Computed errors for a square guarded hot plate for the measurement of thermal conductivities of insulating materials

摘要: Calculations based on a theory for square guarded hot plate (Donaldson 1961) in which the metal plates either side of heater, gap, insulation, etc., are taken into account show that errors due to form construction and operation apparatus fall three categories: actual existence i.e. error occurs when insulation is perfect there no temperature difference across gap; imperfect insulation; any gap. These have been computed range results these computations discussed. It found reduced if guard width also gap increased. shown by choosing edge best suited sample being tested used operating within narrower limits than stipulated Standards, overall thermal conductivity measurements could be less 1%.