Absorption Cycle System Having Dual Absorption Circuits

Abstract

An absorption cycle system utilizes an additional absorption circuit in conjunction with a traditional absorption circuit. The absorbent used in the additional absorption circuit could contain an ionic compound, or any absorbent with relatively low crystallization. Mixtures of such absorbent with water remain liquid at temperatures lower than the minimum feasible operating temperature of the traditional lithium bromide water absorbent solutions of the prior art.

1 . An absorption cycle 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, thereby forming 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, thereby forming 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 with the evaporator.   
     
     
         2 . The system of  claim 1 , wherein the first absorption circuit comprises:
 (a) a first absorber disposed in fluid communication with the evaporator for absorbing 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 for receiving and pre-heating 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 for receiving the pre-heated mixture from the first heat exchanger and transferring additional heat into the pre-heated mixture.   
     
     
         3 . The system of  claim 2 , wherein the second absorption circuit comprises:
 (a) a second absorber disposed in fluid communication with the first generator for absorbing 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 for pre-heating 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 for receiving the pre-heated mixture from the second heat exchanger and transferring additional heat into the second mixture.   
     
     
         4 . The absorption cycle system of  claim 1 , wherein the first absorbent and the second absorbent are each an ionic compound. 
     
     
         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 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 12  and R 13  are independently selected from the group consisting of:
 (a) H 
 (b) halogen 
 (c) —CH 3 , —C 2 H 5 , or C 3  to C 25  straight-chain, branched or cyclic alkane or alkene, optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH 2  and SH; 
 (d) —CH 3 , —C 2 H 5 , or C 3  to C 25  straight-chain, branched or cyclic alkane or alkene comprising one to three heteroatoms selected from the group consisting of O, N, Si and S, and optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH 2  and SH; 
 (e) C 6  to C 20  unsubstituted aryl, or C 3  to C 25  unsubstituted heteroaryl having one to three heteroatoms independently selected from the group consisting of O, N, Si and S; and 
 (f) C 6  to C 25  substituted aryl or C 3  to C 25  substituted heteroaryl having one to three heteroatoms independently selected from the group consisting of O, N, Si and S; and wherein said substituted aryl or substituted heteroaryl has one to three substituents independently selected from the group consisting of:
 (1) —CH3, —C2H5, or C3 to C25 straight-chain, branched or cyclic alkane or alkene, optionally substituted with at least one member selected from the group consisting of Cl, Br, F I, OH, NH 2  and SH, 
 (2) OH, 
 (3) NH2, and 
 (4) SH; 
 
 
         R 7 , R 8 , R 9 , and R 10  are independently selected from the group consisting of:
 (a) —CH 3 , —C 2 H 5 , or C 3  to C 25  straight-chain, branched or cyclic alkane or alkene, optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH 2  and SH; 
 (b) —CH 3 , —C 2 H 5 , or C 3  to C 25  straight-chain, branched or cyclic alkane or alkene comprising one to three heteroatoms selected from the group consisting of O, N, Si and S, and optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH 2  and SH; 
 (c) C 6  to C 25  unsubstituted aryl, or C 3  to C 25  unsubstituted heteroaryl having one to three heteroatoms independently selected from the group consisting of O, N, Si and S; and C 6  to C 25  substituted aryl, or C 3  to C 25  substituted heteroaryl having one to three heteroatoms independently selected from the group consisting of O, N, Si and S; and wherein said substituted aryl or substituted heteroaryl has one to three substituents independently selected from the group consisting of:
 (1) —CH 3 , —C 2 H 5 , or C 3  to C 25  straight-chain, branched or cyclic alkane or alkene, optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH 2  and SH, 
 (2) OH, 
 (3) NH 2 , and 
 (4) SH; and 
 
 
         wherein optionally at least two of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , and R 10  can together form a cyclic or bicyclic alkanyl or alkenyl group; 
         and an anion selected from the group consisting of: 
         [CH 3 CO 2 ] − , [HSO 4 ] − , [CH 3 OSO 3 ] − , [C 2 H 5 OSO 3 ] − , [AlCl 4 ] − , [CO 3 ] 2− , [HCO 3 ] − , [NO 2 ] − , [NO 3 ] − , [SO 4 ] 2− , [PO 3 ] 3− , [HPO 3 ] 2− , [H 2 PO 3 ] 1− , [PO 4 ] 3− , [HPO 4 ] 2− , [H 2 PO 4 ] − , [HSO 3 ] − , [CuCl 2 ] − , Cl − , Br − , I − , SCN − ; BR 1 R 2 R 3 R 4 , BOR 1 OR 2 OR 3 OR 4 , carborates optionally substituted with alkyl or substituted alkyl, carboranes optionally substituted with alkylamine, substituted alkylamine, alkyl or substituted alkyl, 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 ), nitrous oxide (N 2 O), 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 the group consisting of C 1  to C 7  straight-chain, branched or cyclic alkanes and C 1  to C 7  straight-chain, branched or cyclic alkenes. 
     
     
         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), 1,1,1,2,3,3,3-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-difluoroethene (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), 1,1,1,3,3-pentafluoropropene (HFO-1225zc), 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336m/z), 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), fluorotrichloromethane (CFC-11), 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113), 1,2-dichloro-1,1,2,2-tetrafluoroethane (CFC-114), chlorodifluoromethane (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, butane, isobutane, cyclobutane, n-pentane, isopentane, n-hexane, cyclohexane, n-heptane, nitrogen (N 2 ), oxygen (O 2 ), carbon dioxide (CO 2 ), ammonia (NH 3 ), nitrous oxide (N 2 O), argon (Ar), hydrogen (H 2 ), and mixtures thereof. 
     
     
         10 . The absorption cycle system of  claim 2 , further including 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 including a second recirculation line between the second generator and the second absorber for recirculating the second absorbent and refrigerant mixture back to the second absorber. 
     
     
         12 . The absorption cycle system of  claim 3 , further including a heat recovery line extending between the second generator and through the first generator for recovering heat from the refrigerant exiting the second generator, said heat recovery line continuing from the first generator to the condenser, for delivering the refrigerant vapor to the 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.