Experimental Investigation of Heat Removal Factor in Solar Flat Plate Collector for Various Flow Configurations

摘要

This paper reports the performance of a solar flat plate collector for various flow configurations and presents a comparative evaluation. Three cases have been discussed: (i) serpentine flow, (ii) parallel-wall-to-wall flow, and (iii) spiral flow. The heat removal factor (FR) is the ratio of the actual heat transfer to the maximum possible heat transfer through the collector plate. A special case showing the effect of phase change material (PCM) on FR in the case of serpentine is discussed. A sheet-and-tube type collector where the tubes are bonded to the absorber plate by a suitable adhesive is considered. Equations showing the dependence of FR on the fin factor were studied and indoor experiments were conducted to determine the value of FR. Finally, a numerical investigation was done and comparisons were evaluated. Results indicate that when the mass flow rate (⋅m) of water is 1, the value of FR for serpentine and parallel wall-to-wall flow is 0.44 and 0.88, respectively. It was also observed that for the case of PCM, FR is a variable quantity and its value ranges from 0 to 0.28. In this case, FR is a function of the PCM melting and solidifying phases rather than mass flow and is proportional to the melting temperature of the PCM. Also, it is observed that in a conventional water heater with serpentine flow or parallel wall-to-wall flow, the value of FR does not increase significantly beyond a mass flow rate (⋅m) of 4 kg/hr.