Entropy generation analysis of two-bed, silica gel-water, non-regenerative adsorption chillers

Abstract

The current thrust on the use of environmentally friendly technologies for cooling applications, inter alia, envisages the adoption of adsorption systems. Adsorption chillers are known to be 'inefficient' due to their low coefficient of performance. Although the basic physics of heat and mass transfer in various components of the system is well understood, there is a lacuna in the quantification of irreversibilities. In this paper, a silica gel-water, two-bed, non-regenerative chiller is analysed. It is shown that the largest cycle-averaged rate of entropy generation is in the beds and that the least is in the condenser. The entropy generation rates in the beds are further studied, showing that the maximum contribution is made during the switching phase. In general, manufacturers' effort to maximize cooling capacity is shown to correspond to maximum entropy generation in the evaporator.