Influence of the rectangular baffle on heat transfer and pressure drop in the solar collector

Abstract

ABSTRACT The aim study is how to increase the thermal performance in a solar air heater, with a low-pressure drop between an inlet and outlet of the solar collector. In our study, we discussed the experimental study of the solar collector, and this is related to heating the air. We designed the solar collector at the University of Biskra with modifications that do not allow heat loss outside, and in addition to the baffles inside the airway channel that are in the shape of a rectangle which is perpendicular to the fluid flow, where the rectangular plate is installed at an angle of inclination 90°. The mass flow rate represents an important idea to show the effect of the friction factor and the number of baffles with taking account of the distance between the baffle and the next baffle. The idea in this research holding the baffle in the lateral stream channel of the solar collector, so that it is holing with a condition for letting a flow passed under and over the baffle, this is the novelty part of the study to create the turbulent regime and help us for carrying the heat from the absorber plate and the bottom plate with double effect. The experimental results give different results depending on the configuration used, they can be arranged from the most thermal efficiency to the smallest, with several baffles, the preferable thermal efficiency by the number of baffles η = 70%, the second η = 65%, the third η = 65%, the fourth η = 58%, and then the last η = 50%, respectively, the number of baffles 18, 14, 10, 6 and 3, according to low mass flow, low efficiency is implied. We note that mode 1, mode 2, and mode 3 give the best thermal efficiency against other configuration, which equal to η = 70, 85, 72%, respectively.