Distributed Thermal Response Test on a Grouted U-pipe Borehole Heat Exchanger
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
The expansion of the use of geothermal heat pumps makes the study of their performances a keystone in their development. Several parameters are crucial to design properly a geothermal heat pump. Comparing the theoretical characteristics of a system with the actual ones one the field is part of its understanding. This Master thesis gives a closer look for determining from filed data two central parameters, the borehole thermal resistance and the ground thermal conductivity, using a newly developed technique called Distributed Thermal Response Testing (DTRT). These calculations are applied to a U-pipe heat exchanger installed in a private household. From these two parameters, it is possible to estimate the thermal conductivity of the filling material inside the borehole and thus estimate its influence on the performances of the system. Three grouting material are studied here and theoretical values are compared with experimental value in order to try to get a picture of the inside of the borehole. This thesis provides a picture of the actual thermal parameters of the studied borehole, which clearly reveals the influence of the grouting material in each layer. It is also noticed that the laboratory value of the grout thermal conductivities varies when comparing with theoretical values or manufacturer data. The lack of understanding of the actual drying state of the grouts inside the borehole may by one reason why.
Place, publisher, year, edition, pages
Ground source heat exchanger, grout
IdentifiersURN: urn:nbn:se:kth:diva-140876OAI: oai:DiVA.org:kth-140876DiVA: diva2:693226
Master of Science - Sustainable Energy Engineering
2014-01-30, 14:00 (English)