Hydrogen Catalyst Cooling via Para-Ortho Conversion in Vehicles

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Solution Overview

Problem

Existing hydrogen fuel systems in vehicles face challenges with excessive heat accumulation leading to reduced efficiency, accelerated degradation, and increased cooling system size, which affects vehicle performance and cost.

Innovation Solution

A hydrogen catalyst is positioned in the flow path between the storage tank and consumer to convert hydrogen from a para state to an ortho state via an endothermic reaction, coupled with a coolant circuit and heat exchanger to absorb thermal load directly into the hydrogen fuel, enhancing cooling capacity and reducing cooling system size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a larger cooling system is used to reject thermal heat from fuel cells, then heat rejection capability is improved, but system size and cost increase

Engineering Contradiction:
Improveheat rejection capabilityVSAvoidcooling system size
Core Design Contradiction:
TemperatureVSVolume of stationary object

Solution Approach 1:

The patent utilizes the phase transition of hydrogen from para-state to ortho-state, which is an endothermic process that absorbs thermal energy. This phase transition occurs naturally in hydrogen fuel cells and creates a cooling effect that reduces the thermal load on the cooling system, allowing for a smaller cooling system design while maintaining adequate heat rejection capability.

Inventive Principle:
Principle #36Phase transitions

Solution Approach 2:

The patent converts the harmful thermal heat generated by fuel cells into a beneficial cooling effect by utilizing the endothermic para-to-ortho hydrogen conversion. The thermal energy that would otherwise need to be rejected is instead used to drive the hydrogen state conversion, which absorbs heat and creates a natural cooling effect, thereby reducing the burden on the cooling system.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Temperature

If thermal heat is rejected through a liquid to air heat exchanger, then thermal heat rejection is improved, but system complexity and size increase

Engineering Contradiction:
Improvethermal heat rejectionVSAvoidcooling system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent enables the hydrogen fuel cell system to self-cool by utilizing the endothermic para-to-ortho hydrogen conversion that occurs naturally within the fuel cell. This internal cooling mechanism reduces the need for external active cooling components, simplifying the overall cooling system architecture while maintaining effective thermal management.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent exploits the phase transition between para-hydrogen and ortho-hydrogen states, which involves a change in the spin state of hydrogen molecules. This phase transition is endothermic and occurs naturally in fuel cells, providing a passive cooling effect that reduces thermal load without requiring complex active cooling systems.

Inventive Principle:
Principle #36Phase transitions

3Power

If excessive heat accumulates in the fuel cell, then power output is maintained, but efficiency decreases and degradation accelerates

Engineering Contradiction:
Improvepower outputVSAvoidfuel cell efficiency and durability
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent converts the harmful excessive heat accumulation into a beneficial cooling effect by utilizing the endothermic para-to-ortho hydrogen conversion. The thermal energy that would otherwise cause overheating and degradation is instead absorbed by the hydrogen state transition, maintaining optimal operating temperatures and improving fuel cell efficiency and durability while preserving power output.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the thermal parameters of the fuel cell system by utilizing the endothermic hydrogen phase transition. This parameter change creates a natural cooling effect that maintains optimal operating temperatures, preventing excessive heat accumulation that would lead to efficiency loss and accelerated degradation, thereby improving overall system reliability.

Inventive Principle:
Principle #35Parameter changes

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 system increases cooling capacity, improves fuel cell or combustion engine power output, and reduces cooling system size and cost by absorbing latent heat through the para/ortho conversion, maintaining optimal operating temperatures and stabilizing tank pressure.

Implementation Method 1

the catalyst configured to convert hydrogen fuel from a para state to an ortho state via an endothermic reaction

Methodology Applied
Scientific EffectEndothermic reaction: Endothermic Reaction

Implementation Method 2

a coolant-fed heat exchanger configured to thermally couple the coolant in the coolant circuit to the hydrogen fuel

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4711326A1Hydrogen catalyst for vehicle cooling
Publication Date: 2026.03.18 DAIMLER TRUCK NORTH AMERICA LLC
  • EP4711326A1 patent drawingFigure 1
  • EP4711326A1 patent drawingFigure 2
  • EP4711326A1 patent drawingFigure 3

AI summary

A hydrogen catalyst for vehicle cooling is described. A system may include a catalyst positioned in a flow path coupling a hydrogen storage tank to a hydrogen consumer, the catalyst configured to convert hydrogen fuel from a para state to an ortho state via an endothermic reaction. The system may further include a coolant circuit configured to circulate coolant through the hydrogen consumer and a coolant-fed heat exchanger configured to thermally couple the coolant in the coolant circuit to the hydrogen fuel, the coolant-fed heat exchanger arranged upstream of the hydrogen consumer in the flow path.