ASTM D7896-14
(Test Method)Standard Test Method for Thermal Conductivity, Thermal Diffusivity and Volumetric Heat Capacity of Engine Coolants and Related Fluids by Transient Hot Wire Liquid Thermal Conductivity Method
Standard Test Method for Thermal Conductivity, Thermal Diffusivity and Volumetric Heat Capacity of Engine Coolants and Related Fluids by Transient Hot Wire Liquid Thermal Conductivity Method
SIGNIFICANCE AND USE
5.1 This test method covers the measurement of thermal properties for engine coolants (aqueous or non-aqueous) and related fluids.
5.2 With each single measurement, the thermal conductivity (λ) and thermal diffusivity (α) are measured directly, and volumetric heat capacity (VHC) is determined by the relationship:
5.3 The test method is transient and requires only a small amount of specimen and a short duration of time (0.8 s) to run a measurement. These attributes minimize heat convection in the liquid.
5.4 The brief application of current to the sensor wire adds very little heat to the test specimen and ten repetitive tests may be applied at 30-s intervals without causing any significant convection or temperature drift.
SCOPE
1.1 This test method covers the use of a transient hot wire liquid thermal conductivity method and associated equipment (the System) for the determination of thermal conductivity, thermal diffusivity and volumetric heat capacity of aqueous engine coolants, non-aqueous engine coolants, and related fluids. The System is intended for use in a laboratory.
1.2 The System directly measures thermal conductivity and thermal diffusivity without the requirement to input any additional properties. Volumetric heat capacity is calculated by dividing the thermal conductivity by the thermal diffusivity of the sample measured.
1.3 This test method can be applied to any aqueous or non-aqueous engine coolants or related fluid with thermal conductivity in the range of 0.1 to 1.0 W/m∙K.
1.4 This test method excludes fluids that react with platinum.
1.5 The range of temperatures applicable to this test method is –20 to 100°C.
1.6 This test method requires a sample of approximately 40 mL.
1.7 The System may be used without external pressurization for any fluid having a vapor pressure of 33.8 kPa (4.9 psia) or less at the test temperature.
1.8 For a fluid having a vapor pressure greater than 33.8 kPa (4.9 psia) at the test temperature, external pressurization is required (see Annex A2).
1.9 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.9.1 Exception—Inch-pound units are provided in 1.7, 1.8, 4.1, 7.8, and A2.1 for information.
1.10 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
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Designation: D7896 − 14
Standard Test Method for
Thermal Conductivity, Thermal Diffusivity and Volumetric
Heat Capacity of Engine Coolants and Related Fluids by
1
Transient Hot Wire Liquid Thermal Conductivity Method
This standard is issued under the fixed designation D7896; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.10 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers the use of a transient hot wire
responsibility of the user of this standard to establish appro-
liquid thermal conductivity method and associated equipment
priate safety and health practices and determine the applica-
(the System) for the determination of thermal conductivity,
bility of regulatory limitations prior to use.
thermal diffusivity and volumetric heat capacity of aqueous
engine coolants, non-aqueous engine coolants, and related
2. Referenced Documents
fluids. The System is intended for use in a laboratory.
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2.1 ASTM Standards:
1.2 The System directly measures thermal conductivity and
D1176Practice for Sampling and Preparing Aqueous Solu-
thermal diffusivity without the requirement to input any
tionsofEngineCoolantsorAntirustsforTestingPurposes
additional properties.Volumetric heat capacity is calculated by
E691Practice for Conducting an Interlaboratory Study to
dividing the thermal conductivity by the thermal diffusivity of
Determine the Precision of a Test Method
the sample measured.
3. Terminology
1.3 This test method can be applied to any aqueous or
non-aqueous engine coolants or related fluid with thermal
3.1 Definitions of Thermal Related Units:
conductivity in the range of 0.1 to 1.0 W/m·K.
3.1.1 density (ρ),n—the mass per unit volume of a sub-
stance under specific conditions of pressure and temperature.
1.4 This test method excludes fluids that react with plati-
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Unit: kg/m .
num.
3.1.2 specific heat capacity (Cp),n—the amount of heat
1.5 Therangeoftemperaturesapplicabletothistestmethod
required to raise the temperature of a unit mass of material by
is –20 to 100°C.
1°C. See Annex A1. Unit: J/(kg·K).
1.6 This test method requires a sample of approximately 40
3.1.3 thermal conductivity (λ),n—rate of heat flow under
mL.
steady conditions through unit area, per unit temperature
1.7 TheSystemmaybeusedwithoutexternalpressurization
gradient in the direction perpendicular to the area. Unit:
for any fluid having a vapor pressure of 33.8 kPa (4.9 psia) or
W/m·K.
less at the test temperature.
3.1.4 thermal diffusivity(α),n—ameasureoftheabilityofa
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1.8 Forafluidhavingavaporpressuregreaterthan33.8kPa
substance to transmit a difference in temperature. Unit: m /s.
(4.9 psia) at the test temperature, external pressurization is
3.1.5 volumetric heat capacity (VHC),n—the amount of
required (see Annex A2).
heat required to raise the temperature of a unit volume of
1.9 The values stated in SI units are to be regarded as
material by 1°C. Volumetric heat capacity is the thermal
standard. No other units of measurement are included in this
conductivity of a material divided by its thermal diffusivity.
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standard.
Unit: J/m ·K.
1.9.1 Exception—Inch-pound units are provided in 1.7, 1.8,
3.2 Definitions of Terms Specific to This Standard:
4.1, 7.8, and A2.1 for information.
3.2.1 transient hot wire method, n—a method for measure-
ment of thermal properties wherein a thin wire is immersed in
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This test method is under the jurisdiction ofASTM Committee D15 on Engine
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Coolants and Related Fluids, and is the direct responsibility of Subcommittee For referenced ASTM standards, visit the ASTM website, www.astm.org, or
D15.22 on Non-Aqueous Coolants. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved Feb. 1, 2014. Published June 2014. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
D7896-14. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D7896 − 14
Shown are the controller connected to the platinum-wire sensor with the sensor residing in the sampling cell, along with the liquid specimen. For non-ambient
temperature readings, the sampling cell inserts into a temperature control peripheral (not shown). The computer downloads data from the controller for storage and for
the creation of spreadsheets and reports.
FIG. 1 Transient Hot Wire Liquid Thermal Conductivity Apparatus
a liquid specimen that is contained in a sam
...
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