Performance Analysis on Working Parameters of a Flat-Plate Solar Cavity Collector

Abstract

Solar energy is being used over a long period of time for various purposes. Applications like air heating and water heating are the main usage of solar energy. It is globally accepted and being utilized in many countries. Still various types of research work are in progress throughout the world to improve the solar gadgets for more efficiency. It has been evident that every solar gadget needs a little bit of improvement in order to perform well. A better solution for the improvement of flat plate collector is the cavity collector. The objective of this work is to analyze a solar cavity collector experimentally for various working parameters. The outcome of the experiments has been presented in this article. An experimental analysis on solar cavity collector has been done to determine its optimal efficiency under various conditions. A parametric analysis has been carried out to find the optimal performance and effective utilization of the solar energy. Various length -to- diameter ratios have been experimented, viz. 40, 50 and 78.74, based on the commercially available pipe diameter. The gadget has been tested by changing the mode of flow as parallel and serpentine type with an L/D ratio of 78.74, as that L/D ratio has been performing better. Comparisons have been made for its optimal performance with circular- and rectangular- type cavity cover. The formation of eddies at the corners of rectangular casing (cavity cover) withstands or prevents some additional heat losses, thus it should be entertained and thereby the heat losses can be reduced to some extent. As in the case of circular cavities, the heat losses are more because of its simple construction and thereby no prevention of heat losses. But in the rectangular cavities, there is a possibility to hold up the heat in the corners of the cavity and thus the loss of heat can be prevented. Heat can be again radiated back into the cavities in the form of light. Also the collector has been tested with 5 and 7 cavities for the same L/D ratio of 78.74. It has been tested at various mass flow rates of water such as 0.002, 0.0025, 0.003, 0.0035, 0.00417 and 0.0067 kg/sec to investigate its optimal performance. Experimental results show that the L/D ratio of 78.74 of parallel flow mode gives better results than the others at the flow rate of 0.002 kg/sec.