Flow regimes and evaporative heat transfer coefficients for flow boiling in smooth and internally-grooved tubes

摘要

This paper outlines the development of a physics-based heat transfer coefficient model that recognizes the role played by two-phase flow structures in enhancing two-phase thermal transport within internally-grooved tubes. Flow regime data, obtained with dynamic total-internal-reflection measurements, and heat transfer coefficient data, obtained with infrared thermography, are presented and analyzed for two-phase HFE-7100 flow in horizontal 8.84 mm diameter smooth and internally-grooved tubes, with mass fluxes from 25-300 kg/m2s, heat fluxes from 0-56 kW/m2, and vapor qualities approaching 1. This data, along with data from the literature, is then compared to the new flow regime map and associated heat transfer coefficient correlation. The model is shown to predict the current data set and data from several independent researchers, with a marked improvement in predicting performance near the transition from Stratified-Wavy to Annular flow in internally-grooved tubes.