SU1228123A1 - Device for studying substance enthalpy - Google Patents

Abstract

The invention relates to the field of computing and can be used in determining the enthalpy of substances. The purpose of the invention is to improve accuracy. The device contains a differential thermo-sensitive element, the first and second amplifiers of a constant current, the first differentiation unit, the polynomial functional converter, the second differentiation unit, the absolute value calculation unit, the comparator, the reference voltage setting unit, the memory unit, the subtraction unit, the second multiplication unit, sample mass assignment unit, integrator, first multiplication unit, division unit. Accuracy is ensured by eliminating the enthalpy measurement error associated with the deviation of the differential thermal curve from the zero line. I il. i (L

Description

The invention relates to a computing technique, in particular, to a technique for determining the enthalpy of substances by the method of differential thermal analysis.

The purpose of the invention is more scientific research institute of accuracy.

The drawing shows the functional diagram of the device.

The device contains a differential temperature-sensitive element 1, the first 2 and second 3 DC amplifiers, the first differentiating unit 4, the polynomial functional converter 5, the second differentiating unit 6, the absolute value computing unit 7, the comparator 8, the reference voltage setting unit 9, memory, subtraction unit 11, second multiplication unit 12, mass setting unit 13, integrator 14, first multiplication unit 15, division unit 16.

Before the device starts operating, the functional converter 5 is adjusted to the approximate dependence of the heat exchange coefficient on the current temperature; using block 13, the voltage Z is proportional to the sample mass, and using block 9, the voltage corresponds to the absolute value of the first time derivative of the differential signal of the temperature-sensitive element 1 at the time of the start of the thermoanalytical peak.

The device works as follows.

The signal amplified by amplifier 3 from the second output of the temperature-sensitive element 1, proportional to the current heating temperature, is posted to the inputs of differentiating unit 4 and functional converter 5. At their outputs, signals Y, P appear, which are proportional to the speed and heat transfer coefficient of the sample with the furnace space. The first input of the comparator 8 receives the voltage from the output of the block 7, to the input of which through the second differentiating block 6 receives a signal from the output of the amplifier 2, i.e. the first input of the comparator 8 receives a voltage corresponding to the absolute value. the magnitude of the first time derivative of the current differential temperature thermosensitive

1228123

five

element 1, the second input of the comparator 8 receives a voltage corresponding to the absolute value of the value of the first time derivative

 from the differential temperature at the beginning of the thermoanalytical peak.

In the period before the start of the thermoanalytical peak, the voltage on

0 the first input of the comparator 8 is less than the second. At the output of the comparator 8, a signal is generated that permits the recording of voltage from the output of amplifier 2 to block 10, the input signals of block 11 receive the same signals, and zero voltage is present at its output. A zero voltage is also present at the output of the integrator 14.

At the start of the thermoanalytical peak, the voltage at the first input of the comparator 8 becomes greater than at the second. At its output, a signal is generated that prohibits recording.

5 voltages in block 10 until the end of the experiment. Thus, after the onset of the thermoanalytical peak, the output of block II forms a voltage ± X, corresponding to the difference between the current differential temperature of the temperature sensitive element I and the differential temperature at the moment the thermoanalytical peak begins. As a result, a signal proportional to Z

0

0

five

value ± X

14

R. output integration0

five

0

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of torus 14, the signal is proportional to the enthalpy of the test substance, while eliminating the enthalpy measurement error associated with the deviation of the differential thermal curve from the zero line due to the heat capacity of the test substance outside the reaction temperature range.

Claims (1)

Invention Formula A device for analyzing the enthalpy of a substance, containing the first and second DC amplifiers, the first differentiating unit, the polynomial function converter, the subtraction unit, the first and second multiplication units, the division unit, the mass setting unit, the inheater and the differential temperature sensor, the output signal of the differential thermal differential the curve from the zero line through the first DC amplifier is connected to the first input of the subtraction unit; the output of the current heating temperature of the differential temperature sensor through the second DC amplifier is connected to the input of the first differentiating block and the input of a polynomial functional converter, the output of which is connected to the first input of the second the multiplication unit, and the output of the first multiplication unit with the second input of the second multiplication unit, the output of which is connected to the input of the dividend, and .out One of the first differentiating unit is connected to the input of the divider of the division unit, the output of which is connected to the input of the integrator, the output of which is the output of the device; increase accuracy The device has a memory block, a reference voltage setting unit, a comparator, an absolute value calculation unit and a second differentiation unit whose output is connected to the input of an absolute value calculation unit whose output is connected to the first one, and the output of the reference voltage setting unit to the second inputs A comparator whose output is connected to the recording input of the memory unit, the output of which is connected to the second input of the subtraction unit, and the output of the first DC amplifier is connected to the input of the second differentiating unit and the information input of the memory unit. Editor N.Shvyschka Compiled by A.Sheregngov Tehred I. Popovich Order 2288/50 Circulation 671 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 Proofreader A. Obruchar