Cooling Heat Transfer of Supercritical CO₂ in Diverging and Converging Microtubes

Abstract

The motivation of this research was to solve the problem of heat transfer deterioration of supercritical CO 2 in tubes. The cooling heat transfer of supercritical CO 2 in diverging and converging microtubes was numerically studied. Under the conditions proposed, the heat transfer coefficient of the tube wall is relatively uniform. When the heat transfer coefficient becomes most uniform, the diameter change rate of the diverging microtube is greater than that of the converging microtube. Both the Richardson number and the relative difference of the heat transfer coefficient increase with increasing tube diameter, indicating that the buoyancy effect is the reason for different heat transfer coefficients in different flow directions.

Comparison and evaluation of supercritical CO 2 cooling performance in horizontal tubes with variable cross‐section by field synergy theory

“…The heat transfer coefficient of converging microchannel was higher compared with the diverging microchannel. Yi et al 41 performed numerical study on the cooling performance of sCO 2 in diverging and converging microtubes. Li et al 42 also analyzed the cross‐sectional profile of the tube that influences on the heating performance of sCO 2 by changing the diameter of horizontal tube, and meanwhile evaluated the deterioration mechanism of heat transfer when sCO 2 was heated by introducing and defining two new concepts.…”