SU1224695A1 - Method of determining heat conduction of non-metallic wet capillary-porous materials - Google Patents

Abstract

The invention relates to a measurement technique, in particular to methods for determining the physical properties of substances, and can be used to determine the thermal conductivity of various non-metallic capillary-porous materials. The aim of the invention is to increase the accuracy of thermal conductivity determination by ensuring that the material under study is placed in an alternating electric field of a capacitor, its capacitance is measured, and thermal conductivity is determined by the graduation dependence. 2 Il. i (lu to 4 o sd cd

Description

The invention relates to a measurement technique, in particular, to methods for determining the physical properties of substances and can be used to determine the thermal conductivity of various non-metallic capillary-porous materials, for example concrete.

The purpose of the invention is to increase the efficiency and accuracy of thermal conductivity.

Fig. 1 shows experimentally obtained dependences of thermal conductivity j and dielectric constant of claydite-concrete on its

and equilibrium W and density 5 in FIG. 2 is personal humidity. Capacitive perzavisimost thermal conductivity j from capacitance C,

Capacitance measurements (dielectric constant) were carried out at a frequency of 6 MHz by the method of parametric modulation, free from the distorting influence of the through conductivity of the material. Measurements of thermal conductivity were carried out by a non-stationary method with a pulsed heat source. The solid lines (Fig. 1) denote the dependences of thermal conductivity, and the dotted lines indicate the dependences of the dielectric constant.

The proposed method for determining thermal conductivity is based on an experimentally established analogy of the dependences of thermal conductivity K and dielectric constant of wet capillary-porous materials on their humidity W and density U.

The relationship between y and C is obtained experimentally by calibrating the capacitance meter by thermal conductivity on samples of a particular material, and their thermal conductivity is determined by any known method.

The definition of L according to the calibration dependence by measuring the capacitance allows one to exclude the thermal effect on the material, and the electric field in the material is almost inertia-free.

The primary converter of the VSKM-12 device is installed on the surface of one of the samples of keramsit concrete and its capacitance is measured, taken to read in arbitrary units using the digital indicator of the VSKM-12 device. The values obtained from the count are directly translated into the value of thermal conductivity by

25 cabinets of a previously obtained calibration curve for expanded clay concrete with a density of 1200 kg / m (Fig. 2).

Calibration dependence of the device VSKM-2 on thermal conductivity ke

30 ramsit concrete are obtained according to a routine calibration procedure, using as a reference method one of the known non-stationary thermal methods for determining the heat conduction

35

Claims (1)

Invention Formula The method for determining the thermal conductivity of nonmetallic wet ka40 pill-porous materials, based on the measurement of the electrical parameter, characterized in that, in order to improve the accuracy of the determination, the material is placed in 45 the alternating electric field of the capacitor, its capacitance is measured, and the desired parameter is determined from the calibration dependence. Example. As a technical tool, a commercially available VSKM-12 device is used, which is a diesel meter, the kit of which includes a capacitive primary converter of coplanar design with a diameter of 250 mm and a depth of soiai control mm. Based on the design and dimensions of the capacitive transducer, samples of the investigated material are prepared with dimensions of 250 X 250 X 100 mm. In this example, samples of expanded clay are taken with a density of 1200 kg / m personal moisture. A capacitive primary transducer of the VSKM-12 device is installed on the surface of one of the samples of expanded clay concrete and its capacitance is measured, and the readout is taken in arbitrary units using the VSKM-12 digital indicator. The obtained reference values are directly converted into the value of thermal conductivity using a previously obtained calibration curve for claydite concrete with a density of 1200 kg / m (Fig. 2). The calibration dependence of the VSKM-2 device on the thermal conductivity of expanded clay concrete is obtained according to the usual calibration procedure for a technique using one of the known non-stationary thermal methods for determining thermal conductivity as a reference. Invention Formula The method of determining the thermal conductivity of non-metallic wet capillary-porous materials, based on the measurement of the electrical parameter, characterized in that, in order to improve the determination accuracy, the material is placed in the alternating electric field of the capacitor, its capacitance is measured, and the desired parameter is determined by the calibration dependence. ( 45-0 .60 J5-055 .. 26 .. 7.55-. 75-. 7.45OOLO 0.35 0.30 -1r7fff5 FIG. one Zff25 V / 4 w thirty  ( ffmcvffrr fffffocfnt / ttef ffpuSope fyeff. e.j rffa yt / poBoffftt / u s / pcf fn / ff -f (C)  ffe / jaf sumoSemoffa i- f2OO l / yW FIG. 2 Editor I. Casard Compiled by A.Platov Tehred I.Veres. Order 9D4 / 43 Circulation 778 Subscription All-Union State Research Institute of the USSR State Committee for inventions and discoveries PZOZZ, Moscow, Zh-35, Raushsk nab. D. 4/5 Proich L pen to -1gol of the affiliated enterprise, Uzhgorod, Projecto, 4 thirty yeff C) Proofreader E. Sirohman