Theoretical Study of the novel control strategy of Hybrid Solar Air Conditioning System

Abstract

In this paper, a theoretical study of the thermal performance for hybrid solar air conditioning system was presented to investigate the system performance and suitability for the hot climate with a new control system strategy. The system consists of a vapor compression unit combined with evacuated tubes solar collector and water storage tank. A three-way valve is controlled by a proportional integral derivative (PID) controller to regulate the 3-way valve opening towards the solar system to achieve the minimum temperature of refrigerant leaving the condenser (degree of subcooled), in order to enhance the overall COP of the unit. The governing thermal equations concerning the hybrid solar air conditioning system was applied and solved using engineering equation solver (EES) Software. The results showed that the compression ratio of the uncontrolled hybrid solar system is lower than the compression ratio of the conventional one by 5 %, and this ratio could be increased to 28 % when the control system has been used. Also, the minimum value of the power consumption is 830 W at R=0.1 and Tamb =45 oC, while the maximum value is 994 W at R=1 for the same conditions. The power consumption of the uncontrolled system is lower than the power consumption of the conventional one by 7 % and increases to 23 % by using the control system. An acceptable agreement can be achieved when validating the theoretical model results with experimental results.