Fuel cell cooling
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Solution Overview
Problem
In fuel cell systems with closed loop cooling, managing the purity and quantity of water is challenging due to the low liquid water content in cathode exit streams and the risk of conductivity increases from fluoride and corrosion products, which can degrade performance.
Innovation Solution
A method and system for automatically determining and controlling the addition and removal of liquid water in a closed loop cooling circuit based on operational parameters such as current draw, conductivity, pH, or total dissolved solids, ensuring the coolant water remains at a desired purity level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If liquid water is recovered from cathode exit stream to maintain PEM hydration, then water availability for cooling improves, but water purity deteriorates due to low liquid water content and high conductivity from corrosion products
Solution Approach 1:
The patent extracts only the necessary amount of liquid water from the cathode exit stream for PEM hydration, separating it from the bulk exhaust stream. This extraction approach allows maintaining adequate hydration while minimizing the amount of impure water that could contaminate the cooling circuit.
Solution Approach 2:
The patent introduces a purity monitoring system as an intermediary between water recovery and the cooling circuit. This mediator measures conductivity and controls water addition based on purity thresholds, preventing impure water from degrading the cooling system while still allowing sufficient water for hydration.
2Temperature
If water is injected into cathode flow path for cooling, then heat removal efficiency improves, but corrosion risk increases due to contact with fluoride and corrosion products
Solution Approach 1:
The patent implements a feedback control system that continuously monitors water conductivity and adjusts water injection rates accordingly. When conductivity increases indicating corrosion product accumulation, the system reduces water injection or triggers purging, preventing excessive corrosion while maintaining cooling effectiveness.
Solution Approach 2:
The patent changes the operational parameters of water injection by controlling it as a function of measured conductivity and other operational parameters. This dynamic parameter adjustment allows optimizing cooling while staying below corrosion thresholds by modifying injection timing, rate, and duration.
3Loss of substance
If closed loop cooling circuit is used to reduce water consumption, then water efficiency improves, but water quality control becomes more difficult due to accumulated impurities
Solution Approach 1:
The patent implements periodic purging of the closed loop cooling circuit to remove accumulated impurities. By periodically replacing a portion of the cooling water with fresh water from the fuel cell system, the circuit maintains acceptable purity levels over extended operation while still achieving high overall water efficiency through the closed loop design.
Solution Approach 2:
The patent uses feedback control through conductivity sensors to monitor water quality in the closed loop circuit and triggers purging or fresh water addition when quality thresholds are exceeded. This automated quality control maintains precise water quality standards while minimizing water loss through the closed loop architecture.
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 maintains the purity and quantity of coolant water within desired limits, optimizing fuel cell performance by adjusting water management based on operational conditions, thereby reducing corrosion risks and enhancing system efficiency.
Implementation Method 1
Reaction of protons (hydrogen ions) conducted through the PEM from an anode flow path, with oxygen present in a cathode flow path, produces water
Implementation Method 2
The temperature of the exhaust stream is therefore preferably reduced (e.g. using a heat exchanger) so as to reduce the dew point and condense at least part of the vapour to liquid water
Data Source
AI summary
A method of operating a fuel cell system (100) comprising a fuel cell stack (110) and a closed loop water cooling circuit for direct injection of cooling water into the stack (110), the method comprising: measuring an operational parameter of the fuel cell system (100) over a time period; adding an amount of water to the closed loop cooling circuit from the total amount of water generated during operation of the fuel cell stack (110) over the time period; and removing the amount of water from the closed loop cooling circuit generated during operation of the fuel cell stack (110) over the time period is automatically determined by the fuel cell system (100) as a function of the operational parameter.