Critical Analysis of Dual-Probe Heat-Pulse Technique Applied to Measuring Thermal Diffusivity

2018 ◽  
Vol 39 (7) ◽  
Author(s):  
G. Bovesecchi ◽  
P. Coppa ◽  
S. Corasaniti ◽  
M. Potenza
Keyword(s):  
Thermal Diffusivity ◽  
Critical Analysis ◽  
Heat Pulse ◽  
Pulse Technique ◽  
Dual Probe

Measuring peat moisture content using the dual-probe heat pulse technique

Soil Research ◽  
2002 ◽  
Vol 40 (1) ◽  
pp. 177 ◽  
Author(s):  
David I. Campbell ◽  
Claire E. Laybourne ◽  
Ian J. Blair
Keyword(s):  
Moisture Content ◽  
Gravimetric Method ◽  
Heat Pulse ◽  
Time Domain Reflectometry ◽  
Peat Soils ◽  
Pulse Technique ◽  
Mineral Soils ◽  
Reference Measurements ◽  
High Level ◽  
Dual Probe

The dual-probe heat pulse (DPHP) technique for measuring soil volumetric moisture content (Θv) is evaluated for use in peat soils with very high organic matter contents. The method has a greater sensitivity in peat soils compared with mineral soils and excellent resolution is possible, even at moisture contents as high as 90% by volume. Advantages of the DPHP technique are that sensors are simple to construct from inexpensive parts and calibration is not required since the method is based on a physical model of radial heat flow in soil. A multiplexer method was developed to allow multiple probes to be deployed in the field. DPHP measurements of Θv for small peat samples compared closely to reference measurements made using the gravimetric method, and in the field were similar to results obtained using a time domain reflectometry (TDR) method. Peat soils display a high level of spatial variation in Θv at the scales of both DPHP and TDR probes, so that multiple probes of each type are required for adequate spatial sampling of Θv. Rapid changes in peat moisture content were recorded following rainfall infiltration events yet moisture storage did not remain elevated following rainfall, even for peat that was very dry. wetlands, hydrology, soil moisture.

scholarly journals Measuring Soil Water Content under Turfgrass Using the Dual-probe Heat-pulse Technique

1998 ◽  
Vol 123 (5) ◽  
pp. 937-941 ◽  
Author(s):  
Y. Song ◽  
J.M. Ham ◽  
M.B. Kirkham ◽  
G.J. Kluitenberg
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Tall Fescue ◽  
Soil Column ◽  
Gravimetric Method ◽  
Soil Surface ◽  
Heat Pulse ◽  
Pulse Technique ◽  
Dual Probe

Measurements of soil water content near the soil surface often are required for efficient turfgrass water management. Experiments were conducted in a greenhouse to determine if the dual-probe heat-pulse (DPHP) technique can be used to monitor changes in soil volumetric water content (θv) and turfgrass water use. `Kentucky 31' Tall fescue (Festuca arundinacea Schreb.) was planted in 20-cm-diameter containers packed with Haynie sandy loam (coarse-silty, mixed, calcareous, mesic Typic Udifluvents). Water content was measured with the DPHP sensors that were placed horizontally at different depths between 1.5 and 14.4 cm from the surface in the soil column. Water content also was monitored gravimetrically from changes in container mass. Measurements started when the soil surface was covered completely by tall fescue. Hence, changes in θv could be attributed entirely to water being taken up by roots of tall fescue. Daily measurements were taken over multiple 6- or 7-day drying cycles. Each drying cycle was preceded by an irrigation, and free drainage had ceased before measurements were initiated. Soil water content dropped from ≈0.35 to 0.10 m3·m-3 during each drying cycle. Correlation was excellent between θv and changes in water content determined by the DPHP and gravimetric methods. Comparisons with the gravimetric method showed that the DPHP sensors could measure average container θv within 0.03 m3·m-3 and changes in soil water content within 0.01 m3·m-3.

A low-power, low-cost soil-moisture sensor using dual-probe heat-pulse technique

2015 ◽  
Vol 233 ◽  
pp. 108-117 ◽  
Author(s):  
Nikhil Jorapur ◽  
Vinay S. Palaparthy ◽  
Shahbaz Sarik ◽  
Jobish John ◽  
Maryam Shojaei Baghini ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Low Power ◽  
Low Cost ◽  
Heat Pulse ◽  
Pulse Technique ◽  
Moisture Sensor ◽  
Soil Moisture Sensor ◽  
Dual Probe

Root-zone hydraulic lift evaluated with the dual-probe heat-pulse technique

Soil Research ◽  
2000 ◽  
Vol 38 (5) ◽  
pp. 927 ◽  
Author(s):  
Y. Song ◽  
M. B. Kirkham ◽  
J. M. Ham ◽  
G. J. Kluitenberg
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Root Zone ◽  
Sandy Loam ◽  
Soil Column ◽  
Heat Pulse ◽  
Hydraulic Lift ◽  
Pulse Technique ◽  
Dual Probe

Roots are movers of water in the soil. One method of movement is through hydraulic lift, which occurs when plants extract water from a moist subsoil and release it into a dry topsoil. Detection of hydraulic lift has been hampered by the lack of instruments sensitive enough to measure the small amount of water moved. Recently, the dual-probe heat-pulse (DPHP) technique has been used to monitor with fine spatial resolution the soil water content in root-zones. The objective of this research was to determine if water is released by hydraulic lift, using the DPHP technique. Sunflower (Helianthus annuus L.) was grown in a column (38 cm height; 25 cm diam.; bulk density = 1.45 Mg/m3) packed with a Haynie very fine sandy loam (coarse-silty, mixed, calcareous, mesic Mollic Udifluvents; FAO-Eutric Fluvisols) with its roots divided between a top dry layer and a lower wet layer. Eight DPHP sensors installed in the soil column were used to monitor soil water content. During 24 measurement days, hydraulic lift was evident only when the plant was wilted. This occurred when the lower ‘wet’ layer had been allowed to dry and then it was re-watered. At this time, the roots in the upper dry layer released water, increasing the soil water content in the centre of the root mass by 0.019 m3/m3 (increase from 0.121 m3/m3 to 0.140 m3/m3). The soil-water increase was similar to other values reported in the literature and show it to be small.

Comparison of single and dual probes for measuring soil thermal properties with transient heating

Soil Research ◽  
1994 ◽  
Vol 32 (3) ◽  
pp. 447 ◽  
Author(s):  
KL Bristow ◽  
RD White ◽  
GJ Kluitenberg
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Heat Pulse ◽  
Volumetric Heat Capacity ◽  
Transient Heating ◽  
Single Probe ◽  
Soil Thermal Properties ◽  
Dual Probe

Storage and transfer of heat in soils is governed by the soil thermal properties and these properties are therefore needed in many agricultural and engineering applications. In this paper we discuss solutions of the heat flow equation applicable to single and dual probe transient heating methods, and describe measurements made on air-dry sand to show how these methods can be used to obtain soil thermal properties. Measurements show that the two methods yield similar values of thermal conductivity. When determining thermal conductivity from the single probe data, it is best to use nonlinear curve fitting and to include a correction term in the model to account for the presence of the probe. Measurements of volumetric heat capacity made by using the dual probe heat-pulse method agreed well with independent estimates obtained using the de Vries method of summing the heat capacities of the soil constituents. The advantage of using the dual probe method together with the appropriate heat-pulse theory rather than the single probe is that all three soil thermal properties, the thermal diffusivity, volumetric heat capacity, and thermal conductivity, can be determined from a single heat-pulse measurement. Instantaneous heat-pulse theory can be used with the dual probe method to determine heat capacity from short duration heat-pulse data, but it should not be used to determine the thermal diffusivity and thermal conductivity.

Sign in / Sign up

Export Citation Format

Share Document