Fuel Stack Recirculation Layout for Simpler Multi-Stack Supply

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Solution Overview

Problem

Fuel cell devices for commercial vehicles require complex systems for reactant supply and exhaust gas management, leading to high costs and operational complexity, especially when multiple fuel cell stacks are needed to generate high power.

Innovation Solution

A fuel cell device design where only one fuel cell stack is connected to a fuel recirculation line, simplifying the system by reducing the number of recirculation lines and purge valves, and allowing individual activation and deactivation of stacks based on power requirements, with optimized fuel pressure distribution across stacks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If each fuel cell stack is connected to individual fuel recirculation lines, then each stack can be controlled individually, but the system complexity and costs increase significantly

Engineering Contradiction:
Improveindividual stack controlVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The fuel supply system is segmented into multiple partial fuel supply lines, each leading to a specific fuel cell stack. This allows individual control of each stack while maintaining a simplified common recirculation structure. The segmentation enables selective activation of stacks based on power requirements without requiring complex individual recirculation systems for each stack.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A single common fuel recirculation line serves multiple fuel cell stacks, making it a universal component that performs the recirculation function for all stacks. This multi-functional approach eliminates the need for separate recirculation lines for each stack, reducing system complexity while maintaining the ability to control individual stacks through the shared infrastructure.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Power

If multiple fuel cell stacks are used to generate high power, then the required energy output is achieved, but the system costs and operational complexity increase

Engineering Contradiction:
Improveenergy outputVSAvoidoperational complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The fuel cell device is divided into multiple independently controllable stacks connected through a common recirculation system. This segmentation allows the system to scale power output by activating different numbers of stacks based on demand, while the common recirculation infrastructure keeps operational complexity manageable compared to fully independent systems.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple fuel cell stacks are merged into a single device with a common fuel recirculation line. This combining approach allows the system to achieve high power output through parallel stacks while sharing the recirculation infrastructure, thereby reducing overall system complexity and costs compared to having completely separate systems for each stack.

Inventive Principle:
Principle #5Merging (Combining)

3Loss of energy

If fuel is recirculated to all fuel cell stacks, then fuel efficiency is improved, but the system requires complex recirculation infrastructure

Engineering Contradiction:
Improvefuel efficiencyVSAvoidrecirculation infrastructure
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

A single common fuel recirculation line serves multiple fuel cell stacks, making it a universal component that performs the recirculation function for all stacks. This multi-functional approach eliminates the need for separate recirculation lines for each stack, reducing system complexity while maintaining the ability to control individual stacks through the shared infrastructure.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The recirculation system is designed with local flexibility through individual fuel valves at each stack connection point. This allows fuel recirculation to be enabled or disabled locally at each stack based on operational requirements, maintaining fuel efficiency benefits where needed while avoiding unnecessary complexity in the overall recirculation infrastructure.

Inventive Principle:
Principle #3Local quality

4Adaptability or versatility

If individual fuel valves are provided for each partial fuel supply line, then individual stack operation is enabled, but the number of valves and system complexity increases

Engineering Contradiction:
Improveindividual stack operationVSAvoidnumber of valves
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The fuel supply system is segmented into multiple partial fuel supply lines, each leading to a specific fuel cell stack. This allows individual control of each stack while maintaining a simplified common recirculation structure. The segmentation enables selective activation of stacks based on power requirements without requiring complex individual recirculation systems for each stack.

Inventive Principle:
Principle #1Segmentation

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 design reduces system complexity and costs, enhances fuel efficiency, and achieves higher cell voltage and efficiency by ensuring pure fuel supply to non-recirculating stacks, while allowing flexible operation of multiple stacks to meet power demands.

Implementation Method 1

Fuel cells are used to supply energy, particularly in motor vehicles

Methodology Applied
Scientific EffectFuel cell electrochemical reaction: Fuel Cell

Implementation Method 2

This can be a jet pump or a recirculation fan

Methodology Applied
Scientific EffectFluid transport: Pump

Data Source

PatentEP4136693B1Fuel recirculation in a fuel cell device having a plurality of fuel cell stacks
Publication Date: 2024.01.24 AUDI AG
  • EP4136693B1 patent drawingFigure 1

AI summary

The invention relates to a fuel cell device (1) comprising a fuel tank (2) which has a fuel supply line (3) that branches into partial fuel supply lines (4), comprising a plurality of fuel cell stacks (5) which each have, on the anode inlet side, a fuel connection (6) that is fluidically connected to one of the partial fuel supply lines (4). Only one of the fuel cell stacks (5) is connected on the anode outlet side to a fuel recirculation line (7); the flow guidance of the fuel recirculation line (7) is selected in such a way that the fuel can be guided back only into the fuel cell stack (5) that is connected to the fuel recirculation line (7). Moreover, the invention relates to a method for operating the fuel cell device (1).