外推法计算高温气体恒压摩尔热容

恒压摩尔热容是化工热力学中计算过程热力学性质变化所需的基础数据,但手册中通常难以查到计算气体在高温范围恒压摩尔热容所需的数据。文中提出一种计算气体在高温范围的恒压摩尔热容的方法:首先从手册数据适用的温度范围的上限起按一定的温度间隔逐点外推,再用五点曲线平滑法处理各点数据,然后将所得各点数据用线性回归方法处理得到恒压摩尔热容与温度的函数关系式: Cp,m=a0+a1T+a2T2+a3T3+a4T4,用以计算气体在高温范围的恒压摩尔热容。对CO气体,将用此方法计算的结果与用统计热力学方法计算的结果进行了比较,二者具有很好的一致性。

Calculation of Cp,m of Gases at High Temperatures by Using ExtrapolationMethod

It is usually very difficult, if not impossible, to find the data needed in handbooks when calculating the Cp,m of gases at high temperatures. In this paper, a method of calculating the Cp,m of gases at high temperatures is pro-posed. By this method, firstly an extrapolation of temperature is made point by point, according to desired step of increase, starting from the upper limit of the temperature range given in the handbook; secondly, the data aresmoothed by employing the five points data smoothing method, and finally, a linear regression is carried out using the smoothed data points to obtain the Cp,m - T function: Cp,m = a₀ + a₁T + a₂T² +a₃T³ +a₄T⁴,which is then used to calculate the Cp,m of the gases at high temperatures. A comparison is made between the result obtained with this method and that obtained by using statistical thermodynamic method, and the two are very consistent.