PURPOSE: To reduce a heat transfer area, a diameter of a body and to decrease a weight of an apparatus by forming spaces at upper and lower parts of heat transfer tubes of an evaporator body and an absorber body, connecting the spaces by communicating tubes of the upper and lower parts, separating the tube of the absorber body to upper and lower parts, and providing a non- condensible gas detention space therebetween.

CONSTITUTION: Refrigerant liquid 9 is supplied from a distribution tube 10, and heating fluid 11 is supplied from a heating fluid inlet 12. The liquid 9 is heated by the fluid 11 to partly become refrigerant vapor to rise to an upper space 15. The liquid 9 partly drops in a heat transfer tube 8 to generate refrigerant vapor 1 in a lower space 7. The vapor 1 introduced to an absorber body 14 heats absorbed liquid 3 thereby heating fluid 19 to be heated. The vapor 1 and non-condensible gas 25 are stayed from the space 15 or a lower space 16 in a detention space 26. Thus, the vapor 1 is divided to be introduced to an absorber 4, a heat transfer area of the tube can be reduced, and a weight of the entire apparatus can be decreased.