Short-term fluid temperature variations in either a coaxial or U-tube borehole heat exchanger
Borehole heat exchanger, Coaxial, Composite cylindrical model, Thermal response test, Transient cylindrical response, U-tube
This paper uses composite cylindrical heat-source (CCS) models and typical thermal response test procedures to investigate two full-scale borehole heat exchangers (BHE); where one is a U-tube BHE, and the other, a pipe-in-pipe (coaxial) BHE. A previously developed CCS model is compared to a simplified infinite line-source (ILS) model. A time-varying heat-flux term is verified for the U-tube case, noting the error found when using the CCS model. A model is developed using a similar approach accounting for a coaxial configuration showing a root mean square error (RMSE) of less than 0.1 °C over the duration of the test.
Gordon, David; Bolisetti, Tirupati; Ting, David S.K.; and Reitsma, Stanley. (2017). Short-term fluid temperature variations in either a coaxial or U-tube borehole heat exchanger. Geothermics, 67, 29-39.