Experimental research on cavity nucleation mechanism of flow boiling

An experiment was conducted to investigate the nucleation mechanism of flow boiling in an upwards rectangular channel. The good wettability surface can create more continuous and stable nucleation based on the experimental boiling phenomena at the different surfaces. A low superheat wall temperature area occurs during the nucleating, and it is larger than the bubble radius. The radio of the superheat area and the projected bubble area ranges between 1.3 and 1.8. With the microlayer evaporation model, it is concluded that the microlayer thickness is the least at the nucleation site and the heat flux density is just reverse. The flow enhances bubble deviation and convection cooling effect, which results in the low superheat area, exceeds the bubble diameter. The non-linear interaction among nucleated cavities and the convection cooling of main flow cause the discontinuity of nucleation.