BG1-11 Onset of Nucleate Boiling for Plain Surfaces
Nucleate boiling is usually characterized by a high heat transfer rate for a low temperature difference, enhanced by intensive bubble growth and movement. However, there is a minimum wall superheat below which nucleate boiling with higher heat transfer coefficient is not possible. Nucleation theory suggests that wall superheat is required for bubbles to grow at and detach from small cavities on a heated surface. The wall superheat required for nucleation depends on surface conditions, physical properties, local process conditions, and heat transfer in the boundary layer. Based on available HTRI and literature data, we have developed a predictive model for the wall superheat to support nucleation on plain surfaces. Additional experimental research is needed to improve confidence in the model.