Thermal behavior of natural convection flow in an inclined solar air heater

Abstract

The thermal behavior of hot air in a natural convection mode on a solar absorber-plate has not been, so far, modeled experimentally. The present work aimed to assess the performance of the inclined solar air heater [SAH] experimentally by investigating the temperature distribution field in the natural convection flow. The solar plate collector is designed based on the aspect ratio of length to height, L / H, of 6 and 12. The measurements are carried out for the collector tilt angles of 30°, 45°, 60° and 75°. The present investigation demonstrates the temperature distribution of hot air floated in an inclined channel of the SAH. The investigation showed 2D thermal stratification increases when increasing the distance along the collector plate, which looks clear in the SAH with a height of 10 cm. The results of the study show that the thickness of the thermal layers increases with increasing the tilt angle from 30˚ to 75˚. The reason dates back to increasing the buoyancy force of the hot air over the absorber. The results demonstrated that the air temperatures for the height of 0.1 m and 45˚ tilt angle are higher than that for the height of 0.2 m by 23%.