The New Method for Correlation and Prediction of Thermophysical Properties of Fluids. Critical Temperature

On the basis of the linear free energy relationships theory and thermodynamics formulas, a new method predicting critical temperature (<i>T</i>_c) of pure fluids is proposed for the first time. Sixteen homologues of 616 substances have been regressed and correlation equations between <i>T</i>_c and molecular descriptors are obtained. The mean relative deviations of the 16 equations are from 0.01% to 2.73%, and most of them are under 2%. In addition, the squared correlation coefficients are from 0.90 to 0.98. Moreover, the equations are tested through cross-validation by the leave-one-out procedure and most of the squared correlation coefficients are greater than 0.90. The results reveal that the equations exhibit better effect with simple form of equation, high prediction accuracy, and definitude theory meaning. This study successfully combines macroscopic physical properties of fluids with their molecular microstructure and breaks through the experimental or theoretical application scope, perfecting calculation of critical temperature for pure liquids

Grid diagram of the train head.

<p>(a) Longitudinal section of the train head; (b) Surface of the train head.</p

Comparison of the drag coefficients on the streamlined longitudinal section of the head and the tail before and after optimization.

<p>Comparison of the drag coefficients on the streamlined longitudinal section of the head and the tail before and after optimization.</p

Deformation surfaces of the streamlined part.

<p>(a) deformation area of the streamlined part; (b) deformation in different areas.</p

The six-component balance.

<p>The six-component balance.</p

Stagnation point.

<p>Stagnation point.</p

Experimental section of the wind tunnel.

<p>Experimental section of the wind tunnel.</p

The model and the computational domain of EMU1.

<p>(a) EMU1 model of the whole vehicle; (b) Computational domain.</p

Curved surface deformation diagram of the local shape function.

<p>Curved surface deformation diagram of the local shape function.</p

Stagnation pressure of the train.

<p>Stagnation pressure of the train.</p