Enhancing the performance of a solar-assisted adsorption chiller using advanced composite materials

This paper presents multi-level modeling and simulation techniques for a new solar-assisted adsorption chiller using a novel combination of heat transfer fluids (HTF) and composite adsorbents under transient conditions. Multi-walled carbon nanotube and graphene nanofluids (MWCNT/GNF) composite is used as a cooling liquid in the cooling circuit of the chiller, while activated carbon fiber with either barium chloride salt (ACF/BCS) or nickel chloride salt (ACF/NCS) composite are used as adsorbers. The key system components are the adsorption chiller with two beds, an evaporator and condenser, as well as an evacuated tubes collector (ETC), a hot water storage tank and an open circuit cooling tower. Computational fluid dynamics analysis examines the properties of water and ammonia at adsorbed and gaseous phases for adsorption on silica gel and ACF/BCS adsorbers. The non-dimensional specific cooling capacity (NSCC) and the coefficient of performance (COP) are compared for the chiller using the proposed material sets vs the conventional silica gel counterparts. It is found that ACF/NCS and ACF/BCS can improve the COP by 23.4% and 95.7%, respectively. This demonstrates the utility of computation in simulating an adsorption chiller systems carrying advanced composite materials that lead to higher energy conversion efficiency, smaller size solar collectors, and compact storage tanks resulting in tangible economic benefits. (C) 2018 Elsevier Ltd. All rights reserved.