High-Temperature Heat Pump Storage System – Demonstrator Development
A substantial share of non-renewable primary energy is currently consumed for industrial process heat. To reduce this energy demand, the authors developed a novel method within the KETEC project (Research Platform for Refrigeration and Energy Technology, Subproject 10) [1] for providing process heat and steam (100 °C to approx. 300 °C). The system [2] - [4] is based on a heat pump cycle. In contrast to conventional heat pumps, a vapor/liquid storage and a high-temperature storage are integrated into the system. Water was chosen as the preferred working medium because it possesses favorable thermophysical properties. The integration of vapor/liquid storage and high-temperature storage enables cyclic operation. As a result, the system is suitable for discontinuous processes. Therefore, fluctuating power levels on the heat source side (e.g., waste heat from industrial processes) as well as on the drive side (e.g., direct use of electricity from renewable energy sources) can be compensated. This work also presents modifications of the basic process configuration. Compression and expansion stages are varied, and the use of alternative working medium is proposed and examined. The modeling and simulation are carried out using the software EBSILON®Professional [5]. This enables the calculation of coefficient of performance for heating 𝜀H for various evaporation temperatures T0 and condensation temperatures Tc. A comparative evaluation of the variants is then performed. From this, important insights can be derived that contribute to the development of a demonstrator. With the planned demonstrator, the primary goal is to provide proof of function for the novel process. This work also presents the first results from transient simulations of the demonstrator (high-temperature storage). These results show that the new approach is promising as well. The high temperature storage can be charged with superheated steam, and it is also capable of supplying superheated steam.