Method and device for detecting possible throttling losses in a hydrogen tank system - Patents.com

Abstract

[Solution] A method (40) for detecting possible throttling losses (11) in a hydrogen tank system (10) is characterized in that, prior to accessing the hydrogen tank system (10), trends (30) of pressure and temperature (31) are determined at various measurement points in the hydrogen tank system (10) for the access, which are predicted to be free of throttling losses (11), the pressure and temperature (31) are continuously detected at the multiple measurement points during the access, and the throttling losses (11) are possibly detected using a deviation (33) of the pressure or temperature (31) from the predicted trends (30).

Description

[Technical field]

[0001] The present invention relates to a method for detecting possible throttling losses in a hydrogen tank system, and further to a corresponding device, a corresponding computer program and a corresponding machine-readable storage medium. [Background technology]

[0002] Hydrogen filling stations are equipped with a fuel meter, a filling nozzle and a pump with which the energy reservoir of a fuel cell vehicle or other mobile hydrogen consuming device can be filled. According to the prior art, for example, liquid hydrogen (LH2) is provided at temperatures up to -253°C and pressures up to 16.5 bar, and gaseous hydrogen (GH2) is provided at temperatures of 20°C and pressures of 250 or 350 bar, or at temperatures of -40°C and pressures of 700 bar.

[0003] DE 101 1 033 631 A1 relates to a method for fuelling a vehicle having a hydrogen tank for receiving gaseous hydrogen. When carrying out this method, the following method steps are carried out: The vehicle drives into a fuelling area; A fuelling step is carried out on the vehicle; Then a first tank temperature check of the tank contents of the at least one hydrogen tank is carried out; If the temperature of the tank contents of the at least one hydrogen tank exceeds a temperature limit value, the vehicle is brought to a cooling area; Here, after the cooling phase, a second tank temperature check is carried out; If the tank temperature falls below the temperature limit value, a tank pressure check is carried out; If the tank pressure in the at least one hydrogen tank falls below a tank pressure limit value, the vehicle is brought to the fuelling area to carry out a next fuelling; If the tank pressure is within the range of the tank pressure limit value, the fuelling is terminated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] DE 102019219826 Summary of the Invention

[0005] The invention provides a method for detecting possible throttling losses in a hydrogen tank system, a corresponding device, a corresponding computer program and a corresponding storage medium according to the independent claims.

[0006] The proposed solution is based on the recognition that on-board storage of gaseous hydrogen is significantly more expensive than storage of the same amount of liquid hydrocarbon, and therefore prior art hydrogen tank systems, which usually contain multiple tanks, are correspondingly complex and expensive.

[0007] The proposal according to the invention furthermore takes advantage of the fact that each tank is equipped in standard fashion with a temperature sensor in order to obtain information about the amount of stored hydrogen. Furthermore, the pressure is generally measured at several points in the tank system, but usually not in each tank.

[0008] Furthermore, the method described below takes into account the fact that fuel cells are often used for energy conversion in hydrogen-powered vehicles, a process that is characterized by a higher efficiency than in internal combustion engines, but in fuel cells high demands are placed on the purity of the supplied hydrogen in order to ensure its long-term functionality.

[0009] Therefore, various filters are installed in hydrogen tank systems. Even if these filters function satisfactorily, they throttle the hydrogen flow rate to a certain extent. Moreover, the filters can become clogged, which can affect the functioning of the tank system. However, a clogged filter is only one example of an undesirable throttle point in a hydrogen tank system. Other throttle losses can occur due to the fact that such a system is used in the commercial vehicle sector in rough environments, for example in mining or construction site areas. In such environments, the hydrogen lines in the system can be inadvertently deformed to such an extent that significant throttle points become apparent. In addition to the above examples, various other causes for undesirable throttle points in a tank system are conceivable.

[0010] Diagnosis of throttling losses is made difficult by the fact that maintenance work on hydrogen tank systems is itself dangerous due to the hazards posed by hydrogen and is therefore avoided as much as possible. Therefore, a method for detecting and localizing problematic throttling locations during normal operation is desirable.

[0011] Taking into account these challenges, the proposed solution is based on the realization that throttling losses affect the hydrogen pressure and temperature in the tank system depending on the unfavorable throttling point situation during fuel injection and withdrawal. Based on the pressure and temperature trends detected at various measuring points in the tank system and on the knowledge of the pipe connections between these measuring points, the throttling losses in the system can be limited.

[0012] The advantage of this solution is that it opens up the possibility of detecting undesirable throttling points in a closed hydrogen tank system during the control operation of this hydrogen tank system.

[0013] Advantageous developments and improvements of the basic idea as defined in the independent claims are possible by the measures set out in the dependent claims. Thus, it may be provided that a tank that experiences a throttling loss is at least temporarily shut down in order to avoid dangerous interactions of the tank vessels with one another when accessing the system. [Brief description of the drawings]

[0014] [Figure 1] 1 is a system diagram of a hydrogen tank system. [Diagram 2] 1 is a graph showing temperature changes in a side tank and a rear tank without a throttle. [Diagram 3] 5 is a graph showing the corresponding temperature profiles in a side tank and a rear tank with a throttle. [Figure 4] 2 is a flowchart of a method according to a first embodiment. [Diagram 5] FIG. 11 is a schematic diagram of a control unit according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Several embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

[0016] Figure 1 shows a hydrogen tank system 10. Essentially, multiple undesirable throttling points can affect two modes within this system: one during fuel injection and the other during removal of hydrogen from the tank system.

[0017] First, the fuel injection process is observed: here, hydrogen is heated in the respective filled tanks (12-17), which is detected by the tank's temperature sensor. However, possible throttling losses in the system (10) slow down the rate of pressure rise and, therefore, the rate of temperature rise. At several measuring points, such a situation can be deduced to be a throttling point, as is explained below with the aid of the illustrated hydrogen tank system (10).

[0018] If unfavorable throttling points are present between the receiver (20) and the first downstream branch (18) leading to the individual tanks (12-17), these will delay the filling of all tanks (12-17) uniformly, which will manifest itself in an overall relatively slow pressure rise in the hydrogen tank system (10) compared to a system without throttling losses, and which can likewise be determined by a delayed pressure rise at the pressure measuring points or a slowed and delayed temperature rise at the temperature measuring points of all tanks (12-17).

[0019] If an undesirable throttle point exists between a tank and a branch directly upstream of it in terms of fluid technology, for example in the illustrated arrangement between the upper branch (17) and the left-hand side tank (12) as viewed in the drawing, then only this tank (12) will experience a delayed pressure increase, which can be measured directly if a pressure sensor is provided here, or can be derived from at least a further delayed temperature increase in the tank (12).

[0020] In the event of a throttle loss at the throttle point, designated 11, between the branch (18, 19) leading to the side tanks (12, 17) and the rear tank (13-16), only the rear tank (13-16) is subjected to a delayed pressure rise, whereas the pressure in the side tanks (12, 17) follows a predicted course. This effect can also be measured directly if pressure sensors are provided in the tanks (12-17) of the two tank groups. In this case too, the pressure ratio prevailing in certain tanks (12-17) can be deduced alternatively from the temperature in these tanks.

[0021] For example, in Figure 3, a time course (30) with the temperature (31) at said location is shown at the throttling loss (11). It is clearly shown that the temperature (31) in the rear tank (13-16) rises (33) significantly slower due to the throttling compared to the course (30) shown in Figure 2, which would be expected without the throttling loss (11). However, as can be seen from an overview of Figures 2 and 3, the throttling loss (11) has almost no effect on the course (30) of the temperature (31) in the side tanks (12, 17).

[0022] The removal of hydrogen from the tank system (10) is then observed: here, the pressure in the tanks (12-17) drops, which causes a temperature drop due to the isochoric expansion of the tank contents. Of course, as a rule, the hydrogen mass flow rate when removing from the tank system (10) is significantly lower than the mass flow rate during fuel injection. The temperature (31) therefore drops correspondingly slowly, which makes reliable detection of throttling losses in this use case difficult. During the removal of hydrogen from the tank system (10), detection is therefore preferably carried out at stepped-up mass flows, i.e. in the case of a hydrogen-powered road vehicle, for example during relatively long highway journeys.

[0023] Therefore, according to the above embodiment, the throttling losses do not slow down the increase in temperature 31 when emptying the hydrogen tank system 10, but rather slow down the decrease in temperature 31. Nevertheless, such a situation can also be determined at multiple measurement points, as can be seen from the following considerations.

[0024] If an undesirable throttling point is present between the upper branch (18) and the pressure reducer (21) as seen in the drawing, this will reduce the pressure detected here. The extent of this pressure drop depends on the mass flow rate taken off. In the case of a strong throttling, the tank system (10) can no longer provide the desired mass flow rate, even though the tank pressure required for this would still be available in unlimited function. In this case, a significant pressure difference between the pressure reducer (21) and the remaining pressure measuring points can be observed, as well as a delayed temperature drop at the temperature measuring points in all tanks (12-17).

[0025] If an undesirable throttle point exists between a tank and a branch immediately upstream of it in terms of fluid technology, for example in the illustrated arrangement between the upper branch (17) and the left side tank (12) as viewed in the drawing, then only this tank (12) is subjected to a delayed pressure drop, which can be measured directly if a pressure sensor is provided here, or which can otherwise be derived from the slower temperature drop in the tank (12).

[0026] In the case of the throttling losses at the throttling points, marked with 11, between the side tanks (12, 17) and the branches (18, 19) leading to the rear tank (13-16), only the rear tank (13-16) is subject to a delayed pressure drop, whereas the pressure in the side tanks (12, 17) has a predicted course. This effect can also be measured directly if pressure sensors are installed in the tanks (12-17) of the two tank groups. In this case too, the pressure ratio prevailing in certain tanks (12-17) can alternatively be estimated by the temperature in these tanks.

[0027] A specific implementation of the method (40) will now be described with the aid of figure 4. When accessing the hydrogen tank system (10), first the predicted pressure and temperature (31) profiles (30) specific to each tank (12-17) without throttling losses are determined (process 41), taking into account the filling levels and initial temperatures of the individual tanks (12-17) as well as the total mass flow extracted during the extraction as well as the ambient temperature of the hydrogen tank system (10).

[0028] During access, the pressure and temperature (31) at the various measuring points are then continuously detected (process 42). Deviations with respect to the predicted progression (30) for each tank (12-17) can be easily determined. The presence of a deviation (33) is presumed, for example, if the pressure or temperature (31) itself deviates from a preset threshold value after a certain time, or if the respective measured value rises (when filling) or falls (when emptying the hydrogen tank system) less than predicted.

[0029] From the deviation (33) detected in this way, a throttling loss is deduced, which can be determined in accordance with the above-described exemplary embodiment by means of the measuring point associated with this deviation for a given pipeline section. The throttling loss detected in this way is then entered into an error memory when reporting the throttling point in question or is displayed to the operator of the hydrogen tank system (10), for example the driver of a vehicle equipped with a hydrogen tank system.

[0030] Reliable detection can only be achieved in the case of significant adverse throttling, which, if it occurs in the system 10, can lead to significant pressure differences between the tanks 12-17 during fuel filling and unloading. Such pressure differences can lead to a given tank 12-17 being filled from another tank 12-17, especially after opening of the tank valves during start-up of the system 10. Such type of interaction between the tanks 12-17 is dangerous, since it can only withstand a limited number of tank filling processes due to the significantly higher tank pressures.

[0031] To avoid such effects, individual tank containers experiencing throttling losses can be temporarily or permanently deactivated, for example by removing from control the tank valves of the tank containers experiencing throttling losses during start-up of the tank system 10. Such component-protecting measures are taken in hydrogen-powered vehicles at the expense of reduced mileage, which can be communicated to the driver via a suitable human-machine interface.

[0032] The method (40) may be implemented, for example, in software or hardware, or a mixture of software and hardware, for example in a control unit (50) as shown diagrammatically in FIG. [Explanation of symbols]

[0033] 10 Hydrogen tank system, tank system 11. Throttle location and throttling loss 12 Tank, Side Tank 13 Tank, rear tank 14 Tank, rear tank 15 Tank, rear tank 16 Tank, rear tank 17 Tank, side tank 18 First branch, upper branch 19 Branch 20 Receiving part 21 Pressure reducer 30 Changes over time 31 Temperature 33 Rise, deviation 40 ways 41 Process 42 Process 50 Control unit, device,

Claims

1. A method (40) for detecting possible throttling losses (11) in a hydrogen tank system (10), comprising: determining, prior to accessing the hydrogen tank system (10), the progression (30) of pressure and temperature (31) at various measurement points in the hydrogen tank system (10) that would be predicted for access without the throttling losses (11); Detecting the pressure and temperature (31) continuously during the access at the plurality of measurement points; the throttle loss (11) is detected, if necessary, by means of a deviation (33) of the pressure or temperature (31) from the predicted progression (30); A method (40) for detecting possible throttling losses (11) in a hydrogen tank system (10), comprising:

2. the hydrogen tank system (10) includes a plurality of tanks (12-17) having a plurality of the measurement points; determining said predicted progression (30) uniquely for each of said plurality of tanks (12-17); The throttling loss (11) is limited to a specific pipeline in the hydrogen tank system (10) using a measurement point related to the deviation (33). The method (40) of claim 1 .

3. determining an initial temperature and fill level of each of said tanks (12-17) prior to said access; determining the predicted progression (30) as a function of the initial temperature and the filling level; The method (40) of claim 2 .

4. said accessing being to empty said hydrogen tank system (10); determining the predicted progression (30) further depends on the mass flow rate during emptying of the hydrogen tank system (10) and on the ambient temperature of the hydrogen tank system (10); 4. The method (40) according to claim 2 or 3, characterized in that

5. A method (40) according to any one of claims 2 to 4, characterized in that, in accordance with said limitation, said tank (12-17) experiencing said throttling loss (11) is at least temporarily shut down.

6. writing the detected throttle loss (11) in an error memory, or Indicating the detected throttling loss (11) to an operator of the hydrogen tank system (10); The method (40) of any one of claims 1 to 5, characterized in that

7. determining said deviation (33) if the pressure or temperature (31) after a given time (32) of said access deviates from a preset threshold value, or determining said deviation (33) if the pressure or temperature (31) during said access increases or decreases less than expected; The method (40) according to any one of claims 1 to 6, characterized in that

8. A computer program, designed to carry out a method (40) according to any one of claims 1 to 7.

9. 9. A machine-readable storage medium having stored thereon the computer program of claim 8.

10. An apparatus (50) designed for carrying out the method (40) according to any one of claims 1 to 7.

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