CN109708712A - A kind of constant conductance element quality flow measurement device and method based on dynamic pressure drop decaying - Google Patents
A kind of constant conductance element quality flow measurement device and method based on dynamic pressure drop decaying Download PDFInfo
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Abstract
The invention discloses a kind of constant conductance element quality flow measurement devices and method based on dynamic pressure drop decaying, have the characteristics that the mass flow measurement of AAO constant conductance element accurate, efficient and easy.Apparatus of the present invention include: air charging system, the first valve, container A, the first thermometer, differential pressure transmitter, the second valve, third valve, AAO constant conductance element, second temperature meter, container B, the 4th valve, vacuum pump group, when experimental gas flows through AAO constant conductance element under pressure differential, exponential function is fitted according to the attenuation change of the inlet and outlet dynamic pressure drop of AAO constant conductance element at any time, and then counts out and calculates transient state mass flow when gas flows through constant conductance element.
Description
Technical field
The present invention relates to a kind of constant conductance element quality flow measurement devices and method based on dynamic pressure drop decaying, belong to
In field of measuring technique.
Background technique
In recent years, with the development of microelectronics micro mechanical system (MEMS), micro-fluidic technologies have obtained extensive concern, people
Carried out many theoretical and experimental studies, understand and flow related physical phenomenon.Wherein, the survey of low density gas mass flow
Amount is always the hot topic of research.There are three types of currently used measuring techniques, respectively sessile drop method, constant-voltage method and constant volume method.
Sessile drop method is direct measuring, is to measure the speed that drop moves in calibration pipe by low-power microscope or photoelectric sensor
Degree is to obtain the variation of mass flow；The shortcomings that constant-voltage method and constant volume method are indirect measuring technology, constant-voltage method is piston lower
Mass flow under move it is slow, it is difficult to accurate control；Constant volume method can only measure the mass flow of various quasi- steady states.
Invention describes a kind of to be decayed using dynamic pressure drop to measure anodic porous alumina (AAO) constant conductance element
Mass flow new technology, have the characteristics that the measurement of constant conductance element quality flow accurate, efficient and easy.
Summary of the invention
The present invention proposes a kind of constant conductance element quality flow measurement device and method based on dynamic pressure drop decaying, with
Achieve the purpose that precise measurement constant conductance element transient state mass flow.
To achieve the goals above, this invention takes following technical schemes:
The present invention is based on the constant conductance element quality flow measurement devices and method of dynamic pressure drop decaying, it is characterized in that
It is a kind of based on dynamic pressure drop decaying constant conductance element quality flow measurement device include: air charging system, the first valve, container
A, the first thermometer, differential pressure transmitter, the second valve, third valve, AAO constant conductance element, second temperature meter, container B,
Four valves, vacuum pump group.
Container A is connected by the first valve with air charging system, and the first thermometer, container A and container B are equipped in container A
It is connected by the second valve, the high-voltage end of AAO constant conductance element is connected with third valve, the low pressure of AAO constant conductance element
End is connected with container B, and second temperature meter is equipped in container B, and container B is connected by the 4th valve with vacuum pump group, and differential pressure becomes
Device high-voltage end is sent to be connected with container A, low-pressure end is connected with container B.
The container A and container B material are stainless steel, measure container A and peripheral conduits, valve using gas expansion method
High-voltage end volume be V1=1.34 × 10-2m3, container B and peripheral conduits, the low-pressure end volume of valve are V2=7.1 × 10- 4m3。
The dynamic pressure drop variation at differential pressure transmitter measurement AAO constant conductance element both ends, according to the theory derived
Formula calculates the transient state matter that gas flows through AAO constant conductance element using the method for least square method Function Fitting and differential
Measure flow
The AAO material model of the AAO constant conductance element is the AAO-DP- of Shanghai overwood Science and Technology Ltd. production
25, aperture 13mm, use respectively nitrogen, helium, argon gas as experimental gas flow through AAO constant conductance element when, locate always
In molecular flow condition, conductance from vacuum to atmospheric pressure under keep constant.
It is completed according to the following steps using present invention measurement constant conductance element quality flow:
1, the first valve is closed, the second valve, third valve and the 4th valve are opened, is taken out system very using vacuum pump group
Sky is to 1 × 10-3Hereinafter, then turning on the first valve, experimental gas is introduced container A and container B, made Pa by the 4th valve of closing
It reaches certain pressure p0.It is then shut off the second valve and third valve, is filled with experimental gas into container A again, so that holding
Pressure increases again in device A, when the registration of differential pressure transmitter both ends pressure difference increases to 1200Pa from 0Pa, closes the first valve.Deng
To about 15 minutes, the temperature of container A and B, pressure is made to reach stable state, is again turned on third valve, due to the presence of pressure difference,
Gas in container A flows through AAO constant conductance element and enters container B, and the pressure in final two container reaches equilibrium state, this
When, the pressure difference Δ P at differential pressure transmitter both ends is down to the time used in 0Pa from 1200Pa as t.
2, the mass flow of AAO constant conductance element can be derived from by following procedure:
, the quality related with the gaseous mass variation between container A, B by the gas mass flow of AAO constant conductance element
Variation change with time with container inner pressure it is related, according to The Ideal-Gas Equation:
p1V1=M1RT, p2V2=M2RT (1)
In formula, T is temperature, and R is gas constant, ViIt is the total volume of container A, B and their peripheral conduits and valve, piWith
MiIt is the pressure and gaseous mass of container A, B and their peripheral conduits and valve.In entire experiment, vessel temp is kept not
Become.Wherein, container B and peripheral conduits and the variation of valve gaseous mass is:
In entire experiment, the variation dT/T=10 of temperature-3Left and right, the variation of average pressure is in dp/p=10-1Left and right,
Therefore negligible.Gaseous mass in container B and peripheral conduits and valve can be obtained from equation (2):
According to mass conservation law, mass flow is obtained:
Therefore, it from equation (3) and (4), can simply obtain:
Wherein Δ p (t) is the pressure difference between container A and B, Δ p (t)=p2(t)-p1(t).
According to the definition of conductance, the conductance of available AAO constant conductance element:
Q in formula1、Q2It respectively indicates and flows through V1、V2Gas flow, vacuum science and technical field be usually used in indicate gas
The flow Q ˙ of body flow is defined as:
As it appears from the above, from equation (3), (6) and (7), it can be deduced that:
It is hereby achieved that the differential equation of the pressure differential deltap p (t) of container A and B:
Since the conductance C of conductance element is constant, then differential equation (9) can be rewritten as:
In formula, Δ p0Initial differential pressure when being t=0, τ are the characteristic times of experiment.According to formula (5), container B and periphery
The mass flow of gas can be written as in pipeline and valve:
It is equal with the mass flow for flowing through AAO constant conductance element-gas, during the experiment, available container A
It changes with time with the both ends B pressure difference and is worth Δ p (t), according to formula (10), it is quasi- to carry out exponential function to it using Origin software
It closes；Then according to formula (11), to the specific function derivation that fitting obtains, wherein V0, R and T be it is known that finally become at any time
The mass flow function of change.
The present invention has the advantage that compared with prior art
1, it is in molecular flow condition always when the nitrogen in the present invention, helium, argon gas flow through AAO constant conductance element, because
This can measure the mass flow of constant conductance element with multiple gases.
2, the present apparatus can measure the mass flow of any time when nitrogen, helium, argon gas flow through constant conductance element.
3, the conductance of AAO constant conductance element used in the present invention is constant up to being all to maintain under atmospheric conditions, because
This this method is applicable in always from vacuum condition to atmosphere.
4, the device of the invention is not only simple in structure, easy to process, low in cost and strong antijamming capability, measurement result
Accurately.
Detailed description of the invention
Fig. 1 is a kind of structural schematic diagram of constant conductance element quality flow measurement device based on dynamic pressure drop decaying；
Wherein, 1- air charging system, the first valve of 2-, 3- container A, the first thermometer of 4-, 5- differential pressure transmitter, the second valve of 6-
Door, 7- third valve, 8-AAO (anodic porous alumina) constant conductance element, 9- second temperature meter, 10- container B, 11- the 4th
Valve, 12- vacuum pump group.
Specific embodiment
As shown in Figure 1, the present invention is based on the constant conductance element quality flow measurement devices and method of dynamic pressure drop decaying:
Including air charging system 1, the first valve 2, container A 3, the first thermometer 4, differential pressure transmitter 5, the second valve 6, third valve 7,
AAO constant conductance element 8, second temperature meter 9, container B 10, the 4th valve 11, vacuum pump group 12.
Container A 3 is connected by the first valve 2 with air charging system 1, is equipped with the first thermometer 4 in container A, container A 3 and
Container B 10 is connected by the second valve 6, and the high-voltage end of AAO constant conductance element 8 is connected with third valve 7, AAO constant conductance
The low-pressure end of element 7 is connected with container B 10, is equipped with second temperature meter 9 in container B 10, container B 10 by the 4th valve 11 with
Vacuum pump group 12 is connected, and 5 high-voltage end of differential pressure transmitter is connected with container A 3, and low-pressure end is connected with container B 10.
The container A 3 and 10 material of container B are stainless steel, using gas expansion method measure container A 3 and peripheral conduits,
The high-voltage end volume of valve is V1=1.34 × 10-2m3, container B 10 and peripheral conduits, the low-pressure end volume of valve are V2=7.1
×10-4m3。
The differential pressure transmitter 5 measures the dynamic pressure drop variation at 8 both ends of AAO constant conductance element.
The AAO material model of the AAO constant conductance element 8 is the AAO-DP- of Shanghai overwood Science and Technology Ltd. production
25, aperture 13mm, use respectively nitrogen, helium, argon gas as experimental gas flow through AAO constant conductance element when, locate always
In molecular flow condition, conductance from vacuum to atmospheric pressure under keep constant.
It is completed according to the following steps using the mass flow of present invention measurement constant conductance element:
1, the first valve 2 is closed, the second valve 6, third valve 7 and the 4th valve 11 are opened, it will using vacuum pump group 12
System is evacuated to 1 × 10-3For Pa hereinafter, then turning on the first valve 2, experimental gas is introduced container by the 4th valve 11 of closing
A3 and container B 10, reach certain pressure p0.It is then shut off the second valve 6 and third valve 7, is filled again into container A 3
Enter experimental gas, so that pressure increases again in container A 3, the registration of 5 both ends pressure difference of differential pressure transmitter is increased to from 0Pa
When 1200Pa, the first valve 2 is closed.It waits about 15 minutes, so that the temperature of container A 3 and B10, pressure is reached stable state, again
Third valve 7 is opened, due to the presence of pressure difference, the gas in container A 3 flows through AAO constant conductance element 8 and enters container B 10, most
The pressure in two containers reaches equilibrium state eventually, at this point, the pressure difference Δ P at 5 both ends of differential pressure transmitter is down to 0Pa institute from 1200Pa
It is t with the time.
2, the mass flow of AAO constant conductance element 8 can be derived from by following procedure:
Related, the quality by the mass change between the gas mass flow and container A 3, B10 of AAO constant conductance element 8
Variation changes with time related with container inner pressure.According to The Ideal-Gas Equation:
p1V1=M1RT, p2V2=M2RT (1)
In formula, T is temperature, and R is gas constant, ViIt is the total volume of container A 3, B10 and their peripheral conduits and valve, pi
And MiIt is the pressure and gaseous mass of container A 3, B10 and their peripheral conduits and valve.In entire experiment, vessel temp is protected
It holds constant.Wherein, container B 10 and peripheral conduits and the variation of valve gaseous mass is:
In entire experiment, the variation dT/T=10 of temperature-3Left and right, the variation of average pressure is in dp/p=10-1Left and right,
Therefore negligible.Gaseous mass in container B 10 and peripheral conduits and valve can be obtained from equation (2):
According to mass conservation law, mass flow is obtained:
Therefore, it from equation (3) and (4), can simply obtain:
Wherein Δ p (t) is the pressure difference between container A 3 and B10, Δ p (t=p2(t-p1(t.
According to the definition of conductance, the conductance of available AAO constant conductance element 8:
Q in formula1、Q2It respectively indicates and flows through V1、V2Gas flow, vacuum science and technical field be usually used in indicate gas
The flow Q ˙ of body flow is defined as:
As it appears from the above, from equation (3), (6) and (7), it can be deduced that:
It is hereby achieved that container A 3 and B10 pressure differential deltap p (differential equation of t:
Since the conductance C of conductance element is constant, then differential equation (9) can be rewritten as:
In formula, Δ p0Initial differential pressure when being t=0, τ is the characteristic time of experiment, according to formula (5), container B 10 and week
The mass flow of gas can be written as in side pipeline and valve:
It is equal with the mass flow for flowing through 8 gas of AAO constant conductance element, during the experiment, available container
The both ends A3 and B10 pressure difference, which changes with time, is worth Δ p (t), according to formula (10), carries out index letter to it using Origin software
Number fitting；Then according to formula (11), to the specific function derivation that fitting obtains, wherein V0, R and T be it is known that final obtain at any time
Between the mass flow function that changes.
Claims (5)
1. a kind of constant conductance element quality flow measurement device and method based on dynamic pressure drop decaying, it is characterised in that: packet
Include air charging system (1), the first valve (2), container A (3), the first thermometer (4), differential pressure transmitter (5), the second valve (6),
Three valves (7), AAO constant conductance element (8), second temperature meter (9), container B (10), the 4th valve (11), vacuum pump group
(12)；
Container A (3) is connected by the first valve (2) with air charging system (1), and the first thermometer (4), container A are equipped in container A
(3) it is connected with container B (10) by the second valve (6), high-voltage end and third valve (7) phase of AAO constant conductance element (8)
Even, the low-pressure end of AAO constant conductance element (7) is connected with container B (10), and second temperature meter (9) are equipped in container B (10),
Container B (10) is connected by the 4th valve (11) with vacuum pump group (12), differential pressure transmitter (5) high-voltage end and container A (3) phase
Even, low-pressure end is connected with container B (10).
2. it is according to claim 1 it is a kind of based on dynamic pressure drop decaying constant conductance element quality flow measurement device and
Method, it is characterised in that: container A (3) and container B (10) material are stainless steel, measure container A (3) using gas expansion method
It is V with peripheral conduits, the high-voltage end volume of valve1=1.34 × 10-2m3, the low-pressure end of container B (10) and peripheral conduits, valve
Volume is V2=7.1 × 10-4m3。
3. it is according to claim 1 it is a kind of based on dynamic pressure drop decaying constant conductance element quality flow measurement device and
Method, it is characterised in that: the dynamic pressure drop variation at described differential pressure transmitter (5) measurement AAO constant conductance element (8) both ends,
According to the theoretical formula derived, using the method for least square method Function Fitting and differential, calculates gas and flow through AAO and fix
The transient state mass flow of conductance element (8).
4. it is according to claim 1 it is a kind of based on dynamic pressure drop decaying constant conductance element quality flow measurement device and
Method, it is characterised in that: the AAO material model of the AAO constant conductance element (8) is raw for Shanghai overwood Science and Technology Ltd.
The AAO-DP-25 of production, aperture 13mm use nitrogen, helium, argon gas as experimental gas respectively and flow through AAO constant conductance member
When part (8), always be in molecular flow condition, conductance from vacuum to atmospheric pressure under keep constant.
5. it is according to claim 1 it is a kind of based on dynamic pressure drop decaying constant conductance element quality flow measurement device and
Method, specific step is as follows for feature:
One, the first valve is closed, the second valve, third valve and the 4th valve is opened, is vacuumized system using vacuum pump group
To 1 × 10-3Hereinafter, then turning on the first valve, experimental gas is introduced container A and container B, makes it Pa by the 4th valve of closing
Reach certain pressure p0, it is then shut off the second valve and third valve, is filled with experimental gas into container A again, so that container A
Middle pressure increases again, when the registration of differential pressure transmitter both ends pressure difference increases to 1200Pa from 0Pa, closes the first valve and waits about
15 minutes, the temperature of container A and B, pressure is made to reach stable state, be again turned on third valve, due to the presence of pressure difference, container
Gas in A flows through AAO constant conductance element and enters container B, and the pressure in final two container reaches equilibrium state, at this point, poor
The pressure difference Δ P at pressure transmitter both ends is down to the time used in 0Pa from 1200Pa as t；
Two, the mass flow of AAO constant conductance element can be derived from by following procedure:
It is related by the mass change between the gas mass flow and container A, B of AAO constant conductance element, mass change and appearance
Pressure changes with time related in device, according to The Ideal-Gas Equation:
p1V1=M1RT, p2V2=M2RT (1)
In formula, T is temperature, and R is gas constant, ViIt is the total volume of container A, B and their peripheral conduits and valve, piAnd MiIt is
The pressure and gaseous mass of container A, B and their peripheral conduits and valve, in entire experiment, vessel temp is remained unchanged,
In, container B and peripheral conduits and the variation of valve gaseous mass are:
In entire experiment, the variation dT/T=10 of temperature-3Left and right, the variation of average pressure is in dp/p=10-1Left and right, therefore can
It ignores, can obtain gaseous mass in container B and peripheral conduits and valve from equation (2):
According to mass conservation law, mass flow is obtained:
Therefore, it from equation (3) and (4), can simply obtain:
Wherein Δ p (t) is the pressure difference between container A and B, Δ p (t)=p2(t)-p1(t).
According to the definition of conductance, the conductance of available AAO constant conductance element:
Q in formula1、Q2It respectively indicates and flows through V1、V2Gas flow, vacuum science and technical field be usually used in indicate gas flow
Flow Q.Is defined as:
As it appears from the above, from equation (3), (6) and (7), it can be deduced that:
It is hereby achieved that the differential equation of the pressure differential deltap p (t) of container A and B:
Since the conductance C of conductance element is constant, then differential equation (9) can be rewritten as:
In formula, Δ p0Initial differential pressure when being t=0, τ is the characteristic time of experiment, according to formula (5), container B and peripheral conduits
It can be written as with the mass flow of gas in valve:
It is equal with the mass flow for flowing through AAO constant conductance element-gas, during the experiment, available container A and B two
Side pressure difference, which changes with time, is worth Δ p (t), according to formula (10), carries out exponential function fitting to it using Origin software；So
Afterwards according to formula (11), to the specific function derivation that fitting obtains, wherein V0, R and T be it is known that final obtain changes over time
Mass flow function.
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| CN201910205009.9A CN109708712B (en) | 2019-03-18 | 2019-03-18 | Device and method for measuring mass flow of fixed flow guide element based on dynamic differential pressure attenuation |
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