Experimental Measurement and Theoretical Prediction of Bubble Growth and Convection Heat Transfer Coefficient in Direct Contact Heat Transfer

Jun Yang, Biao Li, Hui Sun, Jianxin Xu () and Hua Wang
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Jun Yang: Engineering Research Center of Metallurgical Energy Conservation and Emission Reductio, Ministry of Education, Kunming University of Science and Technology, Kunming 650093, China
Biao Li: Engineering Research Center of Metallurgical Energy Conservation and Emission Reductio, Ministry of Education, Kunming University of Science and Technology, Kunming 650093, China
Hui Sun: Faulty of Science, Kunming University of Science and Technology, Kunming 650093, China
Jianxin Xu: Engineering Research Center of Metallurgical Energy Conservation and Emission Reductio, Ministry of Education, Kunming University of Science and Technology, Kunming 650093, China
Hua Wang: Engineering Research Center of Metallurgical Energy Conservation and Emission Reductio, Ministry of Education, Kunming University of Science and Technology, Kunming 650093, China

Energies, 2023, vol. 16, issue 3, 1-19

Abstract: The measurement of the two-phase contact area is very important to determine the heat transfer coefficient in the process of direct contact heat transfer, but the direct measurement of the two-phase contact area is a difficult problem. The experiments are carried out utilizing a cylindrical Perspex tube of 100 cm in total height and 15 cm inner diameter. The active column height throughout the experiments is taken to be equal to 50 cm. Liquid Therminol ® 66 with four different initial temperatures (50 °C, 60 °C, 70 °C and 80 °C) is used as a continuous phase, while liquid R245fa at a constant temperature of 23 °C is used as a dispersed phase. In this paper, the empirical correlations between bubble growth and local convection heat transfer coefficient are obtained through modeling and measurement, and its correctness is verified by experiments. The results show that the bubble diameter is positively correlated with continuous phase temperature, flow rate ratio, and height, but the local convection heat transfer coefficient is negatively correlated with continuous phase temperature, flow rate ratio, and height. At the same time, it is found that the maximum error between the actual bubble diameter and the theoretical bubble diameter is 7%, and the error between the heat flux calculated by the local convection heat transfer coefficient and the actual heat flux is within 10%. This study provides theoretical guidance for an in-depth understanding of the direct contact heat transfer process and the development of high-efficiency waste heat recovery systems.

Keywords: two-phase flow; bubble dynamics; bubble growth; convection heat transfer coefficient; heat flux (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: 2023
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