Thermal Modeling of Multiple-Line-Heat-Source Guarded Hot Plate Apparatus

摘要: The National Institute of Standards and Technology is building a guarded hot plate apparatus advanced design to provide very accurate thermal transmission properties for specimens insulation 500 mm in diameter, with thicknesses up 110 mm, at mean temperatures from 90 K 900 K. This paper documents some the extensive modeling analyses that were camed out course designing this characterizing potential errors uncertainties. In an idealized apparatus, effective conductivity simply computed measured power input meter heater, area metering plate, temperature two cold plates, specimen thickness. actual there may be (a) variations (b) radial heat flow within specimen, (c) transient fluctuations add uncertainty conductivity. For new both analytical solutions finite element used model distributions critical components, flows might affect values, effects departures ideal steady-state conditions on test results. focuses results these computations.