SU1686316A1 - Calorimeter - Google Patents

Abstract

The invention relates to calorimetry and allows you to extend the measurement range of the calorimeter. For this, the trigger level of the comparator 4 is set to be equal to the upper limit of the optimum range of the amplifying path. Upon reaching the output signal of the differential thermopile 1 of the specified level, the comparator 4 is activated, and the imaging unit 6 generates a pulse of normalized amplitude and duration. This pulse opens key 8, connected via potentiometer 10 and differential thermopile (DT) 1 reference voltage source. Spas m DT 1 current flows, creating a heat flux that compensates for the measured. As a result, the signal from the thermopile output does not exceed the upper limit of the range during the measurement process. The number of complete compensation cycles is recorded, after which the forma-MMpyefCR final measurement result. 1 il. with

Description

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The invention relates to thermophysical measurements and is intended for recording heat fluxes and heat releases.

The purpose of the invention is to expand the measurement range.

The drawing shows the block diagram of the calorimeter.

The calorimeter contains a differential thermopile 1, the first switch 2, whose input is connected to the output of thermopile 1, an amplifier 3 connected by an input to the output of switch 2, a comparator (comparator) 4 connected by a non-inverting input to the output of amplifier 3, the first potentiometer 5 connected by an input to the source of the reference voltage, and the output to the inverting input of the comparator A, the first driver 6, connected by the input to the output of the comparator, the element OR-NOT 7, connected by the first input to the output of the driver 6, and the output to the control it has a key input 2, a second 8 and a third 9 keys, the inputs of which are interconnected and connected to the input of key 2, the control input of the key 8 is connected to the output of the driver 6, and the control input of the key 9 is connected to the second input of the element OR NOT 7 , the second potentiometer 10 connected by the input to the source of the reference voltage, and the output to the output of the key 8, the second driver 11, connected by the output to the control input of the key 9. a generator 12 of pulses connected by the output to the input of the driver 11, the third driver 13 connected by the input to the output of the generator 12 pulses, an analog-to-digital converter (ADC) 14, connected by an information input to the output of the amplifier, and a control input — to the output of the imaging unit 13, the fourth driver 15, connected by an input to the control input of the ADC (End of conversion cycle), counter 16, the counting input, which is connected to the output of the imaging unit 6, and the reset input - with the output of the imaging unit 15, register 17, the first group of inputs of which is connected to the digital outputs of the A / D converter 14, the second group of inputs - to the outputs of the counter 16, and the control input - to the control the output of the ADC 14.

The calorimeter works as follows.

The thermopile signal 1 through the key 2, which is in the open state (in the absence of the logical element OR-NOT 7 levels of the logical unit), enters the non-inverting input of the comparator 4. When the thermopile signal 1 increases, the output signal of the amplifier 3 increases in proportion to since the capacitance of the capacitor connected in parallel with the input of the amplifier 3 does not affect the low resistance of the thermopile

1 shunt this capacitance. The pulses of the generator 12, coming through the shaper 11 to the control input of the key 9 and through the logic element OR NOT 7 to the control input of the key 2, switch the output of the thermopile 1 alternately to the input and output of the amplifier 3. During the connection of the thermopile 1 to the input of the amplifier a signal arises, the rate of increase of which is proportional to the thermal effect

flow. Since the frequency of the pulse generator 12 is stable over time, the magnitude of the amplitude of the signal at the output of amplifier 3 in the same phases of operation of the generator, for example, at the moment of the start of the pulse — the thermal battery switching command from the output of amplifier 3 to its input, which is uniquely related to the thermal battery heat flow. At the moment of connecting the output of amplifier 3 to the thermopile 1

at its input remains the charge of the capacitor, and at the output is a voltage proportional to the output signal at the moment of disconnecting the input of amplifier 3 from the thermopile 1. Current generated in the thermocouple 1 spa,

under the influence of the output voltage of the amplifier 3 creates a counter-current heat flow due to the Peltier effect, thereby cooling the thermopile junction 1, to compensate for the measured heat flux. The signal from the output of the amplifier 3 is fed to the information input of the ADC L and is converted to a digital code by a signal from the output of the imaging unit 13, triggered by the pulses of the generator 12. This code goes to the first

the group of inputs of register 17 and the signal from the control output of the A / D converter 14 is stored in the register.

Thus, the device works if the signal from the output of the amplifier 3 does not exceed the level specified by the trigger threshold of the comparator 4, i.e. within the optimal dynamic range of the amplifying-recording path corresponding to the maximum accuracy

0 measurements.

When the upper limit of operation of the comparator 4 is reached (the signal from the output of thermopile 1 has reached and begins to exceed the upper limit of the optimal range of the amplifying recording path), the output of the comparator 4 goes to the state of a logical unit and the driver 6 generates a pulse on the leading edge of the transition process

normalized duration and amplitude.

The trigger threshold of the comparator 3 is set by a potentiometer 5 equal to the upper limit of the optimal range of the amplifying recording units of the amplifier 3 and the ADC 14. The shaper 10 is simultaneously connected to the thermopile by a signal from the shaper 6, fed to the key 8, and simultaneously the same pulse of the shaper 6 through a logical the element OR-NOT 7 disconnects the input of the amplifier 3 from the thermopile 1. The voltage from the output of the potentiometer 10 goes to the thermopile during the pulse time from the output of the one-vibrator and the current. Flowing under the action of this voltage creates a heat flux directed towards the current acting on the thermopile and compensating for it. At the end of the pulse of the former 6, the input of the amplifier 3 is connected with a switch 2 to the thermopile 1, and the output of the potentiometer 10 is disconnected from the thermopile.

In the case of large heat fluxes, switching the thermopile 1 from the amplifier input to its output and back repeatedly occurs until the pulse from the generator 12 output through the driver 11 connects the output of amplifier 3 to the thermopile 1, disconnecting it through the logical element OR NOT 7 using key 2 from the amplifier input. At the same time, the counter heat flux arising in thermopathic spaces 1 under the action of the current flowing when voltage is applied to thermopile 1 from amplifier 3 output is proportional to thermopile 1 signal at the time of thermopile 1 switching to amplifier 3 compensates heat flux the calorimeter and the signal value of the amplifier 3, as before, is written to the register via the ADC. At the same time, the digital code of the counter 16 is read into the register for the second group of inputs indicating the number of thermopile switches from amplifier 3 at its output, i.e., the total number of cycles of accurate compensation of the heat flux entering the calorimeter. When the recording of the output digital codes is completed, the counter is zeroed.

The device provides automatic maintenance of the signal from the output of the thermopile 1 within the optimum dynamic range of the amplifier-recording path

Claims (1)

maximum accuracy of heat flux measurements, despite the fact that the amplitude of the measured heat flux can significantly (10 times) exceed the heat flux corresponding to the upper limit of the measuring-recording path of known devices. Claims of Invention A calorimeter containing a differential thermopile disposed in a working and reference cell, an amplifier, a pulse generator, and a first cell. that, in order to extend the measurement range, a comparator is connected to it, connected to the output of the amplifier, the second and third keys, the first, second, third and fourth drivers, an OR-NOT element, an analog-to-digital converter, a counter, a register, and the first and second potentiometers with the source of the reference voltage, with the first potentiometer connected between the source of the reference voltage and the inverting input to the omparator. output through the first driver connected to the counter input of the counter, the left input of the element OR NOT and the control input of the second key, the input of which is combined with the inputs of the first and third keys and connected to the output of the differential thermopile, and the output connected to the reference voltage through the second potentiometer The outputs of the first and third analog switches are connected respectively to the input and output of the amplifier connected to the input of the analog-digital converter, the control output of which is connected to the input of the control register directly, and to the reset input of the counter through the fourth driver, the counter outputs are connected to the second group of inputs of the register connected by the first group of inputs to the outputs of the analog-digital converter, the control input of which through the third driver is connected to the output of the pulse generator connected through the second driver to the control input of the third key and to the second input of the element OR NOT, the output connected to the control input of the first key, and the third terminals of the first and second potentials ometrov connected to the common bus calorimeter.