Effect of thermal conductivity of absorber plate on the performance of a solar water heater

Abstract The effect of thermal conductivity of the absorber plate of a solar collector on the performance of a thermosyphon solar water heater is studied by the use of the transient simulation system (TRNSYS) computer program. The system is assumed to supply hot water at 55° and 80°C representing both domestic and industrial uses respectively. Hot water of volumes 50, 125, and 250 l is consumed daily according to the Rand distribution profile. The results have shows that the annual solar fraction of the system and the collector`s characteristic factors (namely, fin efficiency factor, collector efficiency factor, and heat removal factor) have a very strong dependence on the thermal conductivity for its low values, and weak dependence is observed beyond a thermal conductivity value of 50 W/m °C for the solar fraction and beyond a value of 100 W/m °C for the characteristic factors. It is also observed that the annual solar fraction is improved by about 4%–7% and the characteristic factors are improved by about 12%–19% when a steel absorber plate is replaced by an aluminium one, whereas, the solar fraction and the characteristic factors are increased only about 1% and 3%, respectively, when a copper plate is used instead of an aluminium one.

[1]  K.G.T. Hollands,et al.  Optimization of an absorber plate fin having a step-change in local thickness , 1992 .

[2]  K.G.T. Hollands,et al.  A review of low-flow, stratified-tank solar water heating systems , 1989 .

[3]  Carl M. Lampert,et al.  Coatings for enhanced photothermal energy collection I. Selective absorbers , 1979 .

[4]  George O.G. Löf,et al.  Effects of auxiliary heater on annual performance of thermosyphon solar water heater simulated under variable operating conditions , 1997 .

[5]  K.G.T. Hollands,et al.  OPTIMIZATION OF THE FLAT PLATE ABSORBER FOR LOW FLOW , 1990 .

[6]  G. Löf,et al.  The optimization of tank-volume-to-collector-area ratio for a thermosyphon solar water heater , 1996 .

[7]  Austin Whillier,et al.  Effect of materials and construction details on the thermal performance of solar water heaters , 1965 .

[8]  R. A. Worth,et al.  The effect of tube spacing on the cost-effectiveness of a flat-plate solar collector , 1992 .

[9]  F. L. Test.  Parametric study of flat plate solar collectors , 1976 .

[10]  W. Beckman,et al.  Solar Engineering of Thermal Processes , 1985 .

[11]  A. S. Sambo,et al.  Simulation studies on pipe spacings for a collector and tank sizes for a solar water heater , 1992 .

[12]  Erich Hahne,et al.  Parameter effects on design and performance of flat plate solar collectors , 1985 .

[13]  Adnan Shariah,et al.  Optimal design for a thermosyphon solar water heater , 1997 .

[14]  Michael G. Hutchins,et al.  Spectrally selective solar absorber coatings , 1979 .

[15]  S. Klein.  Calculation of Flat-Plate Collector Loss Coefficients , 1975, Renewable Energy.