Untersuchung von Systemkonzepten zur Integration von Haushaltsgeräten als Wärmequelle und Wärmesenke in ein multifunktionales Wärmepumpensystem

Less energy consumption results into less CO2-emission. This remains a matter of fact as long as renewables do not cover the entire energy demand and belongs among others nowadays more than ever to key drivers in research and development. For that reason, energy efficiency improvements became very important to reduce the impact of abundant consuming technology sectors while comfort criteria need to be kept on a high level. In order to reduce the energy consumption by efficiency improvements the relevance of part and entire system solutions becomes increasingly significant for further CO2 reduction steps. Buildings and domestic appliances are responsible for around 25 % of the European electricity demand. Primarily, residential areas, where the choice of application and behaviour adjustments are up to one’s own, provide suitable preconditions for new and energy efficient technologies. Efficiency improvements of single appliances are driven by factors like the evaluation of products by the European energy label since 1998 and not least the rivalry between manufactures. Therefore, manufactures are challenged with advancements since several decades in order to keep a high technology level according to the state of the art, which in the end results into an exhaustion of efficiency improvements for single components. On the one hand, a high development status comes along with high standards but, on the other hand, it possibly opens new fields in research and development that before appeared as much to complex and cost specifically irrelevant.

Combined system solutions like the combination of heating/air conditioning via the heat pump and domestic appliances with heating and/or cooling demand have the potential to benefit from synergy effects. I.e., first, to achieve a reduction of the electricity consumption for single appliances by providing heat efficiently, second, to utilize the waste heat from cooling appliances as the heat source of the heat pump and, third, to reduce investment costs by removing unnecessarily redundant components. As the consequence from the considered characteristics, consumers benefit in electricity and cost effectiveness while the functionality of single appliances should not suffer.

In this thesis, several steps in the development process of a combined system concept are processed in order to determine the potential for a synchronized operation of domestic appliances and the centralized heat pump unit. Therefore, a functional model is developed as the test rig for the experimental investigations at the laboratory. The system allows for the interconnection of domestic appliances to the heat pump system to investigate the operating characteristics of the modified appliances in single mode as well as in different combinations of the integrated system. Due to the operation of the appliances in reasonable system combinations and sequences at the laboratory advantages and disadvantages can be concluded for the real-life conditions. The measurement concept is designed to allow for both the characterization of efficiency improvements of the appliances and the characterization of heat flows within the appliances as well as the system construction. Theoretically, an analysis of loss and demand is carried out to determine the overall system performance for the integrated operation mode. Finally, based on the explored experimental sequences a technology concept for the overall system is evolved, where also the economic potential is evaluated by the system cost and the year-round cost effectiveness yielded from efficiency improvements. For the considered case, heat losses over the system construction are avoided and the waste heat of cooling appliances is utilized for heating purposes by the heat pump. In the end, the electricity consumption of domestic appliances of around 985 kWh/a for a single household can be reduced by 36 % if the appliances are coupled to the centralized heat pump system for cooling and heating purposes. For the scenario for the year 2040, after CO2-emissions in the building sector have been reduced to 50 Mio. t CO2-equivalent by energetic refurbishments, the potential for a further reduction step by the application of the evolved technology amounts to a maximum of 4,78 Mio. t CO2-equivalent, around 10 % of the predicted CO2-emissions in this sector.