Numerical Investigation on Solar Air Heater with Hemispherical Roughness

Abstract

With increase in population, dependency on solar energy is increasing. But space has always been a constraint. The only solution is increasing the efficiency of solar energy harnessing instruments. Solar air heater is one such kind with vast range of applications and research scope. It is observed from previous investigations that there is a significant increase in heat transfer rate between absorber plate and flowing air due to inclusion of different types of artificial roughness. In this paper, numerical investigations on solar air heater with hemispherical vortex generator have been carried out. Commercially available ANSYS 18.0 is used to carry out the overall investigation. The complex turbulent flow equations are solved using standard k-ω model. Various geometrical configurations (pitch, P=8 to 12, eccentricity, e= 0.018 to 0.04) of vortex generator and operating parameters (Reynolds no, Re= 4000 to 20000) are considered for the investigations on solar air heater with aspect ratio of 12. Overall investigation is carried out considering a constant heat flux of 1000 W/m2. Optimum geometrical configuration among the selected configurations is evolved.