Measurement of Thermal Conductivity Using Cyclic Heat, Transient Hot Wire, and Hot Disk Methods

Abstract

We have designed a thermal conductivity measuring apparatus using the Cyclic Heat, the Transient Hot Wire, and the Hot Disk methods. Using the apparatus, the thermal conductivities of Polyurethane foams were measured in the temperature range from -170℃ to 25℃. Comparison of measured values using the Transient Hot-Wire method with the Cyclic Heat and the Hot Disk methods indicated good agreement. It was confirmed that the results of measurement using different methods agree with each other under the conditions of using the same specimen and conducting measurements under the same environment. However, measured values using the Cyclic Heat method at temperatures near 0℃ were larger than those obtained by other methods. It was because that, when a heat wave with the amplitude about 4℃ was conducting through the specimen, the moisture in the specimen changed phases (between ice and water) periodically. Measured values using the Hot Disk method in the temperature range from -170℃ to -120℃ were smaller than the others.