The choice of the optimum conditions for measuring the thermal properties of materials by the plane “instantaneous” heat source method

Non-destructive testing method for determining the solvent diffusion coefficient in the porous materials products

“…The mathematical model of the relative error root-mean-square estimate in determining the sought diffusion coefficient has the form [8,10]: are, respectively, the relative error in determining the coordinate of the calculated cross-section and the time to reach the maximum on the curve of the concentration change in the calculated section; δ m is the total value of the methodical error due to the incomplete correspondence of the mathematical model used to real physical processes.…”

Optimization of Measurements of the Thermophysical Properties of Thermally Insulating Materials

“…A method is created for selection of optimal heat pulse duration, conditions for processing of experimental data, and basic design size of a measuring instrument.Over the last decade, a number of studies have dealt with the development and modernization of techniques and equipment for measuring the thermal properties of materials based on so-called instantaneous heat source methods [1][2][3][4][5][6][7][8][9][10][11][12]. Mathematically, a real heat source of duration 2-6 sec is considered to be instantaneous and is specifi ed by a Dirac delta function [2, 3, 6, 13], i.e., with a very short duration on the order of 0-0.1 sec.…”

“…(5), the formula for calculating the thermal conductivity becomes Choice of Optimal γ and τ p . In accordance with the recommendations of [2,3,6,10,15], the following equations were obtained for calculating the mean square relative deviations δ a and δ λ of the measured thermal diffusivity a and thermal conductivity λ:…”

“…After taking the logarithm of Eq. (11), fi nding the differentials of its left and right sides, and considering the recommendations of the theory of errors [2,3,6,11,12,16], we obtain (13) In these calculations, P(τ p ) was determined using Eq. (12).…”

“…The variations in δ a and δ λ have been calculated using Eqs. (9) and (14) for τ p = 10 s, P = 55 W, a = 1.06·10 -7 m 2 /sec, λ = 0.194 W/(m·K), ΔP = 0.25 W, x = 2-8 mm, Δx = 0.1 mm, ΔT = 0.05 K, and δS = 0.5%.…”