THEORY AND DESIGN CONSIDERATIONS IN DEVELOPING A MULTI-PURPOSE INSTRUMENT FOR DETERMINATION OF TWELVE PROPERTIES
PURDUE UNIV LAFAYETTE IN THERMODYNAMIC AND HEAT TRANSFER SECTION
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The development of a new instrument is described and also techniques of measurement to determine for fluids 1 thermal conductivity, 2 dielectric constant, and hence 3 index of refraction, 4 electrical conductivity a.c., 5 electrical conductivity d.c. for gases and vapors 6 p-v-T properties for liquids 7 thermal expansion coefficient, 8 compressibility, 9 vapor pressure, 10 specific heat c sub p, 11 specific heat c sub v for solids 12 specific heat and for instrument materials thermal expansion coefficient and Youngs modulus. A new thermostat operating from about -190 C to 650 C is described. This device is controlled automatically and can follow pre-set temperature-time functions. Detailed analysis is made for the procedure necessary to establish isothermal conditions at surfaces wetted by the test substances and to evaluate deviations from such conditions due to the disturbance of the temperature field in the neighborhood of the surfaces caused by the temperature sensing elements. This also is important so that the correct surface temperature can be derived from the readings of the thermometer. The construction of the centering rod the most critical part of the multipurpose instrument being a double electrically shielded lead-in and a centering device is described as is also briefly the final design of the apparatus.
- Test Facilities, Equipment and Methods