由反转温度计算N_2的范德瓦尔斯方程

Calculation of Van der Waals Equation of N_2 with the Reverse Temperature

对范德瓦尔斯方程中a,b项的修正一直是提高状态方程计算准确度的方向之一.随着实验方法的不断发展,对其的修正方法也在不断的出现.本文从绝热节流过程出发,推导出了焦耳—汤普森系数反转温度与压强的关系式.再利用Origin 8.0软件,对N2在该实验中测量得到的反转温度随压强变化的实验数据进行曲线拟合,从而得到了N2方程中a与b的取值范围.最后,利用Mathe 4.0软件,将a,b取不同数值的理论曲线与实验数据进行比较,从而确定N2方程中a与b的数值.我们发现当a,b分别取a=0.581 8 Pa.m6mol-2和b=0.218 3×10-3m3.mol-1时,理论曲线与实验数据符合得最好,尤其是在温度高于300 K的范围.

The modifying of a and b in Van der Waals Equatin is an important direction to improve the calculation precision of equation of state. With the development of the technique of experiment, many modifieation methods of Van de Waals Equation had appeared. From the isolated throttling process, we have the relation of the reverse temperature of Joule-Thomson coeffieient and the pressure. Fitting a curve for the experiment data of N2 with Origin 8.0, we obtain the range of a and b for N2 in Van der Waals Equation. At last,we define the value of a and b for N2 with Mathe 4.0.We find when a = 0.058 18 Pa· m6·mol^-2and b = 0. 021 83 × 10^-3m^3· mol^- 1, the theoretical curves is in accordance with experimental data, especially at temperature over 300 K.