Numerical Analysis of Heat and Fluid Flow in Solar Air Heater Having Cylindrical Turbulator on Absorber Plate

Abstract

Solar air heater consist of the flat plate collector called absorber plate which collect the solar insolation and convert it into thermal energy. The air as working fluid gives the lower thermal performance because of its low thermal conductivity. Hence to enhance the performance of the SAH thermal conductivity of air should be enhanced. The presence of roughness component on the inside surface of Solar Air Heater enhance Nusselt no. and friction factor which gives the higher thermal performance. The present work deals with numerical investigation and optimization of pressure drop and heat transfer of the SAH provided with cylindrical turbulator as roughness. The influence of geometrical parameters such as, turbulator diameter (h = 5mm, 10mm, 15mm and 20mm), turbulator height (h=1mm, 2mm, 3mm and 4 mm), pitch ratio (e= 3, 6, 9 and 12) and Reynolds number (Re =10565, 13506, 17624 and 20565) on heat transfer and pressure drop are inspected numerically and optimized by using Taguchi approach. In the analysis, Nusselt no. and pressure drop are assumed as performance parameters and optimized. An orthogonal array of L16 (4*4) is considered as experimental plan. The results indicate that maximum Nusselt number is obtain for d= 20mm, h=3mm e= 12 and Re = 17624, minimum pressure drop is obtained for d= 5mm, h= 1mm, e= 6 and Re=10565, while maximum thermo-hydraulic performance is achieved at d=20 mm, h=1mm, e=12 and Re=20565. The thermal performance of the SAH is increased by 35.8%. The correlations for Nusselt no. and friction factor are established from the numerical data obtained from the CFD simulations and analysis. The values obtained for the Nusselt no. and friction factor are function of Re, (h/d) and (p/d).