Figure 14. Observed vs. predicted values (a) and distribution of the residual (b) of thermal conductivity
Figure 14 (a) indicated that the calculated values agreed very well with observed data for λ values. Also, the good performance of this model could be demonstrated by the high R 2 of 0.9847 and the low AARD of 1.02%. As seen from Figure 14 (b), most of the points fell between -0.0025 and 0.0025 W m-1 K-1, and only a small number of predicted residual errors were greater than 0.0075 W m-1 K-1. Therefore, it might be possible to successfully calculate the λ of ILs at variable temperatures and pressures by this model.
Experimental data on the λ of 87 ILs were collected in this paper, including 5 classes of cations and 12 classes of anions. It can be easily noted from Figure 15 (a) that, despite the great diversity of the cations and anions of ILs, only a few types of ions have been widely studied. Figure 15 (b) shows that the AARD calculated from all reported data of a given cation / anion group is small and all types of ILs residuals are acceptable range except for [Im][N(CN)2]. Therefore, the model is suitable for accessing the λ data of these kinds of ILs with reasonable results.