A method and case study of thermal response test with unstable heat rate

This paper proposed a new method based on modified composite model in the thermal response test (TRT) in the variable heat rate case study. The new method considered the unsteady-state heat transfer in the borehole instead of the line-source model assumption. A Matlab program was compiled which can perform inversion calculation to obtain the ground thermal properties. The superposition principle was used to process the variable-rate problem. This new method was applied to two thermal response tests. The simulation value based on the method shows a good agreement with the measurement data of water temperature. The proposed method would save the time and reduce the cost of TRT when power fluctuation or failure occurs.

► This paper proposed a new method in TRT with variable heat rate.
► It saves the time and reduce the cost of TRT when power failure occurs.
► The method considered the unsteady-state heat transfer in the borehole.
► The superposition principle was used to process the variable heat rate problem.
► The method was applied to two thermal response tests.