Fuel Cell Stack Heat Transfer for Low-Temperature Startup

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Solution Overview

Problem

The power consumption during the starting of multiple fuel cell stacks in a fuel cell system increases, particularly at low temperatures, leading to lower power efficiency.

Innovation Solution

A fuel cell system with a first and second fuel cell stack, each with a cooling system, and a heat transfer system that allows coolant flow between them, enabling heat transfer from the operating stack to the non-operating stack to raise its temperature, thereby reducing the need for battery power during startup.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple fuel cell stacks are started sequentially using battery power, then all stacks can be started, but power consumption during starting increases significantly

Engineering Contradiction:

Improvestarting capabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The first fuel cell stack generates its own heat through power generation operation, and this self-generated heat is used to warm the coolant that will subsequently warm the second stack, making the system self-sufficient and reducing external power requirements

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The cooling systems of the first and second stacks are merged through the heat transfer system, allowing thermal energy from the first stack to be transferred to the second stack, thereby combining their thermal fields to reduce overall power consumption

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If multiple fuel cell stacks are started at low temperature, then all stacks can be started, but power consumption increases due to heating requirements

Engineering Contradiction:

Improvestarting capabilityVSAvoidheating power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The first fuel cell stack performs power generation to generate heat, and this self-generated heat is used to warm the coolant that will subsequently warm the second stack, making the system self-sufficient and reducing external power requirements

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The heat that would normally be wasted during power generation in the first stack is converted into a beneficial resource by transferring it to warm the second stack, transforming what would be thermal loss into useful heating energy

Inventive Principle:

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

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 suppresses power consumption during startup by utilizing heat from the operating stack to thaw and heat the non-operating stack, ensuring efficient and cost-effective initiation of all stacks, even in freezing conditions.

Implementation Method 1

By causing the coolant to flow from the first cooling system to the second cooling system by the heat transfer system, the coolant flows through the second fuel cell stack and the temperature of the second fuel cell stack is increased

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentUS20250323293A1Fuel cell system

Publication Date: 2025.10.16 TOYOTA JIDOSHA KK

AI summary

The fuel cell system includes a first fuel cell stack, a second fuel cell stack, a first cooling system that causes a refrigerant to flow through the first fuel cell stack, a second cooling system that causes the refrigerant to flow through the second fuel cell stack, and a heat transfer system that allows the refrigerant to flow between the first cooling system and the second cooling system and to shut off the refrigerant.