Modeling of Two-Phase Heat Transfer in Smooth Tubes Using Probabilistic Flow Regime Maps

A probabilistic two-phase flow map condensation heat transfer model for R134a in 8mm ID tube is developed in order to more easily predict heat transfer in multiple flow regimes with the same flow regime basis that can be used to model pressure drop and void fraction. Continuous time fraction curve fits of the intermittent, stratified and annular flow regimes with physically correct limits were made for probabilistic two-phase flow maps found in the literature. The time fraction functions are simply multiplied by a respective model developed for each flow regime and summed toobtained the predicted heat transfer coefficient. The developed model is compared to experimentally obtained condensation data and models found in the literature. It is determined that the definition of the annular flow regime or the annular flow regime models used must be modified in order to eliminate inaccuracies of the present model at low quality ranges.