Effect of riser-pipe cross section and plate geometry on the solar flat plate collector's thermal efficiency under natural conditions

The current study aims to enhance the thermal performance of the Solar Flat Plate Collector (SFPC). To achieve that, four proposed models of (SFPC) were investigated in terms of thermal response under transient solar radiation using passive techniques. Two of these models simulate the influence of different riser-pipe configurations, namely models A and B, respectively representing semicircular and elliptical cross sections. While, the other two models, -C- and -D- represent the effect of plate geometry, which represent dimples and channel plates, respectively. All geometric models and the numerical simulations were created using ANSYS 19. R3. The results show that there is good conformity between numerical and experimental findings. Moreover, all four proposed models have been found to have a better thermal response than conventional model. Furthermore, model -D- is found to be the better model among all the other models under investigation due to the increased surface area of the collector, which leads to receive more solar radiation (heat flux) and hence increases the heat transfer to the working fluid within the riser pipe, which increases the temperature of the working fluid and the water inside the container. The thermal response of model -D- in terms of working fluid temperature inside the container and water temperature at the exit is approximately 13.2% and 12.3% higher, respectively, as compared to the traditional model. In addition, the overall thermal efficiency of the model -D- collector is approximately 13.7% higher than the conventional model.