A tutorial on reversed NH3H2O absorption cycles for solar applications

Abstract The NH 3 H 2 O absorption refrigeration cycle is already used in solar applications. The solar heat is either used to operate the vapor generator of the refrigeration units or, in the case of heat pumps, to load the evaporator. In the first case the solar heat is added to the high-temperature part of the unit; in the second, to the low-temperature part. In both cases the absorption unit is rejecting heat to the ambient at a mean temperature level. The present paper considers the addition of solar heat at the mean temperature level and the operation of a reversed absorption NH 3 H 2 O cycle splitting the solar heat into two parts. One part is rejected at a lower temperature level, and the other part, the output, is delivered for use at higher temperature levels. The thermodynamics of the reversed cycle is examined, and its theoretical behaviour is described.