A comparative study for simulating heat transport in large district heating networks

District heating networks are a convenient, economic and environmental-friendly way to supply heat to buildings connected to a central heating plant. However, the control of such a system becomes challenging if the total length of the network reaches several kilometers because the travel time of the information into the system is over hours. One solution consists in instrumenting all the parts of the network and performing a closed loop control to optimize the temperature and the mass flow rate supplied to every single consumption point. However this solution is generally expensive and difficult to implement in existing networks. What is proposed in this paper is to dynamically model the heat waves in the network to determine the temperatures and mass flow rates at key locations considering the ambient losses and the pipe thermal inertia. A study is performed to check the possibility to use the one-dimensional finite volume method to simulate heat waves propagation. First, an adiabatic pipe is considered as a reference test case to determine the limitations of this method. The results are compared to a 2D computational fluid dynamic simulation and numerical diffusion is exhibited for low spatial discretization. Therefore, an improved alternative model is developed to overcome this problem.