Fuel Cell Intermittent Operation Pressure Control

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Solution Overview

Problem

Fuel cell systems face issues with wasteful discharge of fuel gas leading to lowered fuel economy due to abnormal pressure increases in the hydrogen supply passage, which can cause damage and inefficiency.

Innovation Solution

Implementing a fuel cell system capable of intermittent operation, where power generation is temporarily stopped when pressure reaches a predetermined level, allowing the reactant gas to be consumed by the fuel cell without discharge, and incorporating a control device to manage power generation and gas flow, including a power storage device for supplementary power during intermittent operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a relief valve is provided to discharge hydrogen when pressure increases, then damage to the fuel cell and gas supply passage is prevented, but fuel economy is lowered due to discharged hydrogen

Engineering Contradiction:

Improveprevention of damage to fuel cell and gas supply passageVSAvoidfuel economy

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent converts the harmful effect of pressure buildup into a beneficial operation by using the high-pressure state as a trigger to restart power generation. When pressure reaches a predetermined level during intermittent operation, the system automatically resumes power generation, which consumes the accumulated reactant gas and resolves the pressure issue while preventing fuel waste through discharge.

Inventive Principle:

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

Solution Approach 2:

The system uses its own power generation capability to solve the pressure problem. Instead of externally discharging the gas through a relief valve, the fuel cell consumes the accumulated reactant gas by resuming power generation, thereby self-resolving the pressure buildup issue without external intervention or fuel waste.

Inventive Principle:

Principle #25Self-service

2Loss of energy

If intermittent operation is implemented to save fuel, then fuel economy is improved, but abnormal pressure increase occurs in the gas systems

Engineering Contradiction:

Improvefuel economyVSAvoidpressure in gas systems

Core Design Contradiction:

Loss of energyVSStress or pressure

Solution Approach 1:

The system implements a feedback mechanism where the pressure level in the gas system during intermittent operation is continuously monitored. When the pressure reaches a predetermined threshold, this feedback triggers the control device to stop the intermittent operation and resume power generation, thereby automatically adjusting the system state based on the observed pressure condition.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically switches between intermittent operation and power generation modes based on real-time pressure conditions. The operation mode is not fixed but adapts to the current state of the gas system, allowing the fuel cell to resume power generation when pressure buildup is detected during intermittent operation.

Inventive Principle:

Principle #15Dynamics

3Stress or pressure

If reactant gas is discharged to resolve pressure increase, then abnormal pressure is reduced, but fuel economy is lowered

Engineering Contradiction:

Improveabnormal pressure in gas systemsVSAvoidfuel economy

Core Design Contradiction:

Stress or pressureVSLoss of energy

Solution Approach 1:

Inventive Principle:

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

Solution Approach 2:

Instead of discarding the reactant gas through discharge, the system recovers it by consuming it in the power generation process. When pressure buildup occurs during intermittent operation, resuming power generation allows the fuel cell to utilize the accumulated reactant gas for electricity production, thereby recovering what would otherwise be wasted fuel.

Inventive Principle:

Principle #34Discarding and recovering

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 prevents abnormal pressure increases and maintains fuel economy by consuming reactant gas internally, reducing the need for gas discharge and simplifying control logic, thereby enhancing traveling distance and system efficiency.

Implementation Method 1

a fuel cell system which can directly extract, as electrical energy, chemical energy obtained from an oxidation-reduction reaction between fuel gas and oxidation gas

Methodology Applied

Scientific EffectOxidation-reduction reaction: Redox Reactions

Data Source

PatentUS8076036B2Fuel cell system, operation method thereof, and fuel cell vehicle

Publication Date: 2011.12.13 TOYOTA JIDOSHA KK

AI summary

In order to prevent the fuel economy from being lowered by a wasteful discharge of fuel gas, in the operation method of a fuel cell system capable of performing intermittent operation for temporarily stopping power generation of the fuel cell, in the case where the secondary pressure of the tank regulator becomes at least a first threshold during intermittent operation, the intermittent operation is stopped and the normal operation is returned. In the case where the intermittent operation is stopped a number of times, subsequent intermittent operation may be prohibited.