Numerical Analysis of a Solar Air Heater With Jet Impingement—Comparison of Performance Between Jet Designs

Abstract

Abstract One of the ways to improve the performance of solar air heaters (SAHs) is to use jet impingement on the absorber plate to cause turbulence mixing of air in contact with the plate and thereby augment the heat transfer coefficient. Although the jet impingement is a prospective way of improving the SAH performance, comparison of performance between jet designs is not performed so far. The objective of this work is to compare the thermo-hydraulic performance of a SAH with jet impingement through conical protruding jets and circular jets using finite element method based comsol multiphysics software. The simulation studies were conducted for solar radiation in the range 500–1000 W/m2 and mass flowrate in the range 0.01–0.028 kg/s. The flow physics of the jet impingement process is investigated to understand the heat transfer and fluid flow behavior of the SAH with the chosen jet designs thereby obtain their performance insights. The outlet hot air temperature from the heater and its thermal efficiency are compared for different mass flowrates and solar radiations. Also the temperature distributions in the jet plate with the jet configurations are captured and their heat transfer characteristics compared with understand the thermo-fluidic behavior of the SAH. The results demonstrate improved performance of the novel conical protruded jet design that enhances the thermal efficiency up to 78.52%, which is an increase of 13.53% compared with the circular jet design. More elongated streamlines and higher turbulent kinetic energy with increased mass flowrate leading to a wide jet affected area inside the duct are the main reasons of its improved performance.