## 2 Basic Analysis of Prediction Models and Model Verification
### Prediction Models of Viscosity and Thermal Conductivity  
#### 3.4.1 Prediction Models of Viscosity and Thermal Conductivity  
Principle of Corresponding States (PCS)  
Viscosity and thermal conductivity are two transmission properties of fluids and have a relatively great impact on heat transfer. The model based on the principle of corresponding states (hereinafter referred to as the PCS model) is usually used to compute the viscosity \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Electronic Fluoride Fluid** & **PST** & **GST** & **MST** & **DST** & **NST1** & **NST2** \\ \hline \multirow{2}{*}{FC-72} & ARD (\%) & 5.22 & 0.91 & 2.12 & 6.37 & 3.02 & 2.78 \\  & MRD (\%) & 6.80 & 2.32 & 3.04 & 7.44 & 3.07 & 2.94 \\ \multirow{2}{*}{Novec 649} & ARD (\%) & 5.28 & 1.07 & 0.74 & 5.95 & 2.53 & 2.50 \\  & MRD (\%) & 6.53 & 2.27 & 1.32 & 6.70 & 2.88 & 2.72 \\ \multirow{2}{*}{HFE-7100} & ARD (\%) & 9.98 & 3.39 & 3.57 & 0.64 & 1.67 & 2.51 \\  & MRD (\%) & 10.70 & 4.07 & 3.80 & 1.16 & 2.22 & 2.96 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: ARDs and MRDs between the predicted and reference values of different prediction models of the surface tension of electronic fluoride fluids. Figure 10: Relative deviations between the predicted and reference values [71] of the surface tension of HFE-7100. Figure 9: Relative deviations between the predicted and reference values [70] of the surface tension of Novec 649.  
and thermal conductivity in REFPROP v10.0 [107]. The expressions of viscosity and thermal conductivity in the PCS model are shown as Equations (61) and (62), respectively. \[\eta(T_{r}\rho)=\eta^{*}(T)+\Delta\eta(T,\rho)=\eta^{*}(T)+\Delta\eta_{0}(T_{0},\rho_{0})F_{\eta}(T,\rho) \tag{61}\]  
\[\lambda(T,\rho)=\lambda^{int}(T)+\lambda^{*}(T)+\Delta\lambda(T,\rho)=\lambda^ {int}(T)+\lambda^{*}(T)+\Delta\lambda_{0}(T_{0},\rho_{0})F_{\lambda}(T,\rho) \tag{62}\]  
where \(\eta^{*}\) is the dilute gas viscosity, Pa-s; \(\Delta\eta\) is the residual viscosity, Pa-s; \(\Delta\eta_{0}\) is the residual viscosity of the reference fluid, Pa-s; \(F_{\eta}\) is the modified coefficient of the residual viscosity; \(\lambda_{int}\) is the thermal conductivity contributed by the internal motion of molecules of the fluids, W/(m\(\cdot\)K); \(\lambda^{*}\) is the dilute gas thermal conductivity, W/(m\(\cdot\)K); \(\Delta\lambda\) is the residual thermal conductivity, W/(m\(\cdot\)K); \(\Delta\lambda_{0}\) is the residual thermal conductivity of the reference fluid, W/(m\(\cdot\)K); \(F_{\lambda}\) is the modified coefficient of the residual thermal conductivity; and \(T_{0}\) and \(\rho_{0}\) are the conformal temperature and conformal density of the reference fluid, K and kg/m\({}^{3}\), respectively. The expressions of \(T_{0}\), \(\rho_{0}\), \(F_{\eta}\) and \(F_{\lambda}\) are shown in Equations (63)-(66):  
\[T_{0} =T/f(T,\rho) \tag{63}\]  
\[\rho_{0} =\rho h(T,\rho) \tag{64}\]  
\[F_{\eta}(T,\rho) =f^{1/2}h^{-2/3}\left[\frac{M}{M_{0}}\right]^{1/2} \tag{65}\]  
\[F_{\lambda}(T,\rho) =f^{1/2}h^{-2/3}\left[\frac{M_{0}}{M}\right]^{1/2} \tag{66}\]  
where \(f\) and \(h\) are the conformal parameters, based on [PERSON] and [PERSON]'s study [108], and \(M\) and \(M_{0}\) are the molar masses of the studied fluids and the reference fluid, respectively, g/mol. According to the literature [107], the equations for dilute gas viscosity are shown in Equations (67)-(71), the thermal conductivity contributed by the internal motion of molecules is expressed in Equation (72), and the dilute gas thermal conductivity is expressed as Equation (73):  
\[\eta^{*}(T)=4.0785\frac{(MT)^{0.5}}{V_{c}^{2/3}\Omega^{(2,2)}}F^{*} \tag{67}\]  
\[ \begin{array}{c}\Omega^{(2,2)}\!\!=1.16145T_{\rm dim}^{-0.14874}\!+\!0.52487e ^{-0.77320T_{\rm dim}}\!+\!2.16178e^{-2.43787T_{\rm dim}}\!-\\ 0.0006435T_{\rm dim}^{0.14874}\!\sin(18.0323\,T_{\rm dim}^{-0.76830}\!-\!7.2 7371)\end{array}