Numerical investigation on the nonuniform flow distribution and its impact on the heat transfer performance in the microchannel plate heat exchanger

The nonuniform flow distribution among various microchannels will lead to heat load heterogeneity, subsequently influencing the overall heat transfer performance. Current research on non-uniformity flow distribution primarily focuses on the analysis of local structures, while the non-uniformity is closely related to the full-scale configuration. In this paper, a full-scale three-dimensional thermo-hydraulic coupled analysis method tailored for microchannel plate heat exchanger (MCHX) was proposed and established to investigate the non-uniform characteristics of flow distribution and its impact on heat transfer performance. The method was validated through microchannel flow and heat transfer experiment. The distributions of three-dimensional thermal–hydraulic characteristics in the MCHX used in the I²S-LWR were obtained. There is obvious flow distribution non-uniformity in both the primary and secondary sides of the MCHX under the full-scale modeling. The flow distribution inhomogeneous factor D_m of the primary side is 52.06 %, and that of the secondary side is 115.01 %. The structural differences lead to significant variation in the flow distribution characteristics of the primary and secondary sides along both the horizontal and vertical directions. The total heat transfer power of the MCHX is 297.58 MW, which is 16.47 % lower than uniform flow distribution conditions. Additionally, a discernible mismatch in flow distribution exists between the primary and secondary microchannels, further degrading the thermo-hydraulic performance of the MCHX. In the future optimization, it is essential to consider not only the degree of non-uniformity flow distribution but also enhance the matching degree between the primary and secondary sides.