Master's Thesis Patrick Moes
Draft and Modelling of a Heat-Pump Plant for Dual Use in District Heating and District Cooling
The tightening of the German Energieeinsparverordnung (EnEV) requires new technologies to reduce energy requirements and increase the use of renewable energies in heat and cooling generation for buildings. There is a great potential for covering heat generation in urban regions by using industrial low-temperature waste-heat-sources. To achieve this the low-temperature waste-heat-sources in anergy-networks must be combined with heat pumps.
The aim of this thesis is to investigate whether such a concept can be realized using the example of a development area in the north of Munich. The feasibility is tested with regard to energetic, primary energetic, ecological and economic aspects. In addition the economic feasibility is compared with the district heating of the Stadtwerke München that is used today. 60 heat supply concepts with a district heating supply are developed and investigated by a central heating plant. Five models with different district heating structures and central as well as decentralized production possibilities of the domestic hot water requirement are considered. Each model is divided into three variants with regard to peak load coverage. The variants of electric heaters for direct coverage of peak load, long-term storage and a combined heat and power plant for self-generated electricity are being investigated. Each variant is still divided into two storage temperatures, a consideration in the respective system temperature, as well as at 60 °C. In addition to the pure heating operation the possibility of using coldness of heat pumps is considered and assessed according to the mentioned aspects. For the design of the heat supply concepts, the scope of available low-temperature waste-heat and the future residential area is clarified. Options for supplying heat to the residential area by means of district heating will be developed under consideration of the economic conditions with a service life of 20 years. The investigations of the 60 concepts according to the mentioned aspects show good ecological and economic results compared to the district heating supply by Stadtwerke München. 18 of the 60 concepts are also economically realizable.
The peak generation plant veariation, the electric heater, performs best in terms of primary energy consumption, energy consumption and economic efficiency. The use of a CHP can make sense in terms of ecology. Economically, this variation is only slightly worse than that of the electric heater. The economy of the long-term storage variant is less profitable compared to the electric heater and CHP and has high primary energy and energy consumption and CO2-emissions. For economic efficiency, the investment costs of the district heating network are essential. Additionally the use of coldness, the use of the heat pumps and a high storage temperature of 60 °C is recommendable. The storage in the respective system temperature is more useful under primary energetic, energetic and ecological aspects. Considering all aspects the model of the 2-pipe-system with an electric heater as peak load generator with a storage temperature of 60 °C and cooling is the best.