Title of article :
Experimental investigations on heat transfer and frictional characteristics of a turbulator roughened solar air heater duct
Author/Authors :
Santosh B. Bopche، نويسنده , , Madhukar S. Tandale، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2009
Abstract :
An experimental investigation has been carried out to study the heat transfer coefficient and friction factor by using artificial roughness in the form of specially prepared inverted U-shaped turbulators on the absorber surface of an air heater duct. The roughened wall is uniformly heated while the remaining three walls are insulated. These boundary conditions correspond closely to those found in solar air heaters.
The experiments encompassed the Reynolds number range from 3800 to 18000; ratio of turbulator height to duct hydraulic mean diameter is varied from, e/Dh = 0.0186 to 0.03986 (Dh = 37.63 mm and e = 0.7 to 1.5 mm) and turbulator pitch to height ratio is varied from, p/e = 6.67 to 57.14 (p = 10 to 40 mm). The angle of attack of flow on turbulators, α = 90° kept constant during the whole experimentation. The heat transfer and friction factor data obtained is compared with the data obtained from smooth duct under similar geometrical and flow conditions. As compared to the smooth duct, the turbulator roughened duct enhances the heat transfer and friction factor by 2.82 and 3.72 times, respectively. The correlations have been developed for area averaged Nusselt number and friction factor for turbulator roughened duct.
Keywords :
Solar air heater , Heat transfer enhancement , Roughness , Turbulator
Journal title :
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
Journal title :
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER