The Thickness of the Liquid Microlayer Between a Sliding Bubble and a Heated Wall: Comparison of Models to Experimental Data

Sliding vapor bubbles are known to create high heat transfer coefficients along the surfaces against which they slide. The details of this process remain unclear and depend, in part, on the evolution of the liquid microlayer that forms between the bubble and the surface. A mechanistic model of the micro-layer thickness verified by direct observation of the microlayer thickness is needed. This paper describes a comparison of measurements from a recent set of experiments to the results of microlayer models from the literature and to the predictions of a new model presented here for the first time. The measurements were produced by a laser-based method developed to measure the thickness of the liquid microlayer between a cap-shaped sliding bubble and an inclined heated wall. Microlayer thicknesses of 22 to 55 microns were obtained for saturated FC-87 and a uniform-temperature surface inclined at 2° to 15° from the horizontal. The basis of each model, input requirements, limitations, and performance relative to this data set are discussed.