MEASURING SYSTEM FOR DETERMINING A DISPENSED AMOUNT OF HYDROGEN AND METHOD THEREFOR

Abstract

The invention relates to a measuring system for determining a dispensed amount of hydrogen of a hydrogen dispensing location from a hydrogen dispensing unit present there to a receiving tank including a measuring unit. The measuring unit can have a flowmeter, wherein the measuring system is designed to establish a fluid-tight connection between the hydrogen dispensing unit and the receiving tank. Furthermore, the flowmeter has an active cooling. The invention further relates to a measuring method for determining a dispensed amount of hydrogen.

Claims

1. A measuring system for determining a dispensed amount of hydrogen of a hydrogen dispensing location, in particular a hydrogen fueling station, from a hydrogen dispensing unit in form of a filling point present there to a receiving tank, the measuring system comprising a measuring unit, wherein the measuring unit including a flowmeter which can be arranged between the hydrogen dispensing unit in form of a filling point and the receiving tank, the measuring system is designed to establish a fluid-tight connection between the hydrogen dispensing unit in form of a filling point and the receiving tank whereby a fluid-tight connection is established from the hydrogen-dispensing unit in the form of a filling point to the measuring unit and a fluid-tight connection can be is established from the measuring unit to the receiving tank, the measuring unit is designed to lead hydrogen dispensed by the hydrogen dispensing unit in form of a filling point through the flowmeter of the measuring unit to the receiving tank and the flowmeter has is actively cooled in that the flowmeter has an active cooling system which is designed to cool the flowmeter before the start of the transfer of the hydrogen in such a way that there is essentially no change in the temperature in the flowmeter during the transfer.

2. The measuring system according to claim 1, wherein the active cooling system comprises an external cooling system.

3. The measuring system according to claim 1, wherein the active cooling system is realized by means of an external cooling material, in particular dry ice.

4. The measuring system according to claim 1, wherein a receiving device with thermal contact to the flowmeter is designed in the measuring unit.

5. The measuring system according to claim 4, wherein the receiving device is designed as a hollow space accessible from the outside.

6. The measuring system according to claim 4, wherein a wall of the receiving device is designed by way of a body of the flowmeter.

7. The measuring system according to claim 1, wherein the flowmeter is constructed as a Coriolis flowmeter, an ultrasonic flowmeter or a flowmeter using critical nozzles.

8. The measuring system according to claims 1, wherein a connection for transmitting cable-based bidirectional infrared signals between the hydrogen dispensing unit and the receiving tank is provided.

9. The measuring system according to claim 8, wherein the connection is guided around the measuring unit.

10. The measuring system according to claim 8, wherein the connection is guided through the measuring unit.

11. The measuring system according to claim 1, wherein the measuring unit has the flowmeter and a control and evaluation unit.

12. The measuring system according to claim 1 wherein a display unit is provided which has at least a data logger and a measurement display and is that the display unit is in communication connection with the measuring unit.

13. A method for determining the dispensed amount of hydrogen of a hydrogen dispensing location, in particular a hydrogen fueling station, with a hydrogen dispensing unit in form of a filling point to a receiving tank, the method comprising: using a measuring system according claims, wherein a fluid-tight connection is established between the hydrogen dispensing unit in form of a filling point and the measuring unit as well as between the measuring unit and the receiving tank, wherein via the fluid-tight connection hydrogen is transferred from the hydrogen dispensing unit in form of a filling point via the flowmeter of the measuring unit of the measuring system to the receiving tank, wherein the throughflow of hydrogen through the flowmeter is determined during the dispensing of the hydrogen from the hydrogen dispensing unit to the receiving tank and wherein the flowmeter is actively cooled before the beginning of the transfer of the hydrogen from the hydrogen dispensing unit to the receiving tank such that substantially no change in temperature occurs in the flowmeter during the transfer.

14. The method according to claim 13, wherein the flowmeter is cooled by means of cooling material, in particular dry ice, introduced into the receiving space.

Description

[0046] The invention is explained in greater detail hereinafter by way of an exemplary embodiment as well as schematic drawings, wherein show:

[0047] FIG. 1 a diagram to explain a typical filling process at a hydrogen fueling station; and

[0048] FIG. 2 a simplified illustration of the measuring system according to the invention.

[0049] In FIG. 1 a diagram to explain the standard filling process at a hydrogen fueling station is illustrated.

[0050] In this, three different curves K.sub.1, K.sub.2 and K.sub.3 are shown over time. Curve K.sub.1 relates to the pressure prevailing in or on the receiving tank. K.sub.2 shows the mass flow through a connecting hose between the dispensing location and the receiving tank. K.sub.3 illustrates the temperature in the fuel hose during the fueling process.

[0051] In FIG. 1 the time during the fueling process is plotted on the abscissa. On the left ordinate the mass flow is shown in g/s for curve K.sub.3. Illustrated with the same resolution on the right ordinate is the pressure in bar for curve K.sub.1 and the temperature in ° C. for curve K.sub.3.

[0052] In the following the fueling process is explained in principle. At time to the fuel hose is connected between the hydrogen dispensing unit, i.e. the filling pump and the receiving tank. At time t.sub.1 a high pressure pulse is introduced via the system of the fueling station into the closed hose system, which, however, is of short duration only. Subsequently, a test is made as to whether the pressure can be maintained or not. This serves to ensure and verify whether the connection is fluid-tight. Afterwards, at time t.sub.2 refueling is begun.

[0053] As a standard, hydrogen fueling stations in Europe have three different tanks: a low-pressure tank up to approximately 200 bar, a medium-pressure tank up to approximately 600 bar and a high-pressure tank with a filling between 700 bar and 800 bar. At time t.sub.3 determination is made by the fueling station that the filling from the low-pressure tank, with which the process was initially begun, no longer takes place at a sufficiently fast rate and a switchover to the medium-pressure tank is effected. At time t.sub.4 the same determination takes place for the medium-pressure tank so that a switchover to the high-pressure tank is implemented. At time t.sub.5 the fueling process is completed since the maximum permissible pressure is present in the tank of the vehicle. Other embodiments of hydrogen fueling stations use cryogenic liquid hydrogen which, by being vaporized and compressed, is used in a similar process as highly compressed hydrogen for vehicle refueling.

[0054] By means of the measuring system according to the invention which is explained in greater detail hereinafter and illustrated schematically in FIG. 2 the mass flow during the fueling process can be determined with high precision.

[0055] In FIG. 2, on the left side a hydrogen dispensing location 60, for example in the form of a fueling station, is initially provided. This has a hydrogen dispensing unit 61, on which a connector piece 62 is provided. On the right side of the Figure a motor vehicle 70 is illustrated, in which a receiving tank 71 is arranged which, in turn, has a connector piece 72.

[0056] In normal operation a direct fluid-tight connection would be established with a dispensing hose between the hydrogen dispensing location 61 or rather the connector piece 62 and the receiving tank 71 or rather its connector piece 72. However, in order that a calibration of the amount of hydrogen dispensed by the hydrogen dispensing unit 61 or an additional verification is provided a measuring system 1 according to the invention is interposed.

[0057] The measuring system 1 according to the invention consists of two main components. On the one hand this is a measuring unit 10 and on the other hand a display unit 20.

[0058] In the measuring unit 10 a flowmeter 12 is provided that has a corresponding control and evaluation unit 19. Furthermore, two connector pieces 11, 16 are provided. Between the two connector pieces 11, 16 a fluid-tight connection is provided that is guided through the flowmeter 12. On this connection a temperature sensor 13 and a pressure sensor 14 are additionally arranged. In the exemplary embodiment the display unit 20 has a data logger 22 as well as a measurement display 24. Both the data logger 22 and the measurement display 24 are in communication connection with the control and evaluation unit 19 as well as the temperature sensor 13 and the pressure sensor 14. These connections are only outlined in FIG. 1.

[0059] To carry out a measurement of the dispensed amount, according to the invention a fluid-tight connection is established between the hydrogen dispensing unit 61 or rather its connector 62 and the connector piece 11 of the measuring unit 10 as well as the connector piece 16 of the measuring unit 10 and the connector piece 72 of the receiving tank 71. Now hydrogen can flow via the hydrogen dispensing unit 61 into the receiving tank 71. For this, the method previously described with reference to FIG. 1 is applied.

[0060] Due to the fact that the hydrogen is highly compressed and initially filled into an empty tank 71 it heats up again in the receiving tank 71. However, since the tanks, especially in a motor vehicle 70, are only approved up to a temperature of approximately +80° C. this heating-up has to be largely reduced or prevented. For this reason, the hydrogen dispensed by the hydrogen dispensing location 60 via the hydrogen dispensing unit 61 is delivered by being cooled. The consequence of this is that in the fluid-tight connection a temperature in the range from −10° C. to −30° C. is present during the dispensing of the hydrogen.

[0061] However, this leads to problems in the measuring precision of the flowmeter 12 since a very large temperature range has to be covered in this case. Hence, a zero drift occurs that is no longer acceptable for a calibration measurement.

[0062] Therefore, in accordance with the invention the suggestion is made to actively cool the flowmeter 12. According to the invention, for this purpose a receptacle 15 that is accessible from the outside is provided in the measuring unit 10. In FIG. 1 an external cooling material 30, such as dry ice, is provided in a simplified manner in this receptacle 15. The receiving device 15 is constructed such that it ends in the area of the flowmeter 12 and has a common wall 17 with the flowmeter 12 for example. In this way, a thermal contact is brought about so that the flowmeter 12 can be cooled.

[0063] If, for example, dry ice is used as cooling material 30 this offers the advantage that it can be procured relatively easily and is cost-efficient. Since it is inert it can also be used in the explosion-protected area of a fueling station.

[0064] The data determined during such a measurement, on the one hand those of the control and evaluation unit 19 relating to the throughflow and on the other hand the optionally provided data of the temperature sensor 13 and the pressure sensor 14 are passed on to the display unit 20 and stored there in a data logger 22 as well as displayed on a corresponding measurement display 24.

[0065] To enable communication between the hydrogen dispensing unit 61 and the receiving tank 71 provision is made in accordance with the standards for an infrared connection which can be of cable-based design. Via this infrared connection information on the refueling state and the like are exchanged between the receiving tank 71 and the hydrogen dispensing unit 61.

[0066] To allow for continuation of this communication two options are suggested in accordance with the invention. Both of these are illustrated in FIG. 2, yet normally both options are not used at the same time.

[0067] On the one hand the infrared connection can be led past the measuring system 1, as shown by way of the infrared connection 41. In this case, the measuring system 1 does not obtain any information from the infrared channel. On the other hand, the measuring system 1 can be actively interposed. To this end, two infrared connections 42 are provided that are also drawn in FIG. 2.

[0068] This has the effect that the information runs through the measuring unit 10 and can perhaps be read there or can also be additionally evaluated.

[0069] The advantage of the system according to the invention resides in the fact that through this a high-precision measurement can be carried out which does not require considerably more time than a standard fueling process.

[0070] According to the law on measures and calibration at least two to four fueling processes are provided which can be readily carried out in the system according to the invention just as a regular fueling process at the fueling station. This results in a significant time advantage as compared to known systems.

[0071] Hence, with the measuring system according to the invention and the method according to the invention it is possible to carry out a calibration test measurement of a hydrogen fueling station in an efficient and rapid way.