With a recently launched project, researchers at Hof University of Applied Sciences want to contribute to the further improvement of local and district heating network storage systems. The Institute for Hydrogen and Energy Technology (iwe) is focusing in particular on the internal flows within the storage tank during charging and discharging cycles. Hot and cold layers of the storage tanks are to be separated more precisely, thus achieving higher storage tank utilization and, as a result, significant operational optimization.
According to experts, there is currently further potential for increasing the efficiency of local and district heating network storage systems – both in existing properties and in new buildings. The aim of the new research project at Hof University of Applied Sciences is to exploit this potential and store larger amounts of thermal energy.
Separating cold and warm storage layers more precisely
“The aim is to achieve optimization for storage tanks with a volume of up to around 200 m³ – in a vertical and optionally also horizontal configuration,” says project manager Prof. Dr. Robert Honke, explaining the goal of the two-year research project “ITSOpt” (In-Tank Storage Tank Optimization). He and his team want to develop additional components and install them in storage tanks at a later date.
These components can help to reduce the internal flows during charging and discharging cycles, but also in simultaneous operating modes. This enables us to achieve a more precise separation between hot and cold layers in the storage tank. And this in turn leads to an increase in the actual usable storage volume.”
Prof. Dr. Robert Honke
The project, which is being implemented in collaboration with industrial partner DEHOUST GmbH from Baden-Württemberg, is divided into two sub-projects: The first deals with the numerical flow simulation as well as the design and development of the additional in-tank storage geometries. The second sub-project then comprises the technical component development for a reliable and practicable installation, including assembly planning.
Aiming for universal transferability
“Many steps are necessary to achieve this. First, a heat network storage system suitable for our validation must be found and measured. Aspects such as sensor technology and different volumes and geometries also play a major role here, so that the results can ideally be transferred to other storage tanks,” explains project team member Robin Fick. The applicability of the results to cold storage tanks of a similar size will also be tested.
In the investigations, we are also focusing on special operating modes in the field of municipal heat supply and on the numerical flow investigation of different product variants.”
Felix Heineken, DEHOUST GmbH
The project is not only aiming to increase the usable volume in two-shift operation of larger storage tanks, but also to achieve more efficient and more economical use of connected combined heat and power plants, biomass and/or solar thermal systems.
Best installation method sought
After the final installation of the developed components, validation measurements and studies on effectiveness, potential for increasing efficiency and sustainability must be carried out. In addition to different installation methods of the additional components to be tested, the focus of the project is also on their most efficient alignment and positioning.
“In addition, investigations in the field of cold storage and horizontal storage are also conceivable,” says Prof. Honke.
Funding
The ZIM project (Central Innovation Program for SMEs) is funded by the Federal Ministry of Economics and Climate Protection (BMWK). With regard to the Building Energy Act, the project results should also contribute to the increased integration of renewable energies into existing and future systems.
