Finite cylinder-source model for energy pile heat exchangers: Effects of thermal storage and vertical temperature variations

• Published in: Energy (Oxford) Vol. 78; pp. 639 - 648
• Main Authors: Bandos, Tatyana V., Campos-Celador, Álvaro, López-González, Luis M., Sala-Lizarraga, José M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15.12.2014; Elsevier
• Subjects: Applied sciences; Approximation; Borehole heat exchangers; Boreholes; Cylinders; Devices using thermal energy; Energy; Energy piles; Energy. Thermal use of fuels; Exact sciences and technology; Exact solutions; Ground coupled heat pumps; Ground heat exchangers; Heat exchangers; Heat exchangers (included heat transformers, condensers, cooling towers); Integrals; Mathematical analysis; Mathematical models; Energy piles; Borehole heat exchangers; Ground heat exchangers; Ground coupled heat pumps; Cylinder; Temperature; Models; Storage; Modeling; Heat exchanger
• ISSN: 0360-5442
• DOI: 10.1016/j.energy.2014.10.053

A mean integral solution to the FCS (finite cylindrical source) model for ground heat exchangers that takes into account the heat capacity inside the borehole or foundation and allows estimation of temperature field for an arbitrary borehole configuration is presented as a single integral. Approximate expressions for the average temperature over a wide range of time values are derived analytically in the vicinity of both sides of the finite cylindrical surface of heat source. Exact and approximate results for the mean temperature are compared to those calculated at the mid-depth from the exact solution of the same FCS model. •Exact integral mean solution for pile temperature to FCS (finite cylinder-source).•New method based on the FCS improves evaluating pile response test.•Approximate expressions for temperature in the vicinity of cylinder-source of heat.•Mean temperature outside FCS exceeds one from finite line-source, heating mode.