A Transient Hot Wire Thermal Conductivity Apparatus for Fluids

Abstract

A new apparatus for measuring the thermal conductivity of fluids is described. This is an absolute method utilizing a transient hot wire. Measurements are made with a 12.7 p,m diameter platinum wire at real times of up to 1 second. The data acquisition system includes a minicomputer and a digital voltmeter. The experimental core of the system incorporates a compensating hot wire in a Wheatstone bridge circuit. The cell containing the core of the apparatus is designed to accommodate pressures from 0 to 70 MPa and temperatures from 70 to 320 K. Oxygel1 was measured over a wide range of physical states including the dilute gas, the moderately dense gas, the near critical region, the compressed liquid states, and the vapor ai temperatures below the critical temper· ature. Performance checks of the apparatus were conducted with nitrogen, helium and argon. Measurement of rare gases allows a direct comparison to the kinetic theory of gases through the viscosity. A second check looks at the variation of the measured thermal conductivity as a function of the applied power. The precision (2 a) of the new system is between 0.5 and 0.8 percent for wire temperature transients of 4 to 5 K, while the accuracy is estitnated at around 1.5 percent.

Heat transfer under high-power heating of liquids. 1. Experiment and inverse algorithm

“…, 2 cm. As usual [3][4][5][6][7][8][9][10][11][12], probe combines functions of both a heater and a resistance thermometer. Standard reference table for platinum thermometers is implemented for resistance-to-temperature conversio n. A relative version of the method was applied.…”

“…Conventional solution of this problem is probe calibration using reference substances [6]. Generally, saturated hydrocarbo ns, such as n-hexadecane and n-hexane are used as calibration fluids.…”

“…The properties of fluids are normally measure d under conditions of small temperature perturbation s. Both stationar y and non-stationar y measure ment techniques have been developed, with the transient hot-wire method being most prevalent [4][5][6][7][8].…”

Numerical Investigation on the Effect of Cementing Properties on the Thermal and Mechanical Stability of Geothermal Wells

“…The cement specimen was cured in the mold with dimensions of 50 mm × 100 mm × 50 mm to measure the thermal conductivity. The QTM-500 thermal conductivity meter adopts the transient hot wire method corresponding to the following line source model (Kestin and Wakeham 1978;Roder 1981;Coquard et al, 2006) [12][13][14]:…”

Absolute Determination of the Thermal Conductivity of Argon at Room Temperature and Pressures Up to 68 Mpa

“…A new apparatus of the transient hot wire technique has been developed [7] to measure the thermal conductivity of fluids in the temperature range 70-320 K with pressure to 70 MPa. We report here the measurements obtained for argon at 300.65 K.…”