020A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115875865A (en) * | 2023-01-10 | 2023-03-31 | 北京工业大学 | Adjustable single-screw compressor regenerative cascade low-temperature refrigeration system |
-
1994
- 1994-12-23 CA CA002139020A patent/CA2139020A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115875865A (en) * | 2023-01-10 | 2023-03-31 | 北京工业大学 | Adjustable single-screw compressor regenerative cascade low-temperature refrigeration system |
| CN115875865B (en) * | 2023-01-10 | 2023-08-04 | 北京工业大学 | Adjustable single-screw compressor regenerative cascade low-temperature refrigerating system |
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