Computational analysis of an advanced adsorption-refrigeration cycle

We have investigated analytically the performance of the thermally driven, advanced three-stage adsorption chiller utilizing low-grade waste heat of 50°C and lower temperatures as the driving heat source, in combination with a heat sink (cooling water) of 30°C. The closed cycle chiller for use in air-conditioning utilizes the silica-gel-water adsorption system. A cycle-simulation program was constructed to analyze the influence of operating conditions (temperatures, flow rates and adsorption-desorption cycle times) on cooling output, COP and chiller efficiency (η = COP/Carnot COP). The main advantage of this chiller is that it is operational with smaller regenerating temperature lifts (ΔTregen = heat source-heat sink temperature) than other heat-driven chillers. By cycle simulation, it was shown that the three-stage chiller can be operated with heat sources of 50 and 40°C in combination with cooling sources of 39 and 30°C, respectively. The simulation results also show that for the chiller to operate effectively, heat sources of 50°C require cooling sources between 35 and 20°C (ΔTregen = 15 to about 30K), while heat sources of 40°C need cooling sources in the range of 28-20°C (ΔTregen = 12 to about 20 K).