Oscillatory Thermal Response Test (OTRT) – An Advanced Method for Gaining Thermal Properties of the Subsurface
Thermal Response Tests (TRTs) are the state-of-the-art method to obtain the thermal conductivity of the subsurface in the nearby ambience of a borehole heat exchanger (BHE). The results of TRTs are used to determine the necessary depth of the borehole and to make long time predictions about the potential of heat extraction. For a TRT, a constant heat load is injected into the subsurface and the temperature development of the BHE working fluid is recorded. We consider a time dependent sinusoidal heat injection instead of constant heat injection and use COMSOL Multiphysics® for the simulation and evaluation of this new method.