Numerical analysis of a novel solar air heater design with V-ribs and jet cooling

Abstract

The application of solar air heaters (SAHs) is an effective method of utilizing abundant solar energy for heating purposes and reducing the consumption of fossil fuels. However, the performance of SAHs is characteristically low owing to a sublayer formation over the heated surface. To address this low performance, numerical examinations on a novel configuration of SAH have been performed in this study. The proposed design encompasses a combined arrangement of both impinging air jets and rectangular sectioned V-ribs on the absorber surface. The effect of varying roughness height, pitch, and angle of attack from 0.016 to 0.024, 0.264 to 0.792, and 30° to 75° respectively is investigated while keeping impingement parameters fixed and varying Re from 3000 to 18000. Nusselt number (Nu) and friction factor (ff) characteristics as functions of roughness parameters are evaluated. The results exhibit a considerable enhancement of 3.36 and 5.31 in Nu and ff respectively in contrast to conventional SAHs under similar boundary conditions. Moreover, the proposed model performs best at Re = 18000 with the highest thermohydraulic performance (ηcombined) of 1.92. The study concludes that the proposed arrangement of jet cooling with rectangular sectioned V-ribs is an efficacious way for improving the performance of SAHs.