SU1103088A1 - Probe for measuring temperature of medium having small thermal conductivity - Google Patents

Abstract

THE PROBE FOR MEASURING THE TEMPERATURE OF THE MEDIUM WITH A SMALL THERMAL CONDUCTIVITY COEFFICIENT, containing a temperature-sensitive element located in a metascic sleeve, separated from the supporting body of the rod by a thermal insulator, so as to reduce inertia of measurements, using a heat insulator, you will not have to put on the body, you will not have to put on the unit, you will not need to go to the unit to use it. heat insulating SPO51MI, and the heat resistance of the heat insulating layers is 10-50 times higher than the thermal resistance of the metal sections. (

Description

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This invention relates to a technique for measuring temperatures in bulk media with a low thermal conductivity coefficient, such as grain, cotton, peat, coal, and can be used in agriculture and industry. Temperature measuring devices are known that contain a temperature-sensitive element located in a massive protective casing l. The average temperature of the dry grain temperature measurement by such sensors is 2-3 hours. The closest to the invention of the technical essence and the achieved result is a probe for measuring the temperature of the medium with low heat conductivity, containing a temperature-sensitive element placed in a brass tube. , separated from the supporting body of the rod by a vinyl insulating plastic insulator 2J. This design does not allow to obtain temperature measurement time less than 8-10 min for grain in bags, and in bulk 15-20 min with a measurement accuracy of 1 ° C. The aim of the invention is to reduce the inertia of measurements. The goal is achieved by the fact that in a probe for measuring the temperature of a medium with a low thermal conductivity coefficient containing a temperature-sensitive element located in a metal sleeve separated by a thermal insulator from the carrier body of the rod, the thermal insulator is made in the form of metal sections interconnected by heat-insulating layers, Moreover, the value of thermal resistance of heat insulating layers is 10-50 times higher than thermal resistance of metal sections. FIG. Figure 1 shows the construction of sensors with a constant (h) and varying (5) diameter of the cross section; in fig. 2 curves for setting the temperature of sensors with and without sectioning of the liner; in fig. 3 shows temperature curves along the length of the sensor with a constant diameter of the cross section at the instants shown in FIG. 2; in fig. 4 shows the design of the device using protective armature insulated from the rod; in fig. 5 - curves for setting the temperature of thermometric devices with protective valves insulated from the rod, and not thermally insulated. The thermosensitive element 1 is fixed inside a thin-walled metal sleeve 2. Between the rod and the sleeve 2 there are metal sections 4 and 5, which are insulated between them with a heat-insulating layer. B. Thermal insulation layers 7 and 8 isolate the rod from the metal sections and the metal sections from the sleeve, respectively. Wires 9 are used to connect the temperature-sensitive element 1 to the circuit. After the sensor is inserted into the measured medium having a higher temperature, the rod 3, the metal sections 4 and 5, the sleeve 2 begin to heat up, and through the heat insulating layers 6-8 and the temperature-sensitive element 1. At the first moment of time the temperature of the sleeve and the metal sections increases almost by one magnitude, and the temperature of the insulation layers lags behind the temperature of the metal sections (Fig. 3. The temperature difference between the metal sections and the rod is small, so there is practically no heat flow between them. In the subsequent moments The heat flux from the metal sections to the rod increases with time (С 1, Jj) .The temperature difference along the section length is small, the temperature jump will be observed only on the layers of the heat insulator after a certain period of time (od) despite the fact that the temperature of the first section from the rod still does not reach the ambient temperature, the temperature of the sleeve and the section located next to it no longer have a significant temperature difference between themselves and the medium. At this point, a temperature measurement can be taken. The thermal resistance of the insulation layers should be 10-50 times higher than the thermal resistance of the metal sections. The thickness of the heat insulating layer varies, at the bar is 0.15 mm, between the metal sections - 0.1 mm and the minimum at the sleeve - 0.05 mm. The wall thickness of the metal sections and the sleeve is in the range of 0.08-0.2 mm with a length and diameter of 20-15 and 4 mm, respectively. In many cases, for example, when inserting a probe into an embankment, it is impossible to use the sensor without security fittings due to mechanical strength or solid inclusions in the medium. The sensor 10 (Fig. 4) is installed in the recesses of a special thermal insulating sleeve 11. The sleeve has an opening 12 for wires and an extension 13 for installing the sensor, as well as three holes 14 radially at an angle of 120 ° along the axis of the sleeve, installation l, protective fittings 15. The bushing is mechanically fastened at the end of the tangi 16 with the handle 17. The protective armature is located with mechanical strength and protective devices at a distance of 5-10 mm from the sensor and has a blade diameter of 2.5-3.5 mm. Heat flow from safety valves

changes the ambient temperature in the immediate vicinity, as well as around the sensor, the more, the greater heat supply, we bring it from the outside. Thermal insulation of protective armature from the rod reduces its thermal reserve and prevents additional heat outflow from the rod to the armature. Thus, the medium at the measuring point gives up most of the heat to the sensor, and not to the protective fittings, before the sensor and medium temperatures equalize. And How

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shown in FIG. 5, the time taken to measure the temperature of the grain in the mounds with a probe, equipped with protective armature of the sensor, insulated from. the rod is reduced from 15 or more to 1.5-2 min compared with the probe, the protective armature of which is not insulated from the rod.

The proposed probe allows a reduction in the time taken to measure the temperature by more than 10 times.

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Claims (1)

PROBE FOR MEASURING TEMPERATURE OF A MEDIUM WITH A SMALL THERMAL CONDUCTIVITY COEFFICIENT, containing a heat-sensitive element located in a metal sleeve separated from the supporting body of the heat-insulated rod. an emulator, characterized in that, in order to reduce the inertia of the measurements, the heat insulator ^{2 is} made in the form of metal sections interconnected by heat-insulating layers, and the thermal resistance of the heat-insulating layers is 10-50 times greater than the thermal resistance of the metal sections. _from 1103088 '