The Simulated and Experimental Performance of a Solar Heat Generating System

There is little information in the literature on the results of comparing the simulated and experimental performance of solar heat generating systems, yet available detailed simulation packages such as TRNSYS [1] are used as benchmarks against which simplified design procedures are compared. A pilot-sized experimental facility located at the CSIRO Division of Energy Technology was used to generate experimental data for comparison with simulated results. The system consisted of 86.4 m² of double-glazed solar collectors connected to a 9500-1 water storage tank from which energy was rejected at a controlled rate via a heat exchanger and cooling tower. The facility was comprehensively instrumented to measure and record system forcing functions and variables, such as solar radiation, ambient temperature, collector temperatures and flow rates, and load temperatures and flow rates. A series of experimental runs were carried out to compare simulated and experimental performance over a range of operating conditions. An aggregate of approximately 70 days of performance data was collected at 5 or 10 min intervals. The simulated and measured performance of the collectors and the entire system were compared at hourly and daily intervals. The predicted total energy delivered by the system for all data was found to be within 1 percent of the measured value. Agreement on other bases was not quite as close but was good enough to conclude that simulation with TRNSYS is satisfactory for the design of similar solar heat generating systems.