Solid thermal conductivity cells

ITI Company: The model C-600-S Thermal Conductivity Cell is designed to measure the thermal conductivities of all solids within the range of 0.015 to 5 Btu/hr, ft, oF (0.025 to 8.6 W/M,oC).

APPLICATION

The model C-600-S Thermal Conductivity Cell is designed to measure the thermal conductivities of all solids within the range of 0.015 to 5 BTU/hr.ft.°F (0.025 to 8.6 W/M, oC). The cell will accept samples varying in thickness from 1/2” – 1.00”. Typical materials whose conductivities can be measures are polymers, insulations, composites, medical tissues, cloth, natural fibers (wood), rock, etc. With the use of an environmental chamber, the thermal conductivities may be determined over the temperature range of cryogenic to +600 °F.

OPERATION

The specimen to be measured is inserted between the upper and lower sensing units as indicated in Fig. 1). Good thermal contact between the specimen and sensing surfaces can be achieved by means of a thermally conductive compound. The desired operating temperature is adjusted with the digital controller on the readout console. When the cell attains thermal equilibrium, the resulting temperature difference and heat flux signals are displayed upon the digital meters. These values are substituted in Fourier’s one-dimensional conduction equation to yield the thermal conductivity.

ACCURACY

Dual, matched, 1% accurate heat flux transducers monitor the heat flow to and from the specimen being measured. Signals from the heat flux transducers are electronically coupled to account for most edge losses from the specimen. The differential thermocouple, which measures the temperature difference, has known accuracy of better than 1%. At thermal equilibrium, the cell is capable of determining the thermal conductivities within 5% of true values.