Thermal performance investigation of a solar air heater having discrete V-shaped perforated baffles

Abstract

In the present work, thermal performance of solar air heater (SAH) having discrete V-shaped perforated baffles as artificial roughness on absorber surface has been numerically investigated. The effect of relative blockage height (e/H) of proposed roughness on Nusselt number (Nu), friction factor (f) and thermo-hydraulic performance parameter (THPP) has been considered. Parametric investigation covers a range of roughness parameter viz. relative blockage height (e/H) from 0.3 to 0.6 and flow parameter, Reynolds number (Re) from 4000 to 18,000 at constant open area ratio of 23%, relative pitch ratio of 6 and angle of attack of 60○. Performance of SAH with proposed roughness has been compared with other roughness geometries investigated by other researchers. It is noticed that Nusselt number enhancement ratio (Nurat) and friction factor enhancement ratio (frat) are 4.24 and 14.73, respectively, and maximum values of THPP is found to be 2.24 at e/H = 0.4. Abbreviations: CFD: Computational fluid dynamics; LSCB: Least square cell based; RNG: Renormalisation group; SAH: Solar air heater; SIMPLE: Semi implicit method for pressure linked equation; THPP Thermo-hydraulic performance parameter