Anticipated thermal efficiency of solar driven NH3/H2O absorption work producing units

A solar driven, work producing, NH3/H2O absorption cycle is considered, which has a theoretical efficiency 25% higher than the conventional H2O Rankine cycle working at the same temperature levels. At higher temperatures, the efficiency of a solar driven H2O Rankine cycle increases, but the corresponding decrease of the solar collector efficiency is quicker, thus resulting in lower overall efficiency. The NH3/H2O absorption cycle is simulated by a computer model which contains analytic functions describing the behaviour of the binary NH3/H2O mixture. Application of the model is made for operation during a typical year in Athens, with the solar radiation and ambient temperature data available from processing of related hourly measurements of 20 yr. The absorption unit is expected to produce a maximum theoretical specific mechanical power output of 80 W/m2-concentrator aperture at 13.00 h in June and July. A maximum theoretical daily mechanical energy of 1500 kJ/m2-day is anticipated for June. The theoretical total mechanical energy of the typical year is expected to be 339,406 kJ/m2-yr. For a 5-h use of this energy per day, the resulting yearly mean mechanical power is 50 W/m2.