Effectiveness of modified Lee-Charlton's disc apparatus technique for determination of thermal conductivity of heat-insulating panels with large thickness

This research was designed to examine the feasibility of using the Modified Lee-Charlton’s Disc (MLD) apparatus technique to obtain accurate, valid, and reliable thermal conductivities for heat-insulating panels that have large thicknesses, specifically up to 25.0 mm. Test samples were prepared from cement mortar, gypsum plasterboard, medium-density fiberboard, wood dust reinforced composite board, plywood, and expanded polystyrene sheet and then coded as CTM, GPB, MDF, WEC, PLW, and EPS, respectively. A Heat flow meter (HFM) was employed as the gold standard technique, and the EPS samples were used as standard reference materials for validation and uncertainty assessments of the MLD method. In addition to graphical analysis, the results were examined statistically using one-way analysis of variance (ANOVA) at 0.05 and Pearson’s product-moment correlation coefficient (PPMCC). It was found that the results rendered by the MLD method compared well with those obtained using the HFM method, yielding ANOVA of 0.00002 and PPMCC of 0.99999. The validation tests showed deviations ranging from 0.089 % to 0.178 % with respect to the results obtained by the HFM method and 0.030 % to 0.059 % when compared with the thermal conductivity declared in the literature for the EPS. The uncertainty in the measurements made by the MLD method was better than 1.5 %. All these showed that the MLD apparatus technique is effective in producing accurate and reliable thermal conductivity results for assorted kinds of thermal insulation panels with thicknesses as large as up to 25.0 mm.