A linear approach to the fluid-dynamic solution of large district heating network

District heating is one of the most efficient and environmentally friendly ways to satisfy heat demand in densely populated areas. It allows reducing the global fuel consumption for heating purposes thanks to a centralized production. In these systems, thermal energy is sent to users through an underground network that provides hot water to the users. This paper it’s been developed in collaboration with IREN s.p.a. and it deals with Turin district heating network, that is, with its 5700 m3 of heated volume, Italy’s biggest network. Thermo-fluid-dynamic simulations of such large networks usually require large computational resources because of the complex topology that also involved loops. The main novelty of this work is the possibility of simulating the thermal-fluid-dynamic evolution of large network through a very fast model. Having such “light” model is useful to analyze the way extensions and alternative management strategies affect the thermal load evolution. In this respect, peak shaving strategies are adopted to reduce the thermal energy that has to be provided during the morning peak, by modifying the startup schedule at the users. These strategies also allow a better and cheaper operation of the thermal plants. It’s in order to carry that work on users that is important to have an efficient numeric scheme to simulate the return network. This proposed model takes advantage of the simplicity of the fluid dynamics solution of tree-shape networks, in order to modify the topology of the Turin network, moving from the resolution of a nonlinear problem to a linear one.