The Effect of Corrugation on Heat Transfer and Pressure Drop in a Solar Air Heater: A Numerical Investigation

Abstract

Solar is a green source of energy. The foremost objective is the efficient heating of air by enhancing the thermal efficiency of Solar Air Heaters. Even a small enhancement in efficiency will increase its life, power output and reduce its operating cost. In current study double pass, trapezoidal cross-sectioned channel with four different arrangement of corrugations at bottom and trailing wall of outlet pass is numerically investigated at a Re equals to 9400. Corrugations are of trapezoidal shape having pitch to height ratio (p/e) equals to 4. Four different arrangements of trapezoidal corrugation at bottom wall and trailing wall of outlet pass is investigated. When compared to a smooth trapezoidal channel, it turns out that an inline arrangement of corrugation enhances heat transfer by 33% while increasing friction factor by up to 27%. Also, compared to a staggered ribbed trapezoidal channel, inline corrugation patterns improve heat transfer by 7% and reduce friction by up to 16%.. Corrugations with staggered arrangement gives slightly better results but as space for passive cooling ducts in solar air heaters is limited therefore concerns regarding fabrication and less mechanical strength arises. Effect of increasing Reynolds number in trapezoidal corrugated channel shows increasing trend in Nu/Nuo, pressure drop and thermal performance factor.