Analysis of a gas-fired absorption heat pump with different cycle configurations and superheated refrigerant at the absorber inlet.

State-of-the-art fuel driven heating systems are equipped with a condensing boiler technology. Commonly the flue gas is cooled by the return flow of the heat distribution system. If the temperature in the heating system is higher than the dew point, which happens in the retro-fit market, water vapour condensation of the flue gas cannot take place. Studies have shown that implementing a refrigerant cooled flue gas heat exchanger in a GAHP can avoid this issue under all operating conditions. However, superheated ammonia vapour entering the absorber potentially affects the absorption process. Measurements were carried out to determine the influence of different cycle configurations (internal heat exchangers, dephlegmator, …) on the efficiency under various operating conditions. An additional heat exchanger was installed between the evaporator and the absorber in order to investigate the influence of superheated ammonia vapour entering the absorber on the absorption and the overall heat pump process.