Study of a low temperature waste heat driven sorption chiller

With deeper concern regarding global warming problem, a growing interest has been given to adsorption chiller. It acts as a replacement to conventional air-conditioning unit that occupy high usage of electricity from fossil fuelled power plant. In order to make sure that the chiller is functional for all-year-round, the heat source need to be lowered down to compensate for the varying rainy and hot seasons in Malaysia. Therefore multi-staging the chiller is required so that the chiller is able to operate in a low temperature heat source. This paper aims to study the effects of two stages four-bed adsorption chiller of silica gel-water pair based on the cooling capacity, coefficient of performance (COP), cycle time, and temperature profiles. It is highlighted that the adsorbent-refrigerant pair used in this system is of silica gel and water for numerous advantageous reasons. Mathematical equation of the model comprises of adsorption isotherms, adsorption kinetics, isosteric heat of adsorption, energy balance for condenser, evaporator and the system beds is analysed respectively. Simulation method is applied to solve the problem using MATLAB programming in order to achieve the performance of the two-stage four-bed chiller. Results indicated that the system is able to operate below 60°C. With heat source temperature of 55°C, cooling water of 30°C and chilled water running at 14°C, the COP of the system achieved is around 0.24.