METHOD OF DETERMINING THERMAL CONDUCTIVITY COEFFICIENT OF LIQUID HEAT-INSULATING COATINGS

摘要

FIELD: measurement technology.;SUBSTANCE: invention relates to investigation and analysis of thermophysical properties of materials and can be used when determining thermal conductivity coefficient of liquid heat-insulating coatings. Proposed method of determining thermal conductivity coefficient of liquid heat-insulating coatings involves the use of Elcometer 319 and PosiTektor DPM instruments for measuring temperature on the coating surface. Heat source is covered with a metal plate with applied liquid ceramic heat insulation. Plate covers the entire area of the heating element in order to minimise the effect of convective flows from the heated surface of the plate. Heating is performed in steps with time intervals for temperature relaxation with gradual increase of the temperature. Measuring is performed with Elcometer 319 or PosiTektor DPM instrument 3 hours after the heat source switch-on. Then the temperature is measured on the surface of liquid heat insulation, as well as the temperatures of the heat source and the environment. Calculation of thermal conductivity coefficient is performed by formula: ; $\lambda =\frac{\delta \cdot {\alpha }_t\cdot (t_s-t_a)}{(t_t-t_s)},\mathop{\mathrm{image}}$ ;where δ is thickness of liquid heat insulation; α_t - coefficient of heat transfer from the surface; t_s - temperature on the surface of heat insulation; t_a - ambient air temperature; t_s - temperature of the heat source.;EFFECT: higher accuracy of measuring thermal conductivity coefficient of liquid heat-insulating coatings.