Sarah Signorelli, dipl. Natw. ETH
Institute of Geophysics
ETH Hoenggerberg
CH - 8093 Zurich
Phone: +41 1 633 20 74
email: signorelli@ig.erdw.ethz.ch
University Education
1994 - 1999
Student of geophysics at the Swiss Federal Institute of Technology Zürich (ETH). Major subjects: Applied and theoretical geophysics, engineering geology
April - October 1999
Diploma in natural sciences. Diploma thesis: Geothermische Messungen im NEAT Schacht Sedrun und ihre Interpretation. 
(2.2 MB)
present
PhD student at the Institute of Geophysics, ETH Zürich
Employments
1996 - 2000
Technical Assistent at Research Group Geothermics and Radiometrics, Institute of Geophysics, ETH Zürich
Languages
German, English
Productivity Investigation of the System Borehole Heat Exchanger with Heat Pump
Background
Borehole heat exchanger (BHE) heating systems operate as a closed circuit, heat pump (HP)-coupled system. It consists of single or multiple boreholes of typically 50 - 300 m depth (mostly double U-tube plastic pipes in backfilled boreholes). It is suited to supply heat to smaller, decentral buildings like single family or multi-family dwellings. The heat exchangers work efficiently in nearly all kinds of geologic media.
Switzerland is, per capita, world leader in heat pumps (HP) based technology. Every third new single family house is equipped with a HP system. Over 20,000 BHE systems are installed to date, with a total of about 4,000 km of BHE length. At present, 1 m of BHE costs (drilling and installation included) about 70 SFr.
Advantage of BHE Systems
- Environment friendly
- Local and renewable energy
- CO2 free
- Moderate cost
Research Project
The research project "Productivity Investigation of the System Borehole Heat Exchanger with Heat Pump" is financed by the Projekt- und Studienfonds der Elektrizitätswirtschaft (PSEL). It started in late 2000 and covers a three-year period. It is jointly performed with the NOK and will comprise theoretical and practice oriented research.
Research project until now considered either borehole heat exchanger or heat pump. This project accounts for both subsystems:
Borehole Heat Exchanger and Heat Pump
And thus it covers the entire system from the heat source to the end user. The joint investigation of both subsystems is an interdisciplinary geoscientific and engineering approach.
Goals
More detailed this project involves the following 3 points:
- Productivity assessment: In a first step operation and geological data of well documented BHE plants are collected.
- Performance investigation: Since site factors can have a strong effect on productivity, the influence of topography, subsurface structure or population density will be investigated. The assessment of productivity is performed by numerical 3D simulation (see below).
- Optimisation: Financial aspects are important to promote this technology. Therefore constructional (e.g. drilling costs), operational (e.g. pressure losses) and geological factors will be analysed and optimised accounting for the results of the performance investigation (e.g. length of heat exchanger).
Numerical Tool
The thermal behaviour of a BHE system is simulated by the finite element (FE) code FRACTure (Kohl and Hopkirk, 1995, (1.0 MB)). FRACTure allows accurate treatment of thermal transport in the borehole tube and the rock matrix (Kohl et al., 2000, (0.3 MB)). In particular, it allows the calculation of:
- The impact of topography and hydraulic groundwater flow on the BHE performance
- Arbitrary borehole types and configurations
- The transient evolution of selected model parameters and boundary conditions, such as flow in the BHE or surface temperature, by defining appropriate load-time functions
The FE mesh generation is performed by the semi-automated WinFra program which establishes a link to common CAD programs and allows the easy generation of discretization schemes for technical and geological structures.
Signorelli, S., Salton, M., Rybach, L., 1998, Geothermie-Inventar und Energiestatistik / Schweiz, Bundesamt für Energie 01.04.-31.10.1998.
Kohl T, Signorelli, S., Rybach L., 1999, Revisiting Fission Track Uplift Rates by 3D Thermal Models, AGU 1999 Fall Meeting San Francisco, Dec. 16, 1999 (invited paper)
Signorelli, S., 1999, Geothermische Messungen im NEAT Schacht Sedrun und ihre Interpretation. Diplomarbeit am Institut für Geophysik, ETH Zürich. (2.2 MB)
Signorelli, S., Salton, M., Rybach, L., 2000, Geothermie-Statistik Schweiz 1990 -1999 / Schweiz, Bundesamt für Energie.
Rybach, L., Signorelli, S., Salton, M., 2000: Geothermie-Statistik Schweiz 1990 -1999, GeothermieCH, Nr. 27.
Signorelli, S., Rybach, L., 2000, Zugangsstollen/Vertikalschacht Sedrun Geothermische Untersuchungen Schlussbericht. Interner Bericht Nr. 2012. Zhd. Projektleitung Alp Transit.
Kohl, T.; Signorelli, S., Rybach, L., 2000, Constraints on Palaeo-topography by revised Apatite FT uplift rates, 25 April 2000, EGS 25th Gen. Assembly Nice.
Signorelli S., Kohl T., 2001, Determination of ground surface temperature by meteorological data. Abstracts: Fifth International Workshop on Heat Flow and the Structure of the Lithosphere, Kostelec, Czech Republic.
Kohl T., Signorelli S., Rybach L., 2001, Three-dimensional thermal investigation below high Alpine topography, Physics of the Earth and Planetary Interiors, 126, pp. 195-210. (0.3 MB)
Signorelli S.,Kohl T., 2001, Produktivitätsuntersuchung des System Erdwärmesonde mit Wärmepumpe. Jahresbericht, PSEL.
Signorelli S.,Kohl T., 2001, Produktivitätsuntersuchung des System Erdwärmesonde mit Wärmepumpe. Jahresbericht, Bundesamt für Energie.
Geothermics and Radiometrics
Institute of Geophysics
Federal Institute of Technology Zürich (ETH)
Schweizerische Vereinigung für Geothermie