Universal equation of state for engineering application: algorithm and application to non-polar and polar fluids

Engineering equations of state (EOS) deal with the majority of fluids of interest in process and equipment design in the chemical industries. Accuracy and universality are two desirable features the engineering EOS require, however, both of them cannot be simultaneously obtained without some degree of compromise. Therefore a simultaneous optimization algorithm is proposed to develop an accurate but compact engineering EOS for wide range of fluids with one single functional form. The algorithm is based on a simulated annealing method, and operates on different fluids at the same time to achieve the best average results. A 14-term EOS is developed based on this algorithm that has good accuracy for selected non-polar and polar fluids. The resulting equation is compared with two different 12-term EOS developed by Span and Wagner, one for polar fluids, the other for non-polar fluids. The new 14-term EOS also gives good predictions for some associating fluids such as alcohols and water.