Thermal analysis for the materials of the hot and cold storage tanks for a cooling system operating by absorption cycle

Abstract

This research deals with thermal effect of hot and cold storage materials for a cooling system operating by an absorption cooling cycle of lithium bromide-water with a capacity of 4 tons. The heat needed to operate the system was gain from a solar parabolic concentric collector. It heats the hot tank through which it operates the generator of absorption cycle, which is the first part of the system. The extra heat is stored in hot tank as well as a cold tank is used to store the extra cooling capacity for air-conditioning a certain space of (80 m2). The best volume for the hot and cold storage tanks has been chosen along with the solar collector used with the appropriate coefficient of performance, which is determined after simulating the absorption cycle. When the system stops working and this occurs when the temperature of the hot tank is less than (65 °C), then the cold tank performs air-conditioning process. The hot tank volume has been resized (from 0.55 m3 to 1.4 m3) as well as changed the area of solar collector to give the highest temperature that the hot tank could reach with a variation cooling load, which was calculated hourly by Carrier_HAP420 software during the day. The effect of these coefficients has been studied and analyzed separately by setting the area of solar collector and hot tank capacity and changing the volume of cold tank (from 0.9 m3 to 1.5 m3) that receives the extra cooling capacity. The system has been simulated by simplifying and deriving all related equations of thermal balances for hot and cold tanks, solar collector and cooling system with all its parts. The simulation has been performed to predict the best fluid performance used in both tanks. The glycerin was chosen because its withstands high temperatures in hot tank and the very low temperatures in cold tank. The most appropriate volume for hot storage tank is (0.55 m3) when the area of solar collector is (11.7 m2), working to cover (13) hours from 9 a.m. to 10 p.m. The most appropriate volume for cold storage tank is (1.5 m3), giving (3) working hours from 10 p.m. to 12 a.m.