Instrument to measure the thermal conductivity of gases
Abstract
The paper describes a new high-precision instrument to measure the thermal conductivity of gases up to 800°C and 400 atm in an absolute way. The instrument works on the hot-wire principle with a 5 μm platinum wire, and operates in the transient regime thus eliminating completely the effects of natural convection. The design parameters combined with an end-effects compensator ensure that the instrument performs almost exactly like a line source in an infinite fluid, thus permitting us to calculate the thermal conductivity from the slope of a Δ T, log t diagram on which 36-42 conjugate pairs of these quantities have been determined with great precision. The reproducibility of the instrument is several parts in ten thousand, the precision as well as the accuracy being estimated at 0.2% near room temperature. Preliminary results on helium at 300 K and up to 350 atm are given. Equally preliminary measurements on the noble gases Ar, Ne, Kr combined with our best measurements of viscosity, all extrapolated to q = 0, yield Eucken factors at 300 K which do not differ from the theoretical value by more than 0.4%. This allows us to state that the accuracy of each measurement is of the order of 0.2%.
- Publication:
-
Physica
- Pub Date:
- August 1974
- DOI:
- 10.1016/0031-8914(74)90341-3
- Bibcode:
- 1974Phy....75..454D
- Keywords:
-
- Gas Meters;
- Heat Measurement;
- Rare Gases;
- Thermal Conductivity Gages;
- Calibrating;
- Mathematical Models;
- Platinum;
- Specific Heat;
- Temperature Distribution;
- Volt-Ampere Characteristics;
- Wheatstone Bridges;
- Instrumentation and Photography