SYMPOSIA PAPER Published: 01 January 1978
STP35757S

Drift Measurement Technique Applied to Poor Conductors

Source

Many applications require knowledge of thermal properties, over a wide range of temperature, to within 5 percent. The speedy and economical acquisition of the data is often a prime concern. We are investigating the potential of the very simplest system (an unguarded plate system), used in a drift mode rather than in a steady-state mode, to fulfill this need.

When heat flows across a specimen whose mean temperature is drifting slowly and linearly with time, a term of the form CF(dT/dt) must be added to the steadystate equation. Data are taken over a given temperature range with the temperature both increasing and decreasing; the value of CF is then adjusted until the two sets of data produce the same value of conductivity. Since CF is a function of the density of the specimen and its specific heat at constant pressure, an approximate value of the thermal diffusivity is obtained as a by-product in this drift mode of operation.

The successful application of the technique is illustrated by both drift technique and steady-state measurements on microconcrete over the temperature range -20 to +60°C. Corrections for heat losses and nonlinear heat flow have been appraised by finite-element analysis and by comparisons with data from adiabatic linear heat flow systems. Our objective is to develop the apparatus for use up to 500°C.

Author Information

Ashworth, T
South Dakota School of Mines and Technology, Rapid City, S. Dak.
Lacey, WG
South Dakota School of Mines and Technology, Rapid City, S. Dak.
Ashworth, E
South Dakota School of Mines and Technology, Rapid City, S. Dak.
Price: $25.00
Contact Sales
Related
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Details
Developed by Committee: C16
Pages: 426–436
DOI: 10.1520/STP35757S
ISBN-EB: 978-0-8031-4729-4
ISBN-13: 978-0-8031-0589-8