CN101470021B - Temperature-pressure method for hydrogen gas consumption measurement - Google Patents

Abstract

The invention relates to a temperature pressure method for measuring hydrogen gas consumption, belonging to the gas measurement technical field, which utilizes a temperature sensor and a pressure sensor integrated at the tail block of a high pressure gas bottle to directly contact and measure object gas, records the temperature value and pressure value when the measuring point is stable, and calculates via the measurement values to obtain a final consumption value of hydrogen gas. The method directly contacts gas to measure pressure and temperature, to obtain high accuracy, and has equal collection frequency, to keep high consistence on time.

Description

Measure the temperature, pressure method of hydrogen gas consumption

Technical field

The invention belongs to the gasmetry technical field, particularly a kind of temperature, pressure method of measuring hydrogen gas consumption.

Background technology

Vehicle oil consumption generally adopts in the laboratory operating condition method oil consumption to represent that it is according to the behavior method discharging test findings in the world, adopts the carbon balance method to calculate and comes.The consumption numerical error that itself and fuel consumption meter obtain and stipulates all generally in the consumption run method that the fuel consumption meter measuring accuracy is ± 2% about 2%.This is at conventional gasoline machine and diesel engine.And because hydrogen will pass through humidification in course of conveying, the leakage during electrode reaction, airborne moisture and product water all cause and can not come calculated fuel consumption with the method for element conservation in factors such as ducted spontaneous evaporations.Stipulated clearly among the SAE J2572 (2006) that the test of being done on the chassis dynamometer measures the resultnat accuracy of the hydrogen quality that consumes and reach ± 1.0%RD in a test loop.Hydrogen is as a kind of emerging energy, and is the same with conventional gasoline diesel oil, and the calculating direct relation of its consumption the economy of fuel-cell vehicle.

The detection method of three kinds of hydrogen gas consumptions clearly stipulating in SAE J2572 (2006): (1) with the volume of tanks, the pressure and temperature of internal gas is the clean mass change on basis, is called for short the temperature, pressure method; (2) based on the clean mass change of weight before and after the balance weighing gas cylinder, be called for short weight method; (3) count basic cumulative integral quality with mass rate, be called for short the flowmeter method.The series of studies of carrying out shows that three kinds of methods are satisfying the measuring accuracy that all can make hydrogen gas consumption under the prerequisite of certain condition and satisfy ± requirement of 1.0%RD on this basis.But the wherein wt method only is applicable to the test of breadboard chassis dynamometer, is not suitable for the vehicle of testing on the road or travelling, so have only temperature, pressure method in the stable state hydrogen consumption quantity measuring method to have the meaning of practical application.

The cardinal principle that the temperature, pressure method is measured is can ask quality (perhaps molal quantity) after knowing temperature, pressure, three parameters of volume in the thermodynamic equation of state.Wherein to refer to be the internal capacity of gas cylinder to volume.The total measurement (volume) (liter) of regulation gas cylinder should be used in 1atm among the SAEJ2572 (2006), and water capacity volume total in the time of 15 ℃ is represented.Because the gas cylinder of different materials shows different expansion (compression) character under different temperature, pressure, so also need to test or data that related data provides obtain the actual volume of gas cylinder under a certain temperature, pressure.The temperature, pressure data of gas then can be passed through sensor, and measurement means such as foil gauge obtain.When the temperature of preceding state, pressure, volume and after after temperature, pressure, the volume of a state determine, just can select the equation of gas state of suitable gases at high pressure calculate before and after quality, both do poor, just can obtain the consumption of hydrogen.The advantage of temperature, pressure method is to monitor the leak case of hydrogen in the gas cylinder, carries out in real time but more rough measurement, can also provide more easily to use.Shortcoming is that this kind of utilization method vehicle will be transformed through certain.Generally believe that at present there is the high precision of unit rate of flow meter method in this kind method.

Typical temperature, pressure method is at the measurement of pressure the time, mainly at gas bottle mouth position placement force sensor, because pressure is easier to reach equilibrium state.At the measurement of temperature the time, select the perpendicular of gas cylinder to put or the traverse position, stick the temperature strain sheet in many places, gas cylinder surface, through overtesting and emulation, to determine certain regional temperature after certain short period of process, the temperature when gas reaches complete equipilibrium in the more approaching bottle.Last need be sticked the temperature strain sheet by certain point in this zone, and waits for about ten minutes, can treat that just gas reaches complete equipilibrium in the gas cylinder, just can obtain very high-precision temperature.When use is suitable for the state equation calculating hydrogen quality of gases at high pressure, except utilizing van der Waals equation to calculate, because the precision of this equation is too low, can also search density value under this state in the online standard database http://webbook.nist.gov/chemistry/fluid/ of American National Standard and the NIST of technical institute according to temperature, pressure, also can obtain the quality of hydrogen by this density value.In addition, use to such an extent that will count the compressibility factor method the most widely, it is mainly based on such equation: $Z=\frac{\mathrm{PM}}{\mathrm{\ρRT}}$

Wherein: Z---compressibility factor, dimensionless; ρ---density, grams per liter; M---molal weight, 2.016 gram/moles; P---pressure, kPa; T---temperature, Kelvin; R---gas law constant, 8.314472 joules/(mole Kelvin).

The calculating of compressibility factor Z has a variety of methods again.Wherein a kind of is the compressibility factor of hydrogen under known certain test temperature, the spot pressure, and the compressibility factor substitution of the required point of interpolation calculation gets final product then.

The compressibility factor table of hydrogen under each state

P (MPa)

T (Kelvin)

?263.15

?273.15

?283.15

?293.15

?303.15

?313.15

323.15

0.1135791113151719212325272931

?1.0007?1.0066?1.0197?1.0329?1.0462?1.0596?1.0731?1.0868?1.1006?1.1144?1.1284?1.1426?1.1568?1.1711?1.1855?1.2000?1.2146

1.00061.00641.01931.03221.04521.05821.07141.08471.09801.11151.12501.13871.15241.16621.18011.19411.2082

?1.0006?1.0063?1.0189?1.0315?1.0441?1.0568?1.0697?1.0825?1.0955?1.1086?1.1217?1.1349?1.1482?1.1616?1.1750?1.1885?1.2021

?1.0006?1.0061?1.0184?1.0308?1.0431?1.0555?1.0680?1.0805?1.0931?1.1058?1.1185?1.1313?1.1442?1.1571?1.1701?1.1832?1.1963

?1.0006?1.0060?1.0180?1.0300?1.0421?1.0542?1.0663?1.0785?1.0908?1.1031?1.1154?1.1279?1.1403?1.1529?1.1655?1.1781?1.1909

?1.0006?1.0059?1.0176?1.0294?1.0411?1.0529?1.0648?1.0766?1.0885?1.1005?1.1126?1.1246?1.1367?1.1489?1.1611?1.1733?1.1856

1.00061.00571.01721.02871.04021.05171.06321.07481.08641.09801.10971.12151.13321.14511.15691.16871.1807

In addition, the Benedict-Webb-Rubin state equation provided more smart another be state equation with temperature, the direct substitution compressibility factor of pressure Z, 32 parameter clipped forms of the MBWR equation that proposes such as Younglove and McLinden with very high degree of precision:

$p=\mathrm{\ρRT}+\underset{i=1}{\overset{19}{\mathrm{\Σ}}}G\left(i\right){\mathrm{\ρ}}^{n_i}{T}^{m_i}+\underset{i=20}{\overset{32}{\mathrm{\Σ}}}G\left(i\right){\mathrm{\ρ}}^{n_i}{T}^{m_i}\exp \left[\mathrm{\γ}{\mathrm{\ρ}}^2\right]$

Wherein, G (i), n _i, m _i, γ is the constant by the gas characteristic decision.

There is following technological deficiency in the temperature, pressure method of above-mentioned measurement hydrogen gas consumption:

Though pressure reaches balance easily because also will be between from the bottleneck to the pressure transducer through one section pipeline, this section pipeline and on valve can produce crushing to the fluid that flows in the inside, cause the error of measuring.In addition, the measurement of temperature and pressure requires consistance preferably in time, because the temperature, pressure value of certain particular state should be the value that records simultaneously, so if temperature and pressure are divided into existing mode to be measured, also can cause error.The most important thing is pressure error 0.1Mpa, to cause the error of the about 3.5g of Mass Calculation, temperature error 0.5 degree, to cause the error of about 0.6g, this shows Mass Calculation error that pressure brings than temperature bring much bigger, be not a kind of good selection so pressure transducer is placed on the export pipeline.

For the measuring method of temperature, owing to only paste foil gauge, really do not contact with gas at outside surface, the repeatability of measuring accuracy does not guarantee.Determine representation temperature when zone, with the placement location of gas cylinder, the arrangement of foil gauge has much relations, thus this zone determine to exist very big difference.

Search density value under this state on the chemical handbook by American National Standard and the NIST of technical institute and obtain the method for quality of hydrogen and use inconvenience, the first is subjected to the restriction of network, and it two is that computer programming is restricted.So computing method need obtain from the compressibility factor method preferably, 32 parameter clipped forms of the MBWR equation with very high degree of precision that Younglove and McLinden propose can obtain very accurate result, but more complicated is used inconvenience.

Summary of the invention

The present invention provides a kind of temperature, pressure method of measuring hydrogen gas consumption especially in order to solve problems of the prior art.

Technical scheme of the present invention is as follows:

A kind of temperature, pressure method of measuring hydrogen gas consumption, this method comprises the steps:

Step 1, utilize and to be integrated in the temperature sensor of gas cylinder tail on stifled and directly to contact with tested gas with pressure transducer and measure, and write down temperature value and force value after measurement point is stablized; Wherein measurement point can reach stationary value in 4～7 minutes.

Step 2, calculate hydrogen gas consumption by following formula:

$z(p,T)=1+\underset{i=2}{\overset{6}{\mathrm{\Σ}}}\underset{j=1}{\overset{2}{\mathrm{\Σ}}}{v}_{\mathrm{ij}}{(p/1\mathrm{MPa})}^{i-1}{(T/100K)}^{n_{\mathrm{ij}}}$

Above-mentioned equation temperature range is 200-400 Kelvin, the hydrogen of pressure under 45 MPas, shown in wherein each constant sees the following form:

i	j	v ij	n ij
				2 2 3 3 4 4 5 6	1 2 1 2 1 2 1 1	0.036719 -0.039839 -0.0014722 0.0024083 0.65994e-5 -0.15469e-4 -0.13383e-6 0.15608e-8	-1.23 -2.22 -2.68 -3.1 -2.7 -4.3 -3.1 -4.1

Described temperature sensor precision is 0.5%FS, and the pressure transducer precision is 0.01%FS, and both install and sealing by stifled two holes of going up processing of tail.

Beneficial effect of the present invention is: directly contact the gasmetry pressure and temp, precision is higher, because frequency acquisition equates that both have kept consistance preferably in time.Be convenient to simultaneously determine the precision of temperature sensor and the precision of pressure transducer,, when the pressure transducer precision is 0.01%FS, can satisfy the requirement of error in ± 1% of hydrogen quality consumption when the temperature sensor precision is 0.5%FS.In addition, through overtesting and emulation, selected in stifled this bottle of tail temperature variation area measure relatively the most stably for use, the temperature of this measured zone can satisfy the requirement of error in ± 1% of hydrogen quality consumption in the temperature of stablizing can represent gas cylinder inside to reach balance after seven minutes the time.

Description of drawings

Fig. 1 is a system schematic of the present invention;

Wherein 1 is the High Pressure Hydrogen gas cylinder, and 2 is stifled for tail, and 3 be bottleneck, and 4 are the pressure transducer of tail on stifled, 5 temperature sensors that block up for tail, 6 pressure vent valves that block up for tail.

Fig. 2 is a pressure of the inside of a bottle curve map of the present invention.

Fig. 3 is a thetagram of the present invention.

Embodiment

Below by embodiment the present invention is described in further detail.

With reference to shown in Figure 1, gas cylinder is inserted pipeline, and after the data line of temperature and pressure sensor connected, the unlatching of control electromagnetic valve and set flow value begins to measure.Before and after the venting beginning, data acquisition program is constantly gathered each input channel parameter, collection result is shown, deposit and other relevant treatment, this process last till always venting finish after half an hour.Data acquiring frequency is ten somes p.s..The data that obtain can be drawn out a more smooth curve through filtering, with reference to Fig. 2, Fig. 3.

Process by temperature and pressure curve calculation hydrogen consumption quality is as follows: get one section preceding horizontal component of temperature and pressure curve venting, and the mean value of accounting temperature and pressure, obtaining pressure is 10.763 MPas, temperature is 22.04 degrees centigrade; The mean value of a horizontal segment accounting temperature and pressure is got in position between temperature and pressure curve venting ending segment 4～7 minutes again, and obtaining pressure is 10.506 MPas, and temperature is 21.72 degrees centigrade, substitution:

$z(p,T)=1+\underset{i=2}{\overset{6}{\mathrm{\Σ}}}\underset{j=1}{\overset{2}{\mathrm{\Σ}}}{v}_{\mathrm{ij}}{(p/1\mathrm{MPa})}^{i-1}{(T/100K)}^{n_{\mathrm{ij}}}$

Calculate the z1 value before the venting and exit after the z2 value.Utilize formula again: $Z=\frac{\mathrm{PM}}{\mathrm{\ρRT}}$

Calculate hydrogen density ρ 1 and the interior hydrogen density ρ 2 of venting back gas cylinder in the preceding gas cylinder of venting.Density be multiply by the volume of gas cylinder, the hydrogen quality m2 in hydrogen quality m1 before then can obtaining exitting in the gas cylinder and the venting back gas cylinder, it is 120.3 grams that m1-m2 promptly can be obtained the hydrogen consumption quality.The data that obtain of gravimetric method are 120.6 grams, and error is in ± 1%.

Claims (3)

1. a temperature, pressure method of measuring hydrogen gas consumption is characterized in that comprising the steps:

Step 1, utilize and to be integrated in the temperature sensor of gas cylinder tail on stifled and directly to contact with tested gas with pressure transducer and measure, and write down temperature value and force value after measurement point is stablized;

Step 2, as follows by the process of temperature and pressure curve calculation hydrogen consumption quality: get one section preceding horizontal component of temperature and pressure curve venting, the mean value of accounting temperature and pressure, obtaining pressure is 10.763 MPas, temperature is 22.04 degrees centigrade; The mean value of a horizontal segment accounting temperature and pressure is got in position between temperature and pressure curve venting ending segment 4～7 minutes again, and obtaining pressure is 10.506 MPas, and temperature is 21.72 degrees centigrade, substitution:

Calculate the Z1 value before the venting and exit after the Z2 value; Utilize formula again: Calculate hydrogen density ρ 1 and the interior hydrogen density ρ 2 of venting back gas cylinder in the preceding gas cylinder of venting; Density be multiply by the volume of gas cylinder, and the hydrogen quality m2 in hydrogen quality ml before then can obtaining exitting in the gas cylinder and the venting back gas cylinder promptly can obtain the hydrogen consumption quality with m1-m2; In this formula: Z-compressibility factor, dimensionless; ρ-density, grams per liter; The M-molal weight, 2.016 gram/moles; P-pressure, kPa; The T-temperature, Kelvin; The R-gas law constant, 8.314472 joules/(mole Kelvin);

Above-mentioned equation temperature range is 200-400 Kelvin, the hydrogen of pressure under 45 MPas, and wherein constant sees the above table.

2. a kind of temperature, pressure method of measuring hydrogen gas consumption according to claim 1, it is characterized in that: described temperature sensor precision is 0.5%FS, and the pressure transducer precision is 0.01%FS, and both install and sealing by stifled two holes of going up processing of tail.

3. a kind of temperature, pressure method of measuring hydrogen gas consumption according to claim 1 is characterized in that: on behalf of gas cylinder inside, the temperature of measurement point can reach the temperature of steady state (SS) in 4～7 minutes, and write down temperature value and force value.

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