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Extending the Capabilities of the Multiproperty Apparatus for Thermophysical Property Determinations

  • Mukund S. Deshpande
  • Raymond E. Taylor

Abstract

The unique multiproperty apparatus developed at Purdue University has proven to be a powerful scientific and engineering tool. Efforts were made to increase its usefulness even further. Successful efforts were made to relax geometrical constraints on the samples, as a result of which the multiproperty apparatus can handle larger diameter samples. In addition to weakening geometrical limitations on samples, thermal conductivity measurement in an inert argon atmosphere was also demonstrated. Agreement within 5% was obtained with data obtained in vacuum. Since the presence of an atmosphere restricts sample vaporization, higher measurement temperature should be attainable.

Efforts were also made to increase the accuracy of Thomson coefficient values. The iterative approach was adopted to develop computer programs. Our experience in their use showed that the uncertainty in the measurement was reduced, but that the scatter is still unacceptable.

A new method to measure Seebeck Coefficient on multiproperty apparatus was attempted by using AC direct heating rather than DC heating. A signal conditioning unit, which measures very low level DC signals in the presence of large AC signals, was constructed. The results obtained by its use show large errors are associated with this method and further efforts are needed to identify the sources of errors in order to improve it.

Keywords

Seebeck Coefficient Thermal Conductivity Measurement Radial Temperature Gradient Thomson Coefficient Inert Argon Atmosphere 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Nomenclature

A

cross sectional area of a sample

A(z)

cross sectional area of sample at position z

h

convection heat transfer coefficient

hr

overall radiation heat transfer coefficient

I

current flowing through conductor (amps)

j

current density

M

Equation (6)

\(\vec{n}\)

unit normal vector

P

perimeter of sample cross section

r

radial position

SAB

Seebeck coefficient (many times denoted as thermopower of thermocouple in literature)

T

temperature

T(r,z)

temperature as a function of position r and z

T1

temperature of position 1

T2

temperature of position 2

Tm

maximum temperature

To

ambient temperature

Ts

temperature at surface

V

potential

z

longitudinal position

zm

longitudinal position on sample where temperature is maximum

z1

longitudinal position 1

z2

longitudinal position 2

\(\nabla\)

delta operator

Δ

delta — refers differential quantity (e.g., ΔT — temperature difference, ΔV — voltage difference, etc.)

εH

total hemispherical emissivity

εC

convection emissivity factor

εEQ

overall heat transfer emissivity factor

ρ

electrical resistivity

σ

Stephen Boltzmann constant

λ

the thermal conductivity

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References

  1. 1.
    Flynn, D.R., “Measurement of Thermal Conductivity by Steady State Methods in Which the Sample is Heated Directly by Passage of an Electrical Current,” in Thermal Conductivity, Vol. 1, 241–300 (1969).Google Scholar
  2. 2.
    Taylor, R.E., Davis, F.E., and Powell, R.W., “Direct Heating Methods for Heating Thermal Conductivity of Solids at High Temperatures,” High Temperatures–High Pressures, 1, 663–73 (1969).Google Scholar
  3. 3.
    Taylor, R.E., “Survey on Direct Heating Methods for High Temperature Thermophysical Property Measurements of Solids,” High Temperatures–High Pressures, 4, 523–31 (1972).Google Scholar
  4. 4.
    Taylor, R.E., “Thermal Properties of Tungsten SRM’s 730 and 799,” J. of Heat Transfer, 100 (2), 330–3 (1978).CrossRefGoogle Scholar
  5. 5.
    Taylor, R.E. and Groot, H., “Thermophysical Properties of POCO Graphite,” High Temperatures–High Pressures, 12, 147–60 (1980).Google Scholar
  6. 6.
    James, H.M., “Interpretation of Direct Heat Measurements on a Long, but Not Thin Rod,” High Temperatures–High Pressures, 11, 669–81 (1979).Google Scholar
  7. 7.
    Deshpande, M.S., “Extending Capabilities of the Multiproperty Apparatus for Thermophysical Property Determinations,” M.S.M.E. Thesis submitted to the Faculty of School of Mechanical Engineering, Purdue University, May 1979.Google Scholar
  8. 8.
    Blatt, F.J., Schroeder, P.A., Foiles, C.L., Denis, G., “Thermoelectric Power of Metals,” Plenum Press, New York and London, p. 50 (1976).Google Scholar
  9. 9.
    Kraith, F., “Principles of Heat Transfer,” Interscience, New York (1965).Google Scholar
  10. 10.
    Taylor, R.E., “Thermophysical Properties of Proprietary Graphite,” PRL Report 155 (1978).Google Scholar
  11. 11.
    Deshpande, M.S. and Taylor, R.E., “Study of Direct Heating Methods in Heat Transfer Applications,” Annual Progress Report Submitted to Division of Sponsored Programs, National Science Foundation, Grant No. ENG77–16200 (1979).Google Scholar
  12. 12.
    Rice, J.R., “Approximation Formulas for Physical Data,” Pyrodynamics, 6, 231–56 (1968).Google Scholar
  13. 13.
    Lander, J.J., “Measurement of Thomson Coefficient for Metals at High Temperatures and of Peltier Coefficients for Solid-Liquid Interphase of Metals,” Physical Review, 74 (4), 479–88 (1948).CrossRefGoogle Scholar
  14. 14.
    Latchman, J.C. and McGurty, J.A., “The Use of Refractory Metals for Ultra High Temperature Thermocouples,” in: Temperature Its Measurement and Control in Science and Industry, C.M. Hertzfeld and A.I. Dahl, eds., Reinhold, NY, 3(2), 177–87 (1962).Google Scholar

Copyright information

© Purdue Research Foundation 1983

Authors and Affiliations

  • Mukund S. Deshpande
    • 1
  • Raymond E. Taylor
    • 1
  1. 1.Thermophysical Properties Research Laboratory School of Mechanical EngineeringPurdue UniversityWest LafayetteUSA

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