On the Modification of Lee – Charlton’s Disc Apparatus Technique for Thermal Conductivity Determination

In recent years, the demand for thermal insulation has been very high. Consequently, assorted new heat-insulating materials are being developed in order to meet the needs for thermal insulation in buildings, power engineering, refrigeration, spacecraft, mechanical systems, firemanship, installations, and industrial facilities among others. Enhancement of effective thermal conductivity investigation for such materials requires the use of a device that is inexpensive, time-saving, easy-to-use, and capable of rendering reliable/accurate results for a wide range of the materials. If not that the traditional Lee – Charlton’s Disc (TLD) apparatus set-up usually requires a long-time duration to attain thermal balance, it would be the best fit for the task, thus warranting the design of a modified Lee – Charlton’s Disc (MLD) apparatus set-up to solve this problem. Achievement of time-saving in this new approach was feasible by using two metallic discs with electric hotplate or bunsen burner (instead of water) for heating purpose. The present study sought to proffer the possibility of analysing samples that are significantly smaller than the size of the heating element of an available electric hotplate and also compare the MLD apparatus set-up with that of TLD. Steady-state durations were measured. Also, the total weight of components in each set-up was determined and compared for appraisal of portability. It was observed that measurement (steady- state) durations were reduced by about 66.2 % to 66.7 % when using MLD apparatus technique over TLD technique to analyse samples of same dimensions prepared from a particular material. Aside being simple and about 56.69 % to 92.91 % more portable, the MLD apparatus set-up technique rendered more accurate thermal conductivity results than those obtained by employing the TLD apparatus technique. Generally, it was noticed that the MLD apparatus technique could satisfy the above-mentioned conditions with uncertainty better than 1.5 % if applied for determination of thermal conductivity of thermal insulation materials having thickness of up to about 9.0mm.