CN117629326A - Method for measuring moisture flow of small-pipe-diameter hydrogen loop - Google Patents
Method for measuring moisture flow of small-pipe-diameter hydrogen loop Download PDFInfo
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- CN117629326A CN117629326A CN202311609811.7A CN202311609811A CN117629326A CN 117629326 A CN117629326 A CN 117629326A CN 202311609811 A CN202311609811 A CN 202311609811A CN 117629326 A CN117629326 A CN 117629326A
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- 238000000034 method Methods 0.000 title claims abstract description 31
- 239000001257 hydrogen Substances 0.000 title claims abstract description 20
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 20
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 19
- 239000007789 gas Substances 0.000 claims abstract description 72
- 238000005259 measurement Methods 0.000 claims abstract description 61
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000012071 phase Substances 0.000 claims description 21
- 239000007788 liquid Substances 0.000 claims description 15
- 238000000691 measurement method Methods 0.000 claims description 8
- 239000007791 liquid phase Substances 0.000 claims description 7
- 238000012937 correction Methods 0.000 claims description 3
- 239000000523 sample Substances 0.000 claims description 2
- 230000005611 electricity Effects 0.000 description 5
- 230000002902 bimodal effect Effects 0.000 description 4
- 239000012530 fluid Substances 0.000 description 4
- 239000000446 fuel Substances 0.000 description 3
- 238000005070 sampling Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 238000012795 verification Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000012780 transparent material Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
- G01F1/667—Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
- G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- Electrochemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
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- Fluid Mechanics (AREA)
- Measuring Volume Flow (AREA)
Abstract
The invention relates to a method for measuring the wet gas flow of a hydrogen loop, which is characterized by comprising the following steps of: based on the ultrasonic sensor and the capacitance sensor, acquiring a capacitance time sequence signal and an ultrasonic time sequence signal; converting the time sequence signal of the capacitive sensor into a relative capacitance change RCD, and obtaining forward and backward transit time through the time sequence signal of the ultrasonic sensor; obtaining ultrasonic wet gas measurement flow; and determining a boundary value for correcting the gas phase flow rate when the water content of the high section is high through the drift model, judging whether the RCD is smaller than the determined boundary value, executing different steps according to a judging result, and calculating by using different measuring models to realize the measurement of the hydrogen loop wet gas flow rate.
Description
Technical Field
The invention belongs to the field of wet gas flow measurement, and relates to an ultrasonic electricity bimodal small-pipe-diameter wet gas flow measurement method.
Background
Compared with the traditional automobile, the hydrogen fuel cell automobile has obvious advantages in energy conservation and environmental protection, however, hydrogen is not completely consumed in the process of generating electricity by the battery, and unreacted hydrogen needs to be recycled through a circulation loop. Water is an additional product of the power generation reaction, and it is difficult for the water to be completely emptied during operation of the battery, and to flow at high speed in the form of moisture in the circuit. When the liquid phase content is too high, safety problems such as blockage or water hammer can occur, so that the moisture flow in the circulation loop needs to be monitored in real time to ensure the efficient and stable operation of the hydrogen fuel cell.
The traditional wet gas flow measurement means mainly uses a single-phase flowmeter for measurement, and can also be combined with classical flow measurement means such as a differential pressure flowmeter for measurement. Since most single-phase flowmeters interfere with the normal flow of fluid and produce pressure losses, and the repeatability of measurement results is poor, it is difficult to meet the requirements for accurate measurement of hydrogen fuel cell loop moisture.
The moisture content measuring method mainly comprises a quick-closing valve method, a ray attenuation method, an optical method, an ultrasonic method and the like. The quick-closing valve method can interfere with fluid flow and cannot make real-time, on-line measurements of the content. The ray attenuation method has high cost and potential safety hazard. The optical method utilizes a high-speed camera to shoot the flowing state in the pipeline, utilizes a calibration means as a reference to determine the phase content of fluid in the pipeline, has higher requirements on the calibration precision and the calibration means, and is not suitable for a small-pipe-diameter hydrogen circulation loop because the pipeline is made of transparent materials. The ultrasonic method utilizes the attenuation degree of ultrasonic wave propagating in different fluids to measure the phase content, but has the defects of weak energy of received signals, low signal-to-noise ratio, poor measurement accuracy of the water content and the like.
In view of the foregoing, there is a need for a non-contact, disturbance-free, high-precision, and fast-response method for measuring the moisture flow rate of a small-diameter hydrogen circulation loop.
Disclosure of Invention
The invention provides a method for measuring wet gas flow of a small-pipe-diameter hydrogen loop, which utilizes an ultrasonic sensor to measure wet gas flow and a capacitance sensor to measure water content, integrates sound and electricity measurement information on the basis of analyzing the influence of liquid phase distribution on gas flow measurement, and establishes a more accurate wet gas flow parameter measurement model, and the technical scheme is as follows:
a method for measuring the flow of wet gas in a hydrogen circuit, comprising the steps of: based on the ultrasonic sensor and the capacitance sensor, acquiring a capacitance time sequence signal and an ultrasonic time sequence signal; converting the time sequence signal of the capacitive sensor into a relative capacitance change RCD, and obtaining forward and backward transit time through the time sequence signal of the ultrasonic sensor; obtaining ultrasonic wet gas measurement flow; and determining a boundary value for correcting the gas phase flow rate when the water content of the high section is high through the drift model, judging whether the RCD is smaller than the determined boundary value, executing different steps according to a judging result, and calculating by using different measuring models to realize the measurement of the hydrogen loop wet gas flow rate.
The method comprises the following specific steps:
the first step: based on the ultrasonic sensor and the capacitive sensor, collecting two-phase pressure P, two-phase temperature T, capacitive sensor time sequence signal v (T) and ultrasonic sensor time sequence signal s (T);
and a second step of: the gas density ρ is calculated by the two-phase pressure P and the two-phase temperature T respectively g And liquid density ρ l Converting the time sequence signal of the capacitive sensor into a relative capacitance change RCD by the formula (1), and obtaining the forward and backward transit time t through the time sequence signal of the ultrasonic sensor 1 And t 2 ：
Wherein V is g And V w The voltage values obtained by measurement are respectively obtained when the water is empty and full;
and a third step of: obtaining ultrasonic wet gas measurement flow Q through a formula (2) tp ：
Wherein A is the sectional area of the pipeline, L is the distance between two ultrasonic probes of the ultrasonic sensor, theta is the included angle between the ultrasonic sensor and the central axis of the pipeline, and K is the included angle between the ultrasonic sensor and the central axis of the pipeline c Is a correction coefficient;
fourth step: determining a boundary value, judging whether the RCD is smaller than the determined boundary value, and executing a fifth step when the RCD is smaller than the boundary value; otherwise, carrying out a sixth step;
fifth step: judging whether the pipeline isFor the vertical tube, if the vertical tube is the vertical tube, the wet gas flow Q is calculated by the formula (3) g ；
Wherein gamma is the fraction of the entrained droplets in the center of the pipe to the cross-sectional area of the pipe, and alpha under the vertical pipe is obtained by formula (4):
wherein D is the diameter of the pipeline, delta 0 Is the thickness of the liquid film;
in the case of a horizontal tube, the flow rate Q of the wet gas is calculated by the formula (5) g ：
Wherein θ' is half of the corresponding central angle of the gas-liquid interface, and is calculated by the formula (6):
wherein R is the radius of the pipeline, delta 0 For the liquid film thickness, α under the horizontal tube is given by:
sixth step: when RCD is greater than the boundary value, α is determined by equation (8):
wherein K is 1 And K 2 To be fitted as coefficient, Q l Is the liquid phase flow rate;
judging whether the pipeline is a vertical pipe or not, if so, calculating the moisture gas flow Q by a combined formula (4) and a formula (8) g 。
Further, in the third step, K c 1.12;
further, in the fourth step, the boundary value was 28.9%.
Further, in the sixth step, K 1 And K 2 1.14 and 5.06 were taken respectively.
According to the method, the invention realizes the measurement of the small-caliber wet gas flow and has the following advantages:
(1) Can realize moisture gas flow measurement
And establishing a wet gas flow measurement model of the vertical pipe and the horizontal pipe by utilizing ultrasonic and electric bimodal information to obtain the actual gas flow.
(2) Achieving moisture gas flow measurement at higher water content
And the drift model is used for correcting the measurement result of the wet gas flow rate at the high water content, so that the measurement of the wet gas flow rate at the high water content is realized.
(3) Simple, low cost, on-line measurement
And measuring related parameters by using an ultrasonic sensor and a capacitive sensor to realize the measurement of the flow rate of the wet gas. The method is simple to operate and low in cost, and can realize online measurement.
(4) High measurement accuracy
The method is used for measuring the gas phase flow under the wet gas working condition, the average relative error of the vertical pipe is 3.92%, and the average relative error of the horizontal pipe is 4.62%.
Drawings
Fig. 1: flow measurement implementation flow chart for wet gas
Fig. 2: vertical tube liquid film thickness delta and section air content alpha relation chart
Fig. 3: graph for relation between thickness delta of liquid film of horizontal pipe and air content alpha of section
Fig. 4: error diagram for measuring vertical tube gas phase volume flow
Fig. 5: error diagram for measuring gas phase volume flow of horizontal tube
Detailed Description
The invention will now be further described with reference to the accompanying drawings and implementations:
the present embodiment is a moisture gas flow rate measurement method based on an ultrasonic sensor and a capacitive sensor, and is specifically implemented in moisture measurement as follows. The pressure of the wet gas working condition is regulated to be 101kPa, the gas phase flow is 56L/min-150L/min, the liquid phase flow is 2.5L/min-5.5L/min, and the diameter of the pipeline is a fixed value D=10mm. The signal acquisition comprises working condition pressure P output by the pressure sensor and working condition temperature T output by the temperature sensor. The ultrasonic sensor outputs ultrasonic time sequence signals s (t), the capacitive sensor outputs capacitive time sequence signals v (t), wherein the sampling frequency of s (t) is 8MHz, the sampling time of each group of data is 10s, v (t) is a sinusoidal signal of 330kHz, and the sampling frequency is 200kHz.
The method provided by the invention utilizes an ultrasonic sensor and a capacitive sensor to respectively measure the relative capacitance change and the uncorrected gas phase flow. And respectively establishing a vertical pipe measuring model and a horizontal pipe measuring model, and correcting the gas flow rate at the time of high section water content through a drift model. And finally, the measurement of the wet gas flow in the range of higher water content is realized.
The ultrasonic sensor and the capacitive sensor are utilized to solve the gas flow of the wet gas under different flow states through different measurement models, and the specific solving steps are as follows:
the first step: collecting two-phase pressure P, two-phase temperature T, capacitance sensor time sequence signals v (T) and ultrasonic sensor time sequence signals s (T);
and a second step of: calculating the gas density ρ through the working conditions P and T g And liquid density ρ l Converting the capacitance time sequence signal into a relative capacitance change RCD by a formula (1), and obtaining the forward and backward transit time t through an ultrasonic signal 1 And t 2 ：
Wherein V is g And V w The measured voltage values were for empty and full water, respectively. Obtaining the forward and backward transit time t of ultrasonic signals by a cross-correlation method 1 And t 2 。
And a third step of: obtaining ultrasonic wet gas measurement flow Q through a formula (2) tp ：
Wherein A is the sectional area of the pipeline, theta is the included angle between the ultrasonic sensor and the central axis of the pipeline, and K is the included angle between the ultrasonic sensor and the central axis of the pipeline c Taking 1.12 in the experimental range for correcting the coefficient;
fourth step: according to the experimental value of the boundary value w obtained by the experiment, in the embodiment, w=28.9% is selected, whether the RCD is smaller than 28.9% or not is judged, namely, the water content is smaller than 33% or not, and the measurement result of the capacitive sensor is directly adopted at the moment, so that the fifth step is carried out; and when the RCD is more than 28.9%, correcting the capacitance measured value by adopting a drift model, and performing the step six.
Fifth step: when the RCD is less than 28.9%, firstly judging whether the pipeline is a vertical pipe, if so, calculating the moisture gas flow Q through a formula (3) g 。
Where γ is the fraction of the entrained droplets in the center of the pipe over the cross-sectional area of the pipe, α under the vertical pipe can be obtained from equation (4):
wherein D is the diameter of the pipeline, delta 0 Is the thickness of the liquid film.
In the case of a horizontal tube, the flow rate Q of the wet gas is calculated by the formula (5) g ：
Wherein θ' is half of the corresponding central angle of the gas-liquid interface, as shown in fig. 3. Calculated from equation (6):
wherein R is the radius of the pipeline, delta 0 For the liquid film thickness, α under the horizontal tube can be derived from the following formula:
sixth step: when the RCD is greater than 28.9%, α can be determined from equation (8) according to the correction model:
wherein K is 1 And K 2 For the coefficients to be fitted, 1.14 and 5.06 are taken respectively, Q l Is the liquid phase flow. In the application scenario of moisture, liquid phase flow rate Q l Relative to moisture flow rate Q g Smaller and less varying, less for actual measurements. At a known Q l In the case of (1) or Q l While keeping the same within a certain known range, firstly judging whether the pipeline is a vertical pipe, if so, calculating the moisture gas flow Q by the combined formula (4) and the formula (8) g 。
According to the method, the measurement of the small-pipe-diameter wet gas flow is finally realized.
In this example, according to the above method, the moisture gas flow rate measurement is finally achieved. Proved by verification, the ultrasonic electricity bimodal wet gas flow measurement method provided above has the average measurement error of gas flow under different pipeline angles, wherein the vertical pipe is 3.92%, and the horizontal pipe is 4.62% (as shown in fig. 4 and fig. 5), wherein the measurement error= (measured value-true value)/true value is multiplied by 100.
The invention respectively establishes moisture flow measurement models of the vertical pipe and the horizontal pipe, and corrects the ultrasonic flow measurement result through the capacitance measurement value. And further correcting the moisture measurement flow rate at high water content by using a drift model. Finally, the measurement of the wet gas flow in the range of higher water content is realized, and the method is simple to operate, low in cost and wide in measurement range. Real-time and online high-precision measurement can be realized.
Fifth step: judging the relative capacitance change RCD, judging whether the RCD is smaller than 28.9%, if so, judging whether the RCD is smaller than 28.9%, and if so, continuously judging whether the RCD is a vertical pipe, and if so, judging the moisture gas flow Q g The method comprises the following steps:
in the case of a horizontal tube, the flow rate of the wet gas Q g The method comprises the following steps:
wherein θ' is half of the central angle of the wave-shaped flow interface of the horizontal tube, as shown in fig. 3:
wherein R is the radius of the pipeline, delta 0 The relationship with α for the liquid film thickness is as follows:
if it is greater than 28.9%, the humid gas flow rate Q g Alpha in the calculation formula should be:
wherein K is 1 And K 2 Taking 1.14 and 5.06 as coefficients to be fitted respectively;
according to the method, the measurement of the small-pipe-diameter wet gas flow is finally realized.
In this example, according to the above method, the moisture gas flow rate measurement is finally achieved. Proved by verification, the ultrasonic electricity bimodal wet gas flow measurement method provided above has the average measurement error of gas flow under different pipeline angles, wherein the vertical pipe is 3.92%, and the horizontal pipe is 4.62% (as shown in fig. 4 and fig. 5), wherein the measurement error= (measured value-true value)/true value is multiplied by 100.
The invention respectively establishes moisture flow measurement models of the vertical pipe and the horizontal pipe, and corrects the ultrasonic flow measurement result through the capacitance measurement value. And further correcting the moisture measurement flow rate at high water content by using a drift model. Finally, the measurement of the wet gas flow in the range of higher water content is realized, and the method is simple to operate, low in cost and wide in measurement range. Real-time and online high-precision measurement can be realized.
Claims (5)
1. A method for measuring the flow rate of a hydrogen loop wet gas, comprising the steps of: based on the ultrasonic sensor and the capacitance sensor, acquiring a capacitance time sequence signal and an ultrasonic time sequence signal; converting the time sequence signal of the capacitive sensor into a relative capacitance change RCD, and obtaining forward and backward transit time through the time sequence signal of the ultrasonic sensor; obtaining ultrasonic wet gas measurement flow; and determining a boundary value for correcting the gas phase flow rate when the water content of the high section is high through the drift model, judging whether the RCD is smaller than the determined boundary value, executing different steps according to a judging result, and calculating by using different measuring models to realize the measurement of the hydrogen loop wet gas flow rate.
2. The hydrogen circuit wet gas flow measurement method according to claim 1, comprising the further steps of:
the first step: based on the ultrasonic sensor and the capacitive sensor, collecting two-phase pressure P, two-phase temperature T, capacitive sensor time sequence signal v (T) and ultrasonic sensor time sequence signal s (T);
and a second step of: the gas density ρ is calculated by the two-phase pressure P and the two-phase temperature T respectively g And liquid density ρ l Converting the time sequence signal of the capacitive sensor into a relative capacitance change RCD by the formula (1), and obtaining the forward and backward transit time t through the time sequence signal of the ultrasonic sensor 1 And t 2 ：
Wherein V is g And V w The voltage values obtained by measurement are respectively obtained when the water is empty and full;
and a third step of: obtaining ultrasonic wet gas measurement flow Q through a formula (2) tp ：
Wherein A is the sectional area of the pipeline, L is the distance between two ultrasonic probes of the ultrasonic sensor, theta is the included angle between the ultrasonic sensor and the central axis of the pipeline, and K is the included angle between the ultrasonic sensor and the central axis of the pipeline c Is a correction coefficient;
fourth step: determining a boundary value, judging whether the RCD is smaller than the determined boundary value, and executing a fifth step when the RCD is smaller than the boundary value; otherwise, carrying out a sixth step;
fifth step: judging whether the pipeline is a vertical pipe or not, if so, calculating the flow rate Q of the wet gas through a formula (3) g ；
Wherein gamma is the fraction of the entrained droplets in the center of the pipe to the cross-sectional area of the pipe, and alpha under the vertical pipe is obtained by formula (4):
wherein D is the diameter of the pipeline, delta 0 Is the thickness of the liquid film;
in the case of a horizontal tube, the flow rate Q of the wet gas is calculated by the formula (5) g ：
Wherein θ' is half of the corresponding central angle of the gas-liquid interface, and is calculated by the formula (6):
wherein R is the radius of the pipeline, delta 0 For the liquid film thickness, α under the horizontal tube is given by:
sixth step: when RCD is greater than the boundary value, α is determined by equation (8):
wherein K is 1 And K 2 To be fitted as coefficient, Q l Is the liquid phase flow rate;
judging whether the pipeline is a vertical pipe or not, if so, calculating the moisture gas flow Q by a combined formula (4) and a formula (8) g 。
3. The hydrogen circuit wet gas flow rate measurement method according to claim 2, wherein in the third step, K c 1.12.
4. The hydrogen circuit wet gas flow measurement method according to claim 2, wherein in the fourth step, the boundary value is 28.9%.
5. The hydrogen circuit wet gas flow rate measurement method according to claim 2, wherein in the sixth step, K 1 And K 2 1.14 and 5.06 were taken respectively.
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| CN202311609811.7A CN117629326A (en) | 2023-11-29 | 2023-11-29 | Method for measuring moisture flow of small-pipe-diameter hydrogen loop |
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