Internal flow numerical simulation of a cross-flow fan in refrigerant operating condition using user-defined functions
In the paper, a cross-flow fan in refrigerant operating condition is systematically simulated using user-defined functions. Three-dimensional simulations are acquired with Navier-Stokes equations coupled with k-epsilon turbulence model, and internal flow characteristics of an indoor split-type air conditioner are obtained, which is mainly composed of cross-flow fan and heat exchanger. It has systematically been simulated in the isothermal flow condition that the performance of cross-flow fan may be reduced easily with dry or humid air, and in the refrigerant operating condition in which user-defined functions are applied to the humid air, considered as a mixture of dry air and vapor. A density-modulated function is adopted to deal with the condensation of the vapor at the heat-transfer region approximately. The results show flow mechanism of the two gas-phase flow, including phase-vary process. The distribution of the parameters is not uniform at the inlet of the machine, the intensity and position of pressure and velocity vary along the axial direction of the fan, the distribution of vapor volume fraction and turbulent intensity in heat-transfer region is obtained, and the external characteristic data of the indoor machine are obtained and analyzed. Compared with the experimental data, the calculated characteristic curves and designed parameters are on target. (C) British Crown Copyright 2010/MOD. Reproduced with permission. Published by John Wiley & Sons, Ltd.
cross-flow fan refrigerant operating condition air conditioner udf internal and external flow characteristics three-dimensional numerical simulation