Investigations on design and construction of a square guarded hot plate (SGHP) apparatus for thermal conductivity measurement of insulation materials

This paper presents a detailed description of a double-sided square guarded hot plate (SGHP) apparatus designed specifically for testing low to moderate thermal conductivity materials having thermal conductivities in the range of 0.02–3.0 Wm−1K−1. Measurements are conducted in the temperature range of 323–573 K with a temperature difference of 20 K imposed across the test specimen. An analysis of measurement data obtained from tests performed on standard reference materials (SRM) yielded a combined measurement uncertainty of ±6.22%, thereby giving an insight into the precision of the designed SGHP apparatus presented in the study. Experimental investigations on several low thermal conductivity insulation materials having thermal conductivities in the above stated range have been performed to validate the measurement system as a whole and the results are presented.