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Heat Transfer from Impinging Flames in Supercritical Water Used for Contact-Free Drilling

Applicant Rudolf von Rohr Philipp
Number 119969
Funding scheme Project funding (Div. I-III)
Research institution Institut für Verfahrenstechnik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Mechanical Engineering
Start/End 01.04.2008 - 31.03.2011
Approved amount 218'525.00
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All Disciplines (2)

Mechanical Engineering
Other disciplines of Engineering Sciences

Keywords (6)

supercritical fluids; hydrothermal flame; heat transfer; spallation drilling; geothermal energy; supercritical fluid

Lay Summary (English)

Lay summary
This project focuses on heat transfer in flame combustion processes in supercritical water (SCW). Combustion processes in dense supercritical fluids are of great interest not only from scientific point of view, but also in terms of technical applications. Several applications using the properties of SCW emerged in the last years, e.g. hydrothermal synthesis in SCW (HTS-SCW) or the supercritical water oxidation (SCWO).The author of this proposal at the Institute of Process Engineering at the ETH Zurich showed that continuously operated SCWO can be carried out in the flame regime. Such “hydrothermal flames” in wall-cooled burners appeared to have the clear advantage of alleviating the plugging problem and of reducing corrosion. Different reactor concepts were designed and manufactured to investigate the behavior of such flames at various conditions. Hydrothermal flames can be attractive also for further applications, e.g. spallation drilling. Thermal spallation drilling is a possible/alternative way of drilling through hard rock layers in great depths, which will lead to an increased efficiency of geothermal processes. The flame here serves as a heat source for inducing heat stresses within the rock, causing the break-away of rock layers.Flame combustion in SCW is a new field of research and many fundamental phenomena are not yet understood. The main objective of the proposed work is the experimental and theoretical characterization of the heat transfer from hydrothermal flames to defined objects. The results shall primarily lead to a methodology for the design of future spallation drilling burner systems, but provide scientific fundamentals for other applications in the field of hydrothermal flames as well.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants


Name Institute

Associated projects

Number Title Start Funding scheme
111838 Flammen in überkritischem Wasser 01.04.2006 Project funding (Div. I-III)
138090 Thermal Rock Fragmentation under Ambient and Hydrothermal conditions 01.11.2011 Project funding (Div. I-III)
103734 Characterization of Continuous Diffusion Flames in Supercritical Water 01.04.2004 Project funding (Div. I-III)


A major challenge for our society lies in the provision of sufficient renewable energy for future generations. Switzerland with its “2000 Watt program” plays a vanguard role in this specific field of science and technology. This project shall contribute to this ambitious objective.99% of our terrestrial globe is hotter than 1000 °C. But normally high temperatures are quite far away from earth’s surface, i.e. at ~3 km 100°C, at ~5km 200°C. For electricity production a maximum efficiency of 15 % is given. These systems are heat driven and therefore an efficient system for the heat use is necessary. PSI in Würenlingen, Switzerland, is currently working on these concepts.However, the major challenge is an efficient and affordable drilling concept. Standard rotary drilling technologies are very expensive for deep geothermal wells below several kilometers. Therefore we propose to investigate the contact-free drilling by means of a flame in the thermodynamically supercritical water environment. The high amount of heat provided by the flame shall allow building up stresses in the rock in order to disintegrate it. This technology is called spallation. First ever we propose to use the so called hydrothermal flame which works under extreme conditions, say at pressures larger than 270 bar and temperatures above 1000° Celsius for drilling boreholes in great depths. The supercritical pressure is naturally given in water-filled boreholes below 2300 meters. We have extensive experience in this kind of flames in connection with the supercritical water oxidation (SCWO) of organic substances (see our previous projects supported by the SNF).The objectives with this scientific work direct to the understanding of heat transfer from the impinging, hydrothermal flame under defined conditions and to the stable operation of this hydrothermal flame under these extreme conditions with defined obstacles. The rapid changes of properties around the critical point can be favorable for its heat transfer rate. A straightforward research plan shows the realistic probability to reach the ambitious objectives. Theoretical and experimental work is needed and is planned. Under defined conditions basic heat transfer data are being created. The heat transfer directly impacts the size of the fragmented material (= spalls) in the spallation drilling process and is therefore of major interest. Most parts of an existing plant will be used for the experimental investigations. The theoretical part consists of the calculation of the combined heat and mass transfer in a defined environment.The significance of this scientific project is obvious: it will create new ways for future geothermal energy use. Furthermore it offers first ever heat transfer data for impinging flames in supercritical water. However, these data not only provide the fundamentals for the development of a new, efficient drilling system, but is also of interest for other upcoming high efficient energy systems using supercritical water. Scientifically, we strengthen our excellent worldwide position in this research field and build the bridge to future technologies. Collaboration with first class universities (i.e. MIT, Cambridge USA) is guaranteed and allows the exchange of students for master theses or for parts of the doctoral work.