COMPARISON OF EXPERIMENTAL AND SIMULATED THERMAL RATINGS OF DRAIN-BACK SOLAR WATER-HEATERS

Short-term experimental tests of drain-back solar water heaters are co mpared to ratings obtained using TRNSYS to determine if computer simul ations can effectively replace laboratory thermal ratings of solar dom estic hot water heating systems. The effectiveness of TRNSYS in predic ting changes in rating due to limited changes in collector area, colle ctor flow rate, recirculation flow rate, storage tank volume, and stor age tank design is validated to within +/-10 percent. Storage tank des ign is varied by using a stratification manifold in place of the stand ard drop tube. Variations in other component sizes and operating facto rs are based on current industry standards.