Influence of Geometric Parameters on the Thermal Performances of a Double Air Pass Solar Collector

Abstract

This work focused on the numerical study of the thermal performance of a solar collector in order to improve the indirect solar drying of fruit in an environment with high solar potential. It aims to contribute to the reduction of post-harvest losses observed during periods of high production. From the retained physical model, an equivalent electrical scheme has been established and energy balance was applied to each slice of the model using the nodal method. The obtained different equations were discretized using the implicit method of finite differences, and solved by the iterative Gaussian Pivot method written in FORTRAN program. The obtained results showed that, from April to June (mangoes harvest period in Ngaoundere city) the raining period in Adamawa Region, the solar air collector that length to width ratio is between 2 and 3, is sufficient to carry out indirect solar drying of fruits with forced convection. The outlet air temperature of the solar collector was between 45 and 60°C with an average value of 50°C, and the thermal efficiency was between 65 and 95% with an average value of 80%. Double glazing improves efficiency of the solar air collector for a small footprint.

Experimental Evaluation of Double Air Pass Solar Collector in Humid Tropical Environment

“…This means that almost half of the energy produced by the sunlight on the collector is transmitted to the heat transfer fluid in the latter case. This result is in line with the work of Tetang and Ghiaus [17] which shows that by varying the speed of the fluid, the efficiency also evolves according to the same profile, up to a certain threshold. The instantaneous global efficiency obtained in this study ranged from 20 to 79%, a range presented by Fudholi and Sopian [3].…”

“…This figure shows that the solar radiation intensity evolves in a bell shape, with a maximum value of around 1300±26 W/m². This result is in a good agreement with the numerical simulation made by Tetang and Ghiaus [17]. These solar flux values prove the sufficiency of solar irradiance for the performance evaluation of solar collectors since the American Society of Heating, Refrigerating and Air-Conditioning Engineers standard (ASHRAE) requires that for solar collector efficiency tests, solar irradiance must be above 630±12.6 W/m 2 [20].…”

“…The more sunlight, the more it increases. It's average value is 31.86±2°C, which is higher than the annual average temperature in this zone, which is around 26±1°C [17]. This can be translated by the fact that the month of April, in which the present work was carried out, is one of the hottest months of the year.…”

“…They have also shown that the efficiency of the double-glazed collector decreases as the distance between the two panes of glass increases. Similarly, Tetang and Ghiaus [17] analyzed the effect of the distance between the absorber and the lower glass pane and between the absorber and the insulation. The results obtained from the simulation showed that the efficiency is maximum (approximately 50%) when the ratio of these two distances is equal to 1.…”