| Summary: | © 2020 The relationship between bubble departure frequency and diameter is fundamental to the boiling process and needs to be fully understood for prediction of overall boiling heat transfer performance. Hydrodynamic models for bubble departure were developed in previous studies. However, these models could not explain the dependence of bubble frequency on properties of the heating substrate and surrounding liquid, which was observed in many experiments. In this work, we develop a unified bubble departure theory for saturated nucleate pool boiling. The heat transfer in the bubble base region after bubble departure is taken into consideration. Two characteristic timescales, representing two dominant heat transfer processes for different regimes of bubble sizes, are extracted. These timescales, which depend on substrate and liquid properties, are used to determine bubble departure frequency. The results from our theory show reasonably good agreement with existing experimental data. The proposed model provides a unified relationship between bubble departure frequency and diameter for various combinations of heating substrates and working fluids in the saturated nucleate pool boiling regime.
|
|---|