Improved Borehole Technology for the Development of Geothermal Heating Systems
Boreholes with fiber optic measuring equipment makes it possible to evaluate thermal performance for boreholes of different lengths within the same borehole field.
The plus-energy houses are heated via a heat pump system with heat pumps and 12 drill holes totaling 3600m. The geothermal installation design has some unconventional features that make the installation very interesting for research purposes.
The boreholes range from 100 to 350 meters and have been equipped with measuring equipment to be able to evaluate thermal performance for boreholes of different lengths within the same borehole field. Both heat transfer between the loops as well as the temperature along the boreholes will be measured which results in heat transfer information in individual holes and throughout the borehole system. The temperature along the boreholes is measured using Distributed Temperature Detection (DTS), a fiber optic technology, and linear temperature sensors. Fiber cables have been installed in five boreholes and provide measurement values of the borehole temperature profile during operation.
In addition to the areas of monitoring and measurement, drilling research in the KTH Live-In-Lab will also include innovative heat exchangers and borehole testing methods. For this part of the project comes a dedicated "research drill hole" with a length of 100 meters and a coaxial design to be utilized. The concept behind this borehole is to provide borehole researchers with a highly flexible system to experiment with innovative ideas.
For this reason, the pipeline is designed so that the fluid circulating in the "research well" can be directed to a separate heat pump and operated with independent loads compared with the remaining part of the installation of the plus energy houses.
The research heat pump system will be designed to accurately control heat supply and heat output to test the ground for a variety of load profiles with the aim of collecting valuable information to characterize short term thermal response for boreholes.