THERMAL PERFORMANCE ANALYSIS OF VARIOUS GAS FILLED SOLAR FLAT PLATE COLLECTORS

Abstract

The fossil fuels are depleting day by day and energy demand is rising at a high rate. The gap between this depletion and demand can be narrowed by the use of solar energy. The most direct application of solar energy is the conversion of solar radiation into thermal energy like in water heating system which is generally done using flat plate solar collectors. This research focuses on the media between the absorber plate and the glass cover. This study presents the performance evaluation of different gas filled solar flat plate collectors filled with gases like carbon dioxide, methane, nitrous oxide, R410a, sulphur hexafluoride, R22 and R134a to make greenhouse environment inside collector Their performances have been compared with the air filled solar flat plate collector. The complete analysis has been done for four different months (January, June, August, and October) under composite climatic condition of Delhi using MATLAB. The performance characteristic curves and equations for all gas filled collectors have been developed under clear sky condition. The results show that there is 5.6, 2.8 and 2.3% decrease in average overall heat loss coefficient for carbon dioxide, nitrous oxide and R22 filled solar flat plate collector respectively as compared to air filled solar flat plate collector under clear sky condition. The average instantaneous efficiency has increased about 0.9% for carbon dioxide filled solar flat collector and 0.41% for both nitrous oxide and R22 filled solar flat plate collectors. Other filled gas solar flat plate collectors have lower performance than air filled solar flat plate collector. The average convective heat transfer coefficient between the absorber plate and glass cover decreases about 10.43% for carbon dioxide filled solar flat plate collector, 5.05% for nitrous oxide filled solar flat plate collector and 4.71% for R22 filled solar flat plate collector as compared to air filled solar flat plate collector. The characteristic curve shows that the performance of carbon dioxide filled solar flat plate collector become better and better at higher water inlet temperature. Thus, the carbon dioxide filled solar flat plate collector can be marked as the best among all these solar flat plate collectors. The MATLAB code that has been developed in this research can be used to analyze any gas filled solar flat plate collector.