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Specific Heat

Small and versatile, ideal for many applications

Applications

  • Measure Point Water Content

  • Measure Specific Heat

Specifications

  • Accuracy: ± 5%

  • Dimensions:Head is 35mm x 10mm; needles are 30mm x 1.27mm in diameter.

  • Temperature Sensors: 10K Precision Thermistor

  • Material: epoxy body, stainless steel needles.

  • Cable length: 2m standard (additional cable available)

Theory

The Specific Heat Sensor consists of a pair of 30mm-long stainless steel needles, spaced 6mm apart. It is a Dual Needle Heat Pulse sensor (DNHP). One needle contains an Evanohm heater, and the other contains a Precision 10K Thermistor. After the sensor needles are inserted into the sample, a current is applied to the heater for 8 seconds. The temperature rise of the thermistor is then monitored. The specific heat of the material is inversely proportional to the height of the sensed temperature rise, and the thermal diffusivity of the material is related to the time taken for the pulse peak to pass the temperature sensor. The thermal conductivity can then be computed as the product of the thermal diffusivity and the specific heat. 

What you need

  • Heater Control Interface

  • Campbell Scientific Datalogger for accurate results (See datalogger compatibility for more information)

In the Package

DNHP sensor with your desired cable length, up to 45 meters. The sensor will need a heater control interface to guarantee correct and accurate heating, which is essential in obtaining an accurate measurement. Sample programs for use with Campbell Scientific Data loggers and Macros for data processing are also available upon request. 

Selected Publications

Bristow, K.L., R.D. White, and G.L. Kluitenberg, 1994. Comparison of Single and Dual Probes for Measuring Soil Thermal Properties with Transient Heating. Australian Journal of Soil Res. 32:447-464

Bristow, K.L., R.D. White, and R. Horton, 1994. Measurement of Soil Thermal Properties with a Dual-Probe Heat Pulse Technique. Soil Sci. Soc. Am. J. 55:291-293

Bristow, K.L., J.R. Bilskie, G.J. Kluitenberg, and R. Horton, 1995. Comparison of Techniques for Extracting Soil Thermal Properties from Dual Probe Heat Pulse Data. Soil Sci. Am. J. 1:160

Campbell, G.S., C. Calissendorff, and J.H. Williams, 1991. Probe for Measuring Soil Specific Heat Doing a Heat-Pulse Method. Soil Sci. Soc. Am. J. 55:291-293

Kluitenberg, G.J., J.M. Ham, and K.L. Bristow, 1993. Error Analysis of the Heat Pulse Method for Measuring Soil Volumetric Heat Capacity. Soil Sci. Soc. Am. J. 57:1444-1451

Taylor, S.A. and Jackson, R.D. 1986. Heat Capacity and Specific Heat. In "Methods of Soil Analysis. Part 1. Physical and Mineralogical Methods." (2nd Ed.) (Ed. A. Klute) ASA Agronomy Monograph No. 9 pp.941-4

Chief, K., Young, M. H., Lyles, B. F., Healey, J., Koonce, J., Knight, E., . . . Dana, G. 2009. Scaling Environmental Processes in Heterogeneous Arid Soils: Construction of Large Weighing Lysimeter Facility. Desert Research Institute. -see page 40

Young, M.H., Fenstermaker, L.F., Belnap, J., 2017. Monitoring water content dynamics of biological soil crusts. Journal of Arid Environments. Vol 142 (41-49).