Performance enhancement of artificial roughened solar air heater by using perforated multi V ribs in double pass parallel flow

Abstract

The thermal performance of the conventional solar heater was very low because of a lower coefficient of heat transfer and high heat losses. Several studies have been conducted to improve the performance of the SAH using many original designs and flow arrangements. One of the appealing options for boosting the thermal performance of a double pass parallel flow solar air heater DPPFSAH is an arrangement with perforated multi v rib artificial roughness on both sides of the absorber plate. This could be because the repeated passes give increased surface area for heat transfer, resulting in a high heat transfer coefficient. Providing perforated artificial roughness on the heated plate reduces the laminar sub layer and creates turbulence in the flow field near the heated surface, increasing the heat extraction coefficient. Solar radiation is received by the absorber from the upper surface, while heat is taken from both sides, resulting in a more efficient heat transfer between the absorber plate and the circulating air, and thus energy losses from the collector are reduced. In addition, this kind of setup can be manufactured with a small extra expense compared to the conventional Solar Air Heater. A single pass SAH and a DPPFSAH with artificial roughness on top and both sides of the absorbing surface are considered for performance assessment and compared with traditional SAH. Thus, the artificial roughness developed on a perforated multi V shaped rib with variation in relative roughness width ratio and open area ratio as geometric parameters and Reynolds numbers as flow parameters are investigated in this thesis. newline