Forced convection experiments on slotted transpired plates

摘要

Experiments were conducted to measure the thermal effectiveness of perforated transpired plates in a grazing wind. The experiments were motivated by the need to model a novel solar collector design. The perforations in the plate took the form of narrow slots Chat were perpendicular to the wind direction. The measurements were performed in the asymptotic region, where the thermal and hydrodynamics boundary layers assume a periodic behaviour. Four plates made from different materials and having different geometries were tested, using air as the fluid. The range of parameters for the experiments were as follows: wind speed from 1 to 8 m/s, superficial suction velocity from 0.04 to 0.08 m/s, slot spacing from 15 to 25 mm, slot width from 0.18 to 0.25 mm, plate thickness from 0.8 to 1.5 mm, and plate thermal conductivity from 0.2 to 15 W/Km. The results for a given plate were correlated tightly by a single dimensionless flow parameter, γ, a product of a Reynolds number and a velocity ratio (suction to wind velocity) that has arisen from of an integral momentum analysis. Thermal effectiveness results were correlated to dimensionless parameters. Excellent agreement, with an rms error of 1.8%, was obtained.