SU149913A1 - Method for measuring high temperatures by low temperature sensors - Google Patents

Description

Methods for determining high temperatures are known, based on the theory of a regular thermal regime.

A distinctive feature of the described method for determining high temperatures by low-temperature sensors is that they use the point of intersection of the temperature curve with the curve of its derivative of temperature.

This method of detecting high temperatures improves measurement accuracy.

FIG. 1 shows the heating curve of the temperature sensor and the first derivative of this curve; in fig. 2 is a block diagram of an apparatus for carrying out the described method.

The method is based on the use of point B of intersection of the ABC heating curve of the low-temperature sensor with the first derivative of the GDB, this curve, when the temperature sensor is quickly introduced into the medium with the measured high temperature.

The portion of the curve of the regular sensor heating mode is described by the following exponential equation:

East nn /

. „,,,. Where

ist nr °

east- measured true medium temperature;

t - temperature sensor readings at any time moment t of the regular mode;

lp-readings of the temperature sensor at the point in time corresponding to the beginning of the regular mode; e is the indicator of thermal inertia of the sensor.

The first derivative of the regular mode curve is written by the following equation:

.NO 149913- 2 V g -, where

es

G is the first derivative of the temperature sensor at any moment of time in the regular mode.

Since B is at point B of the sensor reading g equals the derivative of Cg, then, at the first selected moment of reading d of the sensor, you can determine the measured true temperature, which is equal to „„ „

 .)

f g, -fg

To determine the true ambient temperature using the described method, it is necessary to measure the sensor ti and its derivative tl as well as the sensor / point at point B at the first selected moment of time.

The true measured temperature of the medium can be determined with a device having a sensor / temperature, a preamplifier 2, a differentiator 3, subtractive devices 4 and 5, a zero-device 6, a storage device 7, and a multiplier-separator 8.

The temperature sensor reads after preamplification go to the differentiator. Subtractor 4 receives the indications from the output of the preamplifier and the derivative of the readings from the differentiator.

The difference of these values at the time ti enters the memory, where the value of the derivative at the time, time p is also supplied.

The difference between the derivative and the sensor readings goes to the zero-device (indicator), which when the difference is zero, which corresponds to the intersection of the heating curve of the sensor with its first derivative, gives a signal to stop the measurement and remove the sensor from the medium. The second subtractive device 5 receives the derivative at the time Ti and the sensor readings at the time of intersection of the heating curve and its first derivative. Differences from subtractive devices 4 and 5, as well as sensor readings at the moment of time:,. .

At the output of the multiplier-separating device, the value of the measured true ambient temperature is obtained. The measurement process lasts until time t, and the sensor element is heated only to the temperature (which allows the use of a low-temperature sensor for measuring high temperatures.

Subject invention

A method of measuring high temperatures with low temperature sensors, based on the theory of a regular thermal mode, characterized in that, in order to improve the measurement accuracy, the point of intersection of the temperature curve with its derivative from temperature is used.

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