関数IAPWS95_calculate_ideal マニュアル

(The documentation of function IAPWS95_calculate_ideal)

Last Update: 2023/9/22


◆機能・用途(Purpose)

Wagner and Pruss (2002)の表6.1の数値および表6.4の計算式を用いて 理想気体項を計算する。
Compute the ideal-gas part using the numerical values given in Table 6.1 and the equations given in Table 6.4 of Wagner and Pruss (2002).


◆形式(Format)

#include <IAPWS95/forward.h>
inline struct IAPWS95_ideal IAPWS95_calculate_ideal
(const double delta,const double tau)


◆引数(Arguments)

delta 無次元化した密度(\(\delta=\rho/\rho_c\))。
The nondimensional density (\(\delta=\rho/\rho_c\)).
tau 無次元化した温度の逆数(\(\tau=T_c/T\))。
The inverse of the nondimensional temperature (\(\tau=T_c/T\)).

これらの変数はWagner and Pruss (2002)の(6.4)式の直後で定義されている。 \(T_c\), \(\rho_c\)は臨界点における温度と密度で IAPWS95/macro.h で与えられている。
These variables are defined just after equation (6.4) of Wagner and Pruss (2002). \(T_c\) and \(\rho_c\) are temperature and density at the critical point, given by IAPWS95/macro.h.


◆戻り値(Return value)

引数で指定した密度・温度における理想気体項とその導関数の値。 戻り値のメンバの値は以下のようになる。
The values of the ideal-gas part and its derivatives at the density and temperature specified by the arguments. The values of the members of the return value are as follows.

メンバ
Member

Quantity
計算式(Wagner and Pruss (2002)の表6.4に基づく)
Formula (from Table 6.4 of Wagner and Pruss (2002))
phi_o 理想気体項\(\phi^o\)。
The ideal-gas part \(\phi^o\).
\(\ln\delta+n_1^o+n_2^o\tau+n_3^o\ln\tau +\sum_{i=4}^8 n_i^o\ln[1-\exp(-\gamma_i^o\tau)]\)
phi_delta_o \(\phi_{\delta}^o \equiv \PartialDiff{\phi^o}{\delta}\) \[\begin{equation*} \frac{1}{\delta} \end{equation*}\]
phi_deltadelta_o \(\phi_{\delta\delta}^o\equiv\PartialDDiff{\phi^o}{\delta}\) \[\begin{equation*} -\frac{1}{\delta^2} \end{equation*}\]
phi_tau_o \(\phi_{\tau}^o \equiv \PartialDiff{\phi^o}{\tau}\) \[\begin{equation*} n_2^o+\frac{n_3^o}{\tau} +\sum_{i=4}^8 n_i^o \gamma_i^o \left[\frac{1}{1-\exp(-\gamma_i^o\tau)}-1\right] \end{equation*}\]
phi_tautau_o \(\phi_{\tau\tau}^o \equiv \PartialDDiff{\phi^o}{\tau}\) \[\begin{equation*} -\frac{n_3^o}{\tau^2} -\sum_{i=4}^8 \frac{n_i^o (\gamma_i^o)^2 \exp(-\gamma_i^o\tau)} {\left[1-\exp(-\gamma_i^o\tau)\right]^2} \end{equation*}\]
phi_deltatau_o \(\phi_{\delta\tau}^o \equiv \PartialCrossDiff{\phi^o}{\delta}{\tau}\) \[\begin{equation*} 0 \end{equation*}\]

\(n_i^o\), \(\gamma_i^o\) (\(i=1,2,\cdots,8\))の値は Wagner and Pruss (2002)の表6.1で以下のように与えられている。
The values of \(n_i^o\) and \(\gamma_i^o\) for \(i=1,2,\cdots,8\) are given as below in Table 6.1 of Wagner and Pruss (2002).

\(i\) \(n_i^o\) \(\gamma_i^o\)
1 -8.32044648201
2 6.6832105268
3 3.00632
4 0.012436 1.28728967
5 0.97315 3.53734222
6 1.27950 7.74073708
7 0.96956 9.24437796
8 0.24873 27.5075105


◆使用例(Example)

const double rho=20.0;
const double T=600.0;
struct IAPWS95_ideal values =IAPWS95_calculate_ideal(rho/IAPWS95_rhoc,IAPWS95_Tc/T);


◆検証(Validation)

(i)密度\(\rho=838.025\) [kg m\(^{-3}\)], 温度\(T=500\) [K] および (ii)密度\(\rho=358\) [kg m\(^{-3}\)], 温度\(T=647\) [K] の2条件で関数IAPWS95_calculate_idealを用いて理想気体項の計算を行い、 いずれの場合にもWagner and Pruss (2002)の表6.6と 完全に同じ値が得られることを確認した。
The ideal-gas part was computed using the function IAPWS95_calculate_ideal with the following two conditions: (i) density \(\rho=838.025\) [kg m\(^{-3}\)] and temperature \(T=500\) [K]; and (ii) density \(\rho=358\) [kg m\(^{-3}\)] and temperature \(T=647\) [K]. In both cases, the results were perfectly identical to the numerical values shown in Table 6.6 of Wagner and Pruss (2002).