A numerical analysis and optimization of the dynamic performance of a multipurpose solar thermal system for residential applications

This article presents results of a multipurpose solar thermal system that provides hot service water, space heating, and space cooling for residential use during all seasons in Pretoria, South Africa. A pressurized system utilizing evacuated tube solar collectors with internal heat pipes was considered for hot water production. Space cooling is achieved using a micro single-effect LiBr-H2O absorption chiller. The focus of the study was on the prediction of seasonal hourly performance trends and determination for optimum performance parameters. The solution was obtained by assembling the system's mathematical model, for which the solution was obtained numerically using Engineering Equation Solver (EES). A solar field consisting of 15 (1.959 m(2)), 20 (2.615 m(2)), and 25 (3.266 m(2)) evacuated tube collectors connected in parallel with three, four, and five arrays was considered. The developed model was validated using data available in literature and found to be valid within +/- 3% of the available data. Results showed that the 20-tube collector with a five-array configuration gave the most favorable and optimal system performance.