A THEORETICAL PROCEDURE FOR ESTIMATING SATURATION TEMPERATURE INSIDE SOLAR TWO-PHASE LOOPS

Abstract

This work presents a theoretical analysis for the prediction of refrigerant saturation temperature inside a typical solar two-phase loop. This loop may be incorporated in any solar heating system for transporting heat between the solar collector and storage tank. The procedure takes into account all influencing parameters such as:- solar irradiance, ambient temperature, heat transfer coefficients in the source (collector) and sink (condenser), collector fill ratio and the geometric parameters of the solar collector and condenser.The trend of change of saturation temperature was studied over a typical daytime period extending 8 hours. Mathematical models were formulated for the collector and condenser to take into account the most influencing parameters. The models are highly interrelated which required an iterative procedure. A computer program was built to implement the iterative procedure and simulate the change of saturation temperature during the studied period. The period was divided into small time intervals of 10 seconds.Results reveal a significant influence of condenser area, collector fill ratio and the working conditions on the calculated saturation temperature.