Experimental study on geometry of a microlayer during single-bubble nucleate boiling

To measure the physical parameters of the simple microlayer model for the prediction of the heat flux and heat transfer rate due to the evaporation of the microlayer during nucleate boiling,the microlayer geometry was experimentally examined. The parameters,including initial thickness,moving velocity and microlayer radius,were measured by total reflection and interferometry techniques using a laser. Single-bubble nucleate boiling experiments were conducted using saturated water on a horizontal surface under atmospheric pressure. The geometric characteristics of the microlayer underneath the bubbles periodically nucleating at a nucleation site at an average heat flux of 200 kW/m² were analyzed. The experimental results in the present study show that the maximum initial thickness of the microlayer and the horizontal moving velocity are 5.4 μm and 0.12 m/s, respectively.