Performance of a 23KW Solar Thermal Cooling System Employing a Double Effect Absorption Chiller and Thermodynamically Efficient Non-tracking Concentrators

Abstract

A solar thermal cooling system using novel non-tracking External Compound Parabolic Concentrators (XCPC) has been built and operated for two cooling seasons (summers of 2011 and 2012). Its performance in providing power for space cooling has been analyzed. This solar cooling system is comprised of 53.3 m2of XCPC trough collectors which are used to power a 23 kW double effect (LiBr) absorption chiller. This is the first system that combines both XCPC and absorption chilling technologies. Performance of the system was measured in both sunny and cloudy conditions. The collector system maintained operating temperatures between 160-200 °C. When operated in this temperature range, the XCPC collector array collected solar energy with an average daily efficiency of 36.7% and reached instantaneous efficiencies up to 40%. The thermal COP of the system (including thermal losses and COP of absorption chiller) averaged at 0.99 and the daily solar COP of the entire system averaged 0.363. It was found that these collectors are well suited at providing thermal power to drive absorption cooling systems and that both the coinciding of available thermal power with cooling demand and the simplicity of the XCPC collectors compared to other solar thermal collectors makes them a highly attractive candidate for cooling projects. XCPC technology has numerous potential applications and is currently being commercialized in the U.S. and India