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

Abstract

Heat pulse methods indude the dual-probe (DP) and single-ptobe (SP) methods. The DP method is a widely used method for determining the thermal conductivity (A^ and thermal difFusivity (ß) of soil. The SP mediod has been traditionally used for measuring A" only. The objective of this study was to examine if the SP method can be used to estimate the dietmal properties of air-dried soils. TKe 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 ofthe perfect conductor model and hollow cylindrical ptobe model wete fitted to the respective small-rime and largetime temperature vs. time curves. Both A" and (3 ofthe soil were determined by the SP method. The DP and SP methods yielded similar A"values for the three air-dried soils with a relarive deviation <6.1%. In comparison with the DSC measurements, the DP method overestimated the specific heat (f) by 19 to 29%, while the SP method with the hollow cylindrical probe model underestimated f 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 perftct conductor model gave the most accurate estimate of c.Abbreviations: DP, dual probe; DSC, difFerential scanning calorimetry; HP, heat pulse; SP, single probe.

Probe Body and Thermal Contact Conductivity Affect Error of Heat Pulse Method Based on Infinite Line Source Approximation

“…To compare with DP measurements, the c value of the sample is also determined by using a differential scanning calorimetry (DSC). The DSC measured c at 20°C is 756 ± 37 J kg-' K-l (Liu and Si, 2011).…”

Measuring Solid Percentage of Oil Sands Mature Fine Tailings Using the Dual Probe Heat Pulse Method

“…There has been a range of values of specific heat for mineral soils reported in the literature (Liu and Si, 2011), and the specific heat of mineral soils measured by the dual probe heat pulse method ranged from 800 to 1000 J kg ‐1 K ‐1 , which was overestimated compared with the standard DSC method. Therefore, the solid percentages of three MFT samples were inferred by assuming c s of all MFT samples to be 750 J kg ‐1 K ‐1 , which corresponding to the typical specific heat of mineral soil measured by DSC (Liu and Si, 2011). The influence of hydrocarbons on the specific heat of MFT solids is discussed in a later section.…”

“…Modulated differential scanning calorimetry is a new technology to measure specific heat (Reading et al, 1994). However, only a few researchers (Smidt and Tintner, 2007; Liu and Si, 2011; Kozlowski, 2012) have applied it to soil samples. The MDSC machine (Model Q2000, TA Instruments) was used to measure the specific heat of oven‐dried MFT solids samples.…”

“…The MDSC technique uses two simultaneous heating rates: a linear heating rate that provides information similar to standard DSC and a sinusoidal modulated heating rate that permits the specific heat measurement. It measures the difference between a sample and a reference in the amount of heat required to increase the temperature by one unit as a function of time (Liu and Si, 2011). The DSC heat flow signal d H ( T , t )/d t is a function of specific heat c as where T is temperature (°C), t is time (s), m is the sample mass (g), d T /d t is the heating rate, f ( T , t ) is the nonreversing (kinetic) heat flow, and c ⋅ m ⋅d T /d T is the reversing heat flow.…”

Thermal Resistivity and Moisture Migration of Soil and Cable Trench Backfill

“…Various techniques on the measurement of thermal resistivity of soil have been developed for decades (Mitchell and Kao 1978;IEEE 1981;Yu et al 2004;Milun et al 2005;Krishnaiah and Singh 2006;Liu and Si 2011). In this laboratory study, a 4-inch long transient needle probe was used to measure the thermal resistivity of soil.…”