Fuel Cell Humidification Control via HFR dHFRdRH Ratio

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing fuel cell systems face challenges in reliably measuring and controlling the hydration of fuel cell stacks due to the unreliability of typical sensors, which are prone to corrosion and swelling, and absolute high-frequency resistance (HFR) measurements are susceptible to variations in contact resistance, making online hydration monitoring and feedback control ineffective.

Innovation Solution

An online system and method using HFR measurements to calculate the d(HFR)/d(RH) ratio, which is correlated with a mathematical model to identify the relative humidity of the fuel cell stack, allowing for real-time control of humidification levels through a humidity regulator, thereby maintaining optimal hydration within a desired range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If typical sensors are used to measure humidity indicators, then feedback control can be implemented, but the sensors exhibit drift and become unreliable due to corrosion and swelling

Engineering Contradiction:

Improvesensor reliabilityVSAvoidcorrosion and swelling

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses HFR measurements as an intermediary parameter to indirectly assess membrane hydration without requiring direct exposure of sensors to the harsh fuel cell environment. The HFR serves as a mediator that correlates with hydration levels while being resistant to the corrosive and swelling effects that plague traditional humidity sensors.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces mechanical/chemical humidity sensors with an electrical measurement system (HFR measurements). This substitution eliminates the physical sensors that are susceptible to corrosion and swelling, using instead an electrical property measurement that is immune to these environmental degradation mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If absolute HFR measurements are used for online hydration monitoring, then real-time data can be obtained, but the measurements are highly sensitive to contact resistance variations

Engineering Contradiction:

Improvehydration measurement precisionVSAvoidsensitivity to contact resistance

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent performs preliminary identification of the relationship between HFR and RH specific to each fuel cell stack before online operation. This preliminary calibration creates a customized transfer function that accounts for individual stack characteristics, including their specific contact resistance levels, thereby enabling accurate online measurements without being sensitive to contact resistance variations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent transforms the HFR measurement parameter from an absolute value to a differential relationship (dHFR/dRH) through preliminary identification. This parameter transformation eliminates the sensitivity to contact resistance while preserving the sensitivity to hydration changes, allowing precise online monitoring.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If traditional feedback indicators are used for humidification control, then control can be implemented, but the sensors are unreliable in fuel cell environments

Engineering Contradiction:

Improvecontrol implementationVSAvoidsensor reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent uses HFR as an intermediary measurement that enables feedback control without requiring unreliable humidity sensors. The HFR measurement serves as a robust proxy indicator that maintains control capability while eliminating sensor reliability issues in the fuel cell environment.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enables reliable online monitoring and control of fuel cell stack humidification, reducing the impact of contact resistance variations and improving the durability and efficiency of fuel cell systems by maintaining optimal hydration levels, thus enhancing their performance and longevity.

Implementation Method 1

The HFR measurement device is adapted to measure an HFR of the fuel cell stack suitable for calculation of a d(HFR)/d(RH) ratio

Methodology Applied

Scientific EffectHigh-frequency resistance measurement: Electrical Resistance

Implementation Method 2

Each of the fuel cells has an electrolyte membrane disposed between an anode and a cathode

Methodology Applied

Scientific EffectProton conduction: Conduction (electrical)

Data Source

PatentUS7687164B2On-line system identification and control of fuel cell humidification via HFR measurements

Publication Date: 2010.03.30 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A fuel cell system is provided, including an HFR measurement device in electrical communication with a fuel cell stack. The HFR measurement is used online to measure an HFR of the fuel cell stack suitable for calculation of a d(HFR)/d(RH) ratio. A humidity regulator is provided in fluid communication with the fuel cell stack. A controller periodically changes stack operating conditions to perturb an RH of the fuel cell stack, process the HFR response, and compute the d(HFR)/d(RH) ratio. A method for online identification and control of the fuel cell stack humidification is also provided. The d(HFR)/d(RH) ratio is an auxiliary measurement of membrane hydration which is used as a feedback for hydration control.