Two-phase Flow Distribution Characteristics of Parallel-flow Evaporator Considering Heat Transfer in Flat Tubes

Abstract:

Considering the phase change process of refrigerant in flat tubes， the SST（shear stress transm ission） k-ω model and the Eulerian-Eulerian two-phase flow model are used to simulate the two-phase distribution characteristics of refrigerant in parallel-flow evaporators. It is found that increasing the refrigerant mass flow rate and inlet quality will lead to a decrease in the uniformity of refrigerant distribution. When the refrigerant mass flow rate increases from 15g·s^-1 to 25 g·s^-1， the distribution inhomogeneity increases by 39.4%； When the inlet quality increased from 0 to 0.3， the corresponding increase in inhomogeneity is 50.8%. Appropriately increasing the inner diameter of the outlet header as well as the aspect ratio of the evaporator is beneficial to improve the uniformity of refrigerant distribution. Doubling the inner diameter of the outlet header results in a decrease of 41.8% in the inhomogeneity； compared with the basic structure， the evaporator with an aspect ratio of 1.455 achieves a decrease of 21.6% in the refrigerant inhomogeneity.

Key words:parallel flow evaporator;phase change process;two-phase flow distribution;inhomogeneity;computational fluid dynamics