International Journal of Heat and Mass Transfer, Vol.138, 390-400, 2019
Experimental study on convective boiling of micro-pin-finned channels with parallel arrangement fins for FC-72 dielectric fluid
The boiling convective heat transfer of dielectric fluid of FC-72 in a microchannel with etched micro fins is experimentally studied. The microchannel test surface is a square of 10 mm size with a height of 100 mu m. The surface of the microchannel is covered with parallel-nucleated fins of a cubic size of 100 mu m. The fins are nucleated with the central pore size of 60 mu m and an opening of 45 mu m. The fins are arranged in the equal space of 400 mu m. There is a planar electrical element below the microchannel, which produces an adjustable surface heat flux below the channel. The dielectric liquid enters the test microchannel and flows over the test surface and the fins. In the experiments, the mass velocity (94-275 kg/m(2) s) and heat flux (0-6 W/cm(2)) are tested with a saturation temperature of either 35 or 50 degrees C. The heat transfer, the outlet vapor quality, and the pressure drop across the microchannel are measured and reported. The boiling behavior of FC-72 over the etched fins is also investigated using photos. The results show that the liquid first go through some superheat states and then the boiling phase change starts. When the boiling heat transfer occurs, a significant pressure-drop can be observed across the microchannel, but the surface temperature difference would also drop significantly. In the case of very low mass velocity of 94 kg/m(2) s, the minimum superheat temperature-difference of 4.7 degrees C is observed. (C) 2019 Elsevier Ltd. All rights reserved.