Bachelor's thesis Lars Schellhas


Impact analysis of thermal storage technologies on the efficiency of air/water-heat pumps

The aim of reducing primary energy consumption in German households has an effect on heat supply and the necessary building technology.Heating systems for space heating and hot water consume most of the energy used in buildings and provide the heat conventionally through the burning of fossil or renewable fuels. In the coming years, more than two million obsolete boilers will have to be replaced by legal framework conditions that the German Energy Saving Ordinance creates. In order to achieve a reduction in primary energy consumption at the same time, heat pumps offer themselves as an alternative as they require only a fraction of primary energy to supply the required heating power. The required energy is obtained as ambient heat, for example from the surrounding realm or the outside air. Heat storage can improve the operation of a heat pump, as well as the operation of classic boilers, and increase the efficiency of the system. This means that heat pumps can be operated during daytime with higher outside temperatures, which increases efficiency. By caching, which usually happens in sensitive hot water stores, additional losses occur. These occur in the formof transmittance heat losses, losses due to the use of heat exchangers, component heating and physical effects during loading and unloading. With the further development of the various thermal storage technologies, it is necessary to investigate whether the use of sensitive hot water reservoirs is the most energy-efficient variant or whether the use of other storage technologies can result in lower losses and thus improvements in efficiency and primary energy consumption. This requires the creation of a catalogue of requirements, which defines the temperature levels of heat pumps, storage and building heating system. The reference case is a stock building built before 1985, which represents the renovation case according to the German Energy Saving Ordinance 2016. This work provides an overview of the existing technologies and examines the aforementioned questions using numerical simulations with Modelica. The aim is to provide an overview of the application possibilities of the thermal storage technologies and to investigate and compare different technologies. By examining the system, possibilities for an increase in efficiency are determined to enable primary energy savings.