SU1582079A1 - Apparatus for determining coefficient of diffusion of liquid vapours in gas - Google Patents

Abstract

The invention relates to instrumentation engineering, in particular, to devices for determining the diffusion coefficients of liquid vapors in gases, and can be used in scientific research practice in determining the thermodynamic properties of gases at various temperatures and pressures. The aim of the invention is to reduce the required quantities of gas and liquid. The goal is achieved by making an element for placing a liquid sample in the form of a wire ring of a material ground by a liquid and located in the center of a sealed gas chamber at a predetermined distance from the chamber walls. The device is equipped with an optical system for measuring the radius of a drop of liquid on a wire ring. 1 il.

Description

The invention relates to instrumentation engineering, namely, devices for determining the diffusion coefficient of the peers of a liquid in gases, and can be used in determining the thermodynamic properties of gases at different temperatures and pressures in various fields of science and technology.

The aim of the invention is to reduce the flow of liquid and gas.

The drawing shows a device for determining the diffusion coefficient of liquid vapors in a gas.

The device contains a thermoelement ring 1, a standard 2, a camera 3 with elongated rings 4, a barometer 5, a measuring device 6, a thermostat 7 and a glass envelope 8 with a cover 9

from the fine mesh. The ring thermoelement 1 is intended to form a spherical drop and measure the temperature of a liquid and air. Reference 2 serves to determine the drop radius from photographs taken with the help of camera 3. Elongated rings 4 are necessary for photographing from a short distance. Barometer 5 is designed to measure air pressure. The device 6 serves to measure the emf of the thermoelement, and the thermostat 7 to maintain the second ends at a constant temperature of 0 ° C. The glass sheath 8 and the cover 9 prevent airflow.

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Yu

about j

with

The element for placing the liquid sample is made as follows.

Initially, arc welding of wires along the end face in alcohol was performed. The resulting spherical flow is mechanically processed to the diameter of the wires. A cylindrical pattern in the joint area of the wire bends the ring with an average diameter of 0.12-0.15 cm. Then the ring is bent so that its plane is perpendicular to the ends of the wire. For measurements, the ends are placed in an insulator with holes, and the distance between the wires near the ring is set to 0.01-0.01 cm.

The element for placing the liquid sample is installed inside the gas chamber so that the distance from the wire ring of the thermoelement to the walls of the gas chamber satisfies the ratio

1 gk (10m3, - Gn

where 1 is the distance from the wire

thermoelement rings to the chamber walls for gas, cm; rk is the radius of the wire lancetermoelement, cm; о - liquid flow ratio, g / cm3; - density of saturated vapors

liquids, g / cm3. Optical windows are made in the side walls of the gas chamber to illuminate a liquid droplet on a wire thermopile ring and measure its radius using a meter for the radius of a liquid droplet located outside the gas chamber and optically coupled to the element for accommodating a liquid sample. A narrow-capillary dosing pipette is passed through the top wall of the gas chamber to form a liquid drop on the wire ring.

The device works as follows.

A gas chamber in the form of a cube with a rib length of 35 cm is filled with gas. Using a dosing narrow capillary pipette, a spherical shape drop of a liquid is formed on a wire thermocouple ring with a diameter of 0.15 cm. After a steady-state temperature is reached, a drop of liquid with

Gn

Using the optical system, the dependence of the radius g of a liquid drop on time is measured. The dependence of (g / r0) 2 on time is plotted, where r0 is the radius of a drop of liquid at the initial moment of time, see. The slope of the rectilinear portion of this dependence is determined. Diffusion coefficient

liquid vapor in a gas is calculated using

D ft Ј "Ld tR"

2fH (tp tg °

five

0

five

where D is the diffusion coefficient of liquid vapors in a gas, cm2 / s; p (t,) is the density of the liquid, g / cm3;

J 6 -TV

o (t) is the density of saturated pag / h

liquid ra, g / cm3;

t.Ј - fluid temperature,

hail; rfl - radius of a drop of liquid in

the initial time, cm;

tg / is the tangent of the angle of inclination. In the study of diffusion in a gas in which the initial concentration of liquid vapor is not zero, for example, 0 in the study of diffusion of water vapor in humid air, the diffusion coefficient is calculated by the formula

5 -) J ts

where f is relative humidity

air; 0 RF) density of saturated units in the center

ditch, g / cm3;

tj - air temperature, degrees

Claims (1)

5 claims A device for determining the diffusion coefficient of liquid vapors in a gas, comprising a chamber for gas, Q equipped with an element for accommodating a liquid sample and a temperature meter, characterized in that, in order to reduce the flow of liquid and gas, the element for accommodating a liquid sample is structurally combined with a temperature meter and made in the form of a wire ring thermoelement, the radius of which ensures the retention of the liquid sample in the form of a spherical droplet, the element for placing the liquid sample is located inside the chamber for gas, made hermetically in such a way that the distance from the wire thermoelement ring to the chamber walls for the gas satisfies the ratio 1, where 1 is the distance from the wire thermoelement rings to the chamber walls for gas, cm; r “the radius of the wire ring thermoelement, cm; II  - density of the liquid, g / cm3; i  - density of saturated liquid vapors, g / cm3, in this case, optical windows are made in the walls of the gas chamber, and an element for placing a liquid sample is optically coupled to a liquid drop radius meter