Control for absorption refrigeration system

Claim 2

In a method of controlling refrigeration system of the type having an evaporator and an absorber connected in a closed circuit for normally conducting a refrigerant and an absorbent solution in an absorption refrigeration cycle, the absorber being arranged in the closed circuit to receive refrigerant vaporized in the evaporator and normally being provided with absorbent solution for absorption of the vaporized refrigerant; means defining a chilling circuit for circulating a chilled fluid in heat-exchange relation with a refrigeration load and including a first heat-exchanger in the evaporator for abstracting heat from the fluid and rejecting it to the refrigerant to chill the fluid and to vaporize the refrigerant; and means defining a cooling circuit for circulating a cooling medium and including a second heat-exchanger in the absorber for normally abstracting heat from the absorbent solution and rejecting it to the cooling medium; and a generator supplied with a heating medium to boil off refrigerant from the absorbent solution; the steps of operating the absorber to condense the vaporized refrigerant by circulating the cooling medium in the second heat exchanger at a temperature lower than a temperature of the chilled fluid which will satisfy the refrigeration load; circulating refrigerant condensed in the abosrber to the evaporator; and supplying heating medium to said generator at a reduced rate sufficient to prevent migration of refrigerant to said absorbent solution.

Claim 3

A method as defined in claim 1 wherein said heating medium is normally controlled by the temperature of said chilled fluid, and including the additional steps of sensing the level of solution is said absorber and transferring control of said heating medium from the temperature of said chilled fluid to said level of solution.

Claim 4

A method as defined in claim 1 including the steps of supplying said heating medium to said generator at a constant rate sufficient to produce some migration of refrigerant from absorbent solution to said circulating refrigerant and transferring excess refrigerant from evaporator to said absorber.

Claim 5

An absorption refrigeration system comprising a generator, a condenser, an evaoporator and an absorber connected in a closed, absorption refrigeration circuit; a common shell enclosing said evaporator and said absorber and having a lower portion thereof defining a sump; a first heat exchanger associated with said evaporator; a refrigeration circuit adapted to circulate refrigerant over said first heat exchanger and abstract heat from a fluid circulating therein; a second heat exchanger associated with said absorber through which a cooling medium may be circulated, said second heat exchanger being located above said sump; means for withdrawing absorbent solution collected in said sump and transferring at least a portion thereof for circulation over said second heat exchanger; means defining a first fluid flow path for absorbent solution passing over said second heat exchanger to said sump during normal operation of the system; means defining a second, alternate fluid flow path for intercepting condensed refrigerant passing from the surface of said second heat exchanger and directing the same to said refrigeration circuit during the free cooling mode of said system, whereby solution may be stored in said sump during operation when refrigerant is being condensed on said second heat exchanger; a third heat exchanger associated with said generator; means for supplying a heated medium to said third heat exchanger in response to the temperature of said fluid circulating in said first heat exchanger; and means for transferring control away from said heated medium supply means during the free cooling mode and supplying a predetermined flow of heated medium to said third heat exchanger sufficient to prevent migration of refrigerant to said absorbent solution.

Claim 6

An absorption refrigeration system comprising a generator, a condenser, an evaoporator and an absorber connected in a closed, absorption refrigeration circuit; a common shell enclosing said evaporator and said absorber and having a lower portion thereof defining a sump; a first heat exchanger associated with said evaporator; a refrigeration circuit adapted to circulate refrigerant over said first heat exchanger and abstract heat from a fluid circulating therein; a second heat exchanger associated with said absorber through which a cooling medium may be circulated, said second heat exchanger being located above said sump; means for withdrawing absorbent solution collected in said sump and transferring at least a portion thereof for circulation over said second heat exchanger; means defining a first fluid flow path for absorbent solution passing over said second heat exchanger to said sump during normal operation of the system; means defining a second, alternate fluid flow path for intercepting condensed refrigerant passing from the surface of said second heat exchanger and directing the same to said refrigeration circuit during the free cooling mode of said system, whereby solution may be stored in said sump during operation when refrigerant is being condensed on said second heat exchanger; a third heat exchanger associated with said generator; means for supplying a heated medium to said third heat exchanger in response to the temperature of said fluid circulating in said first heat exchanger; and means for transferring control away from said heated medium supply means during the free cooling mode and supplying a predetermined flow of heated medium to said third heat exchanger sufficient to prevent migration of refrigerant to said absorbent solution.

Claim 7

A system as defined in claim 4 including means responsive to the level of solution in said sump for controlling the supply of heated medium to said third heat exchanger.

Claim 8

A system as defined in claim 4 including means for supplying heated medium to said third heat exchanger in excess of that required to prevent said migration and means for transferring excess refrigerant from said evaporator to said sump.