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EP-4739523-A1 - SYSTEM AND METHOD FOR CONTROLLING LIQUID GAS STORAGE FOR A VEHICLE POWERED BY LIQUID GAS

EP4739523A1EP 4739523 A1EP4739523 A1EP 4739523A1EP-4739523-A1

Abstract

A system and method for controlling a fuel storage system configured to store a liquid fuel in a fuel storage container of a vehicle powered by the liquid fuel are provided. The control system comprises processing circuitry configured to obtain a request for a shutdown of the vehicle, obtain measurements of a pressure in the fuel storage container, estimate an expected start time for the vehicle that is shut down, and, responsive to detecting that the pressure in the fuel storage container is at or above a boil-off threshold pressure, allow the pressure in the fuel storage container to remain at or above the boil-off threshold pressure or enable venting of the fuel storage container to reduce the pressure in the fuel storage container in dependence on whether or not the expected start time is within a time threshold interval.

Inventors

  • STJERNBERG, OSCAR
  • WILHELMSSON, Martin

Assignees

  • VOLVO TRUCK CORPORATION

Dates

Publication Date
20260513
Application Date
20230706

Claims (20)

  1. 1 . A control system (700) for controlling a fuel storage system (10a, 10b, 12) configured to store a liquid fuel in a fuel storage container (30a, 30b, 30) of a vehicle (100a, 100b, 100) powered by the liquid fuel, the control system comprising processing circuitry configured to: obtain a request for a shutdown of the vehicle; obtain measurements of a pressure in the fuel storage container; estimate an expected start time for the vehicle that is shut down; and responsive to detecting that the pressure in the fuel storage container is at or above a boil-off threshold pressure, allow the pressure in the fuel storage container to remain at or above the boil-off threshold pressure or enable venting of the fuel storage container to reduce the pressure in the fuel storage container in dependence on whether or not the expected start time is within a time threshold interval.
  2. 2. The control system (700) of claim 1, wherein the processing circuitry is configured to allow the pressure in the fuel storage container to exceed the boil-off threshold pressure responsive to determining that the expected start time is within a time threshold interval.
  3. 3. The control system (700) of claim 1 or 2, wherein the processing circuitry is configured to direct at least a portion of the pressure in the fuel storage container to at least one pressure-consuming device to thereby cause the pressure in the fuel storage container to remain at or above the boil-off threshold pressure.
  4. 4. The control system (700) of any one of claims 1 to 3, wherein the processing circuitry is configured to determine whether the vehicle has started within the time threshold interval.
  5. 5. The control system (700) of claim 4, wherein the processing circuitry is configured to, responsive to determining that the vehicle has not started within the time threshold interval, enable venting of the fuel storage container.
  6. 6. The control system (700) of any one of claims 1 to 5, wherein the processing circuitry is configured to estimate the time threshold interval based on a duration of time required for the pressure in the fuel storage container to decrease below the boil-off threshold pressure when the vehicle starts.
  7. 7. The control system (700) of any one of claims 1 to 6, wherein the expected start time is estimated using one or more out of a driver history, vehicle use history, timing data, vehicle location data, and vehicle power consumption data.
  8. 8. The control system (700) of any one of claims 1 to 7, wherein the expected start time for the vehicle is estimated using a prediction model.
  9. 9. A vehicle (100a, 100b, 100) comprising the control system (700) of any one of claims 1 to 8.
  10. 10. A method (400) for controlling a fuel storage system configured to store a liquid fuel in a fuel storage container of a vehicle powered by the liquid fuel, the method comprising: obtaining (402) a request for a shutdown of the vehicle; obtaining (404) measurements of a pressure in the fuel storage container; estimating (406) an expected start time for the vehicle that is shut down; and responsive to detecting (408) that the pressure in the fuel storage container is at or above a boil-off threshold pressure, allowing (410) the pressure in the fuel storage container to remain at or above the boil-off threshold pressure or enabling venting of the fuel storage container to reduce the pressure in the fuel storage container in dependence on whether or not the expected start time is within a time threshold interval.
  11. 11 . The method (400) of claim 10, comprising allowing (420) the pressure in the fuel storage container to exceed the boil-off threshold pressure responsive to determining that the expected start time is within a time threshold interval.
  12. 12. The method (400) of claim 10 or 11 , comprising directing (422) at least a portion of the pressure in the fuel storage container from the fuel storage container to at least one pressure-consuming device to thereby cause the pressure in the fuel storage container to remain at or above the boil-off threshold pressure.
  13. 13. The method (400) of any one of claims 10 to 12, comprising determining (424) whether the vehicle has started within the time threshold interval.
  14. 14. The method (400) of claim 13, further comprising, responsive to determining that the vehicle has not started within the time threshold interval, enabling venting (416) of the fuel storage container.
  15. 15. The method (400) of any one of claims 10 to 14, comprising estimating (415) the time threshold interval based on a duration of time required for the pressure in the fuel storage container to decrease below the boil-off threshold pressure when the vehicle starts.
  16. 16. The method (400) of any one of claims 10 to 15, wherein the expected start time is estimated using one or more out of a driver history, vehicle use history, timing data, vehicle location data, and vehicle power consumption data.
  17. 17. The method (400) of any one of claims 10 to 16, wherein the expected start time for the vehicle is estimated using a prediction model.
  18. 18. The method (400) of any one of claims 10 to 17, wherein the liquid fuel is a fluid that is subject to boil- off.
  19. 19. A computer program product comprising instructions, which, when executed by processing circuitry, cause the processing circuitry to perform the method of any one of claims 10 to 18.
  20. 20. A computer-readable storage medium, having stored thereon a computer program product comprising computer-executable instructions which, when executed by processing circuitry, cause the processing circuitry to perform the method of any one of claims 10 to 18.

Description

TITLE SYSTEM AND METHOD FOR CONTROLLING LIQUID GAS STORAGE FOR A VEHICLE POWERED BY LIQUID GAS TECHNICAL FIELD [0001] The disclosure relates generally to a system and method for storing liquid gas onboard of a vehicle. More particularly, techniques are provided for determining whether and when to perform venting of a fuel storage container storing the liquid gas. [0002] The disclosure can be applied in heavy-duty vehicles, such as trucks, buses, and construction equipment. BACKGROUND [0003] Certain types of vehicles use liquid gas, e.g., Liquefied Natural Gas (LNG) or hydrogen, as a fuel. The fuel is stored onboard and is used to fuel the vehicle. LNG is natural gas that has been cooled to -161 °C or -162 °C. In its liquid state, the cryogenic LNG may be reduced to approximately one-six hundredth (1/600th) of its volume compared to the gaseous form, which facilitates storage and transportation of the gas. [0004] Hydrogen can be stored in a liquified or liquid form which is increasingly becoming a more preferable method of storing hydrogen since it is suitable for long-distance transportation of hydrogen. Liquefaction of hydrogen requires low temperatures, such as -253 °C, at atmospheric pressure. [0005] Liquid gases such as e.g. LNG and hydrogen, are stored at cryogenic tanks at temperatures below their boiling point. Due to heat leaking through insulation of the tank, the liquid gas evaporates whereby a boil-off gas is generated. [0006] The liquified hydrogen evaporates much easier than LNG, and the liquified hydrogen's evaporation rate per volume, or a boil-off rate, may be 10 times that of LNG. Accordingly, during storage or transportation, even at proper cryogenic conditions and using tanks with e.g. several levels of containment, it is challenging to maintain a sufficiently low temperature of the liquid hydrogen. There is natural continuous boil-off due to warming during storage or transportation. It is similarly challenging to avoid a boil-off of LNG during storage and transportation. [0007] Thus, as it is stored in a cryogenic storage tank, liquid gas evaporates, whereby a so-called boil-off occurs as the evaporated gas, also referred to as a boil-off gas, is released from the liquid. The boil-off increases the pressure in the storage tank and the excessive pressure build up can lead to the risk of explosion. Potential consequences of an uncontrolled boil-off can thus be devastating. Furthermore, with the increasing use of liquid hydrogen, e.g., in fuel cell vehicles, addressing problems relating to undesirable boil-off becomes more critical. [0008] Accordingly, the boil-off gas needs to be vented in order to decrease the pressure build-up in a storage tank. This however may result in losses of hydrogen gas, which is costly and may be detrimental to the environment. The LNG can also be subject to boil-off, which results in emissions of methane which is a highly potent greenhouse effect gas. [0009] Accordingly, there is a need in improved approaches to managing boil-off during storage of liquified hydrogen, LNG, and other gases. SUMMARY [0010] Accordingly, a method and system are provided that allow proactively controlling boil-off and pressure build-up in fuel storage containers storing liquid gas such as e.g. liquid hydrogen, LNG, or another liquid or liquified gas. The method, performed by a control system comprising processing circuitry, comprises executing the processing circuitry to determine when and whether to perform venting of a fuel storage container storing liquid gas. [0011] In an aspect, a control system for controlling a fuel storage system configured to store a liquid fuel in a fuel storage container of a vehicle powered by the liquid fuel is provided. The control system comprises processing circuitry configured to obtain a request for a shutdown of the vehicle, obtain measurements of a pressure in the fuel storage container, estimate an expected start time for the vehicle that is shut down, and, responsive to detecting that the pressure in the fuel storage container is at or above a boil-off threshold pressure, allow the pressure in the fuel storage container to remain at or above the boil-off threshold pressure or enable venting of the fuel storage container to reduce the pressure in the fuel storage container in dependence on whether or not the expected start time is within a time threshold interval. [0012] In some examples, the expected start time for the vehicle may be determined before the vehicle has been shut down. [0013] In some examples, the processing circuitry of the control system is configured to, responsive to detecting that the pressure in the fuel storage container is not at or above the boil-off threshold pressure, i.e. below the boil-off threshold pressure, not enable venting of the fuel storage container. [0014] In some examples, the processing circuitry of the control system is configured to allow the pressure in the fuel storage container to exceed the boil-off