HK1165539A - Absorption cycle system having dual absorption circuits - Google Patents

Description

Absorption cycle system with double absorption loops

Cross Reference to Related Applications

This patent application claims the benefit of priority from U.S. provisional patent application 61/118,042 filed on 26.11.2008.

Background

1. Field of disclosure

The present disclosure relates to absorption cycle systems having dual absorption loops. The system can be used in a variety of absorption cycle applications including cryogenic refrigeration, comfort air conditioning and space heating.

2. Background of the invention

Single-effect absorption cycle systems having a single absorption loop are known in the art. In a typical absorption cycle system, a refrigerant, such as water vapor, is absorbed into an absorbent mixture, such as an aqueous solution of lithium bromide (LiBr), and then released from the absorbent mixture. The absorber is part of a single absorption circuit comprising a pump, a heat exchanger, an expansion or pressure reduction device and a generator, wherein refrigerant is released from the absorbent mixture before it enters the condenser and the evaporator.

However, one disadvantage of such standard systems, which typically use lithium bromide and water as the absorbent/refrigerant pair, is that the crystallization temperature of the absorbent/refrigerant mixture limits the lowest feasible operating temperature of the absorber.

It would be desirable to find a suitable absorption cycle configuration and corresponding absorbent/refrigerant mixture, particularly an absorbent/water mixture, that allows the refrigerant returning from the evaporator to be absorbed (e.g., as a result of resistance to crystallization) at temperatures below the lowest possible operating temperature of the absorber that uses a lithium bromide/water solution as the absorbent/refrigerant mixture.

Summary of The Invention

It is an object of the present invention to provide an absorption cycle system which employs a combination of an additional absorption loop and a conventional absorption loop. The absorbent used in the additional absorption circuit may be any absorbent, the absorbent/refrigerant mixture of which is more advantageous at low temperatures (e.g. as a result of crystallization resistance) than the absorbent used in conventional absorption circuits. The absorbent used in the additional absorption loop may be or may contain ionic compounds or other crystallization inhibiting additives. Such mixtures of absorbents with water resist crystallization in compositions effective for recycle operations at lower temperatures than the lowest feasible operating temperatures of prior art conventional absorbers of lithium bromide/water solutions.

With such a system, the additional absorber can operate at a lower temperature than a conventional absorber that circulates lithium bromide and water as an absorbent/refrigerant mixture. It is expected that the lower feasible absorber operating temperatures will be suitable for new cooling and heating applications, especially at low ambient temperatures. It is also expected that lower absorber operating temperatures will also enable higher cycle energy efficiency, which is expressed commercially as a higher coefficient of performance or COP.

Furthermore, the use of two absorption loops allows for the simultaneous use of a heat sensitive absorbent (such as a heat sensitive ionic compound or an absorbent formulation containing a heat sensitive crystallization inhibitor or other heat sensitive additive) in one loop and a high temperature heat source in the other loop.

Thus, according to the present invention, there is provided an absorption cycle system comprising an evaporator for circulating a refrigerant therethrough; a first absorption circuit disposed in fluid communication with the evaporator for mixing the refrigerant from the evaporator with a first absorbent to form a first absorbent and refrigerant mixture and for circulating the first absorbent and refrigerant mixture therethrough; a second absorption circuit disposed in fluid communication with the first absorption circuit for mixing a portion of the refrigerant from the first absorption circuit with a second absorbent to form a second absorbent and refrigerant mixture, and for circulating the second absorbent and refrigerant mixture therethrough; and a condenser disposed in fluid communication with the second absorption loop and the evaporator. The first absorbent/refrigerant mixture is resistant to crystallization and therefore remains operable at lower temperatures than the second absorbent/refrigerant mixture circulating in the second absorption loop.

According to another embodiment of the invention, a portion of the heat of the high pressure refrigerant vapor may be recovered and transferred to the first generator, rather than being rejected at the condenser. This results in higher energy efficiency. Thus, according to this embodiment, the absorption cycle system of the present invention comprises a heat recovery line extending between the second generator and the first generator and through said first generator to recover heat from the refrigerant leaving the second generator. The heat recovery line extends from the first generator to the condenser to deliver refrigerant vapor to the condenser.

Brief Description of Drawings

The invention may be better understood with reference to the following drawings, in which:

FIG. 1 is a schematic view of an absorption cycle system according to one embodiment of the present invention.

FIG. 2 is a schematic view of an absorption cycle system according to another embodiment of the present invention.

Detailed Description

A schematic diagram of an absorption cycle system according to the present invention is shown generally at 10 in fig. 1. The system is first described as an absorption cooling system according to fig. 1. The system includes an evaporator 10-1 for circulating a refrigerant therethrough, a first absorption circuit, shown generally at 20 in FIG. 1, a second absorption circuit, shown generally at 30 in FIG. 1, disposed in fluid communication with the second absorption circuit and the evaporator, the first absorption circuit being disposed in fluid communication with the evaporator for mixing the refrigerant from the evaporator with a first absorbent to form a first absorbent and refrigerant mixture and for circulating the first absorbent and refrigerant mixture therethrough, the second absorption circuit being disposed in fluid communication with the first absorption circuit for mixing a portion of the refrigerant from the first absorption circuit with a second absorbent to form a second absorbent and refrigerant mixture, and for circulating the second absorbent and refrigerant mixture therethrough.

The evaporator in the system of the invention comprises an inlet line 14 for delivering refrigerant to the evaporator. The refrigerant in the system of the present invention is water, as described below, it being understood and appreciated that other refrigerants may be used in the system, as described below. When the refrigerant enters the evaporator, it is a partially evaporated liquid. In some embodiments, the evaporator further comprises tubing (not shown) through which chilled water or other heat transfer fluid is circulated. The partially evaporated refrigerant contacts the tubing in the evaporator and the liquid portion of the refrigerant is evaporated, absorbing heat and forming refrigerant vapor. The chilled water leaves the evaporator through outlet line 11 at a lower temperature than when it entered the evaporator and is sent to the body to be cooled, such as a building, shown at 10-4 in figure 1. The body to be cooled may be any space, place, object or body for which cooling is desired, including building interior spaces requiring air conditioning, and refrigerator or freezer spaces in, for example, hotels or restaurants or industrial production areas, such as those used in processing or producing food products.

Chilled water from the building is delivered back to the evaporator through line 12 and recirculated through the tubing in the evaporator. As shown in fig. 1, refrigerant vapor exits the evaporator through line 13 and is sent to the first suction circuit 20 via this line.

The first absorption circuit 20 includes a first absorber 20-1, a liquid pump 20-2, a first heat exchanger 20-3, and a first or cryogenic generator 20-4. The first absorber has an inlet for delivering refrigerant vapor which is mixed there with a mixture of refrigerant having a low refrigerant content and the first absorbent delivered via line 25 to form a first absorbent/refrigerant mixture having a high refrigerant content. The first absorbent may be or may comprise an ionic compound. Generally, absorbing refrigerant into the first absorbent also generates heat (heat of absorption). Cooling water or other heat transfer fluid is circulated through the tube bundles (not shown) of the absorber to collect this heat of absorption from the system. The high refrigerant content mixture is collected at the bottom of the first absorber so that the first absorption cycle can begin again.

A high refrigerant content first absorbent/refrigerant mixture exits the first absorber through outlet line 21 and is sent to liquid pump 20-2, which pumps the mixture to first heat exchanger 20-3. The mixture is preheated by a first heat exchanger, which may be a shell and tube heat exchanger, and then the mixture enters a first or low temperature generator. After leaving the heat exchanger, the mixture flows into the first generator through line 22. The first generator is provided with low temperature heat from any suitable external source. In one embodiment, a tube bundle (not shown) carrying a heat transfer fluid, which may be hot water, steam, or fuel gas, is located within the generator and is supplied to the first generator via line 23. The heat transfer fluid transfers heat to the high refrigerant content first absorbent/refrigerant mixture. The heat causes the mixture to release refrigerant vapor which exits the first generator via line 26, leaving a mixture of low refrigerant content. The refrigerant is now high pressure vapor. In some cases, only trace amounts of refrigerant are present in the liquid mixture exiting the first generator via line 24. In other cases, a non-negligible amount of refrigerant is present in the absorbent/refrigerant mixture exiting the first generator, the amount ranging from about 1% to about 80% by weight. In any case, the amount of refrigerant in the mixture leaving the first generator via line 24 is lower than the amount in the mixture leaving the first generator via line 21. The exact amount of refrigerant present in the mixture exiting the first generator will depend on a number of factors, including the solubility of the refrigerant in the first absorbent.

The low refrigerant content first absorbent/refrigerant mixture flows via line 24 back to the first heat exchanger where it is cooled by the high refrigerant content first absorbent/refrigerant mixture pumped out of the first absorber. The low refrigerant content first absorbent/refrigerant mixture flows from the first heat exchanger through the expansion or pressure reduction device 20-5 to the first absorber via line 25 and collects at the bottom of the first absorber where it begins the first absorption loop cycle and repeats the cycle in the first absorption loop.

The second absorption loop includes a second absorber 30-1, a second liquid pump 30-2, a second heat exchanger 30-3, and a second or high temperature generator 30-4. As noted above, refrigerant vapor from the first absorption circuit exits the first generator and is delivered to the second absorption circuit via line 26. The refrigerant vapor is delivered to a second absorber 30-1, which includes a tube bundle (not shown). A mixture of low refrigerant content refrigerant and second absorbent is also delivered to the second absorber via line 35. The refrigerant and the second absorbent are collected at the bottom of the second absorber. Lithium bromide may be used as the second absorbent in the system, it being understood that the present invention is not limited to the use of lithium bromide as the second absorbent. Also, as in the first absorber, the refrigerant vapor is absorbed into the low refrigerant-content second absorbent/refrigerant mixture, thereby forming a high refrigerant-content second absorbent/refrigerant mixture. Generally, the refrigerant is absorbed into the second absorbent, also generating heat (heat of absorption). A heat transfer fluid, such as cooling water, is circulated through the tube bundle in the second absorber to collect this heat of absorption from the system.

The second pump 30-2 pumps the high refrigerant content second absorbent/refrigerant mixture to the second heat exchanger 30-3, which may be a shell and tube heat exchanger, as with the first heat exchanger, via line 31. The second heat exchanger preheats the mixture which then enters the second generator 30-4 via line 32. The second generator is supplied with high temperature heat from any suitable external source. In one embodiment, a tube bundle carrying a heat transfer fluid, which may be, for example, gas, steam, or hot water, is located within the second generator and is supplied to the second generator via line 33. In some embodiments, the heat transfer fluid may be heated to an elevated temperature by a concentrated solar thermal system. The heat transfer fluid transfers heat to the high refrigerant content second absorbent/refrigerant mixture. The heat causes the mixture to release refrigerant vapor which exits the second generator via line 36 leaving a mixture of low refrigerant content in the second generator. The refrigerant leaving the generator via line 36 is now high pressure vapor. The low refrigerant content second absorbent/refrigerant mixture flows via line 34 back to the second heat exchanger where it is cooled by the high refrigerant content second absorbent/refrigerant mixture pumped from the second absorber to the second heat exchanger. The low refrigerant content second absorbent/refrigerant mixture flows from the second heat exchanger through an expansion or pressure reduction device 30-5 to the second absorber via line 35 and collects in the bottom of the second absorber where it begins the second absorption loop cycle and repeats the cycle in the second absorption loop. As in the first absorption loop, the amount of refrigerant in the mixture exiting the second generator via line 34 is lower than the amount in the mixture exiting the second absorber via line 31 and can range from a trace amount or more typically from about 1 wt% to about 80 wt%. The exact amount of refrigerant present in the mixture exiting the second generator will depend on a number of factors, including the solubility of the refrigerant in the second absorbent.

As noted above, refrigerant, which is a high pressure vapor, exits the second generator 30-4 via line 36. As shown in fig. 1, the high pressure refrigerant vapor flows to condenser 10-2. In the condenser, a heat transfer fluid, such as cooling water, flows through tubes (not shown) in the condenser, and the refrigerant vapor condenses outside the tubes to form a refrigerant liquid, which collects in a sump (not shown) at the bottom of the condenser. In other condenser designs, the released heat may be supplied to the building space rather than to the heat transfer fluid, and it should be understood that various other condenser designs are within the scope of the present invention. Refrigerant liquid exits the condenser sump via line 14 through an expansion or pressure reduction device 10-3, which partially vaporizes the refrigerant liquid, to the evaporator. The partially vaporized refrigerant liquid contacts evaporator tubes in which water or some other heat transfer fluid flows. The heat transfer fluid is cooled as the liquid refrigerant evaporates to form a refrigerant vapor. The cooled heat transfer fluid is circulated back to the body to be cooled, such as a building, to provide the desired cooling effect, such as air conditioning. The refrigerant vapor moves from the evaporator to the first absorber and repeats the entire refrigerant cycle.

The system of fig. 1 may be used as a heat pump rather than operating as an absorption cooling system as described above. In this case the system is an absorption heating system, where at the first absorber heat is supplied by the cycle in fig. 1, and the second absorber and condenser are used to meet the respective heating requirements, such as heating building space or water. As noted above, refrigerant, which is a high pressure vapor, exits the second generator 30-4 via line 36. As shown in fig. 1, the high pressure refrigerant vapor flows to condenser 10-2. In the condenser, cooling water or other heat transfer fluid flows through tubes (not shown) in the condenser, and the refrigerant vapor condenses outside the tubes to form a refrigerant liquid, which collects in a sump (not shown) at the bottom of the condenser. The refrigerant vapor condenses, releasing heat. In other condenser designs, the released heat may be supplied to the building space instead of to the cooling water, and it should be understood that various other condenser designs are within the scope of the present invention. Refrigerant liquid exits the condenser sump via inlet line 14 through an expansion or pressure reduction device 10-3, which partially vaporizes the refrigerant liquid, to the evaporator. When the refrigerant enters the evaporator, it is a partially evaporated liquid. In some embodiments, the vaporizer further comprises tubing (not shown) through which water or other heat transfer fluid is circulated to provide heat to the vaporizer, the heat being derived from a source external to the circulation system, such as water at the bottom of a lake or pond, or a region at a depth from the surface of the earth that is moderately warm over the years, or low temperature waste treatment heat. The evaporator may receive heat from ambient air. The partially evaporated refrigerant contacts the tubing in the evaporator and the liquid portion of the refrigerant is evaporated, absorbing heat and forming refrigerant vapor. The heat transfer fluid exits the evaporator through outlet line 11 at a lower temperature than the temperature at which it entered the evaporator and is sent back to an external heat source, which in this embodiment replaces the building shown at 10-4 in fig. 1. In this embodiment there is no longer a heat exchange between the chilled water and the building to be cooled, but rather a heat exchange between the water or heat transfer fluid supplying heat to the evaporator and an external heat source. In this case, the heat transfer fluid from the external heat source is delivered back to the evaporator through line 12.

Figure 2 shows a second embodiment of the absorption cooling system of the present invention. Such a system is shown generally at 110. The system includes an evaporator 110-1 disposed in fluid communication with a first absorption circuit, shown generally at 120 in fig. 2, a second absorption circuit, shown generally at 130 in fig. 2, disposed in fluid communication with the first absorption circuit, and a condenser 110-2 disposed in fluid communication with the second absorption circuit and the evaporator.

The evaporator in the system of the present invention includes an inlet line 114 for delivering refrigerant to the evaporator. Likewise, the refrigerant in the second embodiment system of the present invention is water, it being understood and as described below that other refrigerants may be used in the system. The evaporator in the second embodiment operates in the same manner as the evaporator in fig. 1. Thus, when the refrigerant enters the evaporator, it is a partially evaporated liquid. The evaporator also includes tubing (not shown) through which chilled water or other heat transfer fluid is circulated. The partially evaporated refrigerant contacts the tubing in the evaporator and the liquid portion of the refrigerant is evaporated, absorbing heat and forming refrigerant vapor. The chilled water leaves the evaporator through outlet line 111 at a lower temperature than when it entered the evaporator and is sent to the body to be cooled, such as a building, shown in figure 2 at 110-4.

Chilled water from the building is delivered back to the evaporator through line 112 and recirculated through the tubing in the evaporator. As shown in fig. 2, refrigerant vapor exits the evaporator through line 113 and is sent to first suction circuit 120 via this line.

The first absorption circuit 120 includes a first absorber 120-1, a liquid pump 120-2, a first heat exchanger 120-3, and a first or cryogenic generator 120-4. The first absorber has an inlet for delivering refrigerant vapor where it mixes with the mixture of refrigerant with a low refrigerant content and the first absorbent delivered via line 125 to form a first absorbent/refrigerant mixture with a high refrigerant content. The first absorbent may be or may comprise an ionic compound. Generally, absorbing the refrigerant into the absorbent also generates heat (heat of absorption). Cooling water moves through the tube bundles of the absorber (not shown) to remove this heat of absorption from the system. The high refrigerant content mixture is collected at the bottom of the first absorber so that the first absorption circuit cycle can begin again.

The high refrigerant content first absorbent/refrigerant mixture exits the first absorber through outlet line 121 and is sent to liquid pump 120-2, which pumps the mixture to first heat exchanger 120-3. The mixture is preheated by a first heat exchanger 120-3, which may be a shell and tube heat exchanger, and then the mixture enters a first (or low temperature) generator 120-4. After leaving the heat exchanger, the mixture flows into the first generator through line 122. The first generator is provided with low temperature heat from any suitable external source. In one embodiment, a tube bundle (not shown) carrying hot water, steam, or fuel gas is located within the generator, which hot water, steam, or fuel gas is supplied to the first generator via line 123. The hot water, steam, or fuel gas transfers heat to the high refrigerant content first absorbent/refrigerant mixture. The heat causes the mixture to release refrigerant vapor which exits the first generator via line 126, leaving a mixture of low refrigerant content. The refrigerant is now high pressure vapor. In some cases, only trace amounts of refrigerant are present in the liquid mixture exiting the first generator via line 124. In other cases, a non-negligible amount of refrigerant is present in the first absorbent/refrigerant mixture exiting the first generator, the amount ranging from about 1% to about 80% by weight. In any event, the amount of refrigerant in the mixture exiting the first generator via line 124 is lower than the amount in the mixture exiting the first generator via line 121. The exact amount of refrigerant present in the mixture exiting the first generator will depend on a number of factors, including the solubility of the refrigerant in the first absorbent.

The low refrigerant content first absorbent/refrigerant mixture flows via line 124 back to the first heat exchanger where it is cooled by the high refrigerant content first absorbent/refrigerant mixture pumped out of the first absorber. The low refrigerant content first absorbent/refrigerant mixture flows from the first heat exchanger through the expansion or pressure reduction device 120-5 to the first absorber via line 125 and collects at the bottom of the first absorber where it begins the first absorption loop cycle and repeats the cycle in the first absorption loop.

The second absorption loop includes a second absorber 130-1, a second liquid pump 130-2, a second heat exchanger 130-3, and a second or high temperature generator 130-4. As noted above, refrigerant vapor from the first absorption circuit exits the first generator and is delivered to the second absorption circuit via line 126. The refrigerant vapor is delivered to a second absorber 130-1, which includes a tube bundle (not shown). A mixture of low refrigerant content refrigerant and second absorbent is also delivered to the second absorber via line 135. The refrigerant and the second absorbent are collected at the bottom of the second absorber. Lithium bromide may be used as the second absorbent in the system, it being understood that the present invention is not limited to the use of lithium bromide as the second absorbent. Also, as in the first absorber, the refrigerant vapor is absorbed into the low refrigerant-content second absorbent/refrigerant mixture, thereby forming a high refrigerant-content second absorbent/refrigerant mixture. Generally, absorbing the refrigerant into the absorbent also generates heat (heat of absorption). Cooling water moves through the second absorber tube bundle to remove the heat of absorption from the system.

Second pump 130-2 pumps the high refrigerant content second absorbent/refrigerant mixture to second heat exchanger 130-3, which may be a shell and tube heat exchanger, as with the first heat exchanger, via line 131. The second heat exchanger preheats the mixture, which then enters the second generator 130-4 via line 132. The second generator is supplied with high temperature heat from any suitable external source. In one embodiment, a tube bundle (not shown) carrying gas, steam, or hot water is located within the second generator, to which the gas, steam, or hot water is supplied via line 133. The fuel gas, steam, or hot water transfers heat to the high refrigerant content second absorbent/refrigerant mixture. The heat causes the mixture to release refrigerant vapor that exits the second generator via heat recovery line 136a, leaving a low refrigerant content mixture in the second generator. The refrigerant, now high pressure vapor, exits the second generator via line 136 a. The heat recovery line extends between and through the second generator and recovers heat from refrigerant exiting the second generator. In this embodiment, all of the high pressure refrigerant vapor is sent back to the first or low temperature generator 120-4, rather than being sent to the condenser. As in the first embodiment, a portion of the heat of the high pressure refrigerant vapor may be recovered and transferred to the first generator, rather than being rejected at the condenser. This results in higher energy efficiency. The heat recovery line extends from the first generator to the condenser to deliver refrigerant vapor to the condenser. From there, the high pressure refrigerant vapor is sent to the condenser via line 136 b.

The low refrigerant content second absorbent/refrigerant mixture flows via line 134 back to the second heat exchanger where it is cooled by the high refrigerant content second absorbent/refrigerant mixture pumped from the second absorber to the second heat exchanger. The low refrigerant content second absorbent/refrigerant mixture flows from the second heat exchanger through an expansion or pressure reduction device via line 135 to the second absorber and collects in the bottom of the second absorber where it begins the second absorption loop cycle and repeats the cycle in the second absorption loop.

As shown in fig. 2, the high pressure refrigerant vapor flows to the condenser 110-2. In the condenser, cooling water flows through tubes (not shown) in the condenser, and the refrigerant vapor condenses outside the tubes to form a refrigerant liquid, which collects in a sump (not shown) at the bottom of the condenser. Refrigerant liquid exits the condenser sump via inlet line 114 through an expansion or pressure reduction device 110-3, which partially vaporizes the refrigerant liquid, to the evaporator. The partially vaporized refrigerant liquid contacts evaporator tubes in which water or some other heat transfer fluid flows. The heat transfer fluid is cooled as the refrigerant liquid portion evaporates to form a refrigerant vapor. The cooled heat transfer fluid is circulated back to the body to be cooled, such as a building, to provide the desired cooling effect, such as air conditioning. The refrigerant vapor moves from the evaporator to the first absorber and repeats the entire refrigerant cycle.

It is also within the scope of the invention to use the configuration of fig. 2 for heating. The only difference in fig. 2 with respect to fig. 1 is that the working fluid vapor leaving the high temperature generator II (130-4) is directed to the line of the low temperature generator I (120-4) where the working fluid supplies part of its heat to the low temperature generator I (120-4) where it is then condensed in the condenser (110-2). The heat released upon condensation in condenser 110-2 is now used for heating, rather than being discarded to the environment (as is the case in the cooling mode of cyclic operation). In the heating mode of the circulation operation, an external heat source is used instead of the building 110-4 as shown in fig. 2. Also in this embodiment there is no longer a heat exchange between the chilled water and the building to be cooled, but rather a heat exchange between the water or heat transfer fluid supplying heat to the evaporator and an external heat source. Generally, the selectivity of the fig. 2 embodiment to redistribute heat from the high temperature generator to the low temperature generator enables better utilization of the available heat sources in some cases.

In the embodiment of fig. 1 or 2 in which the absorption cycle is an absorption heating system as described above, the use of an absorbent solution in the first (low temperature) absorber that resists crystallization at low temperatures, thereby allowing the first absorber to operate at temperatures closer to the ambient low temperature during the heating season, can significantly improve energy efficiency. Such absorbent solutions that resist crystallization at low temperatures are disclosed in U.S. provisional patent application serial nos. 61/112,415 and 61/112,428, both filed on 7/11/2008, and 61/165,089, 61/165,093, 61/165,147, 61/165,155, 61/165,161, 61/165,160, 61/165,166, and 61/165,173, all filed on 31/3/2009. They include compositions comprising LiBr, water and inorganic salts that have been shown to lower the temperature at which LiBr crystallizes causing system failure. LiBr crystallization temperature depressants include, but are not limited to, cesium formate and other group I metal salts, phosphonates, and ionic liquids containing fluorinated anions, cations, or both.

These anti-crystallization compositions are based primarily on the use of water as the refrigerant. It should be noted that the phase diagram of the working fluid used in the absorption cycle of the present invention should allow for both vapor and liquid phases in equilibrium in the evaporator at lower temperatures than the temperature at which heat is drawn from the heat source. In other words, the triple point temperature of the working fluid should be lower than the temperature at which external heat is provided to the evaporator.

The triple point temperature of water is 0.0098 ℃. Thus, when the ambient air temperature falls below 0.0098C, or more practically below, for example, 4℃, water is used as the refrigerant, and an absorption cycle is used for heating, the heat supplied to the evaporator must come from a source external to the system that is not ambient air. External heat sources available at temperatures above the triple point temperature of water include subsurface regions, natural bodies of water (e.g., water at the bottom of a nearby lake or pond), and low temperature waste treatment heat.

Refrigerant/absorbent pair：

Refrigerant：

The present invention provides a refrigerant pair composition for use in an absorption cycle that can be used for cooling or for transferring heat from the outside to the inside, depending on the application. In one embodiment, water is used as the refrigerant in the present invention. In another embodiment, the refrigerant may be a hydrofluorocarbon, hydrochlorofluorocarbon, chlorofluorocarbon, fluorocarbon, chlorocarbon, nitrogen (N)₂) Oxygen (O)₂) Carbon dioxide (CO)₂) Ammonia (NH)₃) Dinitrogen monoxide (N)₂O), argon (Ar), hydrogen (H)₂) Non-fluorinated hydrocarbon, or mixtures thereof, by mixtures of which is meant mixtures of any of the foregoing refrigerants in this paragraph. The non-fluorinated hydrocarbon being selected from C₁-C₇Linear, branched or cyclic alkanes, and C₁-C₇Linear, branched or cyclic olefins are also within the scope of the invention.

Hydrofluorocarbon refrigerants may include compounds having hydrogen and any combination of fluorine and carbon, and include compounds having at least one carbon-carbon double bond. Examples of hydrofluorocarbon refrigerants to be used in the present invention include, but are not limited to, difluoromethane (HFC-32), fluoromethane (HFC-41), pentafluoroethane (HFC-125), 1, 1, 2, 2-tetrafluoroethane (HFC-134), 1, 1, 1, 2-tetrafluoroethane (HFC-134a), 1, 1, 1-trifluoroethane (HFC-143a), 1, 1-difluoroethane (HFC-152a), fluoroethane (HFC-161), 1, 1, 1, 3, 3-pentafluoropropane (HFC-245fa), 1, 1, 1, 3, 3, 3-hexafluoropropane (HFC-236fa), 1, 1, 1, 2, 3, 3-hexafluoropropane (HFC-236ea), 1, 1, 1, 2, 3, 3, 3-heptafluoropropane (HFC-227ea), 1, 1, 1, 3, 3-pentafluorobutane (HFC-365mfc), 1, 1, 1, 2, 3, 4, 4, 5, 5, 5-decafluoropentane (HFC-43-10mee), 1, 1, 1, 2, 2, 3, 4, 5, 5, 6, 6, 7, 7, 7-tetradecafluoroheptane (HFC-63-14mcee), 1, 2-difluoroethylene (HFO-1132), 2, 3, 3, 3-tetrafluoropropene (HFO-1234yf), 1, 3, 3, 3-tetrafluoropropene (HFO-1234ze), 1, 2, 3, 3-tetrafluoropropene (HFO-1234ye), 3, 3-trifluoropropene (HFO-1243zf), 1, 2, 3, 3, 3-pentafluoropropene (HFO-1225ye), 1, 1, 1, 3, 3-pentafluoropropene (HFO-1225zc), 1, 1, 1, 4, 4, 4-hexafluoro-2-butene (HFO-1336mzz), 1, 1, 1, 2, 2, 5, 5, 5-octafluoro-2-pentene (HFO-1438mczz), 1, 1, 1, 2, 2,4, 5, 5, 6, 6, 7, 7, 7-tridecafluoro-3-heptene (HFO-162-13mczy), and 1, 1, 1, 2, 2, 3, 5, 5, 6, 6, 7, 7, 7-tridecafluoro-3-heptene (HFO-162-13mcyz), and mixtures thereof. In one embodiment of the present invention, the hydrofluorocarbon refrigerant is selected from the group consisting of difluoromethane (HFC-32), pentafluoroethane (HFC-125), 1, 1, 1, 2-tetrafluoroethane (HFC-134a), 1, 1, 1-trifluoroethane (HFC-143a), 1, 1-difluoroethane (HFC-152a), 2, 3, 3, 3-tetrafluoropropene (HFO-1234yf), and mixtures thereof.

Additionally, in another embodiment, the hydrofluorocarbon refrigerant may comprise 2-chloro-3, 3, 3-trifluoropropene (HCFO-1233xf, CF)₃CCl＝CH₂) Cis-or trans-1-chloro-3, 3, 3-trifluoropropene (HCFO-1233zd, CF)₃CH ═ CHCl), 3, 4, 4, 4-tetrafluoro-3-trifluoromethyl-1-butene ((CF) (-CHCl), and a pharmaceutically acceptable salt thereof₃)₂CFCH＝CH₂HFO-1447fzy), cis-or trans-1, 1, 1, 4, 4, 5, 5, 5-octafluoro-2-pentene (CF)₃CF₂CH＝CHCF₃HFO-1438mzz), and combinations thereof.

Chlorofluorocarbon refrigerants may include compounds having chlorine and any combination of fluorine and carbon, and include compounds having carbon-carbon double bonds. Representative chlorofluorocarbon refrigerants useful in the present invention include, but are not limited to, dichlorodifluoromethane (CFC-12), trichlorofluoromethane (CFC-11), 1, 2-trichloro-1, 2, 2-trifluoroethane (CFC-113), 1, 2-difluoro-1, 1, 2, 2-tetrafluoroethane (CFC-114), and mixtures thereof.

Hydrochlorofluorocarbon refrigerants may include compounds having hydrogen, chlorine, and any combination of fluorine and carbon, and include compounds having carbon-carbon double bonds. Representative hydrochlorofluorocarbon refrigerants useful in the present invention include, but are not limited to, difluoromethane monochloride (HCFC-22), 2-chloro-3, 3, 3-trifluoropropene (HCFO-1233xf), 1-chloro-3, 3, 3-trifluoropropene (HCFO-1233zd), and mixtures thereof.

Fluorocarbon refrigerants may include compounds having any combination of fluorine and carbon, and include compounds having carbon-carbon double bonds as well as cyclic compounds. Examples of fluorocarbon refrigerants that may be used in the present invention include, but are not limited to, perfluoromethane (FC-14), perfluoroethane (FC-116), perfluoropropane (FC-218), perfluorocyclobutane (FC-C318), octafluoro-2-butene (FO-1318my), and mixtures thereof.

The chlorocarbon refrigerant may include compounds having only chlorine, carbon, and optionally hydrogen. Examples of chlorocarbon refrigerants include, but are not limited to, 1, 2-dichloroethylene, dichloromethane, trichloroethylene, perchloroethylene, and mixtures thereof.

Non-fluorinated hydrocarbon refrigerants useful in the present invention can include, but are not limited to, methane, ethane, ethylene, propane, cyclopropane, propylene, n-butane, isobutane, cyclobutane, n-pentane, isopentane, n-hexane, cyclohexane, n-heptane, and mixtures thereof.

In some embodiments, mixtures of various types of refrigerants are intended to be included within the scope of the present invention. Moreover, azeotropes and azeotrope-like compositions formed from two or more of the many refrigerants disclosed herein can be particularly useful in the absorption cycle systems of the present invention.

In another embodiment, the hydrofluorocarbon working fluid may comprise mixtures or blends of hydrofluorocarbons with other compounds such as hydrofluorocarbons, hydrochlorofluorocarbons, hydrocarbons or other compounds. Such working fluid blends include the following compositions:

HFO-1447fzy with at least one compound selected from cis-or trans-HFO-1438 mzz, cis-or trans-HFO-1336 mzz, HCFO-1233xf, and cis-or trans-HCFO-1233 zd;

cis-HFO-1438 mzz with at least one compound selected from the group consisting of trans-HFO-1438 mzz, cis-or trans-HFO-1336 mzz, HCFO-1233xf, and cis-or trans-HCFO-1233 zd;

trans-HFO-1438 mzz with at least one compound selected from cis or trans-HFO-1336 mzz, HCFO-1233xf, cis-or trans-HCFO-1233 zd, and isopentane;

cis-HFO-1336 mzz with at least one compound selected from the group consisting of trans-HFO-1336 mzz, HCFO-1233xf, cis-or trans-HCFO-1233 zd, isopentane, n-pentane, cyclopentane, methyl formate, 1-dichloro-2, 2, 2-trifluoroethane (HCFC-123), and trans-1, 2-dichloroethylene; trans-HFO-1336 mzz with at least one compound selected from HCFO-1233xf and cis-or trans-HCFO-1233 zd;

HCFO-1233xf with at least one compound selected from cis-and trans-HCFO-1233 zd.

In another embodiment, the working fluid that is a mixture may be an azeotrope or azeotrope-like composition as follows:

from about 51% to about 70% by weight cis-HFO-1336 mzz, and from about 49% to about 30% by weight isopentane;

from about 62 to about 78 weight percent cis-HFO-1336 mzz, and from about 38 to about 22 weight percent n-pentane;

from about 75% to about 88% by weight cis-HFO-1336 mzz, and from about 25% to about 12% by weight cyclopentane;

from about 25% to about 35% by weight of cis-HFO-1336 mzz, and from about 75% to about 65% by weight of HCFC-123;

from about 67 to about 87 weight percent cis-HFO-1336 mzz, and from about 33 to about 13 weight percent trans-1, 2-dichloroethylene; and

from about 61% to about 78% by weight trans-HFO-1438 mzz, and from about 39% to about 22% by weight isopentane.

In one embodiment, the refrigerant as used herein may also be selected from water, and water with HFC-32, HFC-125, HFC-134a, HFC-143a, HFC-152a, HFC-161, HCFC-22, FC-14, FC-116, CFC-12, NH₃、CO₂、N₂、O₂、H₂Ar, methane, ethane, propane, cyclopropane, propylene, butane, butene, and isobutane.

Although some refrigerants are specified above, in general, the inventive absorption cycle of the present invention is advantageous for any refrigerant or mixture of refrigerants that can use two absorbents, such that the first absorbent/refrigerant mixture is preferably at a low temperature and the second absorbent/refrigerant mixture is preferably at a high temperature. The absorbent/refrigerant mixture used in the low temperature absorption loop is preferred depending on various characteristics of the absorbent/refrigerant mixture at the preferred operating concentration and temperature range for the intended application, including reduced crystallization temperature, favorable refrigerant absorption/desorption characteristics at low temperatures, reduced viscosity, and enhanced heat and mass transfer in the absorber. The absorbent/refrigerant mixture used in the high temperature absorption loop is preferred depending on various characteristics of the absorbent/refrigerant mixture at the preferred operating concentration and temperature range for the intended application, including higher thermal stability, low corrosion of equipment construction materials, favorable refrigerant absorption/desorption characteristics at high temperatures, and enhanced heat and mass transfer characteristics.

Mixtures of refrigerants may also be used to achieve a suitable boiling temperature or a suitable pressure for the absorption means. In particular, mixtures that form azeotropes, azeotrope-like mixtures, or constant boiling mixtures are sometimes preferred because if refrigerant leaks from the absorption cooling system, minimal or no fractionation of the mixture will occur.

Absorbent agent：

In a preferred embodiment of the absorption cycle according to the invention, the absorbent used is an ionic compound, which can in principle be any ionic compound that absorbs water. Suitable ionic compounds that absorb water are ionic compounds that are at least to some extent miscible with water, or ionic compounds that are at least to some extent soluble or dispersible in water to form a sufficiently stable emulsion. The energy efficiency of the absorption cycle generally increases with the increase in the water absorption of the ionic compound (i.e., water is highly miscible therewith, or water is soluble therein to a greater extent). One such ionic compound is lithium bromide (LiBr).

Many ionic compounds are formed by reacting a nitrogen-containing heterocycle, preferably a heteroaromatic ring, with an alkylating agent, such as an alkyl halide, to form a quaternary ammonium salt, and performing ion exchange or other suitable reaction with various lewis acids or their conjugate bases to form ionic compounds. Examples of suitable heteroaromatic rings include substituted pyridines, imidazoles, substituted imidazoles, pyrroles and substituted pyrroles. These rings can be used with virtually any straight, branched or cyclic C_1-20Alkyl groups, but preferably C_1-16A group. Various triarylphosphines, thioethers, and cyclic and acyclic quaternary ammonium salts may also be used for this purpose. Counter-ions that can be used include chloroaluminate, bromoaluminate, gallium chloride, tetrafluoroborate, tetrachloroborate, hexafluorophosphate, nitrate, trifluoromethanesulfonate, methanesulfonate, p-toluenesulfonate, hexafluoroantimonate, hexafluoroarsenate, tetrachloroaluminate, tetrabromoaluminate, perchlorate, hydroxide anion, copper dichloride anion, iron trichloride anion, zinc trichloride anion, and various types of compounds containing lanthanum,Anions of potassium, lithium, nickel, cobalt, manganese and other metals.

Ionic compounds can also be synthesized by salt metathesis reactions, by acid-base neutralization reactions, or by quaternizing selected nitrogen-containing compounds; or they are commercially available from several companies such as Merck (Darmstadt, Germany) or BASF (Mount Olive, New Jersey).

Representative examples of ionic compounds useful herein include among those described in the following sources, such as "j.chem.tech.biotechnol." 68: 351-356 (1997); chem.ind.68: 249-263 (1996); "J.Phys.condensed Matter" 5: (supp 34B): B99-B106 (1993); "Chemical and Engineering News" (30/3/1998) 32-37; "j.mater.chem." 8: 2627-2636 (1998); "chem.rev." 99: 2071-2084 (1999); and WO 05/113,702 (and references cited therein). In one embodiment, libraries of ionic compounds, i.e., combinatorial libraries of ionic compounds, can be obtained, for example, by preparing alkyl derivatives of various quaternary ammonium cations and varying the anions that are bound. The acidity of the ionic compound can be adjusted by varying the molar equivalents and types and combinations of lewis acids.

Ionic compounds suitable for use as absorbents include those having a cation selected from the group consisting of:

lithium, sodium, potassium, cesium and the formula:

wherein R is¹、R²、R³、R⁴、R⁵、R⁶、R¹²And R¹³Independently selected from:

(i)H

(ii) halogen element

(iii) Optionally substituted by at least one element selected from Cl, Br, F, I, OH, NH₂and-CH substituted by members of SH₃、-C₂H₅Or C₃-C₂₅Linear, branched or cyclic alkanes or alkenes;

(iv) containing one to three heteroatoms selected from O, N, Si and S and optionally substituted by at least one heteroatom selected from Cl, Br, F, I, OH, NH₂and-CH substituted by members of SH₃、-C₂H₅Or C₃-C₂₅Linear, branched or cyclic alkanes or alkenes;

(v)C₆-C₂₀unsubstituted aryl, or C having one to three heteroatoms independently selected from O, N, Si and S₃-C₂₅An unsubstituted heteroaryl group; and is

(vi)C₆-C₂₅Substituted aryl, or C having one to three heteroatoms independently selected from O, N, Si and S₃-C₂₅A substituted heteroaryl group; and wherein the substituted aryl or substituted heteroaryl has one to three substituents independently selected from the group consisting of:

(1) optionally substituted by at least one element selected from Cl, Br, F, I, OH, NH₂and-CH substituted by members of SH₃、_-C2H₅Or C₃-C₂₅Linear, branched or cyclic alkanes or alkenes,

(2)OH，

(3)NH₂and are and

(4)SH；

R⁷、R⁸、R⁹and R¹⁰Independently selected from:

(i)-CH₃、-C₂H₅or C₃-C₂₅Straight, branched or cyclic

(ii) An alkane or alkene optionally substituted with at least one;

(iii) selected from Cl, Br, F, I, OH, NH₂And a member of SH;

(iv)-CH₃、-C₂H₅or C₃-C₂₅Straight, branched or cyclic

(v) Containing one to three heteroatoms selected from O, N, Si and S and optionally substituted by at least one heteroatom selected from Cl, Br, F, I, OH, NH₂And SH-substituted alkanes or alkenes

(vi)C₆-C₂₅Unsubstituted aryl, or C having one to three heteroatoms independently selected from O, N, Si, and S₃-C₂₅An unsubstituted heteroaryl group; and is

(vii)C₆-C₂₅Substituted aryl, or C having one to three heteroatoms independently selected from O, N, Si and S₃-C₂₅A substituted heteroaryl group; and wherein the substituted aryl or substituted heteroaryl has one to three substituents independently selected from the group consisting of:

(1) optionally substituted by at least one element selected from Cl, Br, F, I, OH, NH₂and-CH substituted by members of SH₃、-C₂H₅Or C₃-C₂₅Linear, branched or cyclic alkanes or alkenes,

(2)OH，

(3)NH₂and are and

(4) SH; and is

Wherein optionally R¹、R²、R³、R⁴、R⁵、R⁶、R⁷、R⁸、R⁹And R¹⁰At least two of which are taken together to form a cyclic or bicyclic alkyl or alkenyl group.

Ionic compounds suitable for use as absorbents include those having an anion selected from the group consisting of: [ CH ]₃CO₂]^-、[HSO₄]^-、[CH₃OSO₃]^-、[C₂H₅OSO₃]^-、[AlCl₄]^-、[CO₃]^2-、[HCO₃]^-、[HCO₂]^-、[NO₂]^-、[NO₃]^-、[SO₄]^2-、[PO₃]^3-、[HPO₃]^2-、[H₂PO₃]^1-、[PO₄]^3-、[HPO₄]^2-、[H₂PO₄]^-、[HSO₃]^-、[CuCl₂]^-、Cl^-、Br^-、I^-、SCN^-；BR¹R²R³R⁴、BOR¹OR²OR³OR⁴Carborane optionally substituted with alkyl or substituted alkyl (1-carborane (1-)), carborane optionally substituted with alkylamine, substituted alkylamine, alkyl or substituted alkyl (dicarbadodecaborane (1-)), and preferably any fluorinated anion. Fluorinated anions useful herein include [ BF ]₄]^-、[PF₆]^-、[SbF₆]^-、[CF₃SO₃]^-、[HCF₂CF₂SO₃]^-、[CF₃HFCCF₂SO₃]^-、[HCClFCF₂SO₃]^-、[(CF₃SO₂)₂N]^-、[(CF3CF₂SO₂)₂N]^-、[(CF₃SO₂)₃C]^-、[CF₃CO₂]^-、[CF₃OCFHCF₂SO₃]^-、[CF₃CF₂OCFHCF₂SO₃]^-、[CF₃CFHOCF₂CF₂SO₃]^-、[CF₂HCF₂OCF₂CF₂SO₃]^-、[CF₂ICF₂OCF₂CF₂SO₃]^-、[CF₃CF₂OCF₂CF₂SO₃]^-、[(CF₂HCF₂SO₂)₂N]^-、[(CF₃CFHCF₂SO₂)₂N]^-(ii) a And F^-. Other suitable anions include those of the formula:

wherein R is¹¹Selected from:

(i) optionally substituted by at least one element selected from Cl, Br, F, I, OH, NH₂and-CH substituted by members of SH₃、-C₂H₅Or C₃-C₁₀Linear, branched or cyclic alkanes or alkenes;

(ii) containing one to three heteroatoms selected from O, N, Si and S and optionally substituted by at least one heteroatom selected from Cl, Br, F, I, OH, NH₂and-CH substituted by members of SH₃、-C₂H₅Or C₃-C₁₀Linear, branched or cyclic alkanes or alkenes;

(iii)C₆-C₁₀unsubstituted aryl, or C having one to three heteroatoms independently selected from O, N, Si and S₃-C₁₀An unsubstituted heteroaryl group; and is

(iv)C₆-C₁₀Substituted aryl, or C having one to three heteroatoms independently selected from O, N, Si and S₃-C₁₀A substituted heteroaryl group; and wherein the substituted aryl or substituted heteroaryl has one to three substituents independently selected from the group consisting of:

(1) optionally substituted by at least one element selected from Cl, Br, F, I, OH, NH₂and-CH substituted by members of SH₃、_-C2H₅Or C₃-C₁₀Linear, branched or cyclic alkanes or alkenes,

(2)OH，

(3)NH₂and are and

(4)SH。

in another embodiment, the ionic compounds suitable for use herein may have a cation selected from the group consisting of pyridine and an anionPyridazinePyrimidinesPyrazine estersImidazolePyrazolesThiazolesAzoleTriazole compoundsAmmonium, benzyltrimethylammonium, cesium, choline, dimethylimidazoleGuanidine (guanidine)Lithium,Choline (hydroxyethyl trimethyl)) Potassium, sodium, tetramethylammonium, tetramethylThe anion is selected from: aminoacetate (glycine), ascorbate, benzoate, catechol, citrate, dimethylphosphate, formate, fumarate, gallate, glycolate, glyoxylate, iminodiacetate, isobutyrate, kojic acid (5-hydroxy-2-hydroxymethyl-4-pyrone ion), lactate, levulinate, oxalate, pivalate, propionate, pyruvate, salicylate, succinamate, succinate, Crotonate (CH)₃CH＝C(CH₃)COO^-) Tetrafluoroborate, tetrafluoroethanesulfonate, and tropolate (2-hydroxy-2, 4, 6-cycloheptatrien-1-one ion), [ CH₃CO₂]^-、[HSO₄]^-、[CH₃OSO₃]^-、[C₂H₅OSO₃]^-、[AlCl₄]^-、[CO₃]^2-、[HCO₃]^-、[NO₂]^-、[NO₃]^-、[SO₄]^2-、[PO₄]^3-、[HPO₄]^2-、[H₂PO₄]^-、[HSO₃]^-、[CuCl₂]^-、Cl^-、Br^-、I^-、SCN^-、[BF₄]^-、[PF₆]^-、[SbF₆]^-、[CF₃SO₃]^-、[HCF₂CF₂SO₃]^-、[CF₃HFCCF₂SO₃]^-、[HCClFCF₂SO₃]^-、[(CF₃SO₂)₂N]^-、[(CF₃CF₂SO₂)₂N]^-、[(CF₃SO₂)₃C]^-、[CF₃CO₂]^-、[CF₃OCFHCF₂SO₃]^-、[CF₃CF₂OCFHCF₂SO₃]^-、[CF₃CFHOCF₂CF₂SO₃]^-、[CF₂HCF₂OCF₂CF₂SO₃]^-、[CF₂ICF₂OCF₂CF₂SO₃]^-、[CF₃CF₂OCF₂CF₂SO₃]^-、[(CF₂HCF₂SO₂)₂N]^-、[(CF₃CFHCF₂SO₂)₂N]^-、F^-And any fluorinated anion. Whether we have covered various gen0.5 crystallization inhibiting additives that we have filed over the past months?

Generally, it is expected that water will be somewhat more miscible with or soluble in hydrophilic ionic compounds, and therefore ionic compounds having a cation with at least one alcohol side chain, or those having an anion with at least one acetate or sulfate, will be desirable choices for use in various embodiments of the present invention. It is also preferred that the water will be miscible with or soluble in the ionic compound as used herein within the operating temperature range of the absorption system, especially within the evaporator temperature to generator temperature range. The evaporator temperature can be as low as about 5 ℃. The single effect generator temperature may be up to about 150 c and the dual effect generator temperature may be up to about 200 c. Thus, a variety of different relative amounts of water of refrigerant and absorbent in the absorption cycle are suitable over a temperature range of about 5 ℃ to about 200 ℃, and the concentration of water or ionic compound in the composition formed from water and ionic compound may range from about 1% to about 99% by weight of the combined weight of ionic compound and water therein.

In various embodiments of the present invention, ionic compounds formed by selection of any individual cation described or disclosed herein, and by selection of any individual anion described or disclosed herein that is paired with the cation, may be used as an absorbent in an absorption heating or cooling cycle. Thus, in other embodiments, a subgroup of ionic compounds may be used as the absorbent, which may be formed by selecting (i) a subgroup of cations of any size, taken from the total group of cations described or disclosed herein in all of the various different combinations of the individual members of the total group, and (ii) a subgroup of anions of any size, taken from the total group of anions described or disclosed herein in all of the various different combinations of the individual members of the total group. In forming the ionic compound or the ionic compound subgroup by selecting as described above, the selection may be made using the ionic compound or the ionic compound subgroup in the absence of the member of the group of cations and/or anions to be ignored in the total group thereof, and if desired, the selection may be made according to the member of the total group to be ignored in use, rather than the member of the group to be included in use.

The absorbent used in the absorption heating or cooling cycle is suitably a compound having high solubility for the refrigerant (e.g. water) and a very high boiling point with respect to the refrigerant.

While certain absorbents are described above, in general, any two absorbents can be used as the first and second absorbents of the present invention, provided that the first absorbent is more advantageous at low temperatures (e.g., more resistant to crystallization, or lower viscosity) and the second absorbent is more advantageous at high temperatures (e.g., thermally stable). Any one absorbent may (but is not required to) comprise or consist essentially of an ionic compound, i.e. it may comprise or consist essentially of a non-ionic compound. Suitable nonionic compound absorbents include, but are not limited to, ethers, esters, amides, and ketones.

Mixtures of ionic compounds may also be used herein as absorbents, and it is desirable that such mixtures can, for example, achieve suitable absorption properties, particularly when water is mixed with other components such as alcohols, esters, or ethers that can be used in conjunction with the absorption apparatus.

Additives such as lubricants, corrosion inhibitors, stabilizers, dyes, crystallization inhibitors (e.g., cesium formate, etc.), and other suitable materials may be added to the refrigerant compositions useful in the present invention for a variety of purposes, provided they do not have an undesirable effect on the solubility of water in the ionic compound absorbent. The refrigerant pair compositions of the present invention may be prepared by any convenient method including mixing or combining the appropriate amounts of each component in a suitable vessel using, for example, a known type of agitator having rotating mixing elements.

In the embodiments described above, cooling water is used in the absorber and condenser. For simplicity, the flow of cooling water through the two absorbers and the condenser is not shown. In one embodiment, the cooling water will flow into the first and second absorbers where the water is heated due to the heat of absorption of the refrigerant absorbed into the first or second absorbent. The cooling water flows from the first absorber to the second absorber. From the second absorber, the cooling water flows to the condenser tube bundle where it will provide a cooling effect to condense the refrigerant vapor to a refrigerant liquid. The cooling water is thereby further heated and flows out of the condenser via a line (not shown) to a cooling tower or other means intended to release the heat taken up by the system into the surrounding environment and to provide the cooling water to the system again.

The present invention allows for a variety of configurations and methods to remove the heat of refrigerant absorption from both absorbers, as well as to remove the heat of refrigerant condensation (and possibly secondary cooling) from the condenser, and should not be limited to those configurations specifically described herein.

Generally, the present invention allows for a variety of configurations to optimize energy management to improve cycle energy efficiency and heat recovery, and in particular, to recover heat from a high temperature, high pressure refrigerant before the refrigerant releases heat at a condenser, it being understood that various configurations to recover heat before the condenser are within the scope of the present invention.

The present invention allows for various designs of the various equipment components required for the specific implementation of an absorption cycle, particularly the design of the absorber, generator, heat exchanger and condenser used to implement the required heat and mass transfer operations, and should not be limited to those designs specifically described herein.

The hot water, steam or gas supplied to the first or second generator to release refrigerant vapour from the first or second absorbent/refrigerant mixture may be provided from a number of sources, including water heated by waste heat of an internal combustion engine (gas), solar heated water and the like.

In one embodiment, disclosed herein is a method of refrigeration comprising forming a first absorbent/refrigerant mixture at a first absorber, heating the first absorbent/refrigerant mixture to release refrigerant vapor, sending the refrigerant vapor to a second absorber, forming a second absorbent/refrigerant mixture, heating the second absorbent/refrigerant mixture to release refrigerant vapor, condensing the refrigerant vapor to form a liquid refrigerant, evaporating the liquid refrigerant at low pressure in the vicinity of a heat transfer fluid, transferring the heat transfer fluid to the vicinity of a body to be cooled, and reforming the hot first and second absorbent/refrigerant mixtures. Reforming refers to the re-dilution of the concentrated first and second absorbent/refrigerant mixtures by absorbing refrigerant vapor to restore the ability of the mixtures to deliver refrigerant to the first and second generators, respectively.

In another embodiment, an absorption cycle may be employed to generate heat using, for example, an absorption heat pump in a manner similar to the refrigeration process described above. In this method, the heat of absorption resulting from absorption of refrigerant in the absorber into the absorbent and the heat of condensation resulting primarily from condensation of refrigerant vapor in the condenser into refrigerant liquid can be transferred to water or some other heat transfer fluid used to heat any space, location, object or body.

Furthermore, the present invention is not limited to only those embodiments shown or described herein. For example, it is also within the scope of the invention to extend the invention to cycles in which the refrigerant passes successively through three absorption circuits connected in series, and to facilitate optimal utilization of the available heat source at three different temperatures.

Claims (14)

1. An absorption cycle system, the system comprising:

(a) an evaporator for circulating a refrigerant therethrough;

(b) a first absorption circuit disposed in fluid communication with the evaporator for mixing the refrigerant from the evaporator with a first absorbent to form a first absorbent and refrigerant mixture and for circulating the first absorbent and refrigerant mixture therethrough;

(c) a second absorption circuit disposed in fluid communication with the first absorption circuit for mixing a portion of the refrigerant from the first absorption circuit with a second absorbent to form a second absorbent and refrigerant mixture and for circulating the second absorbent and refrigerant mixture therethrough; and

(d) a condenser disposed in fluid communication with the second absorption circuit and the evaporator.

2. The system of claim 1, wherein the first suction circuit comprises:

(a) a first absorber disposed in fluid communication with the evaporator to absorb the refrigerant from the evaporator into the first absorbent and refrigerant mixture,

(b) a first heat exchanger disposed in fluid communication with the first absorber to receive and preheat the first absorbent and refrigerant mixture from the first absorber,

(c) a first liquid pump for pumping the first absorbent and refrigerant mixture from the first absorber to the first heat exchanger, and

(d) a first generator disposed in fluid communication with the first heat exchanger to receive the preheated mixture from the first heat exchanger and transfer additional heat to the preheated mixture.

3. The system of claim 2, wherein the second absorption loop comprises:

(a) a second absorber disposed in fluid communication with the first generator to absorb a portion of the refrigerant from the first generator into a second mixture comprising the refrigerant and a second absorbent in the second absorber;

(b) a second heat exchanger disposed in fluid communication with the second absorber to preheat the second absorbent and refrigerant mixture from the second absorber,

(c) a second liquid pump for pumping the second absorbent and refrigerant mixture from the second absorber to the second heat exchanger, and

(d) a second generator disposed in fluid communication with the second heat exchanger to receive the preheated mixture from the second heat exchanger and transfer additional heat into the second mixture.

4. The absorption cycle system of claim 1, wherein the first absorbent and the second absorbent are each ionic compounds.

5. The absorption cycle system of claim 4, wherein the ionic compound comprises a cation and an anion, wherein the cation is selected from the group consisting of:

lithium, sodium, potassium, cesium,

Wherein R is¹、R²、R³、R⁴、R⁵、R⁶、R¹²And R¹³Independently selected from:

(a)H

(b) halogen element

(c) Optionally substituted by at least one element selected from Cl, Br, F, I, OH, NH₂and-CH substituted by members of SH₃、-C₂H₅Or C₃-C₂₅Linear, branched or cyclic alkanes or alkenes;

(d) containing one to three heteroatoms selected from O, N, Si, and S and optionally substituted with at least one heteroatom selected from Cl, Br, F, I, OH, NH₂and-CH substituted by members of SH₃、-C₂H₅Or C₃-C₂₅Linear, branched or cyclic alkanes or alkenes;

(e)C₆-C₂₀unsubstituted aryl, or C having one to three heteroatoms independently selected from O, N, Si, and S₃-C₂₅An unsubstituted heteroaryl group; and

(f)C₆-C₂₅substituted aryl, or C having one to three heteroatoms independently selected from O, N, Si, and S₃-C₂₅A substituted heteroaryl group; and wherein the substituted aryl or substituted heteroaryl has one to three substituents independently selected from the group consisting of:

(1) -CH3, -C2H5, or C3-C25 linear, branched or cyclic alkanes or alkenes optionally substituted with at least one member selected from Cl, Br, F, I, OH, NH2, and SH,

(2)OH，

(3) NH2, and

(4)SH；

R⁷、R⁸、R⁹and R¹⁰Independently selected from:

(a) optionally substituted by at least one element selected from Cl, Br, F, I, OH, NH₂and-CH substituted by members of SH₃、-C₂H₅Or C₃-C₂₅Linear, branched or cyclic alkanes or alkenes;

(b) containing one to three heteroatoms selected from O, N, Si and S and optionally substituted by at least one heteroatom selected from Cl, Br, F, I, OH, NH₂and-CH substituted by members of SH₃、-C₂H₅Or C₃-C₂₅Linear, branched or cyclic alkanes or alkenes;

(c)C₆-C₂₅unsubstituted aryl, or C having one to three heteroatoms independently selected from O, N, Si, and S₃-C₂₅An unsubstituted heteroaryl group; and C₆-C₂₅SubstitutionAryl, or C having one to three heteroatoms independently selected from O, N, Si, and S₃-C₂₅A substituted heteroaryl group; and wherein the substituted aryl or substituted heteroaryl has one to three substituents independently selected from the group consisting of:

(1) optionally substituted by at least one element selected from Cl, Br, F, I, OH, NH₂and-CH substituted by members of SH₃、-C₂H₅Or C₃-C₂₅Linear, branched or cyclic alkanes or alkenes,

(2)OH，

(3)NH₂and are and

(4) SH; and is

Wherein optionally R¹、R²、R³、R⁴、R⁵、R⁶、R⁷、R⁸、R⁹And R¹⁰At least two of which may be taken together to form a mono-or bicyclic alkyl or alkenyl group;

the anion is selected from:

[CH₃CO₂]^-、[HSO₄]^-、[CH₃OSO₃]^-、[C₂H₅OSO₃]^-、[AlCl₄]^-、[CO₃]^2-、[HCO₃]^-、[NO₂]^-、[NO₃]^-、[SO₄]^2-、[PO₃]^3-、[HPO₃]^2-、[H₂PO₃]^1-、[PO₄]^3-、[HPO₄]^2-、[H₂PO₄]^-、[HSO₃]^-、[CuCl₂]^-、Cl^-、Br^-、I^-、SCN^-；BR¹R²R³R⁴、BOR¹OR²OR³OR⁴a carborane acid radical optionally substituted with an alkyl or substituted alkyl group, a carborane optionally substituted with an alkylamine, a substituted alkylamine, an alkyl or substituted alkyl group, and a fluorinated anion.

6. The absorption cycle system of claim 4, wherein the refrigerant comprises water.

7. The absorption cycle system of claim 4, wherein the refrigerant is selected from the group consisting of hydrofluorocarbons, hydrochlorofluorocarbons, chlorofluorocarbons, fluorocarbons, chlorocarbons, nitrogen (N)₂) Oxygen (O)₂) Carbon dioxide (CO)₂) Ammonia (NH)₃) Dinitrogen monoxide (N)₂O), argon (Ar), hydrogen (H)₂) Non-fluorinated hydrocarbons, and mixtures thereof.

8. The absorption cycle system of claim 7 wherein the non-fluorinated hydrocarbon is selected from C₁-C₇Straight, branched or cyclic alkanes, and C₁-C₇Linear, branched or cyclic olefins.

9. The absorption cycle system of claim 7, wherein the refrigerant comprises at least one refrigerant selected from the group consisting of: difluoromethane (HFC-32), fluoromethane (HFC-41), pentafluoroethane (HFC-125), 1, 1, 2, 2-tetrafluoroethane (HFC-134), 1, 1, 1, 2-tetrafluoroethane (HFC-134a), 1, 1, 1-trifluoroethane (HFC-143a), 1, 1-difluoroethane (HFC-152a), fluoroethane (HFC-161), 1, 1, 1, 3, 3-pentafluoropropane (HFC-245fa), 1, 1, 1, 3, 3, 3-hexafluoropropane (HFC-236fa), 1, 1, 1, 2, 3, 3-hexafluoropropane (HFC-236ea), 1, 1, 1, 2, 3, 3-heptafluoropropane (HFC-227ea), 1, 1, 1, 3, 3-pentafluorobutane (HFC-365mfc), 1, 1, 1, 2, 3, 4, 4, 5, 5, 5-decafluoropentane (HFC-43-10mee), 1, 1, 1, 2, 2, 3, 4, 5, 5, 6, 6, 7, 7, 7-tetradecafluoroheptane (HFC-63-14mcee), 2, 3, 3, 3-tetrafluoropropene (HFO-1234yf), 1, 2-difluoroethylene (HFO-1132), 1, 3, 3, 3-tetrafluoropropene (HFO-1234ze), 1, 2, 3, 3-tetrafluoropropene (HFO-1234ye), 3, 3, 3-trifluoropropene (HFO-1243zf), 1, 2, 3, 3, 3-pentafluoropropene (HFO-1225ye), 1, 1, 3, 3-pentafluoropropene (HFO-1225zc), 1, 1, 1, 4, 4, 4-hexafluoro-2-butene (HFO-6 mz), 1, 1, 1, 4, 4-hexafluoro-2-butene (HFO-6 mze), 1, 1, 1, 2, 2, 5, 5, 5-octafluoro-2-pentene (HFO-1438mczz)1, 1, 1, 2, 2,4, 5, 5, 6, 6, 7, 7, 7-tridecafluoro-3-heptene (HFO-162-13mczy) and 1, 1, 1, 2, 2, 3, 5, 5, 6, 6, 7, 7, 7-tridecafluoro-3-heptene (HFO-162-13mcyz), dichlorodifluoromethane (CFC-12), trichlorofluoromethane (CFC-11), 1, 1, 2-trichloro-1, 2, 2-trifluoroethane (CFC-113), 1, 2-dichloro-1, 1, 2, 2-tetrafluoroethane (CFC-114), difluorochloromethane (HCFC-22), 2-chloro-3, 3, 3-trifluoropropene (HCFO-1233xf), 1-chloro-3, 3, 3-trifluoropropene (HCFO-1233zd), Perfluoromethane (FC-14), perfluoroethane (FC-116), perfluoropropane (FC-218), perfluorocyclobutane (FC-C318), octafluoro-2-butene (FO-1318my), 1, 2-dichloroethylene, methylene chloride, trichloroethylene, perchloroethylene, methane, ethane, ethylene, propane, cyclopropane, propylene, N-butane, isobutane, cyclobutane, N-pentane, isopentane, N-hexane, cyclohexane, N-heptane, nitrogen (N-C-R), nitrogen (N-C-R), and mixtures thereof₂) Oxygen (O)₂) Carbon dioxide (CO)₂) Ammonia (NH)₃) Dinitrogen monoxide (N)₂O), argon (Ar), hydrogen (H)₂) And mixtures thereof.

10. The absorption cycle system of claim 2, further comprising a first recirculation line between the first generator and the first heat exchanger, and between the first heat exchanger and the first absorber, for recirculating the first absorbent and refrigerant mixture back to the first absorber.

11. The absorption cycle system of claim 3, further comprising a second recycle line between said second generator and said second absorber for recycling said second absorbent and refrigerant mixture back to said second absorber.

12. The absorption cycle system of claim 3 further comprising a heat recovery line extending between said second generator and said first generator and through said first generator to recover heat from said refrigerant exiting said second generator, said heat recovery line extending from said first generator to said condenser for delivering said refrigerant vapor to said condenser.

13. The system of claim 1, wherein the system is an absorption cooling system.

14. The system of claim 1, wherein the system is a heat pump.