An improved algorithm for calculating the compressibility factor of natural gases

It would take much time to compute the compressibility factor of natural gas with AGA8-92DC method due to the iteration algorithm. To reduce the number of iterations, several curves of relationship between the gas molar density ρ_m and temperature T under different values of pressure P are fit by the Least-Square method. And then, the value of the molar density ρ_m under the current pressure P is obtained by the linear interpolation method, which is applied to the iterative calculation. Thus, the number of iterations is decreased and the real-time performance of the algorithm is improved. The modified algorithm is tested by some real-world data sets, and the results show that the improved algorithm is of high accuracy and good reliability, which can meet the requirements of industrial processes.