Experimental Investigation of the Effects of Fluid Properties and Geometry on Forced Convection in Finned Ducts With Flow Pulsation

Abstract

An experimental study was conducted on the effects of flow pulsation on the convective heat transfer coefficients in a flat channel with series of regular spaced fins. Glycerol-water mixtures with dynamic viscosities in the range of 0.001–0.01 kg/ms were used as working fluids. The device contains fins fixed to the insulated wall opposite to the flat and smooth heat transfer surface to avoid any heat transfer enhancement by conduction of the fins. Pulsation amplitude xo=0.37 mm and pulsation frequencies f in the range of 10 Hz<f<47 Hz were applied, and a steady-flow Reynolds number in the laminar range of 10<Re<1100 was studied. The heat transfer coefficient was found to increase with increasing Prandtl number Pr at a constant oscillation Reynolds number Reosc. The effect of the dh/L ratio was found to be insignificant for the system with series of fins and flow pulsation due to proper fluid mixing in contrast to a steady finned flow. A decrease in heat transfer intensification was obtained at very low and high flow rates. The heat transfer was concluded to be dynamically controlled by the oscillation.