INVESTIGATION ON SUPERCRITICAL FLUIDS HEAT TRANSFER DETERIORATION AND ITS MITIGATIONS

Research output: Chapters, Conference Papers, Creative and Literary Works (RGC: 12, 32, 41, 45)32_Refereed conference paper (with ISBN/ISSN)Not applicablepeer-review

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Detail(s)

Original languageEnglish
Title of host publicationProceedings of the 16th International Heat Transfer Conference, IHTC-16
Chapter16
Pages7842-7850
Number of pages8
Publication statusPublished - Aug 2018

Publication series

Name
ISSN (Electronic)2377-424X

Conference

Title16th International Heat Transfer Conference (IHTC-16)
LocationChina National Convention Center
PlaceChina
CityBeijing
Period10 - 15 August 2018

Abstract

A numerical study of the heat transfer deterioration (HTD) phenomena for supercritical fluids flowing upward in circular tubes at high heat fluxes and low mass fluxes is carried out using ANSYS-FLUENT code and employing the k-ω SST turbulence model. Numerical results on wall temperature distribution for both water and CO2 are compared with experimental data and a good agreement is obtained. Two wall temperature peaks are found when HTD occurs. Analysis of these peaks reveals that the first is caused by buoyancy effect while the second is caused by the shear stress effect. These effects cause the flattening of velocity distribution and eventual reduction of turbulent kinetic energy leading to heat transfer deterioration. In other to explore ways of mitigating HTD, Diameter effect on HTD is numerically studied for supercritical water flowing upward in circular tubes and annular channels at high heat flux and low mass flux. When the same boundary conditions are applied, it is found that in circular tubes the first wall temperature peak moves upstream and the magnitude of the peak increases first and then decreases with the increase of tube diameter. Whereas in annular channels, the HTD is suppressed when the outer diameter is small and HTD occurs gradually with the increase of outer diameter. These phenomena are consistent with previous experimental results. Also, Vortex Generator (VG) effect is numerically studied for supercritical water flowing upward in annular channels. The effects of VG’s size, number and distance on HTD mitigation are investigated. The results show that the VG can significantly decrease the peak of temperature along the fuel rod. The size of VG has little effect on HTD mitigation. The number of VG has great effect on HTD mitigation. The distance of VGs also has great effect on the HTD mitigation. There exists an optimal distance at which the largest decrease of the peak temperature is achieved. Heat transfer coefficient also increased at the positions where VGs are installed.

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Research Unit(s) information for this publication is provided by the author(s) concerned.

Citation Format(s)

INVESTIGATION ON SUPERCRITICAL FLUIDS HEAT TRANSFER DETERIORATION AND ITS MITIGATIONS. / Chika, Eze; Cheng, Hui; Zhao, Jiyun.

Proceedings of the 16th International Heat Transfer Conference, IHTC-16. 2018. p. 7842-7850 023302.

Research output: Chapters, Conference Papers, Creative and Literary Works (RGC: 12, 32, 41, 45)32_Refereed conference paper (with ISBN/ISSN)Not applicablepeer-review