SU1332158A1 - Method of measuring temperature - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to reduce the time required to carry out measurements and determine the measured temperature of the medium while maintaining the required accuracy of the measured 7 rhenium. The first temperature measurement of the thermoconverter 1 is made after it is supplied to it from power regulator 2. The obtained temperature value is recorded by instrument 4. At time t. According to the signal of the tanner 5, the power supplied to the thermal converter 1 increases, after which the second and third temperature measurements are taken at time t, and t. At the end of the third measurement, the power supplied to the thermal converter 1 is reduced. Timer 5 operation is organized so that tj- t t. Measurement under the specified conditions of temperature values at given heating powers of heat transfer agent 1 determines the temperature of the controlled medium. 1 il. - with & (L 00 CO EL 00 Vv V V

Description

1 ti

The invention relates to a measuring technique and can be used substantially when measuring low-temperature liquid or gaseous media by resistive thermal conductivity: g, when the influence of the measuring current does not allow to achieve full thermal equilibrium between the measuring thermocouple and the medium under study.

The aim of the invention is to reduce the time required to make measurements and determine the measured temperature of the medium while maintaining the required measurement accuracy.

The drawing shows a block diagram of a device implementing the proposed method of measuring temperature.

The device includes a thermal converter 1 connected to the power controller 2 and the secondary measuring transducer 3 connected to the recording device 4, and a timer 5 connected to the power regulator 2, the secondary measuring converter 3 and the recording device 4.

When using a thermistor impedance converter as a power regulator and a secondary measuring transducer, a stabilization device can be used, in which, by introducing non-linear feedback, the power supplied to the thermistor is kept constant by using a time exponential junction. is proportional to the temperature of the thermistor.

The method is carried out as follows.

First, the temperature measurement of the thermocoupler 1 is carried out in a setting of the thermal mode after supplying it with power P from controller 2. Temperature value

The corresponding powerful and received by the secondary measuring transducer 3 is recorded by the device 4. At the end of the first measurement at time t, the signal from timer 5 feeds the thermal converter 1 and the power increases to the value P. Then at the moment of time 1 "the second measurement is carried out by the signal of timer 5

ten

15 .

3321582

temperature transducer and then at time tj - the third temperature measurement transducer. The temperature values b and 0, obtained from the second and third measurements, are recorded by instrument 4. At the end of the third measurement. The temperature of the power supplied to the thermal converter 1 is reduced to the previous level. The timer operation is organized in such a way that for moments of time t, t, the relation t

t right t, - t.

Measured under the above conditions, the values of 0, 0 and ©. The temperature of the thermoconverter at specified heating powers P. and P, unambiguously determine the temperature of the controlled medium, which is calculated as follows.

It is known that the heating of a body with the power Pj, exchanging heat with the surrounding (controlled) medium, is described by the differential equation

Pj with / (e-t) + with:. (one)

where d is the heat transfer coefficient of the body with the environment; body heat capacity; t is the current time; 8 - body temperature; T - ambient temperature

environment.

The solution of a linear inhomogeneous differential equation (1), found taking into account the initial conditions

e (t, 0)

has the appearance

0

and

e (t) 0, + (

P, (8, -T)

-1) (e, -t) (-f}

Since measurements 6 (t) are carried out at equal intervals of time (tj-. T., And assuming t О, we get the system of equations

8 (h), ČRg (p -, - 1) 19g) 0- .e / CpjlPrOierTiht

which is oTHoc-httatbHo

(13, - ei)

1 1р 7р 1Т {2у; -1 - e; y

J ,,

With the help of prodables, it is possible to simultaneously determine the index of thermal inertia of the J-thermoelectric converter.

12-6

,

(..)

r

The value of f can be used to quickly evaluate the dynamic characteristics of the thermal converter and to find possible temperature measurement errors.

Claims (1)

Invention Formula The method of temperature measurement, which consists in heating a thermal converter placed in a controlled medium, successive measurements of the temperature of the thermal converter at two fixed different heating powers and the subsequent determination of the medium temperature by calculation, differing from the fact that, in order to reduce the measurement time, Compiled by V.Golubev Editor G.Volkova Tehred M.Didzh, Proofreader S.Shekmar "- - - - .. I .-- .--". . . ".". M -.,. ", IH., ....,„ „..„ „ Order 3822/36 Edition 776 Subscription VNI1-SHI USSR State Committee for inventions and discoveries 113035, Moscow. Zh-35, Raushska nab., D.4 / 5 Production and printing company, Uzhgorod, st. Project, 4 B ten 2138 The second fixed power of the heater makes an additional measurement of the temperature of the thermal converter, the second and third measurements of the temperature of the thermal converter are carried out in the process of establishing a stationary mode of its heating after two equal intervals of time, which count from the measured temperature of the medium is calculated by the formula W.:. L1, (PJ / P, -1) (26j- 63-9,) 6j are the temperature values of the thermal converter during the first, second and third measurements, respectively; - heating power of the thermal converter, 15 G e where b ,, d 20 2P