Unsteady simulation of natural gas networks

Gas networks work with time-dependent flow demand and sometimes in emergency conditions or the presence of undesired situations. In this scenario, unsteady simulations are necessary to design, control and analyze gas network systems. The Gas Network Solver, developed by the authors, aims to simulate the behavior of gas transportation pipelines with large diameter and length as well as gas distribution networks with branching pipes. This paper focuses on the implementation of the pipe model that is the most significant component with dynamic characteristics. A finite difference method is used to solve 1-D equations of compressible viscous fluids. The gas in the pipes is considered in thermal equilibrium. Therefore, an isothermal approach is adopted. The unsteady model is tested through an application example of a looped gas network. The results, compared with numerical data of some studies in the literature, show good accuracy of the tool developed. In conclusion, it is analyzed the effect of the gas composition on the behavior of the network.