Fuel Cell Air Cut-Off Valve Control for Temperature-Driven Seal Drift

Solution Overview

Problem

The existing fuel cell systems face challenges in accurately controlling the air cut-off valve (ACV) due to temperature-related expansion and contraction of seals, leading to errors in hydrogen discharge concentration and potential voltage drops below the lower limit, which can cause degradation and performance issues.

Innovation Solution

A fuel cell system with a controller that adjusts the position of the ACV based on the operating temperature of the fuel cell stack, using equations to calculate the degree of seal expansion or contraction and fine-tune the open area of the air flow line to ensure compliant hydrogen discharge and maintain voltage within limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the ACV is opened all at once, then hydrogen gas is discharged quickly from the fuel cell stack, but the concentration of hydrogen gas discharged may exceed environmental regulation standards

Engineering Contradiction:

Improvehydrogen discharge speedVSAvoidhydrogen concentration exceeding standards

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The ACV opening degree is dynamically adjusted based on operating conditions. The controller varies the ACV opening degree according to the stack temperature and current, transitioning from a small initial opening degree to a larger opening degree as the stack warms up, thereby optimizing both discharge speed and concentration control throughout the operating cycle

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control parameters for the ACV are changed based on temperature conditions. The controller stores multiple ACV opening degree values corresponding to different temperature ranges and selects the appropriate opening degree based on the current stack temperature, allowing the system to adapt to thermal expansion and contraction of internal components

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If the ACV opening degree is not adjusted according to temperature, then the control system is simple, but seal expansion and contraction causes errors in hydrogen discharge concentration control

Engineering Contradiction:

Improvecontrol system complexityVSAvoidhydrogen discharge concentration accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The controller continuously monitors the stack temperature and uses this feedback to adjust the ACV opening degree. By measuring the temperature and comparing it with stored reference values, the system automatically compensates for thermal effects on the seal and internal components, maintaining accurate hydrogen discharge concentration control without requiring complex mechanical adjustments

Inventive Principle:

Principle #23Feedback

3Ease of operation

If the ACV position is not micro-adjusted, then the valve operation is simple, but voltage may drop below the lower limit causing degradation

Engineering Contradiction:

Improvevalve operation simplicityVSAvoidvoltage stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The ACV opening degree is dynamically adjusted based on operating conditions. The controller varies the ACV opening degree according to the stack temperature and current, transitioning from a small initial opening degree to a larger opening degree as the stack warms up, thereby optimizing both discharge speed and concentration control throughout the operating cycle

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The controller continuously monitors the stack temperature and uses this feedback to adjust the ACV opening degree. By measuring the temperature and comparing it with stored reference values, the system automatically compensates for thermal effects on the seal and internal components, maintaining accurate hydrogen discharge concentration control without requiring complex mechanical adjustments

Inventive Principle:

Principle #23Feedback

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 solution effectively prevents hydrogen discharge errors and voltage drops, maintaining the performance and durability of the fuel cell stack by micro-adjusting the ACV position according to temperature variations, ensuring compliance with environmental regulations and preventing degradation.

Implementation Method 1

a seal made of rubber, which constitutes the ACV, expands or contracts to a large degree according to the coefficient of expansion of the seal

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS20240162457A1Fuel cell system and a fuel cell system control method

Publication Date: 2024.05.16 HYUNDAI MOTOR CO LTD

AI summary

A fuel cell system includes an air flow line connected to a cathode, a cut-off valve provided in the air flow line so as to adjust an opened/closed state of the air flow line, a cooling medium configured to cool or heat a fuel cell stack, and a controller configured to adjust a position of the cut-off valve according to a driving mode of the fuel cell stack and to further adjust the position of the cut-off valve on the basis of a temperature of outside air or a temperature of the cooling medium.