Three-dimensional model of single tube with an inner diameter of 1.31 mm was established; using CFD software Fluent

the flow and heat transfer characteristics of supercritical carbon dioxide in the micro-capillary tube was analyzed. The influences of the heat flux

inlet mass flow rate

flow direction and pressure on the heat transfer of supercritical carbon dioxide and pressure drop are analyzed. It was shown that: boundary wall thinning by increasing the import mass flow rate; which could enhance heat transfer. Changing the heat flux has little influence on heat transfer and pressure drop of supercritical carbon dioxide. Due to the effects of gravity and buoyancy

the impact of the flow direction on the heat transfer performance was large; the heat transfer coefficient of vertically upward fluid flow is greater than that of the vertical downward flows and horizontal flow.