Optimization analysis of the length of baffles for solar air heaters based on CFD
Chang Yuan, Tian Mu, Binguang Jia
Abstract
Incorporating baffles was demonstrably efficacious in augmenting the functionality of solar air heaters (SAHs). A duly validated mathematical model is formulated for SAHs with baffles, aimed at the optimization of baffle length (Lb). Our findings demonstrated that with air velocity (v) spanning from 0.5 to 3.0 m·s−1 and baffle length (Lb) varying between 150 and 750 mm, a discernible rise in pressure loss ensued. This phenomenon is ascribed to the extension of baffles, resulting in escalated air velocity and heightened vortex intensity. In the range of v = 0.5 ~ 3.0 m·s−1, the collection efficiency evinced a marked surge by 4.61% to 11.32% when Lb traversed from 150 to 450 mm, while the collection efficiency tended to be constant as Lb exceeded 450 mm. A holistic evaluation of both pressure loss and heat collection efficiency culminates in the deduction that the pinnacle of operational effectiveness, measuring 60.78%, was attained at Lb = 600 mm and v = 3.0 m·s−1. The economic scrutiny of baffled SAHs unveiled a Coefficient of Useful Energy (Cue) of a mere 0.057￥·kwh−1, notably inferior to that resultingensuing from the incineration of fossil fuels under the conditions of v = 3.0 m·s−1 and Lb = 600 mm.