SU504105A1 - Adiabatic calorimeter for measuring heat capacity - Google Patents

Description

(54) ADIABATIC CALORIMETER FOR MEASURING HEAT CAPACITY

one

The invention relates to measuring equipment for determining the heat capacity of substances and may find wide application in laboratory practice.

Calorimeters are known, in which adiabatic conditions are created by establishing a certain temperature difference only between the internal radiation screen and the container, since: radiation and conductive (through the supply wires) heat flows between them are controlled together on this screen; The same ring and outer shield serve only to increase the accuracy of controlling the temperature of the inner

radiation screen.

However, with this assignment of screens for creating adiabatic conditions, it is not necessary to establish and maintain taafeM a different temperature difference between the container and the internal radiation screen. On svyzl; With this, when the temperature in the main period of the calorimetric temperature rises, the radiant flux between them changes and the prioritization of the adiabatisation, GH is disturbed, the final temperature variation increases, and the correction for heat exchange and the error in determining it becomes: - Essential, this is especially important: temperature above 250 ° C. Therefore, to obtain a convenient end-of-temperature temperature measurement, it is necessary to reduce the amount of temperature rise in the main period and thereby increase the number of calorimetric experiments and, consequently, the time of the entire process of measuring hfs, as a study of the temperature dependence of the heat capacity, it should be carried out continuously throughout the entire temperature range.

In addition, replacing the test samples in this colorimeter is very laborious, since it requires removing the external and internal radiation shields, for which it is first necessary to unplug the connecting wires from the contact pins, and then remove the container ( . Reverse order). Such an operation takes a lot of time and is difficult, so it’s a link to soldering wires / wires of an amotroma less than OD mm to the contacts with very good free access

labor-intensive, the multi-fold connection makes the connecting wires fragile so that they can break during installation and measurement. Loose suspension of the shield and container further increases the possibility of breakage of the connecting wires,

The aim of the invention is to improve the accuracy of measurements of thermal capacity in an adiabatic colorimeter.

This is achieved by the fact that the lead wires from the container, the internal radiation shield is bred, are led out onto the fire ring and then to the outer radiation shield, and the lead wires located on different screens are connected by a spring-wound circular connector with spring-loaded contacts. the same material, and the cover is inserted inside the screen.

FIG. 1 schematically shows the proposed calorimeter, longitudinal section; in fig. 2 partial connections with partial cut, plan,

The container 1 with the plug-in heater2 and the platinum resistance thermometer 3 is rigidly attached to the lid of the internal radiation screen using thin stainless steel ribbons 4.

To reduce thermal conductivity and to break the electrical contact between the container and the screen, the fastening to the lid is made through washers 5 made of an insulating ionic material.

The inner radiation shield 6 is rigidly attached to the outer shield 7 through KQfibiio 8 from insulating matter, and the cover 9 is connected with a similar ring 1O to two rigid wires

hinges (with two-dimensional play for retrieval). An outer screen cover 11 and a flat metal cylinder 12 are also attached to the ring 10, which serves as a hot ring.

The rings Yu and 8 are at the same time the connector body. To shrink split rings, hinged locks 13 are attached to the rings. The connector has bottom contacts 14 and BepxjEiue 15 in the guide of a two-stage cylinder (Fig. 3). The material for the contacts must be the same in thermoelectric relation with the materials of the wires to be connected (in this copper calorimeter ). Bottom contacts secured

| are still in the drilled in the ring 8 hole; tn x. The upper ones are placed in the openings of the ring 1O, springed up by P1) with dinners 16 and secured with pins 17. Bdahh is a gift for such a crepet and they have the necessary free running in the vertical direction. The connector has two nag rasha pins to the ring 10 of the connector and also the claws of the lugs 18 of the hinged holder of the cover 9 {fig. 2}. The lead wires pass through a hole in the lid of the external screen and under, dd T to the external contact group of connectors. 19, then through the lower contacts of the connector, they are brought to the inner surface of the external radiation screen, glued to it with heat-resistant glue (silica) for the entire screen (down and then up), then the black connector of the CO connector is removed to the mountains whose ring Heaters are heated; Lee 21 (BHeiuHero and internal radio dialing screens) are directly outputted to: external contacts, and, in each case, their radiators are connected in series with their main heaters, detectively through liwyTpciHJffie and external contacts of the connector. The lead wires to the heater and the thermometer of the container (eight; pieces) come directly from the mountains of the 1st ring. Differential thermocouples 22 and 23 are installed between a container with one crof | ron and a hot ring and an internal radiation screen with another, and a differential thermocouple 24 between the inner and outer shields of the thermocouple thermocouple; They can be soldered to the surface of the screens with tin, while the iBbiuie is bonded with silicon glue. The thermocouple junction located on the container is tightly pressed against it with a spring ring attached to the container.

When the container heater is turned off (Fig. 2), the zero position of the temperature regulator of the internal radiation screen, i.e. With the help of a regulator in the heater of this screen, such a current is set, at. which signal ter; mopar 24, and of course, and the difference; temperatures between the container and the screen are reduced to zero. The own temperature course of the calorimeter established at the same time is recorded by a thermometer. 3. Then, the operating mode of the hot ring temperature regulator is set so that the proper temperature variation becomes equal to vudd (to the signal of the thermocouple 3 and o