Boiling heat transfer properties of copper surface with different microstructures

The T-shaped groove surface with groove width of 0.3-1.2 mm and groove depth of 0.6-1.5 mm is prepared on the copper surface by using electric spark wire cutting technology, Set up a set of wall temperature measurement, bubble visualization and steady flow heating test bench. Experimental observations of boiling heat transfer of deionized water on different heat transfer surfaces are achieved. The boiling curves of T-shaped surface such as superheat, heat flux and heat transfer coefficient were plotted. The effect of heat transfer area on the heat transfer performance was investigated, and the bubble growth process was studied by using finite element simulation software. The effect of size on heat transfer performance is explained by experiment and simulation. It is found that the influence of groove width on heat transfer performance is greater than that of groove depth, under the reasonable width of the groove, the larger the depth of the groove, the easier it is to reach the required temperature for the vaporized core generation. The optimal size value of T-shaped grooves in this size range is selected, and the surface of T-grooves at different scales is constructed by laser marking technology. The boiling heat transfer performance of four kings of surfaces including smooth surface and laser scanning surface was studied. Studies have shown, heat transfer effect of multi-scale T surface is always the best,1.31 times of single scale surface,2.38 times of smooth surface and 2.83 times of laser scanning surface. The surface with micro structure can effectively promote boiling heat transfer by wire cutting and laser machining.