16 Nov 2021
by IEA DHC

District LAB Experimental Facility in Kassel, Germany

Especially LTDH is recognized as a key technology for the (cost-) efficient integration of renewable energy and waste heat sources in our energy systems. A further development of LTDH systems is needed for a decarbonisation of the heating sector. On the other hand, district heating is also put into question. To face these challenges research on innovative district heating concepts integrating decentral feed-in of renewable energy is needed.

Figure 90-CS14.png

The Fraunhofer IEE in Kassel has started to set up a new research and experimental facility as a test and development platform for innovative district heating systems in close cooperation with industry partners. This facility consists of a real district heating grid in a lab-scale and expands the possibilities of the already existing facilities. This experimental environment is more flexible than experiments compared to tests in real operating district heating grid (demonstration) since no public utility mandate is connected to the District-LAB facility. Tests with varying temperatures and pressures can be conducted; new components and operating modes can be tested. The real behaviour of components and systems can be tested in a real life environment and simulation models can be validated in this facility (Schmidt, 2019).

First project ideas are within three different fields as the tests of new operational strategies (e.g. dynamic and changing boundaries for feed-in and utilization, grid operation with new temperature regimes, dynamic pressure and temperature changes) or tests of components (as piping systems, heat exchanger / sub-stations, pumps, control elements) or within the field of the development of simulation tools and validation (e.g. static hydraulic simulations incl. heat losses, dynamic simulations of control strategies and pressure changes).

As shown in the Figure 90, the District LAB has three main fields of application:

  1.  Thermo-hydraulic tests at a flexible heating grid: As part of the District LAB, a flexible heating grid in a lab scale provides the investigation of different district heating scenarios. Based on a flexible design of distribution pipes with supply and return pipes as well as heat sources and sinks, a wide range of temperature levels (5…130°C) can be implemented. 
  2. Mechanical tests of piping materials using an underground test section: Due to the increasing implementation of volatile energy sources, district heating systems are faced with new and fluctuating operating conditions. To measure the impact of these and other conditions on the piping system, the District LAB includes a 40-meter underground test section for various investigations regarding the mechanical piping behaviour. 
  3. Development of new control concepts based on Hardware-in-the-Loop systems: Based on an extensive measurement and control system as well as a digital management system, the experiments will be parameterised and monitored. Due to Hardware-in-the-Loop (HiL) systems, defined loads, temperatures, and pressure levels can be applied to the test network enabling the development and evaluation of control concepts and energy management systems.