Liquid Desiccant based Solar Air Conditioning System with Novel Evacuated Tube Collector as Regenerator

Abstract

Growing demand for air conditioning and pollution concerns related with production of electrical energy have compelled researchers to investigate new technologies for air conditioning. Liquid desiccant based air conditioning technology is adaptable to pollution-free renewable energy source like solar energy. It has additional advantages like air washing and high density energy storage. Use of solar energy for air conditioning is logical as higher availability of solar radiation matches with higher demand for air conditioning in summer. A novel evacuated tube collector (ETC) with heat pipes is developed in the Heat Pump Laboratory at IIT Bombay (HPL_IITB). In spite of being a not-tracking type, temperatures much beyond the range of flat plate or conventional ETC can be achieved and liquids can even be boiled in this collector. This collector was used as regenerator for liquid desiccant based solar air conditioning system. Objective of this work was to demonstrate and investigate performance of this solar collector with in-situ regeneration. Liquid desiccant was preheated in solution heat exchanger and pumped into the solar regenerator. Steam and regenerated liquid desiccant at outlet of collector were separated and steam was condensed downstream to the collector. Average thermal COP of 0.82 over 5 h experiment period could be achieved with single stage regeneration and insolation range from 509 to 752 W/m2. Parasitic power consumption was less than 40 W, which works out to be 1.5% of the regeneration duty. Solar collector efficiency up to 44.7% was achieved at 117 °C regeneration temperature and 719 W/m2 global radiation along with distilled water production of 5.14 kg/h.