Development of a new generation of cold district heating systems with water as heat transfer medium
Abstract
The purpose of cold district heating systems is to cover the heating and cooling demand of connected consumers. Generally, they consist of a thermal energy source, a thermal energy store, heat pumps and a cold district heating network for distribution. Some of these cold district heating systems use thermal energy sources like an ice store or solar thermal air-brine-collectors supplying temperatures below the freezing point of water and therefore in these conventional cold district heating systems a mixture of water and antifreeze as heat transfer medium is necessary. As the use of antifreeze leads to ecological and economic disadvantages, the development of a new generation of cold district heating systems with water as heat transfer medium is being performed. In this contribution to the EuroSun conference this new innovative system concept and a simulation model of this system concept is presented. Furthermore, an evaluation of the operation strategy of the ice store integrated into the overall system based on simulation results is presented. In addition, the results of a simulation study related to an energetic comparison of heat losses and gains between the new innovative cold district heating network using water and a conventional network using a mixture of water and antifreeze are introduced. In conclusion, the evaluations performed clearly show the important role of the ice store as a seasonal thermal energy store and the higher heat losses of the new innovative cold district heating network compared to the conventional network. It is expected that the new generation of cold district heating systems with water as heat transfer medium has ecological and economic advantages compared to conventional cold district heating systems. Demonstrating this is part of the ongoing research project “SolKaN2.0” related to the development of a new generation of cold district heating systems.