Development of a numerical analysis model for a multi-port mini- channel heat exchanger considering a two-phase flow distribution in the header. Part I: Numerical modeling

A refrigerant could boil and condense as it flows through heat exchangers such as evaporators and condensers. A multi-port mini-channel heat exchanger (MMHX) has a header that acts as a manifold. To analyze the performance of a multi-port mini-channel heat exchanger, it is necessary to predict the quality distribution of the two-phase flow in the header as well as the mass flow rate distribution to each channel. A numerical algorithm was developed to analyze the distribution of the two-phase flow to the channels of a MMHX. Conservation equations for each segment of the MMHX were linearized to construct a system of linear algebraic equations. Because all the distributed parameters of the MMHX were solved simultaneously, the two-phase flow and mass flow rate distributions were solved. The proposed method decreased the calculation time and increased the convergence of the solution. A computer program named M-Cube was written based on this numerical method and used to simulate several sets of experimental data. It was found that the evaluation of the heat transfer rate for an evaporator was either overestimated with a mean absolute error (MAE) of 4.81% or underestimated with an MAE of 22.18% depending on the phase distribution in the inlet header. Furthermore, this discrepancy increased as the quality increased. (C) 2019 Elsevier Ltd. All rights reserved.