Triple-effect vapor absorption refrigeration system

Abstract

A triple-effect vapor absorption refrigeration system is disclosed. The system comprises a high temperature generator, a medium temperature generator, and a low temperature generator, for concentrating a dilute Li—Br solution from an absorber, through a flow path from the high temperature generator to the low temperature generator via the medium temperature generator. In the system maximum Li—Br solution temperature and maximum Li—Br solution concentration does not occur simultaneously, hence, Li—Br corrosion rate is reduced and minimum non-condensable gases are generated, this helps in maintaining vacuum during operation thus providing a smoother operation.

1 . A triple-effect vapor absorption refrigeration system comprising: a high temperature generator, a medium temperature generator, a low temperature generator, a condenser, an absorber, and an evaporator;
 characterized in that:   said high temperature generator is in operative communication with said absorber to receive a dilute Li—Br solution, said high temperature generator being adapted to concentrate the dilute Li—Br solution by means of a heat source having temperature in the range of 200-250° C. to provide a concentrated Li—Br solution and generate water vapors having temperature in the range of 130-150° C.;   said medium temperature generator is in operative communication with said high temperature generator to receive the concentrated Li—Br solution and the water vapors having temperature in the range of 130-150° C., said medium temperature generator being adapted to further concentrate the concentrated Li—Br solution by means of the water vapors to provide a further concentrated Li—Br solution and generate water vapors having temperature in the range of 80-100° C. and a first condensate;   said low temperature generator is in operative communication with said medium temperature generator to receive the further concentrated Li—Br solution and the water vapors having temperature in the range of 80-100° C., said low temperature generator being adapted to still further concentrate the further concentrated Li—Br solution by means of the water vapors to provide a still further concentrated Li—Br solution and generate water vapors and a second condensate;   said condenser is in operative communication with said medium temperature generator to receive the first condensate and said low temperature generator to receive the second condensate and the water vapors generated in the low temperature generator, said condenser being adapted to further condense the condensate and the water vapors by means of cooling water, to provide a further condensed condensate, and to generate heated water having temperature in the range 30-40° C.;   said evaporator housed together with said absorber is in operative communication with said condenser to receive the further condensed condensate, said evaporator being adapted to evaporate the further condensed condensate by extracting heat from cold water circulated there through, to provide chilled water having temperature in the range of 0-10° C. and to generate water vapors;   said absorber housed together with said evaporator is in operative communication with said low temperature generator to receive the still further concentrated Li—Br solution and said condenser to receive the heated water, said absorber being adapted to absorb the vapors generated in said evaporator in the still further concentrated Li—Br solution to provide the dilute Li—Br solution, thereby completing the refrigeration cycle, wherein, heat of dilution generated during the absorption process is absorbed by the heated water circulated there through to provide further heated water having temperature in the range of 35-45° C.; and said system further comprises a low temperature heat exchanger, a medium temperature heat exchanger, a high temperature heat exchanger, a low temperature drain heat exchanger and a high temperature drain heat exchanger, being adapted to heat the dilute Li—Br solution leaving the absorber, to a temperature in the range of 150-180° C., prior to being concentrated in said high temperature generator and optionally a heat reclaimer for heating the dilute Li—Br solution leaving the absorber by extracting left-over heat from said heat input.   
     
     
         2 . The triple-effect vapor absorption system as claimed in  claim 1 , wherein said low temperature heat exchanger, said medium temperature heat exchanger, and said high temperature heat exchanger and said low temperature drain heat exchanger and said high temperature drain heat exchanger are operatively connected in a consecutive manner. 
     
     
         3 . The triple-effect vapor absorption system as claimed in  claim 1 , wherein said low temperature drain heat exchanger and said high temperature drain heat exchanger are connected in parallel to said low temperature heat exchanger and said medium temperature heat exchanger. 
     
     
         4 . The triple-effect vapor absorption system as claimed in  claim 1 , wherein said low temperature drain heat exchanger, said high temperature drain heat exchanger and said heat reclaimer are operatively connected in a consecutive manner and in parallel with said low temperature heat exchanger, said medium temperature heat exchanger and said high temperature heat exchanger. 
     
     
         5 . The triple-effect vapor absorption system as claimed in  claim 1 , wherein said high temperature heat exchanger is operatively positioned between said high temperature generator and said medium temperature generator, said high temperature heat exchanger being adapted to extract heat from the concentrated Li—Br solution. 
     
     
         6 . The triple-effect vapor absorption system as claimed in  claim 1 , wherein said low temperature drain heat exchanger is operatively positioned between said low temperature generator and said condenser, said low temperature drain heat exchanger being adapted to extract heat from the second condensate. 
     
     
         7 . The triple-effect vapor absorption system as claimed in  claim 1 , wherein said high temperature drain heat exchanger is operatively positioned between said medium temperature generator and said condenser, said high temperature drain heat exchanger being adapted to extract heat from the first condensate. 
     
     
         8 . A method for operating a triple-effect vapor absorption refrigeration system to generate refrigeration effect, said method comprising the following steps:
 vaporizing a dilute Li—Br solution having concentration in the range of 53-58% in a high temperature generator by using a heat source having temperature in the range of 200-250° C. to obtain a concentrated Li—Br solution having concentration in the range of 55-60% and water vapors having temperature in the range of 130-150° C.;   vaporizing the concentrated Li—Br solution in a medium temperature generator by using the water vapors having temperature in the range of 130-150° C. to obtain a further concentrated Li—Br solution having concentration in the range of 57-62% and water vapors having temperature in the range of 80-100° C., and thereby generate a first condensate;   vaporizing the further concentrated Li—Br solution in a low temperature generator by using the water vapors having temperature in the range of 80-100° C. to obtain a still further concentrated Li—Br solution having concentration in the range of 59-64% and water vapors, and thereby generate a second condensate;   condensing the first condensate, the second condensate, and the water vapors generated in the low temperature generator in a condenser by using cooling water having temperature in the range of 25-35° C. to obtain a further condensed condensate having high pressure, and to generate heated water having temperature M the range of 30-40° C.;   evaporating the further condensed condensate in an evaporator by extracting heat from cold water circulated there through to generate water vapors and provide chilled water having temperature in the range of 0-10° C.; and   absorbing the vapors in the still further concentrated Li—Br solution in an absorber to obtain the dilute Li—Br solution, wherein, heat of dilution generated during the absorption process is absorbed by the heated water to form further heated water having temperature in the range of 35-45° C.   
     
     
         9 . A method for operating a triple-effect vapor absorption refrigeration system to generate refrigeration effect, said method comprising the following steps:
 vaporizing a dilute Li—Br solution having concentration in the range of 53-58% in a high temperature generator by using a heat source having temperature in the range of 200-250° C. to obtain a concentrated Li—Br solution having concentration in the range of 55-60% and water vapors having temperature in the range of 130-150° C.;   vaporizing the concentrated Li—Br solution in a medium temperature generator by using the water vapors having temperature in the range of 130-150° C. to obtain a further concentrated Li—Br solution having concentration in the range of 57-62% and water vapors having temperature in the range of 80-100° C., and thereby generate a first condensate;   vaporizing the further concentrated Li—Br solution in a low temperature generator by using the water vapors having temperature in the range of 80-100° C. to obtain a still further concentrated Li—Br solution having concentration in the range of 59-64% and water vapors, and thereby generate a second condensate;   condensing the first condensate, the second condensate, and the water vapors generated in the low temperature generator in a condenser by using cooling water having temperature in the range of 25-35° C. to obtain a further condensed condensate having high pressure, and to generate heated water having temperature in the range of 30-40° C.;   evaporating the further condensed condensate in an evaporator by extracting heat from cold water circulated there through to generate water vapors and provide chilled water having temperature in the range of 0-10° C.;   absorbing the vapors in the still further concentrated Li—Br solution in an absorber to obtain the dilute Li—Br solution, wherein, heat of dilution generated during the absorption process is absorbed by the heated water to form further heated water having temperature in the range of 35-45° C.; and   bifurcating the dilute Li—Br solution leaving the absorber, wherein a first portion is received in a low temperature heat exchanger and a second portion is received in a low temperature drain heat exchanger and further comprises heating the first portion of the dilute Li—Br solution in a low temperature heat exchanger by extracting heat from the still further concentrated Li—Br solution to obtain a first portion of heated dilute Li—Br solution having temperature in the range of 65-75° C.   
     
     
         10 . The method as claimed in  claim 9 , which comprises further heating the first portion of the heated dilute Li—Br solution in a medium temperature heat exchanger by extracting heat from the further concentrated Li—Br solution to obtain a first portion of further heated dilute Li—Br solution having temperature in the range of 120-130° C. 
     
     
         11 . The method as claimed in  claim 9 , which comprises heating the second portion of the dilute Li—Br solution in a low temperature drain heat exchanger by extracting heat from the second condensate to obtain a second portion of heated dilute Li—Br solution having temperature in the range of 65-75° C. 
     
     
         12 . The method as claimed in  claim 9 , which comprises further heating the second portion of the heated dilute Li—Br solution in a high temperature drain heat exchanger by extracting heat from the first condensate to obtain a second portion of further heated dilute Li—Br solution having temperature in the range of 120-130° C. 
     
     
         13 . The method as claimed in  claim 9 , which comprises combining the first portion of the further heated dilute Li—Br solution and the second portion of the further heated dilute Li—Br solution to obtain a combined stream of the further heated dilute Li—Br solution having temperature in the range of 120-130° C. and optionally which comprises still further heating the combined stream of the further heated dilute Li—Br solution in a high temperature heat exchanger by extracting heat from the concentrated Li—Br solution to obtain a still further heated dilute Li—Br solution having temperature in the range of 170-190° C. 
     
     
         14 . The method as claimed in  claim 9 , which comprises still further heating the first portion of further heated dilute Li—Br solution in a high temperature heat exchanger by extracting heat from the concentrated Li—Br solution to obtain a first portion of still further heated dilute Li—Br solution having temperature in the range of 170-190° C. 
     
     
         15 . The method as claimed in  claim 9 , which comprises still further heating the second portion of further heated dilute Li—Br solution in a heat reclaimer by extracting left-over heat from the heat input to obtain a second portion of still further heated dilute Li—Br solution having temperature in the range of 170-190° C. 
     
     
         16 . The method as claimed in  claim 9 , which comprises combining the first portion of still further heated dilute Li—Br solution and second portion of still further heated dilute Li—Br solution. 
     
     
         17 . The method as claimed in  claim 9 , which comprises vaporizing the still further heated dilute Li—Br solution in the high temperature generator. 
     
     
         18 . The method as claimed in  claim 9 , which includes the step of maintaining vacuum during the operation of the triple-effect vapor absorption refrigeration system to generate refrigeration effect in a manner that the maximum Li—Br solution temperature and maximum Li—Br solution concentration do not occur simultaneously, thereby reducing the Li—Br corrosion rate and generating minimum non-condensable gases. 
     
     
         19 . The method as claimed in  claim 9 , which includes the step of allowing the Li—Br solution to flow in series from the high temperature generator via the medium temperature generator to the low temperature generator, by gravity, by using a single solution pump between the absorber and the high temperature generator or allows the concentrated Li—Br solution to flow by gravity, wherein, only the flow of the dilute Li—Br solution from the absorber to the high temperature generator is controlled and which includes the step of feeding the cooling water primarily at the condenser so as to lower the overall operating pressure, temperature and effect an increase in the COP.