The determination of the minimal permissible inflow temperature of geothermal probes under the premise
(a) of frost prevention in the backfill material and in the underground as well as
(b) of a sufficiently low system permeability in the backfill material and in the contact zones between backfill material and borehole wall or probes requires a detailed investigation of different geometrical as well as material and operational boundary conditions of a geothermal probe.
For this purpose, a two-stage set-up of laboratory experiments is planned. This will make it possible - supplemented by numerical simulations - to describe and predict the behaviour of borehole heat exchanger backfill materials under temperature strains and freeze-thaw cycles. The physical processes of the freeze-thaw cycle will be analyzed by the development of a modeling approach to take the phase change in the backfill material into account. With the knowledge gained in this way, calculations are then carried out with variations of the geotechnical and hydrogeological boundary conditions in order to obtain conclusive statements on the minimal inflow temperature under which - in the sense of an intact subsoil / backfill system - a safe operation of a geothermal probe is possible.
In TP1 (VEGAS): "Experimental investigations of the temperature-dependent system permeability" the experimental parameters for the building materials (small-scale experiment) and for the entire system (medium-scale experiment) will be determined within two work packages.
This is a follow-up project to: Definition des Nahbereichs von EWS
- Project manager
- Research assistants
2018-10-01 to 2021-08-31
- Cooperation partners
Steinbeis Innovation gGmbH - Solites
Institute of Geotechnical Engineering, University of Stuttgart