Computer modelling of non-stationary flows with phase transitions in countercurrent heat exchangers

The problems of mathematical and numerical modeling of non-stationary processes of heat and mass transfer in countercurrent heat exchangers with phase transitions in heat carriers are discussed. A one-dimensional problem statement with spatially distributed flow parameters (temperature, density, velocity, heat transfer coefficient) is considered. A method for determining the two-phase zone of the vapor-liquid state and a method for calculating its parameters is proposed. Examples of numerical simulation for a specific heat exchanger with heat carriers in the form of air and liquid oxygen, which boils during the flow are given. The influence of the heat transfer coefficient on the length of the boiling zone is shown, which in turn has a significant effect on the heat transfer process and, accordingly, on the temperature distribution in the coolant flows. In the end, this significantly affects the operation of the heat exchanger.