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Abstract
1- Introduction
2- Literature survey on existing database and correlations of heat transfer coefficient for upward no-phase-change two-phase flow in inclined pipes
3- Development of heat transfer multiplier correlation for upward two-phase flow in inclined pipes
4- Performance evaluation of the newly-developed two-phase heat transfer coefficient correlation for upward two-phase flow in inclined pipes
5- Conclusions
Acknowledgement
Appendix
References
Abstract
This study aims at developing a robust and theoretically-supported correlation of two-phase heat transfer coefficient for upward no-phase-change two-phase flow in inclined pipes based on the concept of extended Chilton-Colburn analogy. Firstly, a comprehensive literature survey was conducted to gather over 1800 experimental data and 12 correlations of two-phase heat transfer coefficient. The comparison results indicated that none of the existing correlations could predict the entire database satisfactorily. Then, the dependence of twophase heat transfer enhancement ratio (or two-phase heat transfer multiplier) on liquid fraction, two-phase pressure drop multiplier and inclination angle was analysed, and the two-phase heat transfer coefficient correlation was developed. The performance assessment indicated that the newly-developed correlation could predict 95% of the experimental data within ± 30% error with the mean absolute relative deviation of 12.9%. The newly-developed semi-theoretical correlation would be useful in designing no-phase-change two-phase heat transfer systems, such as petroleum pipelines and nuclear power plants.
Introduction
Upward no-phase-change two-phase flow in inclined pipes has extensive industrial and engineering applications in petroleum pipelines, chemical reactors and nuclear power plants [1]. Various flow patterns such as bubbly flow, intermittent flow, stratified flow and annular flow, occur in inclined pipes depending on different flow conditions [2]. Due to the significant interaction between gas and liquid phases, the flow characteristics of upward no-phase-change two-phase flow in inclined pipes are complicated. The thermal characteristics of no-phase-change two-phase flow in inclined pipes is attracting more and more attention recently. Substantial efforts have been made on understanding the flow and heat transfer characteristics of upward no-phase-change two-phase flow in inclined pipes.
Hetsroni et al. [3] investigated the local heat transfer coefficient of upward air-water flow in inclined pipes and claimed that the pipe inclination enhanced two-phase heat transfer. Mosyak and Hetsroni [4] also measured the temperature difference between the top and bottom of a horizontal pipe and slightly inclined pipes, and found that increasing pipe inclination could drastically reduce the temperature difference. Vaze and Banerjee [5] studied the effect of pipe inclination on flow and heat transfer characteristics of air-water two-phase flow experimentally. Trimble et al. [6] conducted experimental study on heat transfer characteristics of upward two-phase slug flow in inclined pipes.