“…In the literature several mathematical models are proposed to estimate Z , including the Van der Waals equation (Van Der Waals & Rowlinson, ), the Redlich‐Kwong equation (Redlich & Kwong, ), the Soave‐Redlich‐Kwong equation (Soave, ), and the Peng‐Robinson equation (Peng & Robinson, ). Most recently, improved Van der Waals equation (Travalloni et al, ), Peng‐Robinson equation (Luo et al, ), and Redlich‐Kwong equation (Wu, Chen, et al, ) are also introduced to model fluid phase behavior at the nanoscale considering confinement and adsorption phenomenon, especially when the characteristic length scale is smaller than 10 nm (Salahshoor et al, ; Jin & Firoozabadi, ). In this study, the Peng‐Robinson equation is used for predicting the properties of hydrocarbons, in which EOS is given as where T c and P c are the critical temperature and the critical pressure of the gas, respectively.…”