A new model for predicting flow boiling heat transfer coefficients in horizontal microfin tubes

Copyright © 2016 by ASME. The objective of the current work is to present a new correlation for predicting heat transfer coefficients (HTCs) for flow boiling in horizontal microfin tubes. Correlations to predict HTCs have been proposed by numerous authors such as Yu et al., Thome et al., Cavallini et al., Yun et al., Chamra and Mago, Wu et al., and other researchers. The correlations proposed are semi-empirical due to the difficulties associated with modeling the physics of flow boiling in microfin tubes. The above correlations are based on smooth tube flow boiling correlations which are modified to capture the effect of the inner grooves in the microfin tubes on the boiling process. In a previous work, it has been demonstrated that no single correlation can reasonably predict the flow boiling HTCs over a wide range of operating conditions and tube geometric parameters (Merchant and Mehendale). A new model has been proposed and validated using an experimental database of 1576 points from published literature. For the full dataset, the new correlation has X30%of 67.3%, compared to Cavallini et al. and Wu et al. with X30%of 44.2%and 40.6%respectively. The performance of the new model for tube diameters less than and greater than 5 mm has also been discussed for halogenated refrigerants and CO2