A Statistical Model of Bubble Coalescence and Its Application to Boiling Heat Flux Prediction—Part II: Experimental Validation

A mechanistic model for the boiling heat flux prediction proposed in Part I of this two-part paper (2009, “A Statistical Model of Bubble Coalescence and Its Application to Boiling Heat Flux Prediction—Part I: Model Development,” ASME J. Heat Transfer, 131, p. 121013) is verified in this part. In the first step, the model is examined by experiments conducted using R134a covering a range of pressures, inlet subcoolings, and flow velocities. The density of the active nucleation sites is measured and correlated with critical diameter $Dc$ and static contact angle $θ$⁠. Underlying submodels on bubble growth and bubble departure/lift-off radii are validated. Predictions of heat flux are compared with the experimental data with an overall good agreement observed. This model achieves an average error of $±25%$ for the prediction of R134a boiling curves, with the predicted maximum surface heat flux staying within $±20%$ of the experimentally measured critical heat flux. In the second step, the model is applied to water data measured by McAdams et al. (1949, “Heat Transfer at High Rates to Water With Surface Boiling,” Ind. Eng. Chem., 41(9), pp. 1945–1953) in vertical circular tubes. The consistency suggests that the application of this mechanistic model can be extended to other flow conditions if the underlying submodels are appropriately chosen and the assumptions made during model development remain valid.