SU609981A1 - Differential microcalorimeter - Google Patents

Description

(54) DIFFERENTIAL MIKGOKALORIMETR

one

This invention relates to the field of calorimetry, in particular to high temperature differential microthermal diathermy microcalorimeters.

Differential calorimeters are known for accurately recording thermal effects, accompanied by almost all chemical and biological phenomena. Thermoelectric batteries are in good thermal contact with the measuring cell and core. When a certain working temperature is reached, all elements must be heated to the working temperature (heat-leveling body, thermoelectric switch, cell) 1.

The limiting temperature capability in these calorimeters is determined by the heat resistance of the weakest structural element, for example, a thermoelectric battery. For a higher temperature, expensive, insensitive thermoelectric batteries made of noble metals (Pt-Rh) are used.

The closest in technical essence is a differential microcalorimeter containing cells, heaters for calibration, differentially connected thermoelectric batteries, thermal equalization of the body, source of constant power 2.

This calorimeter has the impossibility of accurately measuring heat fluxes and heats with a change in the temperature of the setting, a change in the ambient temperature, and the resulting instability of the drift zero of the differential cells of the converter, which is caused by the asymmetry of the heat flux between the heat-leveling body and the thermostat housing. Thermal level. 10 flows in the calorimeter is proportional to the difference in temperature between the statisation and the environment. Changing this difference leads to instability of the zero drift value, which limits the accuracy of the measurement.

15

The aim of the invention is to expand the range of operating temperatures while increasing sensitivity and reliability.

This goal is achieved due to the fact that

20 calorimeter containing cells, heaters for calibration, differentially connected thermoelectric batteries, heat equalizing body, constant power source, additional heaters are placed on the cells, connected after 25

The driver is connected to a constant power source, with respect to which the thermoelectric switch is installed with a gap.

The drawing shows the differential

microcalorimeter.

The microcalorimeter contains a heat equalizing body 1, cells 2, thermoelectric batteries 3, heaters 4 for calibration, an additional heater 5, a stand-alone power source 6 of power, a gap 7 between the surface of the thermoelectric battery and the cell.

The calorimeter works as follows.

When power is supplied, cells 2 are overheated by from 1 to 1 to thermoelectric switch m 3 for a constant value of At. The actual operating temperature of 2 TO in this case may be much higher than the temperature of the sealed battery 3 Tjj and heat-leveling body.

Therefore t TD - T -t -

The temperature capabilities of the Rasigar yut calorimeter are in the region of higher temperatures with respect to the limiting temperatures of the thermoelectric battery proper 3. When the same power is supplied to cell 2 by connecting additional heaters 5 to a constant source of power 6 due to the presence of a gap of 7 cells 2 and thermoelectric meters 3, the cells 2 are overheated with respect to the thermoelectric meter m 3 and the getto-equalizing body 1 by the value of At.

The power supplied to cells 2 is absorbed by thermoelectric batteries 3, since this power is the same, and thermoelectric batteries 3 are switched on opposite, and the supplied power does not pick up a signal. If the power from the object is released in one of the cells, then it also falls on the thermoelectric battery 3 and is necessarily recorded. The power supplied to the additional heater 5 to de-thermalize the thermal jump does not affect the change in thermal power from the object studied in the cells 2. The thermal jump power is applied to both cells 2 at once and its influence is compensated. Thermoelectric batteries 3 cover cells 2,

you are not in mechanical contact with them. The heat from the measurement unit is dissipated by the cells 2 and, having passed through the surface of one of the thermoelectric batteries 3, results in a corresponding signal to this heat. Heaters 5 are sequentially interconnected and connected to a constant power source 6, which gives the same degree of temperature rise relative to thermoelectric battery 3.

To heat cells 2 with a capacity of 17–2 cm to temperatures of 800–1000 ° C under vacuum conditions, a power of 8–10 W is sufficient. In a normal atmosphere, these temperatures are reached at a power of 15-25 W per cell. In this case, the cells 2 can be made of a more heat-resistant material, for example, from AljOa or BeO ceramics. Heat transfer from the heated cells 2 to the covering plane of thermoelectric batteries 3 occurs mainly due to radiation, since the inertial indicators of the calorimeter and cells 2 do not deteriorate with respect to conventional thermal-contact calorimeters. Since the most critical parts and assemblies of the calorimeter, in particular thermoelectric battery 3, are at a lower temperature, the calorimeter as a whole can operate under normal atmospheric conditions without the need for vacuum or inert gases.

One of the most important advantages of this calorimeter is also the ease of setting the temperature, since this operation is performed by applying power to the light cells 2, and not to the massive details of the calorimeter. The design of the calorimeter allows the use of conventional Tej detector modules in high-temperature instruments and expands the range of operation of the kororimeter due to a jump of 500-600 to 1500 ° C. At the same time, supersensitivity is achieved when working in air.

Claims (2)

1. US patent number 3314288, cl. 73-190, 1967. 2. Patent Foralli N 1402122, cl. G 01 K, 1967. oh oh