A Theoretical Model to Predict Pool Boiling CHF Incorporating Effects of Contact Angle and Orientation

TLDR

Momentum flux from evaporation at the bubble base is a key parameter in pool boiling. The study develops a theoretical model to predict critical heat flux for surfaces oriented from horizontal to vertical. The model incorporates hydrodynamic vapor‑liquid interface dynamics and surface‑liquid interaction via the dynamic receding contact angle. It accurately predicts CHF for water, refrigerants, and cryogenic liquids, capturing trends with dynamic receding contact angle and subcooling.

Abstract

A theoretical model is developed to describe the hydrodynamic behavior of the vapor-liquid interface of a bubble at the heater surface leading to the initiation of critical heat flux (CHF) condition. The momentum flux resulting from evaporation at the bubble base is identified to be an important parameter. A model based on theoretical considerations is developed for upward-facing surfaces with orientations of 0 deg (horizontal) to 90 deg (vertical). It includes the surface-liquid interaction effects through the dynamic receding contact angle. The CHF in pool boiling for water, refrigerants and cryogenic liquids is correctly predicted by the model, and the parametric trends of CHF with dynamic receding contact angle and subcooling are also well represented.