Determining Soil Thermal Conductivity Through Numerical Simulation of a Heating Test on a Heat Exchanger Pile

Heat exchanger pile foundations have a great potential of providing space heating and cooling to built structures. This technology is a variant of vertical borehole heat exchangers. A heat exchanger pile has heat absorber pipes firmly attached to its reinforcement cage. Heat carrier fluid circulates inside the pipes to transfer heat energy between the piles and the surrounding ground. Borehole heat exchangers technology is well established but the heat exchanger pile technology is relatively new and requires further investigation of its heat transfer process. The heat transfer process that affects the thermal performance of a heat exchanger pile system is highly dependent on the thermal conductivity of the surrounding ground. This paper presents a numerical prediction of a thermal conductivity ground profile based on a field heating test conducted on a heat exchanger pile. The thermal conductivity determined from the numerical simulation was compared with the ones evaluated from field and laboratory experiments. It was found that the thermal conductivity quantified numerically was in close agreement with the laboratory test results, whereas it differed from the field experimental value.