interaction of a heat exchanger with its environment is a complex
process that is determined by a number of physical and technical
factors. For geothermal installations such as surface collectors,
borehole heat exchangers (BHE) andthermal-active building systems, in
addition the local geological and hydrogeological conditions have to
be taken into consideration. Numerical models help to understand e.g.
what thermal power a heat exchanger can sustainably achieve or whether
and how much a BHE field affects groundwater temperatures.
special challenge in the simulation of such systems is the robust
linkage of the small-scale physics of the heat exchanger with the
large-scale processes of the geological environment. The goal here is
to create numerically stable models that can reproduce long-term
processes with the shortest possible calculation times.
in-house software SHEMAT or SHEMAT-Suite for
which we have developed various additional modules for the calculation of heat exchangers, has proven itself here. These
modules are so-called model-in-model solutions in which the processes within the heat exchanger are solved by analytical functions, while
the processes in the geological environment are calculated numerically.
This approach allows a significantly faster calculation than a purely
numerical approach and at the same time offers the possibility to
flexibly adapt the environment of the heat exchange to the local
range of services includes points such as
and long-term simulation of the performance of geothermal heat
forecasts for different operating and storage scenarios
taking into account changing flow rates, temperatures and varying
of geothermal effects of heat exchangers on the underground or
of the influence of groundwater flow on the performance
Model-in-Model modules exist for coaxial and double U-shaped BHEs, whereby probe parameters such as tube geometries, wall thickness, borehole diameter, thermal
resistances etc. can be freely configured. Additional modules have been developed that can be used to predict the performance of thermal active construction elements such as sealing walls and sheet pile walls. These, as well as a module for the simulation of
freezing processes in the subsurface have been developed in cooperation with the Institute for Geotechnical Engineering at RWTH Aachen University.
Geothermal effects of heat
exchangers on the underground (1Jear and 20 Jears).