Liquid Hydrogen Tank Fill Level Optimization
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Solution Overview
Problem
Hydrogen evaporation losses in liquid hydrogen tanks installed on vehicles lead to increased carbon footprint and operating costs, as heat transfer causes hydrogen to boil off, resulting in vented losses.
Innovation Solution
A method that provides data for the next refill of the liquid hydrogen tank based on the duration of the next parking operation, using a thermodynamic model to determine a target fill level that minimizes hydrogen loss through the tank vent during parking phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the tank is filled to a high level to maximize hydrogen availability for driving, then the hydrogen supply for journeys is improved, but hydrogen evaporation losses increase during parking phases
Solution Approach 1:
The system performs preliminary calculation of the optimal fill level before refueling occurs. By determining the target fill level (L-targ) in advance based on the planned parking duration, the system prepares the optimal refueling strategy beforehand, preventing excessive filling that would lead to evaporation losses during subsequent parking phases.
Solution Approach 2:
The refueling strategy is made dynamic by adapting the target fill level to the specific duration of the next parking operation. Instead of using a fixed fill level, the system continuously adjusts L-targ based on varying parking durations, ensuring optimal hydrogen retention for each specific operational context.
2Loss of substance
If the tank is filled to a low level to minimize evaporation losses during parking, then hydrogen loss through venting is reduced, but hydrogen availability for driving journeys is insufficient
Solution Approach 1:
The system calculates the optimal fill level in advance by considering both the parking duration and the required hydrogen supply for upcoming journeys. This preliminary calculation ensures that the target fill level is set to provide sufficient hydrogen for driving while minimizing evaporation losses during parking, balancing both requirements before refueling occurs.
Solution Approach 2:
The system changes the fill level parameter dynamically based on the parking duration. By adjusting L-targ as a function of the planned parking time, the system optimizes the balance between hydrogen retention and hydrogen availability, transforming a static fill level into a context-dependent parameter.
3Loss of substance
If the tank is filled to an optimal level to minimize evaporation, then hydrogen loss is reduced, but the refueling strategy complexity increases
Solution Approach 1:
The system performs the optimization calculation automatically using onboard computing resources, without requiring external assistance or complex manual procedures. The control unit self-determines the target fill level by processing parking duration data and thermodynamic parameters, making the system self-sufficient in generating optimal refueling strategies.
Solution Approach 2:
The complex thermodynamic calculations and optimization processes are performed electronically by a control unit rather than through mechanical or manual methods. By replacing potential mechanical complexity with electronic computation, the system achieves sophisticated optimization while maintaining operational simplicity through software-based solutions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively reduces hydrogen evaporation losses by optimizing the refueling strategy and adapting the tank fill level to the duration of parking, thereby minimizing vented hydrogen and reducing operational costs.
Implementation Method 1
heat being transferred between the outside and the hydrogen that is stored at temperatures of between 20 and 150 kelvins
Implementation Method 2
evaporation of the hydrogen (a phenomenon referred to as 'boil-off')
Implementation Method 3
hydrogen that is stored at temperatures of between 20 and 150 kelvins... evaporation leads to losses through the vent
Data Source
AI summary
The invention relates to a method for reducing hydrogen losses in a liquid hydrogen tank, this tank being refillable and installed on board a vehicle, being provided with a vent for discharging gaseous dihydrogen out of the tank in the event of overpressure, the method comprising the following steps:providing data on the next refill of the tank as a function of a next parking operation of the vehicle planned after the next refill, this data providing at least a target fill level to be reached for the next refill, this target fill level being determined in such a way that, at the start of the parking operation of the vehicle after a possible journey of the vehicle between the refill to the target fill level and the start of the parking operation, the tank has a start-of-parking fill level designed such that, for the duration of this parking operation, the loss of dihydrogen through the vent is minimized.