Optimization of fin configurations and layouts in a printed circuit heat exchanger for supercritical liquefied natural gas near the pseudo-critical temperature

In this study, the effects of fin configurations and layouts on thermal and hydraulic performances of printed circuit heat exchangers (PCHEs) with supercritical liquefied natural gas as the working fluid are studied by a numerical method, and the overall heat transfer performance of various parameters is evaluated by the JF factor. Firstly, the effect of four different airfoil configurations, i.e., NACA 0015, NACA 0018, NACA 0021, and NACA 0024, on thermal and hydraulic performances is investigated. The comparative results indicate that NACA 0024 offers the best overall heat transfer performance. Furthermore, the effect of the vortex generator (VG) minimum transverse distance on thermal and hydraulic performances is analyzed in detail. The results show that, for a given VG configuration, the VG minimum transverse distance should not be too small or too large, so that the longitudinal vortices (LVs) generated will not interact with each other and the LVs' influences may reach a longer distance. The optimal VG minimum transverse distance is 2.0W(a). Finally, the nonuniform segmented heat transfer enhancement mechanism of PCHEs with VG and airfoil fins near the pseudo-critical temperature is explained. The results indicate that the upstream-denser VG and airfoil fins are good choices for improving the overall heat transfer performance, and an optimal VG and airfoil fin arrangement is suggested.