Heat transfer performance of liquid lead-bismuth eutectic and supercritical carbon dioxide in double D-type straight channel

The printed circuit heat exchanger is currently the most recommended heat exchanger type for the lead-bismuth eutectic fast reactor coupled Brayton cycle system. Here, the flow and conjugate heat transfer for lead-bismuth eutectic and supercritical carbon dioxide in a double D-type straight channel printed circuit heat exchanger was investigated using numerical simulations. The results indicated that the overall heat transfer coefficient was positively correlated with the mass flux of both lead-bismuth eutectic and supercritical carbon dioxide, with the latter having a greater effect. Moreover, increasing the temperature difference between the two fluids inhibited the heat transfer effect on the supercritical carbon dioxide side, while increasing the pressure reduced the overall heat transfer coefficient. Further, a reduction in the tube diameter and wall thickness strengthens the overall heat transfer efficiency through enhancing the turbulent kinetic energy of the fluid and reducing the heat transfer thermal resistance, respectively. A performance evaluation criterion and Grey relational analysis were combined to evaluate the heat transfer performance of the printed circuit heat exchanger, and the results showed that a smaller diameter and wall thickness, an increased inlet mass flow rate of supercritical carbon dioxide, and an appropriate reduction in the temperature difference would improve the heat transfer performance.