Stochastic Interpretation of Thermal Response Test with Complex Ground Heat Exchanger Model

English Abstract:

Integrating the temperature measurements made in the grout or in the vertical pipes of a ground heat exchanger during a thermal response test can be challenging for conventional interpretation methods. To fill this gap, a quasi-3D thermal response and capacity model is used to generate the transfer functions of the borehole at the location of the temperature probes. The transfer functions are then convolved in the spectral domain with an input function describing the variation of the heating power to obtain the simulated temperatures at the probes location. The unknown thermal parameters (thermal conductivity and volumetric heat capacity of the ground and grout, pipes spacing, initial ground temperature) are identified by an inversion method. It is shown that use of a spectral method combined with a response model allows integration in a stochastic framework of the measurements made at various depth in the borehole.