Enhancing Heat Transfer from a Porous Plate with Transpiration Cooling

Year 2017, Volume: 2 Issue: 1, 12 - 20, 25.02.2017

Mustafa Kılıc

Abstract

The present study is
focused on developing structural solid surface geometry to improve heat
transfer by cooling of air with transpiration cooling. Effects of flow rate of
water (ṁ_water= 0.000083, 0.000116, 0.000166, 0.000249 kg/s) and particle
diameter of porous plate (Dp= 40, 50, 100, 200 μm) on local wall
temperature and cooling efficiency of porous plate and the system inside a
rectangular channel with air as a hot gas stream and water as a coolant were
investigated experimentally. High performance polyethylene as a porous media
was used not only to form a thermal barrier but also an active cooling plate by
evaporating water from the surface of porous media to cool air. Temperatures
were measured by T-type thermocouples. Two electric heaters were used to
support enough power to the system. It was observed that increasing water flow
rate did not cause a prominent decrease on surface temperature and cooling
efficiency of porous plate. The higher injection rates result in further
increase of the cooling effectiveness. Cooling efficiency of porous plate
changed from 38 to 90 %. Increasing water flow rate as a coolant causes a
prominent increase on cooling efficiency of the system. Increasing water flow
rate three times causes an increase of 26.4 % on cooling efficiency of the
system. Decreasing particle diameter causes a significant decrease on surface
temperature. Difference of cooling efficiency of porous plate from Dp=40 to
Dp=200 μm decreases from 12% to 2 % from inlet region to end of
porous plate.

Keywords

Heat transfer, porous plate, structured surface

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