Experimental Validation of Forced Circulation of Solar Water Heating Systems in TRNSYS

There is no doubt that experimental measurement is the best way to obtain accurate valuable information of the behaviour of a system. However, theoretical approach or simulation modeling can have many advantages over experiment, as we can predict easily (and up to an acceptable accuracy) the performance of systems under varying climatic conditions, design parameters, and operating conditions in a very short time compared to experiments. In addition, simulation models can be used for designing purposes and in optimizing the various design parameters of the systems, without the need of very expensive test rigs equipped with accurate instruments. Recently, there are a number of computer programs that have been developed and are commercially available for use in the design, optimization, and evaluation of thermal performance of solar water heating systems. TRNSYS, PolySun, MINSUN, WATSUN, and T*sol, are among the best software available commercially. The present paper attempts to test how accurate TRNSYS simulation program can be in simulating different configuration of forced circulation solar water heating systems, and to inspect the most prominent parameters that affect the discrepancy between simulation and experiment. Preliminary experiments showed that there was a discrepancy which has most likely come as a result of the position of the temperature sensors controlling the circulation of the pump. (C) 2014 The Authors. Published by Elsevier Ltd.