SU744282A1 - Method of determining temperature factor of liquid surface tension and apparatus for realizing the same - Google Patents

Description

to Si, H is the distance from the cut-off of the capillary, to the bottom, the height of the liquid column in a rigid vessel, respectively.

The way it is organized, in the device which is BbinoJii jHo in the form of ide ::: tiichi communal capillaries, immersed in communicating vessels with the test liquid, each of which is equipped with a heater, the couplings are connected to an inert gas source, and the vessels are connected to an evacuation system, one of the vessels is set relative to the capillary with the possibility of its vertical movement.

The drawing shows schematically the proposed device for determining the temperature coefficient of the surface tension of a liquid.

The device consists of two cylindrical vessels 2 and 3 communicating via tube 1 with the test piece. into which two identical communicating capillaries 4 and 5 are also immersed. The communicating vessels are connected via a valve to the pumping system, and the capillary is connected via a leak valve 7 to an inert gas source (n.a, not shown). Vessels 2 and 3 are equipped with heaters 8 and 9, with the help of which a temperature difference is created at the tips of the caps in the vessels. The temperature difference between the liquid in KOKChL.KOV KA1P-LYAROV f P is determined by the differential thermopa 10-10. The liquid baud of the investigated liquid B vessels 2 and 3 are produced by EC; re-holes 11-11, which. The covers are closed (sealed:) about the blagar, which is transmitted through the kvvarovye transitions to the bellows 12, the depth of the capillary 4 immersion in the liquid in the vessel 2 is regulated by means of М1гр: the rotor screw 13 with high accuracy. The entire device is placed in a thermostat 14.

Us.Trejso: in works in the following way

By means of a thermostat 14 around a horizontal axis 15, the device is rigidly fixed in it and is mounted in the working position. In this case, parallel capillaries are arranged vertically and immersed in a liquid at the same depth. The latter is achieved in a friendly way. With the help of needle-like chain 7, by means of capillaries 4 and 5, inert gas bubbles (He, Ar) are slowly passed through the liquid. By simultaneously adjusting the depth of loading of the capillary 4 into the liquid, microvines 13 are achieved when the gas bubbles at the same temperature at the tips of the capillaries detach from them simultaneously. At this time, the position of the micrometer screw is fixed.

When the heater 9 increases the temperature of the liquid in the vessel 3, leaving the temperature of the liquid in the second vessel 2 unchanged, then the bubbles are not separated from both capillaries at the same time. The bubbles now exit through that capillary, the cut of which is total, the pressure (hydrostatic plus Laplace) is less. Parallel by moving the bottom of vessel 2 to & h by turning the macro screw through a certain angle, one achieves a position where the bubbles re-emerge simultaneously through both capillaries. Since the diameters of the capillaries at the same temperature are exactly the same, then there is equality. d6 h

) (u)

(L4 dkAT)

where is 6

surface tension

-the density of the liquid;

R

-radius capillary;

g

s

- its linear coefficient of thermal expansion,

- the depth of the capillary in the liquid at a temperature t;

.-2

.- a change in the immersion depth of the l-5t capillary while turning the microscrew through the QH angle; screw pitch;

Pi h,

the density of the fluid at, the value that would take h, if the vessel walls did not experience thermal expansion when it was heated by q T,

& h

the correction term takes into account the thermal expansion of the vessel and the liquid in it when heated in dT.

The neglect led by a higher order of smallness, the formula (2) is rewritten as

 d5 ..;

: h:

About LT About

.C, T 47t J & T

It is easy to see that the most significant contribution to the correction term

()

is introduced by the ratio between the volumetric expansion coefficient of the liquid phase () and the solid wall (. 3 s) of the instrument.

In fact, for the overwhelming majority of liquid substances b 10 100 dyne / cm. If made

Q is from quartz, thenOch b 10 dyn / cm-grad, and since r is 10 cm, g / cm, qirlO cm / sec, and then / yrgd Ydin / cm-deg.

Claims (2)

In the transition from quartz to molybdenum glass Cd (H o deg), these corrections do not acquire practical significance. By neglecting them, the final result is 5f-isV.-5P (), 1 where X and H are the distance from the cut of the capillary to the bottom and the height of the liquid column in a hard vessel at temperature T, respectively. Knowing the parameters of the instrument and the density of the liquid at the temperature of the experiment, according to formula C), is determined with the specified accuracy. To do this, it is sufficient to measure the angle of rotation of the LCP micro screw and the temperature difference l T at the tips of the capillaries. LO, if the depth of the capillary in the liquid decreases (and vice versa) as a result of the rotation of the micro screw. The method is applicable to wetting and non-wetting capillaries. At the same time, it allows one to determine the sign without any measurements. The proposed device can also be simultaneously used for measuring surface tension, for which it is sufficient to attach a pressure gauge to it. Claim 1. The method of determining the temperature coefficient of the surface for milling fluids by measuring the surface characteristics and the subsequent calculation is also different because, in order to improve accuracy and reduce the labor intensity of measurements, they create a temperature difference between the two communicating vessels with the liquid under study. , in which identical communicating capillaries are lowered, counterbalance the hydrostatic pressure of the liquid under investigation due to the temperature change of the pressure in the capillaries and, from;) 1en is the position of one of the vessels relative to the capillary, and the desired value is found by the formula d g Lj g / .. 5t aR. (where r is the radius of the capillary; q is the acceleration of gravity; p is the density h — change in the depth of the capillary immersion in a liquid when its hydrostatic pressure changes at the cut-off of the capillary by an amount equal to the increment of pressure of the capillary forces when the temperature changes by amp ft; and p are the volume coefficients of thermal expansion of the liquid sample and the capillary material ra respectively; X and H are the distance from the cut-off of the capillary to the bottom and the height of the liquid column in a rigid vessel, respectively. 2. A device for carrying out the method according to claim 1, characterized in that it is made in the form of two identical communicating capillaries immersed in communicating vessels with the test liquid, each of which is equipped with a heater, the capillaries are connected to an inert gas source, and the vessels - with a pumping system, one of the vessels being installed relative to the capillary with the possibility of its vertical movement. Sources of information taken into account during the examination 1. V. Semenchenko. Surface Surface Phenomena in Metals and Alloys, M., Gostekhizdat, 1957, p. 61-75 (prototype). About About About About About OS About COOQO LLC ../s/hc/h/h