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. A validated numerical model is
used to investigate the effect of varying roughness height, pitch, and angle of attack
from 0.016 to 0.024, 0.264 to 0.792, and 30 respectively while keeping impingement parameters fixed and varying Re from 3000 to 18000. The analysis results in terms of Nusselt number (Nu) and friction factor (ff) characteristics as a function 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 presented results conclude that the proposed arrangement of jet cooling with rectangular sectioned V-ribs is an efficacious way for improving the performance of SAHs.
