Experimental Comparison of Four Borehole Heat Exchangers
2008 (English)In: Refrigeration Science and Technology Proceedings, Copenhagen: International Institute of Refrigeration, 2008, SEC09-W1-09 p.Conference paper (Refereed)
The most common way to exchange heat with the bedrock in ground source heat pump applications is circulating a secondary fluid through a closed U-pipe loop in a vertical borehole. This fluid transports the heat from the rock to the ground source heat pump evaporator. The quality of the heat exchange with the ground and the necessary pumping power to generate the fluid circulation are dependent on the type of fluid and its flow conditions along the pipe. Four different borehole heat exchangers are tested using ethyl alcohol with 20% volume concentration. The fluid temperatures are logged at the borehole inlet, bottom, and outlet. The collectors are compared based on their borehole thermal resistance and pressure drop at different flow rates. The results indicate that the pipe dimensions play an important roll, spacers might not contribute to better heat transfer, and inner micro fins in the pipes improve the performance of the collectors.
Place, publisher, year, edition, pages
Copenhagen: International Institute of Refrigeration, 2008. SEC09-W1-09 p.
Borehole Heat Exchanger, Borehole Thermal Resistance, Pressure Drop
IdentifiersURN: urn:nbn:se:kth:diva-73160ISBN: 978-87-92127-03-7OAI: oai:DiVA.org:kth-73160DiVA: diva2:488591
8th IIR Gustav Lorentzen Conference on Natural Working Fluids. Copenhagen, Denmark. September 7-10, 2008
QC 201205142012-02-012012-02-012012-05-14Bibliographically approved