Method and device for detecting possible throttle losses in a hydrogen tank system

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 throttle 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 fuel nozzle and a pump, which can be used to fill the energy reservoir of a fuel cell vehicle or other mobile hydrogen consuming device. 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] Patent document 1 relates to a method for refueling a vehicle having a hydrogen tank for receiving gaseous hydrogen. When carrying out this method, the following method steps are performed: the vehicle drives into a refueling area; a refueling step is carried out on the vehicle; a first tank temperature check of the tank contents of at least one hydrogen tank is then carried out; if the temperature of the tank contents of the at least one hydrogen tank exceeds a temperature limit, the vehicle is transported 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, a tank pressure check is carried out; if the tank pressure in the at least one hydrogen tank falls below a tank pressure limit, the vehicle is transported to the refueling area to carry out a next refueling; if the tank pressure is within the tank pressure limit, the refueling is terminated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] German Patent Application Publication No. 102019219826 Summary of the Invention

[0005] The invention provides a method for detecting possible throttle 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 an equivalent amount of liquid hydrocarbon, and therefore prior art hydrogen tank systems, which typically 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 with a temperature sensor in the standard way in order to obtain information about the amount of hydrogen stored. Furthermore, pressure is generally measured at several points in the tank system, but usually not within 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, and although this process is characterized by higher efficiency than in internal combustion engines, high demands are placed on the purity of the supplied hydrogen in fuel cells in order to ensure their long-term functionality.

[0009] Therefore, various filters are installed in hydrogen tank systems. Even when these filters function satisfactorily, they restrict the hydrogen flow rate to some extent. Moreover, filters can become clogged, which can affect the functioning of the tank system. However, a clogged filter is just one example of an undesirable restriction in a hydrogen tank system. Other throttling losses can occur when such systems are used in harsh environments in the commercial vehicle sector, such as mining areas or construction sites. In such environments, the hydrogen lines in the system can be inadvertently deformed to the point that significant restrictions become apparent. In addition to the above examples, there are many other possible causes of undesirable restrictions in a tank system.

[0010] Diagnosing throttling loss 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 identifying problematic throttling locations during normal operation is desirable.

[0011] In view of these challenges, the proposed solution is based on the recognition that throttling losses affect the pressure and temperature of the hydrogen in the tank system depending on the unfavorable throttling point conditions during fuel injection and removal. Based on the pressure and temperature trends detected at various measuring points in the tank system and on 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] The measures set out in the dependent claims allow advantageous developments and improvements of the basic idea set out in the independent 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 explanation of the drawings]

[0014] [Figure 1] 1 is a system diagram of a hydrogen tank system. [Figure 2] 10 is a graph showing temperature changes in a side tank and a rear tank without a throttle. [Figure 3] 4 is a graph showing the corresponding temperature profiles in the side tank and rear tank with a throttle. [Figure 4] 1 is a flowchart of a method according to a first embodiment. [Figure 5] FIG. 10 is a schematic diagram of a control unit according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[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 hydrogen removal from the tank system.

[0017] First, the fuel injection process is observed: here, hydrogen is heated in each filled tank (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, consequently, the rate of temperature rise. At several measurement points, such a situation can be deduced as a throttling point, as explained below using the illustrated hydrogen tank system (10).

[0018] If unfavorable throttling points exist between the receiver (20) and the downstream first 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 a relatively slow overall 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 measurement points or a slowed and delayed temperature rise at the temperature measurement points of all tanks (12-17).

[0019] If an undesirable throttle point exists between a tank and a branch located directly upstream of it in terms of fluid flow, such as in the illustrated arrangement between the upper branch 17 and the left-hand side tank 12, 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 indicated by 11 between the branches (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 increase, while the pressure in the side tanks (12, 17) follows 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 a given tank (12-17) can be estimated from the temperature in these tanks.

[0021] For example, Figure 3 shows a time course (30) of the temperature (31) at the throttling loss (11) at said location. It clearly shows that the temperature (31) in the rear tanks (13-16) rises (33) significantly more slowly 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, the mass flow rate of hydrogen during removal from the tank system 10 is usually significantly lower than the mass flow rate during fuel injection. The temperature 31 therefore drops correspondingly slowly, which makes reliable detection of throttling losses difficult in this use case. Therefore, during the removal of hydrogen from the tank system 10, detection is preferably carried out at an increased mass flow rate, i.e., in the case of a hydrogen-powered road vehicle, during relatively long highway journeys.

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

[0024] If an undesirable restriction exists between the upper branch (18) and the pressure reducer (21) as seen in the drawing, this will reduce the pressure detected there. The extent of this pressure drop depends on the extracted mass flow rate. If the restriction is too strong, the tank system (10) will no longer be able to provide the desired mass flow rate, even though the tank pressure required for this will still be available in unrestricted operation. In this case, a significant pressure difference between the pressure reducer (21) and the remaining pressure measurement points will be observed, as well as a delayed temperature drop at the temperature measurement 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, such as in the illustrated arrangement between the upper branch 17 and the left side tank 12 as viewed in the drawing, only this tank 12 will be subjected to a delayed pressure drop, which can be measured directly if a pressure sensor is provided here, or else the pressure drop can be derived from the slower temperature drop in the tank 12.

[0026] Due to 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, while 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. Again, the temperature in certain tanks (12-17) can alternatively be used to estimate the pressure ratio prevailing in these tanks.

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

[0028] Then, during access, the pressure and temperature (31) at the various measuring points are continuously detected (process 42). Deviations from the predicted progression (30) for each tank (12-17) can be easily determined. For example, a deviation (33) is assumed to exist 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 that can be determined in a given pipeline section using the measuring point associated with this deviation can be estimated according to the above-described embodiment. The throttling loss detected in this way can then be entered into an error memory when reporting the throttling point in question or can be 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. Such significant adverse throttling in the system 10 can cause significant pressure differences between the tanks 12-17 during fuel filling and withdrawal. Such pressure differences can result in one tank 12-17 being filled from another tank 12-17, particularly after opening the tank valves during system 10 startup. This type of interaction between the tanks 12-17 is dangerous because it can only withstand a limited number of tank filling cycles due to the significantly higher tank pressures.

[0031] To avoid such effects, individual tank vessels that experience throttling losses can be temporarily or permanently deactivated, for example by excluding the tank valve of the tank vessel that experiences throttling losses from the control during start-up of the tank system 10. Such component-protective measures, which are taken at the expense of reduced mileage in hydrogen-powered vehicles, 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 tanks, side tanks 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 throttling loss (11) caused by clogging of a filter in a hydrogen flow path or deformation of a hydrogen pipeline in a hydrogen tank system (10), comprising: Before accessing the hydrogen tank system (10), determining the predicted pressure and temperature (31) trends (30) at various measurement points in the hydrogen tank system (10) for the access in the absence of the throttling losses (11); detecting the pressure and the temperature (31) continuously at the plurality of measurement points during the access; The throttle loss (11) is detected using a deviation (33) of the pressure or the temperature (31) detected during the access from the predicted progression (30). A method (40) for detecting throttling losses (11) caused by blockage of a filter in a hydrogen flow path or deformation of a hydrogen pipeline in a hydrogen tank system (10), characterized by:

2. the hydrogen tank system (10) includes a plurality of tanks (12-17) having a plurality of the measurement points; determining the predicted progression (30) uniquely for each of the plurality of tanks (12-17); The throttling loss (11) is limited to a predetermined pipeline in the hydrogen tank system (10) using a measurement point involved in 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, characterized in that

4. said access being to empty said hydrogen tank system (10); The predicted progression (30) is further determined depending on the mass flow rate during emptying of the hydrogen tank system (10) and depending 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 claim 2 or 3, characterized in that, according to said limitation, said tank (12-17) suffering from said throttling loss (11) is at least temporarily shut down.

6. A method (40) for detecting possible throttling losses (11) in a hydrogen tank system (10), comprising: Before accessing the hydrogen tank system (10), determining the predicted pressure and temperature (31) trends (30) at various measurement points in the hydrogen tank system (10) for the access in the absence of the throttling losses (11); detecting the pressure and temperature (31) continuously at the plurality of measurement points during the access; The throttle loss (11) is detected, if necessary, by means of a deviation (33) of the pressure or temperature (31) from the predicted course (30), the hydrogen tank system (10) includes a plurality of tanks (12-17) having a plurality of the measurement points; determining the predicted progression (30) uniquely for each of the plurality of tanks (12-17); The throttling loss (11) is limited to a predetermined pipeline in the hydrogen tank system (10) using a measurement point involved in the deviation (33); said access being to empty said hydrogen tank system (10); The predicted progression (30) is further determined depending on the mass flow rate during emptying of the hydrogen tank system (10) and depending on the ambient temperature of the hydrogen tank system (10).

1. A method (40) for detecting possible throttling losses (11) in a hydrogen tank system (10), comprising:

7. determining an initial temperature and fill level of each of the 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 6, characterized in that

8. A method (40) as described in claim 6, characterized in that the tank (12-17) experiencing the throttling loss (11) is at least temporarily shut down in accordance with the limitation.

9. A method (40) for detecting possible throttling losses (11) in a hydrogen tank system (10), comprising: Before accessing the hydrogen tank system (10), determining the predicted pressure and temperature (31) trends (30) at various measurement points in the hydrogen tank system (10) for the access in the absence of the throttling losses (11); detecting the pressure and temperature (31) continuously at the plurality of measurement points during the access; The throttle loss (11) is detected, if necessary, by means of a deviation (33) of the pressure or temperature (31) from the predicted course (30), the hydrogen tank system (10) includes a plurality of tanks (12-17) having a plurality of the measurement points; determining the predicted progression (30) uniquely for each of the plurality of tanks (12-17); The throttling loss (11) is limited to a predetermined pipeline in the hydrogen tank system (10) using a measurement point involved in the deviation (33); According to the limitations, at least temporarily shutting down the tank (12-17) that is experiencing the throttling loss (11), 1. A method (40) for detecting possible throttling losses (11) in a hydrogen tank system (10), comprising: 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 9, characterized in that

11. The access is to empty the hydrogen tank system (10), The predicted progression (30) is further determined depending on the mass flow rate during emptying of the hydrogen tank system (10) and depending on the ambient temperature of the hydrogen tank system (10). The method (40) of claim 9, characterized in that

12. recording the detected throttle loss (11) in an error memory, or Indicating the detected throttle loss (11) to an operator of the hydrogen tank system (10); 12. The method (40) according to any one of claims 1 to 3 and 6 to 11, characterized in that at least one of

13. determining said deviation (33) if the pressure or temperature (31) after a predetermined 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; 12. The method (40) according to any one of claims 1 to 3 and 6 to 11, characterized in that:

14. A computer program designed to carry out the method (40) according to any one of claims 1 to 3 and 6 to 11.

15. 15. A machine-readable storage medium having stored thereon the computer program of claim 14.

16. An apparatus (50) designed to carry out the method (40) according to any one of claims 1 to 3 and 6 to 11.

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