PURPOSE: To control delicate refrigerating capacity responsive to the change of the refrigerating load of a single-effect and dual-effect combination absorption refrigerating cycle.

CONSTITUTION: A single-effect and dual-effect combination absorption refrigerating cycle 4 uses the exhaust gas exhaust heat of an engine 2 as the heat source of a high temperature regenerator 21, and uses the warm water drain heat of the engine 2 and the condensation heat of vapor refrigerant generated by the regenerator 21 as heat source of a low temperature regenerator 22, and has a refrigerant channel 31 for introducing the vapor refrigerant generated from the regenerator 21 to a refrigerant condenser 23 via a coil tube 35, a refrigerant channel 32 for introducing the vapor refrigerant generated from the regenerator 21 directly to the condenser 23, and a refrigerant flow control valve 34 for regulating the opening of the valve 34. The opening of the valve 34 is controlled based on the temperature of the chilled water heat exchanged with the refrigerant of a refrigerant regenerator 24, thereby changing the refrigerant generation quantity of the regenerator 22 in response to the refrigerating load.