Numerical Investigation on Maldistribution of Supercritical CO2 Flow Inside Printed Circuit Heat Exchanger

Abstract

Supercritical CO2 (S-CO2) Brayton cycle has been identified as a promising power conversion method for the next generation of nuclear reactors due to its high efficiency and compactness. The heat exchanger is one of the most important components for S-CO2 Brayton cycle, and the printed circuit heat exchanger (PCHE) is supposed to be one of the promising candidates for the heat exchangers in S-CO2 Brayton cycle. It should be noted that the fluid maldistribution would induce heat transfer deterioration, especially for heat exchangers with micro- or mini-scale channels like PCHE. The thermal-physical properties of S-CO2 change violently during the heat transfer process, which makes the flow inside PCHE more complex. In this paper, the distribution of S-CO2 flow inside PCHE would be studied by 2-D CFD simulations. For the working fluids with constant properties, the flow nonuniformity increases with the mass flow rate. For the working fluid with S-CO2, the thermal-physical properties change significantly with temperature, and there exist a minimum value in the flow nonuniformity-mass flow rate curves (1.64 × 105 ≤ Rein ≤ 1.31 × 106). Insertion of baffles at manifolds could significantly improve the flow distribution uniformity and reduce the pressure drop. And it has been found that insertion of baffles at the collecting manifold has better performance compared with that at the distributing manifold or both.