Simultaneous Measurements Of Thermal Conductivity Research Articles

Simultaneous measurement of thermal conductivity and specific heat of short-lived liquid

The thermal conductivity and specific heat of a short-lived liquid are measured simultaneously by a pulsed version of the probe method. The nonuniformity of the temperature in the body of the probe is taken into account. A block diagram of experimental apparatus realizing the method is described.

Pressure dependence of the thermal conductivity, thermal diffusivity, and specific heat of some polymers

AbstractThe pressure dependence of the specific heat of poly(methyl methacrylate), polystyrene, and atactic and isotactic polypropylene was determined from simultaneous measurements of thermal conductivity and diffusivity in a cylindrical geometry at 300°K and in the pressure range 0–37 kbar. The thermal conductivity and the diffusivity both increase strongly with pressure, while the specific heat decreases. The pressure dependencies are most pronounced at low pressures. The results are compared with other experimental results and with theoretical calculations.

Simultaneous Measurement of Low-Temperature Specific Heat and Thermal Conductivity by Temperature-Wave Method

An experimental procedure is proposed for a simultaneous measurement of thermal conductivity and thermal diffusivity of a specimen by a modified temperature-wave (Ångström's) method. The temperature wave is generated by an AC current in a heater attached to the specimen. The diffusivity can be obtained from the phase difference of the temperature wave between two positions of the specimen, and the conductivity is determined from the static temperature gradient produced by the DC component of input power. The temperatures and their variation at two positions are detected by carbon film resistance thermometers. The specific heat of the specimen is derived from the values of thermal diffusivity and conductivity. An example of experimental results is given for the case of Cu-Al alloy specimen. The reliability of the measured values of conductivity and diffusivity is estimated to be 5∼8% in liquid-helium temperature range.

Pressure dependence of the thermal conductivity, thermal diffusivity, and specific heat of polyethylene

The pressure dependence of the specific heat of high-density polyethylene was determined from simultaneous measurements of thermal conductivity and diffusivity in a cylindrical geometry at 300 K and in the pressure range 0–25 kbar. The thermal conductivity and the diffusivity both increase strongly with pressure, the values at 25 kbar being higher by factors of 2.75 and 2.77, respectively, than those at atmospheric pressure. The specific heat decreases, most strongly so at low pressures, and its value at 25 kbar is 0.80 times that at atmospheric pressure. The thermal conductivity of low-density polyethylene was determined as a function of pressure. Its value at 25 kbar was found to be 2.19 times that at atmospheric pressure. The difference in conductivity response to pressure between the two varieties is given a simple theoretical interpretation.