Performance of solar NH3/H2O absorption cycles in the athens area

Abstract The performance of solar driven NH3/H2O absorption units, operating in conjunction with high and intermediate temperature solar collectors in Athens, is predicted along the typical year, in the cases (a) of absorption refrigeration units working as refrigerators, (b) of absorption refrigeration units working as heat pumps and (c) of reversed absorption units working as heat transformers. In all cases, the operation of the units and the related thermodynamics are simulated by suitable computer codes, and the required local climatological data (i.e. the incident solar radiation and the ambient temperature) are determined by statistical processings of related hourly measurements over a considerable number of years. It is found that in the case of the refrigerator, for operation over the whole year, the theoretical coefficient of performance varies in the range from 72 to 75% and a maximum theoretical specific cooling power of 223 W/m2 is observed on July at 13 hrs. In the case of the heat pump, for operation from November to April, a maximum theoretical heat gain factor of about 170% is obtained on December with corresponding specific heat gain power amounting to 213 W/m2 at 14 hrs, while a maximum theoretical specific heat gain power of 344 W/m2 is observed on April at 13 hrs with a corresponding heat gain factor of about 165.5%. Lastly, in the case of the heat transformer, for operation over the whole year, a maximum theoretical heat gain factor of about 48.3% is observed during winter at about 13 hrs but with very small specific heat gain power, while a maximum specific heat gain power of 175 W/m2 is obtainable on July at noon with a corresponding heat gain factor of 44.5%.