车用散热器高原传热性能仿真研究

Heat Transfer Simulation of Vehicle Heat Exchanger in Plateau Environment

研究高原环境对车用散热器传热性能的影响机理,依据空气特性参数随海拔高度的变化规律,对散热器传热公式进行修正。基于热网络法,采用Flow Master软件建立车用散热器传热仿真模型,研究海拔高度和传热介质流量对散热器传热性能的影响规律。结果表明:大气压力和空气密度减小是车用散热器高原传热性能显著下降的主要原因,随着海拔升高和冷却空气流速减小,空气侧换热通道内冷却空气的雷诺数减小,冷却空气的流动状态从湍流渐变为层流,对流换热强度下降,进而使散热器传热系数减小,导致散热器的高原散热能力下降。海拔每升高1 000 m,散热器空气侧对流换热系数和散热量分别下降约9.5%和9.0%。

The effect of heat transfer caused by plateau environment in vehicle heat exchanger was investigated. The heat transfer equation for heat exchanger was modified by introducing air parameters at different altitudes. A heat transfer modeling approach for vehicle heat exchanger was proposed by using the thermal network method. The heat transfer effect of the plateau and the flow state of fluid medium were analyzed in the vehicle heat exchanger by using the simulation software FlowMaster. Simulation results show that the decrease of pressure and density of air in altitude was the primary cause to heat transfer ability. With the altitude increasing and airflow velocity decreasing, the Re of airflow decreased while the flow state of air in the channel changed from turbulence to laminar state, therefor the convective heat transfer strength declined; and the heat transfer coefficient and the heat transfer ability of heat exchanger both decreased. With every 1 000 m rising in altitude, the heat transfer coefficients of air side and the heat emission Of heat exchanger declined by 9.5% and 9.0% respectively.