Modeling of Solar Absorption Cooling System for Educational Institutes of Pakistan

Abstract

Cotemporary Energy issues, like depletion of energy resources, rising energy costs and the related environmental issues demand exploration of renewable energy technologies. Solar powered absorption refrigeration systems using evacuated tube collector (ETC) or flat plate collector (FPC) is an emerging renewable energy technology. These systems are very attractive alternative to conventional refrigeration systems for reduction in peak load demand of electricity. This research reveals the feasibility and optimization analysis of a solar absorption cooling (SAC) system by using TRNSYS simulation software for Typical Meteorological Year data of different cities of Pakistan (Islamabad, Lahore, Karachi, Multan and Quetta). TRNSYS is a tool used for modeling of renewable energy systems. A simulation model that contains solar collectors (FPC, ETC), storage tank, absorption chiller and the building is developed. The results depict that absorption system of rated capacity 40,000 kJ/hr is required to provide cooling in the selected building located in NUST Islamabad. The study also reveals that to increase the reliability of operation, an optimized system containing 8 m2 area of ETC sloped at 15o is required. Hot water storage tank of 0.6 m3 and auxiliary heater having set point temperature of 87 0C is essential to provide effective cooling to the building. The economic analysis shows that the system has payback period of 12 yrs. It could reduce to 10.3 yrs by using natural gas auxiliary heater instead of Electric heater with net present value (NPV) of 8,10,263 PKR for Islamabad. Next, SAC system with ETC is tested for climatic conditions of other four cities of Pakistan. It is investigated that Quetta has minimum payback period with the highest NPV of all the analyzed cities. Meanwhile for Lahore, payback period is the highest with a comparatively low NPV. CO2 emissions for Karachi are the highest at Optimized conditions as compared to other selected cities.