EXPERIMENTAL RESEARCH ON POOL BOILING HEAT TRANSFER FROM A SPRAYING POROUS SURFACE

Boiling heat transfer on the flame spraying porous surface is experimentally investigated. The tested spraying porous layers made of gear bronze have three different thicknesses. Distilled water, ethyl alcohol and R-113 were used as working liquids. The experiment was performed at the saturated temperature under local atmospheric pressure. The experimental results show that for such porous layer, the wall superheat required to initiate boiling is low, the boiling heat transfer coefficient can be higher than that of smooth plane surface by about twofold to fivefold. At the same time, the critical heat flux of such spraying porous layer is also higher than that of smooth plane, and it can enhance the boiling heat transfer within wide heat flux range. The experiment also reveals that the spraying porous surface also has the boiling curve hysteresis, but the temperature overshoot is not serious. The spraying technique not only has the advantages of simple equipment, convenient operation and low cast, but also can be suited for irregular base surfaces with complex geometry shapes. So, the spraying porous surface is a promising type of wick structure for heat pipe and vapor chamber.