Local Measurements in Heat Exchangers: A Systematic Review and Regression Analysis

It is widely known that most of the heat transfer and pressure drop measurements in heat exchangers are global measurements that are based on surface averaged parameters that do not measure the growth of the hydraulic and thermal boundary layer. Recent local heat transfer coefficient investigations on hydrocarbon condensation in plate heat exchangers suggest that the mean heat transfer coefficients obtained from local measurements are 10–20% higher than those obtained from studies based on a uniform wall heat flux assumption. Consequently, process heat exchangers which were rated by global measurements could be underrated. This systematic review presents a meta-analysis and regression analysis of the available pressure drop and heat transfer data for both single-phase and two-phase flows in enhanced heat exchangers. Data was compiled from studies in the last decade for similar Reynolds, Prandtl, Dean, Weber, and boiling numbers, pitch/diameter ratio, and other parameter ratios for statistical analysis and correlation development. State-of-the-art local measurement techniques like liquid crystal thermography are also discussed. Both practicing engineers and graduate students should benefit from this study.