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Center for Nonlinear Studies |
District heating networks constitute an important infrastructure for the implementation of efficient methods to provide heating and domestic hot water to buildings located in urban areas. Modern district heating networks may involve the use of waste heat, renewable sources and heat from cogeneration thermal storage systems. In addition, management is operated through advanced ICT solutions able to minimize the global primary energy consumption and to increase end user awareness. Detailed thermos fluid-dynamic simulation tools can be of extreme importance for the optimal management of modern district heating networks. Some of the issues that simulation tools are requested to face are: peak shaving, selection of the operating temperature, operation in the case of malfunctions, storage management. An important requirement consists in the possibility to perform fast simulations, even in the case of complex networks.This work aims at presenting a detailed simulation approach that can be applied to large district heating networks. The entire network is represented as constituted by the main pipeline, which may be a tree shaped or a looped network, and various tree shaped subnetworks that distribute water from the main network to each single building. The main pipeline is fully modeled considering fluid flow and transient heat transfer. Subnetworks are simulated using a reduced model obtained from the full model.The modeling approach is applied to the analysis of transient operation of the Turin district heating network, which is the largest network in Italy. The thermal request of the users is obtained from temperature and mass flow rate measurements at the thermal substations, available with a frequency of six minutes. Thermo-fluid dynamic simulation allows one obtaining the corresponding thermal load profiles at the various thermal plants. Results show that a peak request is caused by the temperature reduction in the entire system caused by request reduction at night. Due to the advection transport of water in the network and the thermal losses, the shape and amplitude of the peak at the plant is completely different than that at the users. Using this simulation approach it is possible to optimize the thermal request profiles of the buildings in order to minimize the effects of the morning peaks. This can be achieved through installation of storage units or direct exploitation of the thermal capacities of the buildings and the network. Results of various simulations and applications to the real network are shown. The proposed simulation approach is shown to represent a versatile and important tool for the implementation of advanced management to district heating systems.
Host: Michael Chertkov