The coupled process-component modeling and optimization for heat exchanger of supercritical CO2 with property variation based on heat current method

Abstract

A powerful and accurate modeling and analysis method for supercritical carbon dioxide (sCO2) heat exchanger plays an increasingly significant role in numerous applications such as power plants, nuclear reactors, and refrigeration systems. This manuscript introduces the inlet temperature difference-based general thermal resistance to construct an overall heat current model by combining with the segmentation method. This proposed model can consider the thermophysical properties, structural and operational parameters, simultaneously. On this basis, we derived and obtained an overall thermal resistance formula of heat exchanger that is the function of thermophysical properties, heat transfer coefficient and area, mass flow rate, and flow arrangement. For validation, we introduced a numerical simulation case. The results show that the deviation by the proposed heat current method is less than 2.74% compared with simulation results. Meanwhile, the multi-factors analysis presents that the total heat transfer rate will reach up to the maximum, and the total thermal resistance is the minimum when the inlet pressure of sCO2 is 11 MPa in the introduced heat exchanger. Finally, we introduced a series heat exchanger network, including three counter-flow heat exchangers, and optimized the inner tube diameters by heat current method by using a genetic algorithm. After optimization, the total heat transfer rate increases and the outlet temperature reduces.