SE-14-014 -- Quality Control Assessment of Vertical Ground Heat Exchangers PDF

Heattransfer performances of vertical groundheat exchangers can be determined in the field through the evaluation of the effectiveborehole thermal resistance withathermal response test. Acomparison of this parameter to that calculated with an analytical solution taking into account the ground heat exchanger configuration can be used to assess the quality of underground installations. A procedure to perform this comparison is proposed by drawing, in the first case, a box plot of the predicted two-dimensional borehole thermal resistance, and in the second case, a surface chart of the predicted three-dimensional borehole thermal resistance. Uncertainty related to the pipe spacing and the grout thermal conductivity is considered in the comparison, illustrated with three field tests performed on similarly configured ground heat exchangers installed at distinct locations.