NUMERICAL ANALYSIS ON ABSORBER PLATE OF SOLAR COLLECTOR PROVIDED WITH ARTIFICIAL ROUGHNESS OF SQUARE SHAPE
Increased conventional fuel costs and their availability in the future forced the researchers to create an alternate solution - solar energy which is the viable option to construct the thermal systems. Solar air heaters are simple in design, cheap and require little maintenance, so it is most widely used for heating purpose. Analysis of solar air heater using Computational Fluid Dynamics (CFD) helps to find the optimized design parameter to improve its efficiency by predicting the behavior and performance of a solar air heater. The value of the heat transfer coefficient between the absorber plate and the air is low and this result in lower efficiency. Heat transfer rate to the fluid flow in the collector can be enhanced by providing the artificial roughness on a surface of the absorber. The present paper is related to the study of fluid flow and heat transfer in a solar air heater of a square duct provided with square rib roughness on the absorber plate. The practical domain is modeled using the tool ANSYS CFD. The analysis of roughness is done for 2D flows through the solar air heater for relevant Reynolds number ranges from 3800 to 18,000. The Reynolds number, relative roughness pitch (P/e), relative roughness height (e/D) and thermo-hydraulic performance parameter (THPP) are chosen as design variables. The effect of Reynolds number and roughness on Nusselt number corresponding to their relative pitch is investigated. A commercial finite volume package ANSYS FLUENT 16.0 is used to analyze and visualize the nature of the flow in the duct of a solar air heater. The RNG k–ε turbulence model is used to solve the transport equations for turbulent flow energy and dissipation rate.