Experimental study on heat transfer performance of sCO₂ near pseudo-critical point in airfoil-fin PCHE from viewpoint of average thermal-resistance ratio

The printed circuit heat exchanger (PCHE) is one of the leading heat exchanger candidates in the supercritical carbon dioxide Brayton cycle, which has high efficiency and compactness. In the present paper, a novel type of PCHE with airfoil fins was proposed and tested. The effect of the thermal resistance variation on the heat transfer performance near the pseudo-critical point was analyzed. Meanwhile, a non-dimensional factor defined as the ratio of bulk temperature to the pseudo-critical temperature was applied to evaluate the heat transfer performance. The results indicate that the variation of the heat transfer performance can be attributed to the different average thermal-resistance ratios, where a larger the average thermal-resistance ratio corresponds to a better heat transfer performance. When the non-dimensional factor is around 1.03, the heat exchanger exhibits the highest heat transfer performance. In this regard, a working condition analysis method based on the non-dimensional factor and the average thermal-resistance ratio is suggested. Finally, a modified heat transfer correlation considering the non-dimensional working parameters near the pseudo-critical point is obtained.