Single‐ and Dual‐Probe Heat Pulse Probe for Determining Thermal Properties of Dry Soils

Heat pulse methods include the dual‐probe (DP) and single‐probe (SP) methods. The DP method is a widely used method for determining the thermal conductivity ( K ) and thermal diffusivity (β) of soil. The SP method has been traditionally used for measuring K only. The objective of this study was to examine if the SP method can be used to estimate the thermal properties of air‐dried soils. The thermal properties of three sands were measured using differential scanning calorimetry (DSC) and the DP and SP methods. For the SP method, the small‐time and large‐time solutions of the perfect conductor model and hollow cylindrical probe model were fitted to the respective small‐time and large‐time temperature vs. time curves. Both K and β of the soil were determined by the SP method. The DP and SP methods yielded similar K values for the three air‐dried soils with a relative deviation <6.1%. In comparison with the DSC measurements, the DP method overestimated the specific heat ( c ) by 19 to 29%, while the SP method with the hollow cylindrical probe model underestimated c by 21 to 8%, and the SP method with the perfect conductor model resulted in −4 to 7% error. Therefore, the SP method with the perfect conductor model gave the most accurate estimate of c .