Abstract: A computer-implemented method for designing and assessing the performance of a hollow fibre membrane contactor (MBC) in a natural gas sweetening process using a MBC model is described in an embodiment. The MBC model comprises model parameters, model equations and boundary conditions for calculating data associated with the natural gas sweetening process. The natural gas sweetening process comprises removal of acid gas from natural gas using a solvent comprising at least one component. The method comprises: (i) forming a regression model using empirical data; (ii) determining a Henry's constant of CO2 in the solvent using the regression model; (iii) inputting the determined Henry's constant of CO2 in the MBC model as one of the model parameters; and (iv) determining CO2 absorption in the solvent using the MBC model for designing and assessing the performance of the MBC.