Numerical simulation of flow and heat transfer between supercritical CO 2 tube and flue gas

To further improve the thermal efficiency of the coal‐fired boiler, lower environment restraints, and minimize key components, the supercritical CO 2 Brayton cycle was considered to replace the conventional steam Rankine cycle. In this paper, a three‐dimensional mathematical model of the thermal behaviors between the supercritical CO 2 tube and flue gas was established using the Lam–Bremhorst k – ε model, the gas real model, and the P‐1 radiation model. The distributions of the velocity and the temperature between the supercritical CO 2 tube and flue gas were investigated numerically. Furthermore, the effects of the supercritical CO 2 inlet temperature on the thermal behaviors were also examined. The results show the surface heat transfer coefficient goes up with the supercritical CO 2 inlet temperature due to the rise of the thermal conductivity. More significant thermal behaviors and detailed physical explanations were elaborated, which would offer a novel insight to understand, design, and optimize the supercritical CO 2 Brayton cycle for engineering applications.