Performance Evaluation of Roughened Solar Air Heaters for Stretched Parameters

Artificial roughness applied to a Solar Air Heater (SAH) absorber plate is a popular technique for increasing its total thermal efficiency (eta(t-th)). In this paper, the influence of geometrical parameters of V-down ribs attached below the corrugated absorbing plate of a SAH on the eta(t-th) was examined. The impacts of key roughness parameters, including relative pitch p/e (6-12), relative height e/D (0.019-0.043), angles of attack alpha (30-75 degrees), and Re (1000-20,000), were examined under real weather conditions. The SAH eta(t-th) roughened by V-down ribs was predicted using an in-house developed conjugate heat-transfer numerical model. The maximum SAH eta(t-th) was shown to be 78.8% as predicted under the steady-state conditions of Re = 20,000, solar irradiance G = 1000 W/m(2), p/e = 8, e/D = 0.043, and alpha = 60. The result was 15.7% greater efficiency compared to the default smooth surface. Under real weather conditions, the eta(t-th) of the roughened SAH with single- and double-glass covers were 17.7 and 20.1%, respectively, which were higher than those of the smooth SAH.

Automated summary

This paper investigates the impact of artificial roughness applied to a Solar Air Heater (SAH) absorber plate on its total thermal efficiency. The study examines the influence of geometrical parameters of V-down ribs attached below the corrugated absorbing plate of a SAH on the efficiency under real weather conditions. The results show that the roughened SAH with V-down ribs can achieve a maximum efficiency of 78.8%, which is 15.7% higher than the default smooth surface. Furthermore, the roughened SAH outperforms the smooth SAH under real weather conditions, with higher efficiencies of 17.7% and 20.1% for single- and double-glass covers, respectively.