ANALYSIS OF VARIOUS DESIGN AND OPERATING PARAMETERS OF THE THERMAL-CONDUCTIVITY PROBE

The thermal conductivity (k) probe is derived from an idealized transi ent heat transfer model; therefore, there are inevitable differences b etween the real probe and the theoretical model. However the k probe i s still an accurate and practical measurement device with wide-ranging applications if designed and used properly. Users of a thermal conduc tivity probe must be aware of its limitations and the possible errors that can develop in its application. This paper includes a theoretical derivation of the k probe equation and some experimental and theoreti cal simulations of parameters that can cause errors in the application of the k probe. An explanation is given of the significance of certai n design and operating parameters. Some of the findings in the study a re that the time-correction factor is not required and contact resista nce does not affect accuracy. The calibration factor is necessary sinc e it compensates for the difference in the thermal masses of the probe and the sample. Errors due to edge effects and convection can be avoi ded by limiting data analysis to the linear section of the time-temper ature plot. The truncation error is minimized by making beta as small as possible. Copyright (C) 1996 Elsevier Science Limited