Electricity Consumption of Heat Pumps in Thermal Networks depends on Network Topology

Low-temperature networks (LTN) with temperatures below 20 degrees C are district heating and cooling networks of the future, since they can be operated (i) emission-free, (ii) are suitable for space heating and cooling and (iii) incorporate low-temperature environmental heat or waste heat from industrial processes. In Switzerland, the number of LTNs is continuously increasing. The aim of the present study is a comparison between two existing, but simplified, network topologies with either a central circulation pump or distributed circulation pumps. Modelica/Dymola simulations show that for four different annual heating and cooling scenarios, the heat pumps in the topology with decentralized circulation pumps consume 1 % to 5 % less electric energy than the same heat pumps in a topology with a single centralized circulation pump.