Geometry optimization of double pass solar air heater with helical flow path
Solar air heaters (SAH) are widely used in solar energy extraction, which is why they have been studied by many researchers. This research is in line with previous research of the authors of this article in which an experimental and numerical study was performed to analyze the energy efficiency and heat transfer performance of a double pass solar air heater with helical flow path (HFP) in a triangular cross sectional channel. Here, the effect of different geometric parameters of this SAH has been investigated numerically on heat transfer performance combined with an optimization procedure using differential evolution (DE). In this study, by referring to the grid independency and validation of the previous work of the authors, the results will be developed. Finally the effects of triangular section angles and dimensions and location of the entrance section of each channel have been investigated and optimized. The results indicated that Optimized geometry results in considerably higher thermo-hydraulic performance parameter in compared with reference geometry for all Reynolds numbers. It is increased at least 16.5% due to optimization. The amount of inactive vortices produced at the edge of entrance flow passage in each channel is reduced due to optimization which results in decreasing the pressure drop.