A Study on the Mechanism of Convective Heat Transfer Enhancement Based on Heat Convection Velocity Analysis

Hui Xiao, Zhimin Dong, Rui Long, Kun Yang and Fang Yuan
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Hui Xiao: School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Zhimin Dong: School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Rui Long: School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Kun Yang: School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Fang Yuan: School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China

Energies, 2019, vol. 12, issue 21, 1-22

Abstract: This paper explores the mechanism of convective heat transfer enhancement in a new perspective. In this paper, a new parameter called heat convection velocity is proposed based on the field synergy principle. It is defined as the velocity projection on the temperature gradient vector and reflects the magnitude of the velocity component that contributes to heat convection. Three typical cases are taken into consideration to investigate the influence factors of Nusselt number theoretically. The results indicate that the Nusselt number can be enhanced by increasing the mean heat convection velocity and the dimensionless mean temperature difference. Through theoretical analysis, three suggestions are found for designing heat transfer enhancement components: (a) the overall synergetic effect should be improved; (b) the fluid with lower temperature gradient should be guided to the region where the temperature gradient is higher; (c) temperature distribution should be an interphase distribution of hot and cold fluid. Besides, the heat convection velocity is used to investigate the mechanism of convective heat transfer in the smooth tube. It is found that the increase of Nusselt number is due to the increase of heat convection velocity. In addition, according to design suggestions, a new insert is invented and inserted in the circular tube. With heat convection velocity analysis, it is found that there is much potential of increasing heat convection velocity for enhancing the convective heat transfer in the circular tube.

Keywords: heat convection velocity; temperature distribution; heat transfer enhancement; field synergy principle (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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