Short-term fluid temperature variations in either a coaxial or U-tube borehole heat exchanger. (May 2017)

• Record Type: Journal Article
• Authors: Gordon, David; Bolisetti, Tirupati; Ting, David S.-K.; Reitsma, Stanley
• Is Part Of: Geothermics. Volume 67(2017:May)
• Page Start: 29
• Page End: 39
• Publication Date: 2017-05
• Subjects: BHE borehole heat exchanger -- TRT thermal response test -- GCHP ground coupled heat pump -- ILS infinite line source -- ICS infinite cylindrical source -- CCS composite cylindrical source -- RMSE root mean square error; Borehole heat exchanger -- Thermal response test -- U-tube -- Coaxial -- Transient cylindrical response -- Composite cylindrical model; Hydrogeology -- Periodicals; Geothermal resources -- Periodicals; Énergie géothermique -- Périodiques; GEOTHERMAL ENGINEERING; GEOTHERMAL ENERGY; GEOTHERMAL EXPLORATION; Geothermal resources; Hydrogeology; Periodicals; Electronic journals; 621.44
• DOI: 10.1016/j.geothermics.2016.12.001
• Languages: English
• ISSNs: 0375-6505

Abstract

Highlights: Validates a composite cylindrical model for coaxial BHEs. Model accounts for thermal heat capacity of piping material. Model accurately simulates short-term fluid temperatures within a coaxial BHE. 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.