Fuel Cell Hydrogen Pressure Control Under Nitrogen Crossover

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Solution Overview

Problem

Conventional hydrogen purging methods in fuel cell systems lead to a reduction in hydrogen partial pressure at the hydrogen electrode due to nitrogen crossover from the air electrode, affecting reaction efficiency and durability, as the hydrogen partial pressure is not maintained constant between purging events.

Innovation Solution

A method to control the hydrogen partial pressure by setting a target hydrogen supply pressure that accounts for nitrogen partial pressure, temperature, and current conditions, using sensors or estimators to adjust the hydrogen supply pressure dynamically and determine optimal purging times, thereby maintaining constant hydrogen partial pressure at the hydrogen electrode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional hydrogen purging is performed periodically, then nitrogen and water are removed from the hydrogen electrode, but hydrogen partial pressure decreases between purging events

Engineering Contradiction:

Improvestack performanceVSAvoidhydrogen partial pressure

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The control device calculates nitrogen partial pressure based on crossover amount from the air electrode and uses this feedback information to dynamically adjust the target hydrogen supply pressure, ensuring hydrogen partial pressure is maintained despite nitrogen accumulation

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The target hydrogen supply pressure is dynamically adjusted based on calculated nitrogen partial pressure, temperature, and current conditions. By changing the hydrogen supply pressure parameter in response to varying operating conditions, the system maintains constant hydrogen partial pressure at the hydrogen electrode

Inventive Principle:

Principle #35Parameter changes

2Reliability

If hydrogen purge valve is opened frequently to maintain hydrogen concentration, then hydrogen use efficiency decreases, but stack performance is maintained

Engineering Contradiction:

Improvestack performanceVSAvoidhydrogen use efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The control device continuously calculates nitrogen partial pressure and uses this feedback to determine optimal purging timing and adjust hydrogen supply pressure, reducing the need for frequent purging while maintaining stack performance

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system uses the calculated nitrogen partial pressure information to self-adjust the hydrogen supply pressure, reducing dependency on frequent purge valve operations and improving hydrogen utilization efficiency

Inventive Principle:

Principle #25Self-service

3Quantity of substance

If target hydrogen supply pressure is increased to compensate for nitrogen crossover, then hydrogen partial pressure is maintained, but energy consumption increases

Engineering Contradiction:

Improvehydrogen partial pressureVSAvoidenergy consumption

Core Design Contradiction:

Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of continuously maintaining high hydrogen supply pressure, the system applies partial compensation by adjusting pressure only when nitrogen crossover occurs, using calculated nitrogen partial pressure to determine the necessary adjustment magnitude

Inventive Principle:

Principle #16Partial or excessive action

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

This approach extends the purging period, reduces the frequency of hydrogen purge valve openings, enhances hydrogen use efficiency, and improves fuel cell stack durability by maintaining constant hydrogen partial pressure, optimizing hydrogen supply based on operating conditions.

Implementation Method 1

nitrogen in air supplied to the air electrode (cathode) and water (water and vapor) generated in the air electrode of the stack moves via a crossover across an electrolyte membrane within the stack and reaches the hydrogen electrode

Methodology Applied

Scientific EffectCrossover: Permeation

Implementation Method 2

a fuel cell stack for generating electric energy from an electrochemical reaction of a reactive gas (hydrogen as fuel, and oxygen as an oxidant)

Methodology Applied

Scientific EffectElectrochemical reaction: Fuel Cell

Data Source

PatentUS11855321B2Method of controlling hydrogen partial pressure for fuel cell system

Publication Date: 2023.12.26 HYUNDAI MOTOR CO LTD

AI summary

A method of controlling a hydrogen partial pressure can be carried out in a fuel cell system including a stack having a hydrogen electrode and an air electrode. The method includes: determining a point of time to purge the hydrogen electrode using a hydrogen concentration at an outlet of the hydrogen electrode or an accumulated amount of charge generated in the stack; and setting a target supply pressure of hydrogen supplied to the stack, in which the target hydrogen supply pressure is set in consideration of a hydrogen pressure and a partial pressure of nitrogen resulting from crossover in the stack.