KR20070013385A - Method for measurement of hydrogen content in metallic hydride for fuel cell car - Google Patents

Abstract

A method for measuring the quantity of hydrogen in a hydrogen storing alloy for a fuel battery vehicle is provided to simply and accurately measure the quantity of the hydrogen in the hydrogen storing alloy by using a Seebeck coefficient measuring unit. A method for measuring the quantity of hydrogen in a hydrogen storing alloy for a fuel battery vehicle includes the steps of: measuring the Seebeck coefficient of a hydrogen storing alloy(10) by using a Seebeck coefficient measuring unit; and calculating the quantity of the hydrogen actually stored in the hydrogen storing alloy from the measured Seebeck coefficient by using a proportional correlation between the measured Seebeck coefficient and the quantity of the hydrogen.

Description

Method for measurement of hydrogen content in hydrogen storage alloys for fuel cell vehicles {Method for measurement of hydrogen content in metallic hydride for fuel cell car}

Figure 1 is showing the relationship between the hydrogen storage alloy LaNi _{4 .6} amount of hydrogen stored in the Sn _{0 .4} (H / M) and the equilibrium pressure (P _eq) graph,

2 is a block diagram showing a sensing portion of the Seebeck coefficient measuring apparatus used in the present invention,

3 is a block diagram illustrating a connection relationship between a sensing unit and a control unit of the Seebeck coefficient measuring apparatus according to the present invention;

4 is LaNi _{4 .6} Sn _{0 .4} graph showing the relationship between hydrogen amount obtained through the Seebeck coefficient and the PCT device, and a quantitative measurement equipment hydrogen of the hydrogen storage alloy obtained through the Seebeck coefficient measuring device.

<Explanation of symbols for the main parts of the drawings>

10: hydrogen storage alloy powder 11: the first sensing block

12: second sensing block 13: plastic tube

14, 15: thermocouple 16: voltmeter

17 control unit 18 heater

The present invention relates to a method for measuring the amount of hydrogen in a hydrogen storage alloy for fuel cell vehicles, and more particularly, a process for measuring the Seebeck coefficient of a hydrogen storage alloy containing hydrogen using a Seebeck coefficient measuring device, and the measured Seebeck The present invention relates to a method for measuring the amount of hydrogen in a hydrogen storage alloy using the Seebeck coefficient consisting of a process of calculating the actual amount of hydrogen in the hydrogen storage alloy using a proportional correlation between the Seebeck coefficient and the amount of hydrogen experimentally measured from the coefficients.

In general, a fuel cell is a device that converts chemical energy of a fuel into electrochemical energy directly in a cell without being converted into heat by combustion, and is a pollution-free power generation device that has been recently studied with interest.

In such a fuel cell, a fuel cell stack including a fuel cell assembly in which unit cells that generate electricity are stacked and peripheral parts thereof is supplied with hydrogen as a fuel gas as an anode and oxygen as an oxidant as a cathode to generate electricity. .

In a vehicle equipped with a fuel cell, hydrogen used as fuel is precharged to a storage tank, and then hydrogen stored in the storage tank is supplied to the fuel cell through related pipes to produce electricity. Thus, hydrogen is supplied to the fuel cell. The vehicle is driven by the electricity generated.

Hydrogen used as fuel in fuel cells is the most popular as the next-generation alternative energy because it can be stored for a long time and can be easily converted into electrical energy, and when used as a fuel for future fuel cell vehicles, very little NOx is generated during combustion. However, there is an advantage that no pollutant is produced.

Hydrogen can be easily transported as gas or liquid, and is easily stored in various forms such as high pressure gas, liquid hydrogen, and hydrogen storage alloy.

Among them, the hydrogen storage using hydrogen storage alloy is currently in a state of much development, and efforts are being made to develop an alloy capable of storing a larger amount of hydrogen.

On the other hand, when using hydrogen as fuel in a fuel cell vehicle, measuring the amount of residual hydrogen is one of the important functions in automobiles. The residual amount can be easily measured.

However, in the case of the hydrogen storage alloy, since hydrogen is stored in the alloy, the residual amount of hydrogen cannot be measured by the pressure measurement method.

Figure 1 is the hydrogen storage alloy LaNi _{4 .6} Sn _{0 .4} amount of hydrogen stored in the (H / M) and the equilibrium pressure (P _eq) as a graph showing the relationship between the area of the 'α + β' (hydrogen Since there is no change in pressure in the stored area, it is impossible to measure the hydrogen capacity using the change in pressure.

In addition, since the equilibrium pressure is different at the time of hydrogen absorption and release, this problem is also difficult to measure the amount of residual hydrogen.

Therefore, as a method of measuring the amount of hydrogen in the current hydrogen storage alloy, the hydrogen storage alloy is introduced into the reaction vessel by using a Sirvert type measuring equipment, a certain amount of measured hydrogen is injected, and the pressure after the hydrogen is stored is measured. There is a method of calculating by converting to volume.

However, this measuring method has a problem in that the volume and pressure difference of the storage container must be accurately measured, and also has the disadvantage of continuously recording the volume of the initially injected hydrogen and the volume of residual hydrogen.

In addition, since the measurement method requires expensive pressure and other measurement equipment for accurate measurement, it is expected to have a great influence on the price increase of the fuel cell vehicle.

Therefore, the present invention has been invented to solve the above problems, the process of measuring the Seebeck coefficient of the hydrogen storage alloy containing hydrogen using the Seebeck coefficient measuring device, and experimentally measured from the measured Seebeck coefficient Comprising a proportional correlation between the Seebeck coefficient and the amount of hydrogen, it is a process of calculating the amount of hydrogen in the actual hydrogen storage alloy. It is an object of the present invention to provide a method for measuring the amount of hydrogen in a hydrogen storage alloy for battery vehicles.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The present invention is a method for measuring the amount of hydrogen in a hydrogen storage alloy for fuel cell vehicles,

Measuring the Seebeck coefficient using a Seebeck coefficient measuring apparatus for a hydrogen storage alloy in a hydrogen-containing powder form;

Calculating, by the controller, the actual amount of hydrogen stored in the hydrogen storage alloy from the Seebeck coefficient measured in the step by using a proportional correlation between the Seebeck coefficient and the hydrogen amount experimentally measured;

Characterized in that it comprises a.

Here, the step of measuring the Seebeck coefficient,

A first sensing block made of oxygen-free pure copper and maintained at room temperature, a second sensing block temperature-controlled by a heater operation, a tube filled with hydrogen storage alloy powder, a thermocouple for measuring the temperature of each sensing block, and two sensing. By using a voltmeter for measuring the voltage difference (thermal electromotive force) between blocks, and a Seebeck coefficient measuring device including a control unit for controlling the heater operation,

Fixing the hydrogen storage alloy in the tube and inserting the coupling portions of the two sensing blocks into both ends of the tube to contact the hydrogen storage alloy powder;

The control unit receives a signal of each thermocouple and controls the heater operation based on this to maintain a constant temperature difference between the two sensing blocks; And

Calculating, by the controller, a Seebeck coefficient using a temperature difference between two sensing blocks and a thermoelectric power input from the voltmeter;

Characterized in that consists of.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the amount of hydrogen in a hydrogen storage alloy for fuel cell vehicles, and in particular, a method for measuring the amount of residual hydrogen in a hydrogen storage alloy using a Seebeck coefficient measuring device. Calculating the Seebeck coefficient from the temperature difference and the voltage difference measured by the measuring device, and then calculating the amount of hydrogen from the calculated Seebeck coefficient.

First, the Seebeck coefficient (S) is a constant value determined according to a material and can be obtained by measuring the thermoelectric power (called Seebeck effect) generated when a temperature difference is formed in the material.

The Seebeck coefficient can be obtained by the following equation 1 by measuring the thermoelectric power (V _s ) when the temperature on one side of the sample is T ₁ and the temperature on the other side is T ₂ .

S = (T ₂ -T ₁ ) / V _s

In order to measure the Seebeck coefficient, it is important to form a temperature gradient at both ends of the material to be measured. In the Seebeck coefficient measuring apparatus used in the present invention, a temperature gradient is formed by installing a heater whose operation is controlled by a controller. .

2 is a block diagram illustrating a sensing part of the Seebeck coefficient measuring apparatus used in the present invention, which is used to calculate a Seebeck coefficient by measuring a temperature difference ΔT and a voltage difference (thermal electromotive force) ΔV.

3 is a block diagram illustrating a connection relationship between a sensing part and a control part of the Seebeck coefficient measuring device according to the present invention, in which the control part 17 measures the temperature difference measured by the thermocouples 14 and 15 and the voltmeter 16 of the sensing part. The Seebeck coefficient and the amount of hydrogen are calculated from ΔT and the voltage difference ΔV.

2 and 3 show the configuration of a device that enables the measurement of Seebeck coefficient in the hydrogen storage alloy in the form of a powder, the Seebeck coefficient measurement device shown therein is a Seebeck coefficient measurement available in the hydrogen content measurement process according to the present invention Only one example of the apparatus is shown, and other known Seebeck coefficient measuring apparatuses may be used, and the present invention is not necessarily limited to using the Seebeck coefficient measuring apparatus of FIGS. 2 and 3.

First, two sensing blocks 11 and 12 made of oxygen-free pure copper are provided, and the first sensing block 11 on one side of the two sensing blocks 11 and 12 maintains a room temperature temperature. The second sensing block 12 on the other side is configured to maintain a constant temperature difference (eg, 10 ° C.) from the first sensing block 11 at all times by the heater 18.

The heater 18 is provided to be on (on) / off (off) controlled by the control signal of the control unit 17, which is on (that is, operated) by the control signal of the control unit 17 In this case, the second sensing block 12 is heated, and the temperature of the second sensing block 12 is adjusted while being properly on / off controlled according to the control signal of the controller 17.

The controller 17 controls the heaters so that the two sensing blocks always maintain a constant temperature difference ΔT, for example, 10 ° C, from the signals of the two thermocouples 14 and 15 detecting the temperature of each of the sensing blocks 11 and 12. 18). When the temperature difference ΔT of the two sensing blocks 11 and 12 is less than 10 ° C. from the signals of the thermocouples 14 and 15, the heater 18 is operated to operate the second sensing block 12. Heating to ensure that the temperature difference ΔT between the two sensing blocks is always 10 ° C.

As the heater 18, a cartridge type heater may be used.

In the Seebeck coefficient measuring apparatus, the hydrogen storage alloy powder 10 is filled and fixed in the plastic tube 13, and coupling portions 11a and 12a of the two sensing blocks 11 and 12 are connected to the hydrogen storage alloy powder 10. It is inserted into both ends of the plastic tube 13 to be in contact.

As is well known, existing fuel cell automotive hydrogen storage alloys are mostly in powder form due to the stresses generated by the inhalation and release of hydrogen, so the Seebeck coefficient must be measured in the hydrogen storage alloy with hydrogen stored therein. .

Inside the sensing blocks 11 and 12, thermocouples 14 and 15 are installed inside the sensing blocks 11 and 12, and the thermocouples 14 and 15 are connected to the controller 17 so that an output temperature signal can be input. The analog signals of the thermocouples 14 and 15 are amplified by an amplifier (not shown) in the control unit 17 and then converted into digital signals by an A / D converter (not shown). 17a)).

In addition, a voltmeter 16 for measuring a voltage difference (thermal electromotive force) ΔV between the two sensing blocks 11 and 12 is provided, and the voltmeter 16 is configured to input an output voltage difference measurement signal. It is connected to the control unit 17 so that.

The controller 17 controls the operation of the heater 18 to maintain the temperature difference ΔT between the two sensing blocks 11 and 12 at 10 ° C based on the signals of the thermocouples 14 and 15. The computer 17a of 17 receives the signals of the thermocouples 14 and 15 and the signal of the voltmeter 16 and calculates the Seebeck coefficient based on these.

At this time, the computer 17a of the control unit 17 uses Seebeck using equation 1 from the temperature difference ΔT and the voltage difference (thermoelectric force) ΔV measured by the thermocouples 14 and 15 and the voltmeter 16. Calculate the coefficients.

In addition, the computer 17a of the control unit 17 calculates the calculated Seebeck coefficient as the amount of hydrogen using a previously measured correction value, and the calculated data is displayed through the storage and display device 19.

Figure 4 is a graph showing the relationship between hydrogen amount obtained through the LaNi _{4 .6} Sn _{0 .4} Seebeck coefficient and PCT equipment and quantitatively measuring the hydrogen of the hydrogen storage alloy devices obtained through the Seebeck coefficient measuring device, the hydrogen in the hydrogen storage alloy The change in Seebeck coefficient with increasing storage is measured.

As shown in the results, the Seebeck coefficient decreases proportionally as the amount of stored hydrogen increases. The measuring principle of the present invention uses the principle that the Seebeck coefficient changes proportionally according to the amount of hydrogen in the hydrogen storage space.

The proportional change of the Seebeck coefficient increases the total number of electrons in the alloy by transferring the electrons of hydrogen to the alloy when hydrogen is absorbed into the hydrogen storage alloy, where the increased number of electrons increases proportionally with the measured Seebeck coefficient or Due to the decreasing principle, the proportional increase or decrease of the Seebeck coefficient makes it possible to measure the amount of hydrogen in the hydrate region which was not possible with conventional pressure measurements.

As a result, the Seebeck coefficient obtained from the Seebeck coefficient measuring apparatus may be converted into the amount of hydrogen using the calibration curve of FIG. 4, and thus, the amount of hydrogen occluded in the alloy is accurately measured from the Seebeck coefficient of the hydrogen storage alloy powder. You can do it.

Thus, the method for measuring the amount of hydrogen according to the present invention measures the Seebeck coefficient using a Seebeck coefficient measuring apparatus for a hydrogen storage alloy, and the proportional correlation between the Seebeck coefficient and the experimentally measured hydrogen from the measured Seebeck coefficient It is characteristic that the relationship can be used to calculate the amount of hydrogen in the actual hydrogen storage alloy.

Such a method of measuring the amount of hydrogen of the present invention can be applied to a fuel gauge of a fuel cell vehicle. When the controller 17 drives the fuel gauge 20 as shown in FIG. Through this, the amount of residual fuel (hydrogen) can be known.

As described above, according to the method for measuring the amount of hydrogen in a hydrogen storage alloy for fuel cell vehicles according to the present invention, the Seebeck coefficient of the hydrogen storage alloy containing hydrogen is measured using the Seebeck coefficient measuring device, and the measured By using the proportional correlation between the Seebeck coefficient experimentally measured from the Seebeck coefficient and the amount of hydrogen, it is composed of a process of calculating the amount of hydrogen in the actual hydrogen storage alloy, and has the following effects.

1) Using the Seebeck coefficient measuring device, it is possible to accurately measure the amount of hydrogen in the hydrogen storage alloy in a relatively simple manner, and when it is installed in the storage tank, it can be applied as a fuel gauge of a fuel cell vehicle.

2) The low cost Seebeck coefficient measuring device can be used to reduce fuel cell price increases in fuel gauge applications.

Claims (2)

In the method for measuring the hydrogen content of the hydrogen storage alloy for fuel cell vehicles, Measuring the Seebeck coefficient using a Seebeck coefficient measuring apparatus for a hydrogen storage alloy in a hydrogen-containing powder form; Calculating, by the controller, the actual amount of hydrogen stored in the hydrogen storage alloy from the Seebeck coefficient measured in the step by using a proportional correlation between the Seebeck coefficient and the hydrogen amount experimentally measured; Method for measuring the hydrogen content of the hydrogen storage alloy for fuel cell vehicle comprising a. The method according to claim 1, Measuring the Seebeck coefficient, A first sensing block made of oxygen-free pure copper and maintained at room temperature, a second sensing block temperature-controlled by a heater operation, a tube filled with hydrogen storage alloy powder, a thermocouple for measuring the temperature of each sensing block, and two sensing. By using a voltmeter for measuring the voltage difference (thermal electromotive force) between blocks, and a Seebeck coefficient measuring device including a control unit for controlling the heater operation, Fixing the hydrogen storage alloy in the tube and inserting the coupling portions of the two sensing blocks into both ends of the tube to contact the hydrogen storage alloy powder; The control unit receives a signal of each thermocouple and controls the heater operation based on this to maintain a constant temperature difference between the two sensing blocks; And Calculating, by the controller, a Seebeck coefficient using a temperature difference between two sensing blocks and a thermoelectric power input from the voltmeter; Method for measuring the hydrogen content of the hydrogen storage alloy for fuel cell vehicle, characterized in that consisting of.

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