Sensible heat storage in district heating networks: a novel control strategy using the network as storage

District heating (DH) networks distribute heat generated at one or many heating plants to groups of buildings in order to cover their space heating and domestic hot water needs. The fact that consumers´ peak heating loads are often occurring at the same time leads to a peak in heat generation. Additional peak boilers, usually operating with fossil fuels at high costs, are traditionally used to compensate peak demands for few hours. As an alternative, by considering the water volume contained in the DH network piping, the network itself can be assimilated to large storage units and used effectively for peak reduction purposes. But even if this effect is known by district heating network operators, it is not applied systematically. Therefore a control technique is proposed and assessed by using simulation methods in this paper. The district heating network of Altenmarkt im Pongau (Austria) is modeled in the simulation environment Modelica/Dymola, using the standard library Modelica Fluid [2] and the DistrictHeatingLib developed at the Austrian Institute of Technology (AIT). Network simulations are performed to assess the impact of the proposed strategy. The results show a potential reduction of 15% of the daily peaks with an increase in heat losses of 0.3% compared to the reference scenario.