Model of R134a Liquid–Vapor Two-Phase Heat Transfer Coefficient for Pulsating Flow Boiling in an Evaporator Using Response Surface Methodology

Peng Yang,Ting Zhang,Yingwen Liu,Yuheng Zhang,Sophie Wang

doi:10.3390/en13143540

Peng Yang, Ting Zhang + Show 3 more

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https://doi.org/10.3390/en13143540

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Abstract

The present study proposes a model to predict the heat transfer coefficient in R134a liquid–vapor two-phase pulsating flow boiling in an evaporator using the experimental data and response surface methodology (RSM). The model is based on the current existing empirical correlation for R134a liquid–vapor two-phase continuous flow with an imposed modification factor. The model for the imposed modification factor is the function of the pulsating period and inlet/outlet vapor quality, which is obtained using the limited experimental data. An analysis of variance (ANOVA) is carried out to test the significance of the model and normal probability of residuals is analyzed as well. Results show that the regression model produces a mean error of −4.3% and a standard deviation of 15.4%, compared to experimental results. Of the data 95.1% is contained inside a ±50% error window, which indicates that the proposed model could predict the heat transfer coefficient of R134a liquid–vapor two-phase pulsating flow boiling well.

Highlights

Numerous strategies, including passive and active techniques such as a fin-tube, coiled wires, and swirl/pulsating flow generator are widely used to improve the thermal performance of heat exchangers [1,2,3]
The suitable correlation was selected to predict the results in the two-phase continuous flow, which will be one important component of the heat transfer coefficient (HTC) in the two-phase pulsating flow
A new model for predicting HTC in the R134a liquid–vapor two-phase pulsating flow was developed based on the heat transfer model in the two-phase continuous flow and response surface methodology

Summary

Introduction

Numerous strategies, including passive and active techniques such as a fin-tube, coiled wires, and swirl/pulsating flow generator are widely used to improve the thermal performance of heat exchangers [1,2,3]. Studies on pulsating flow in a heat exchanger are essential because they are beneficial to understanding flow characteristics and improve heat transfer performance. Different from the single-phase flow, the two-phase heat transfer coefficient (HTC) predictions require a broad, accurate experimental database, and a good knowledge of the heat transfer mechanism. For this purpose, many research proposed different empirical correlations to predict the HTC in the two-phase flow. One classical type is based on the HTC of liquid flow with

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Conclusion