Solar Energy
Fatemeh karami; Majid Sabzpooshani
Abstract
This paper presents a comparative analytical investigation of five distinct configurations of single-pass flat plate solar air heaters (SAHs), incorporating fins, baffles, porous matrix, and internal air recycling. A steady-state, one-dimensional mathematical model was developed and solved analytically ...
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This paper presents a comparative analytical investigation of five distinct configurations of single-pass flat plate solar air heaters (SAHs), incorporating fins, baffles, porous matrix, and internal air recycling. A steady-state, one-dimensional mathematical model was developed and solved analytically to evaluate both thermal and thermo-hydraulic performance under various mass flow rates and reflux ratios. The results indicate that using a porous matrix alone results in approximately 14% lower thermal efficiency compared to configurations with fins and baffles. Placing the matrix beneath the absorber plate improved thermal efficiency by about 1.5%, but reduced thermo-hydraulic efficiency by roughly 2.5% compared to placing it above. While combining enhancement techniques does not always yield superior performance, the SAH equipped with fins and baffles alone achieved the highest thermal and thermo-hydraulic efficiencies across most conditions. Furthermore, increasing solar radiation intensity and air mass flow rate enhanced useful heat gain, although higher pressure losses caused the thermo-hydraulic efficiency to decline at elevated flow rates. Overall, this study provides valuable insights into the optimal integration of thermal enhancement methods in solar air heaters for improved energy performance.
Solar Energy
H. Hoseini; R. Mehdipour
Abstract
Solar chimney power plants are plants based on solar thermal power including three parts of collector, chimney and turbine, which is able to produce electrical energy. One of the effective parameters in increasing the power production is the collector angles versus horizon. In the present study, a numerical ...
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Solar chimney power plants are plants based on solar thermal power including three parts of collector, chimney and turbine, which is able to produce electrical energy. One of the effective parameters in increasing the power production is the collector angles versus horizon. In the present study, a numerical analysis of a solar chimney power plant for different angles of the collector (divergent, convergent and horizontal type collector) is proposed. The introduced numerical model uses mathematical models of heat transfer. In this regard, effect of various angles of the three considered collectors on temperature distribution and power production of the solar chimney is evaluated. Divergent type collectors produce more power than convergent and horizontal collectors, as they produce more velocity and mass flow rates. It will be shown that by increasing the angle of divergent-type collector (keeping the inlet height constant), the power production will be increased and the output temperature will be decreased, in a way that the angle variation of 0.8 to 1 will increase the divergent type collector output power by 11 % and will decrease the output temperature by 0.78%. In the other case, when the output height is kept constant and the collector angle changes, performance of the divergent type collector is better than the other two collectors. Power production in a constant mean height is shown to be 3 times and 1.5 times more than the convergent and horizontal collectors respectively.
