Vertical temperature profiles and borehole resistance in a U-tube borehole heat exchanger

Colloquium 2016: Assessment of subsurface thermal conductivity for geothermal applications

“…Numerical simulations of GHE temperature illustrated in Figure 4 has demonstrated that this condition is rarely met and alternative averages have been proposed to account for the asymmetric temperature profile along the descending and ascending pipes (Marcotte and Pasquier 2008;Beier et al 2012). …”

Accuracy of borehole thermal resistance calculation methods for grouted single U-tube ground heat exchangers

“…The expression is based on the well-known two-dimensional heat conduction shape factor [52] for a circular isothermal cylinder eccentrically placed in another cylinder of same length. The same shape factor has also been used by other researchers, including Koenig and Helmke [53], Beier [15] and Koenig [54], to determine the grout thermal resistance. However, the expression proposed by Bauer et al [35] has been corrected for U-tube geometry using numerical simulations.…”

“…More recently, several verifications or improvements of the earlier expressions have been published. Noteworthy studies include Beier et al [15], Zhang et al [16], Zhang et al [17], and Beier and Spitler [18]. The proposed improvements are partially based on experimental data provided by Acuña [19] and/or Beier et al [20].…”

Thermal response testing for ground source heat pump systems—An historical review

“…Further developments in the analysis procedures include analysis of tests with groundwater flow [60,[94][95][96][97], correction of tests for ambient losses [98,99], improved analysis of tests with variable heat flow rates with [100] or without [101] parameter estimation, improved error analyses [100,102] and proposals to compute the mean temperature more accurately by going beyond the simple mean fluid temperature [70,[103][104][105].…”