Heat transfer enhancement of supercritical CO2 in a novel triangular − prism rib tube based on field synergy principle

Supercritical CO 2 (sCO 2 ) Brayton cycle can address the challenges of high-temperature corrosion of materials and improve the power generation efficiency to over 50%. However, sCO 2 flow in horizontal tubes is prone to exhibit low heat transfer efficiency due to circumferentially non-uniform heat transfer. Conventional heat transfer enhancement (HTE) methods often lead to excessive frictional loss. In this work, triangular-prism rib tube with local arrangement is proposed to enhance heat transfer and decrease frictional loss. The results show that local ribs effectively decrease the top wall temperature ( T w ) and improve the heat transfer. For a fixed rib distribution range, the tube with a circumferential spacing of 30° makes that the temperature difference between the upper and lower levels is reduced to 17 K, heat transfer coefficient ( HTC ) rises by 38%, and friction factor ( ƒ ) only increases by 0.03. For a fixed circumferential spacing, the value of performance evaluation criterion ( PEC ) in the tube with a distribution range of 360° is 41% higher than that of the smooth tube.