Theoretical and Experimental Analyses of Heat Transfer in a Flat-Plate Solar Collector

Abstract

In this paper, the heat transfer in a flat-plate solar collector with water tubes spreading across its ‎width was analyzed. The performances of the system both theoretically and experimentally were ‎evaluated and compared. The theoretical results obtained agreed well with the experimental results, ‎except that a slight higher deviation of heat loss was obtained in the experimental analysis and low solar ‎radiation in the morning and late afternoon affects the system. An average heat loss coefficient of 0.68 ‎W/m2.oC was obtained in the experimental analysis, while 0.65 W/m2.oC was obtained in the theoretical ‎analysis. The collector efficiency was high around the mid-day when the collector receives the highest ‎energy and the useful heat rate was at its maximum. The results also reveal that the performance of the ‎solar collector depends much on the heat rate. The collector efficiency increases as the heat rate ‎increases until the maximum efficiency of 72.2% was reached at optimum heat rate of 785 W.‎