COMPARATIVE STUDY OF THE EFFECT OF TWO TYPE OF RIBS ON THERMAL PERFORMANCE OF SOLAR AIR HEATERS

Abstract

This paper aims to analyze fluid flow characteristics and heat transfer augmentation in the air duct of a solar air heater using CFD techniques. The air duct has a rectangular section, the top wall is the glazing and the bottom one is the absorber provided with transverse rectangular or squared ribs. The simulations are performed in the turbulent regime and RANS formulation is used to modelize the flow and resolve mass, momentum and energy equations using Finite Volumes method. The air flow analysis shows that the velocity profile was not disturbed by the ribs outside the laminar sublayer. Heat transfer analysis based on the calculation of Nusselt Number, friction factor and thermo-hydraulic performance has highlighted the heat transfer enhancement, and no big friction losses were recorded. A comparative study between two ribs shape (square and rectangular) was achieved and showed a better thermohydraulic performance for rectangular ribs.