PURPOSE: To enhance energy efficiency by compressing refrigerant vapor generated at a refrigerant vapor generator so as to produce superheat vapor, sending the superheat vapor to a generator, heat-exchanging the vapor with an absorption solution, heating the absorption solution, and condensing and liquefying the superheat vapor.

CONSTITUTION: At the top of a generator 2 an outlet 2b of refrigerant vapor generated is installed thereby forming an outlet 2c of an absorption solution which has become thick due to the generation of vapor at the bottom of the generator 2. A compressor 3 is connected to the outlet of the vapor where the vapor is compressed with the compressor and turned into a superheat refrigerant vapor. The superheat vapor is introduced into a heat exchanger 4 of the generator 2where an absorption solution is heated while the refrigerant vapor is condensed and fed to an absorber 7 by way of a pressure reduction means 5. The enriched absorption solution of the generator 2 is fed to an absorber 7 by way of a heat exchanger 9 where the refrigerant from a vaporizer 6 absorbed and returned to the generator 2. This construction makes it possible to reduce heating energy drastically by using self-vapor generated from the generator as a heating source when heating the absorption solution in the generator.