A novel numerical model for the thermal response of borehole heat exchangers fields
2014 (English)Conference paper, Poster (Refereed)
The design of a borehole field should be based on a long-term simulation of its thermal response for specified energy loads. This response can be calculated from a pre-calculated dimensionless function, the g-function. This paper is focused on a new approach to the calculation of g-functions; in particular with a precise representation of the boundary conditions at the borehole wall. First, the almost constant temperature along the borehole heat exchanger requires a boundary condition of essentially isothermal boreholes along the depth. In a common case the borehole heat exchangers are connected in parallel, thus all boreholes should have the same temperature. Also, the total heat flow to the borehole field should be constant over time. A numerical model in which the boreholes are filled with a highly conductive material has been built, reproducing the isothermal condition. By thermally interconnecting the boreholes, the equal temperature condition is satisfied. The g-functions of some simple borehole field configurations are presented in this paper. The results show, in general, a good agreement with the existing solutions for a similar boundary condition.
Place, publisher, year, edition, pages
2014. 1-10 p.
borehole, heat exchanger, g-function, long-term performance, uniform borehole temperature
IdentifiersURN: urn:nbn:se:kth:diva-145882OAI: oai:DiVA.org:kth-145882DiVA: diva2:720839
The 11th International Energy Agency Heat Pump Conference,Montreal, May 12-16, 2014
QC 201406192014-06-022014-06-022016-09-23Bibliographically approved