A Review on Working Pair Used in Adsorption Cooling System

Adsorption cooling system find its application in refrigeration, air conditioning, chiller, Ice making, etc. It uses thermal energy as driving force. Adsorption systems are environmental friendly (zero global warming potential and ozone depleting potential) and also eliminates use of compressor and minimize vibration problem. So it can be used as substitute for conventional vapor compression refrigeration system or vapor absorption system. The adsorption generally classified in two types as physical adsorption (due to weak van der waal forces) and chemical adsorption (chemical reaction between adsorbent and adsorbate form new molecules). The working pair of adsorber and adsorbate play vital role in the performance of adsorption system. Activated carbon, zeolite, silica gel are commonly used adsorber and water, ammonia, methanol and ethanol can be used as adsorbate. The poor heat and mass transfer performance of adsorption is major challenge for researchers. The heat transfer performance of adsorption system can be increased by increasing heat transfer area of adsorber bed i.e., design of new adsorber bed, while mass transfer performance is improved by use of new adsorbent with higher sorption rate. Composite adsorber solve the problem of heat and mass transfer performance of chemical adsorbents and adsorption quantity of physical adsorbents by combination of chemical and physical adsorbent but it can add some limitation with it. In this paper, various adsorption pair, their selection, design of adsorber bed, methods to improve thermal performance of adsorber bed is reviewed with their properties, advantages and limitations.