Stochastic interpretation of thermal response test with TRT-SInterp

Abstract

A program designed to analyze thermal response tests by deterministic or stochastic inversion is presented. In its current state, the program treats variable heating power signals and emulates a borehole heat exchanger by a finite line-source model or a thermal resistance and capacity model. The possibly unknown parameters identified may comprise the thermal conductivity and volumetric heat capacity of the ground or grout, as well as the pipes spacing and initial ground temperature. If the thermal resistance and capacity model is used as the interpretation model, it is possible to integrate to the inversion the temperature measurements made at various depths in the fluid and grout and to take into account the thermal capacity of the underground components and the fluid flow rate. The program is tested under real field conditions by using the temperature measurements recorded by 18 probes installed at various depths in a borehole heat exchanger during a thermal response test. The test results indicate a relative insensitivity of the fluid temperature to the ground volumetric heat capacity and suggest that it is currently illusive to try identifying its real value from a conventional thermal response test.