Exergetic efficiency prediction of roughened solar air heater

Abstract

Energy losses of flowing air through solar air heater (SAH) duct does not consider in the ther-mal performance. Therefore, thermohydraulic performance based on exergetic efficiencies is a tool to assess the performance by considering energy losses in propelling the air simul-taneously to identify the best ribs configuration. This paper presents the thermohydraulic performance of SAHs exploiting various ribs roughness’s. The performance of SAHs is based exergetic evaluation based on IInd law of efficiency is most suitable for design of artificial-ly roughened SAH as it includes both requirement of pumping power and effective energy output. In this paper exergetic evaluation of differently roughened SAH has been done. The exergy efficiency of roughened SAH was calculated analytically with the help of correlations developed by researchers and the results also compared with conventional SAH under same operating parameters. The thermal and exergy efficiency curve as a function of temperature rise parameter (ΔT/I) has been plotted. As a results, hybrid ribs configuration exhibited the highest exergetic efficiencies when temperature rise parameters greater than 0.01 K.m/W, however, smooth duct also showed a significant exergetic efficiency when temperature rise parameters had low values.