Heat transfer enhancement in a solar air heater channel with discrete V-baffles

This article presents the study of heat transfer enhancement in a uniform heat-fluxed channel fitted with discrete V-shaped baffles. The experiments are carried out by varying airflow rate for Reynolds number ranging from 4100 to 22,000. The V-baffles with relative height ratio, e/H = 0.15 and the attack angle, a = 45o, are mounted repeatedly on the upper plate only, similar to an absorber plate of solar air heater systems. The effects of four baffle-pitch to channel-height ratios (PR= 0.5, 1.0, 1.5 and 2.0) on heat transfer in terms of Nusselt number and pressure loss in the form of friction factor are experimentally investigated. The experimental results show that the use of the discrete V-baffles leads to a considerable increase in Nusselt number and friction factor in comparison to the smooth channel alone. The V-baffled channel with PR=0.5 provides the highest heat transfer, friction factor and thermal enhancement factor. © (2014) Trans Tech Publications, Switzerland.