Title

Short-term fluid temperature variations in either a coaxial or U-tube borehole heat exchanger

Document Type

Article

Publication Date

5-1-2017

Publication Title

Geothermics

Volume

67

First Page

29

Keywords

Borehole heat exchanger, Coaxial, Composite cylindrical model, Thermal response test, Transient cylindrical response, U-tube

Last Page

39

Abstract

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.

DOI

10.1016/j.geothermics.2016.12.001

ISSN

03756505

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