ISSN Online: 2377-424X
ISBN Print: 1-56032-797-9
International Heat Transfer Conference 11
EXPERIMENTAL INVESTIGATION OF TURBULENT HEAT TRANSFER AND FLUID FLOW IN INTERNALLY FINNED TUBES WITH SURFACE ROUGHNESS
Sinopsis
An experimental investigation of simultaneously developing, steady, turbulent flow under heating conditions in both straight and helically finned tubes with surface roughness (sand grain type) has been performed. Length-averaged heat transfer and pressure drop were obtained using air as the test fluid in twelve rough fin tubes and one rough tube without fins. Adiabatic friction factors and Nusselt numbers were measured for fin geometries of 18≤N≤60, 0.056≤H≤0.269, 7.562 µm ≤Rat,i ≤14,941 µm and 0° ≤ y≤26° . Turbulent flow operating conditions ranged from 7,500<Re<43,000 and Pr~O.7. In addition, adiabatic friction factors were obtained for the range 9,100<Re<54,000 using ambient air at the test fluid. The results are compared to existing smooth fin tube correlations. The rough fin tube results exhibited substantial increases in friction factors while corresponding increases in Nusselt numbers were found only in limited cases compared to smooth fin tubes.