热网络法预测车内温度的理论和实验研究

Theoretical and Experimental Study on the Thermal Network Method for Temperature Prediction in a Car

为对车内温度水平进行预测,采用热网络法对车辆停车和行驶状态下的车内温度进行计算。太阳辐射是影响车内温度水平的主要因素,而热网络法通过建立和求解节点热平衡方程,获得各节点的温度,尤其适用于以辐射为主的换热问题。车内外的对流换热采用实验关联式进行计算。由热网络法建立的节点热平衡方程组为非线性方程组,采用牛顿迭代法进行了求解。计算结果与实测温度值的比较显示,两者吻合较好,表明热网络法用于车内温度预测的有效性。另外,计算结果也显示车窗玻璃的透射率对车内温度有明显影响,在考虑安全的前提下,选取合适透射率的车窗玻璃材料可起到减少车辆能耗的作用。

In order to predict temperature in a car, the thermal network method (TNM) was used to calculate the temperature when the car was parked or driven. Considering the solar radiation is the main factor which affects the temperature level in the car, TNM was used to calculate the temperature at each node after energy equations for all nodes have been established and solved, which is especially suitable for heat transfer problems dominated by thermal radiation. Empirical correlations were adopted to calculate the convection heat transfer between car surfaces and air. The established equations are nonlinear, so the Newton iteration method was used to solve the equations. The calculation results are in consistent with the measured temperature, which indicates the effectiveness of TNM for the temperature prediction. Furthermore, the transmissivity of glass has obvious effect on the temperature level of the car. Without violating safety requirements, using glass with proper transmissivity can save energy for the car.