Combined Cooling Circuit for Fuel Cell Heat Dissipation

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Solution Overview

Problem

Fuel cell vehicles face challenges in dissipating waste heat efficiently at high temperatures and require multiple cooling and air conditioning systems, leading to design space, cost, and weight issues due to the need for separate coolers, hoses, and pumps.

Innovation Solution

A combined cooling and refrigerating system using a refrigerant that evaporates in the fuel cell to dissipate heat, coupled with a heat pump chiller, which shares a condenser with a second refrigerant circuit for enhanced cooling performance and reduced component count, utilizing a single refrigerant across multiple circuits for simplified operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate cooling systems are used for fuel cell and air conditioning, then cooling reliability is improved, but device complexity and weight increase

Engineering Contradiction:

Improvecooling reliabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the fuel cell cooling system and air conditioning system into a single integrated refrigerant circuit. The refrigerant flows through the fuel cell stack to absorb waste heat, then proceeds to the evaporator for air conditioning, and finally to the condenser for heat rejection. This merging eliminates the need for separate cooling systems while maintaining adequate cooling reliability for both functions.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The refrigerant circuit performs multiple functions: it cools the fuel cell stack by absorbing waste heat, provides air conditioning through the evaporator, and rejects heat at the condenser. This multi-functional design replaces what would traditionally require separate dedicated systems, reducing overall system complexity and component count.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Productivity

If evaporative cooling is used in the fuel cell, then cooling efficiency at high temperatures is improved, but control complexity increases due to temperature fluctuations

Engineering Contradiction:

Improvecooling efficiencyVSAvoidcontrol complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The system utilizes phase change (evaporation) of the refrigerant as the key parameter change mechanism. When the refrigerant evaporates in the fuel cell stack, it absorbs large amounts of latent heat, providing highly efficient cooling at high temperatures. The system design accepts and manages the inherent temperature fluctuations as part of the evaporative cooling process rather than attempting to completely eliminate them.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The refrigerant continuously circulates through the fuel cell stack, absorbing heat during evaporation and releasing heat during condensation. This continuous cyclic process ensures sustained cooling efficiency regardless of temporary temperature variations in the fuel cell operating conditions.

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If multiple coolers and pumps are used for separate cooling circuits, then cooling performance is improved, but weight and design space increase

Engineering Contradiction:

Improvecooling performanceVSAvoidsystem weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent merges multiple cooling functions into a single refrigerant circuit that serves both fuel cell cooling and air conditioning purposes. This eliminates the need for separate coolers, hoses, and pumps for each system, thereby reducing overall system weight and design space requirements while maintaining adequate cooling performance for both applications.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single refrigerant circuit is designed to perform multiple cooling functions: cooling the fuel cell stack, providing air conditioning, and rejecting heat. This universal system replaces what would traditionally require multiple dedicated systems, significantly reducing weight and design space occupation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution improves fuel cell cooling efficiency at high temperatures, reduces component complexity and weight, and maintains efficient cooling performance without increasing the number of components, offering cost and design space savings.

Implementation Method 1

the refrigerant which is evaporated at least partly, i.e., at operating points with high temperature and waste heat, in the at least one fuel cell and gives up the heat to the outside air

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 2

Due to the evaporation enthalpy, the heat dissipation from the fuel cell and thus the cooling performance is increased

Methodology Applied

Scientific EffectHeat absorption during phase change: Latent Heat

Implementation Method 3

gives up the heat to the outside air at a condenser or cooler

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 4

this cooling circuit is coupled by a chiller to the refrigerant circuit of a heat pump

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentUS11728495B2Combined cooling circuit for a fuel cell

Publication Date: 2023.08.15 AUDI AG

AI summary

A fuel cell system includes a combined cooling circuit for a motor vehicle that provides a method of cooling a fuel cell of a fuel cell system.