Performance analysis of arc rib fin embedded in a solar air heater

Abstract

Abstract A thermal model is developed for analysing the influences of arc rib fin arrangement and length of absorber plate on the heat transfer characteristics of a solar air heater. The arc rib fin arrangement is designed by varying the fin relative roughness height ratio (e/De) in the absorber plate. Solar air heater with fixed arc rib fin configuration with e/De (0.0422) and variable arc rib fin configuration with two different relative roughness height ratios of e/De (0.0422 and 0.0541) are modelled. The influence of absorber plate length (1 and 2\xa0m) on the solar air heater performance is compared with the configurations mentioned above at various mass flow rates of air (0.02 kgs−1 to 0.06 kgs−1). The outlet air temperature of solar air heater, mean absorber plate temperature, heat transfer characteristics (Nusselt number and frictional factor), pressure drop, thermo-hydraulic performance parameter, efficiencies (thermal, effective, and exergy), collector efficiency factor, and collector heat removal factor are predicted at different air flow rates. The variable arc rib fin arrangement in the solar air heater leads to maximum utilization of available solar energy from the absorber plate, and reported maximum outlet air temperature and lower mean absorber plate temperature when compared to fixed arc rib fin arrangement and smooth duct. Further, the variable arc rib fin arrangement has better heat transfer and thermo-hydraulic characteristics than the fixed arc rib fin arrangement and smooth duct. Thus implementation of the variable arc rib fin arrangement will significantly enhance the overall performance of the solar air heater.