Experimental investigation on cooling heat transfer and buoyancy effect of supercritical carbon dioxide in horizontal and vertical micro-channels

2021 ◽  
Vol 181 ◽  
pp. 121792
Author(s):  
Yuchuan Lei ◽  
Bo Xu ◽  
Zhenqian Chen
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Experimental Investigation ◽  
Supercritical Carbon Dioxide ◽  
Buoyancy Effect ◽  
Micro Channels ◽  
Supercritical Carbon

Measurements of Heat Transfer Coefficients From Supercritical Carbon Dioxide Flowing in Horizontal Mini/Micro Channels

2002 ◽  
Vol 124 (3) ◽  
pp. 413-420 ◽  
Author(s):  
S. M. Liao ◽  
T. S. Zhao
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Constant Temperature ◽  
Transfer Coefficients ◽  
Circular Tubes ◽  
Horizontal Tubes ◽  
Micro Channels ◽  
Supercritical Carbon

Heat transfer from supercritical carbon dioxide flowing in horizontal mini/micro circular tubes cooled at a constant temperature has been investigated experimentally. Six stainless steel circular tubes having inside-diameters of 0.50 mm, 0.70 mm, 1.10 mm, 1.40 mm, 1.55 mm, and 2.16 mm were tested. Measurements were carried out for the pressures ranging from 74 to 120 bar, the temperatures ranging from 20 to 110°C, and the mass flow rates ranging from 0.02 to 0.2 kg/min. It is found that the buoyancy effect was still significant, although supercritical CO2 was in forced motion through the horizontal tubes at Reynolds numbers up to 105. The experimental results also indicate that the existing correlations developed in the previous studies for large tubes deviate significantly from the experimental data for the present mini/micro tubes. Based on the experimental data, a correlation was developed for the axially averaged Nusselt number in terms of appropriate dimensionless parameters for forced convection of supercritical carbon dioxide in horizontal mini/micro tubes cooled at a constant temperature.

scholarly journals Experimental study on forced convective heat transfer of supercritical carbon dioxide in a horizontal circular tube under high heat flux and low mass flux conditions

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983080 ◽  
Author(s):  
Junhui Wang ◽  
Pengcheng Guo ◽  
Jianguo Yan ◽  
Fengling Zhu ◽  
Xingqi Luo
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Flux ◽  
Supercritical Carbon Dioxide ◽  
Mass Flux ◽  
High Heat ◽  
High Heat Flux ◽  
Buoyancy Effect ◽  
Low Mass ◽  
Supercritical Carbon

This study focuses on the convective heat transfer characteristics of supercritical carbon dioxide flowing in a horizontal circular tube under high heat flux and low mass flux conditions. The influences of thermophysical property, buoyancy effect, and thermal acceleration on the heat transfer characteristics are discussed. The parameters are as follows: system pressure is 7.6–8.4 MPa, mass flux is 400–500 kg/m2 s, heat flux is 30–200 kW/m2, fluid temperature is 20°C −62°C, and Reynolds number is 1.23 × 104 to 4.3 × 104. The wall temperature and heat transfer coefficient of supercritical carbon dioxide are obtained. The results show that, under the condition of high heat flux and low mass flux, heat transfer deterioration would happen, in which thermophysical property and buoyancy effect are the main factors. When the pressure is 7.6 MPa, the buoyancy factor is greater than 10−3 in the whole heat transfer area, and the buoyancy effect cannot be ignored, while the thermal acceleration factor is 9.5 × 10−8 to 4 × 10−6 and the effect of thermal acceleration can be negligible. The experimental data are compared with the predictions using seven empirical correlations, in which the Liao–Zhao correlation shows the best performance.

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