HTPEM Cathode Spray Cooling With Phosphoric Acid Replenishment
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Solution Overview
Problem
High temperature proton exchange membrane (HTPEM) fuel cells face challenges in cooling efficiency, leading to increased weight, volume, and cost, as well as reduced energy efficiency due to drag from ram air cooling systems. Additionally, water spray cooling has been considered impractical due to phosphoric acid depletion at the cathode.
Innovation Solution
The solution involves incorporating phosphoric acid into the cooling water spray, ensuring that the spray composition replenishes the cathode electrolytes, thereby maintaining high power density operation. This approach simplifies fuel-cell manufacturing, reduces weight and complexity, and optimizes cooling capability by potentially eliminating isolated coolant passages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water spray cooling is used at the cathode, then cooling efficiency is improved, but phosphoric acid is depleted from the cathode by entrainment with the water mist
Solution Approach 1:
The patent recovers phosphoric acid from the exhaust stream by condensing water vapor that carries entrained phosphoric acid mist, then returns the recovered phosphoric acid to the cathode electrolyte, preventing depletion while maintaining effective water spray cooling
Solution Approach 2:
The system implements a feedback loop where phosphoric acid loss is monitored and the recovered acid is fed back to replenish the cathode electrolyte, ensuring continuous operation at high power density
2Temperature
If heat exchangers or coolant media are used in HTPEM fuel cells, then cooling capability is improved, but the overall weight and volume of the system increase
Solution Approach 1:
The patent extracts and eliminates the separate heat exchanger component by integrating cooling functionality directly into the cathode air supply system through water spray injection, significantly reducing system weight and volume
Solution Approach 2:
The water spray system serves multiple functions simultaneously: it provides evaporative cooling, replenishes phosphoric acid electrolyte, and utilizes existing airflow infrastructure, eliminating the need for dedicated coolant circulation systems
3Temperature
If ram air is used as a cooling medium in a vehicle, then cooling efficiency is improved, but the vehicle experiences increased drag which reduces energy efficiency
Solution Approach 1:
Instead of using full ram air flow for cooling, the patent applies partial cooling through targeted water spray injection that leverages the existing ram air flow, achieving sufficient cooling with minimal additional drag
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 method enhances cooling efficiency, allows continuous high-power operation of HTPEM fuel cells, and integrates evaporative cooling in the cathode, thereby improving energy efficiency and reducing operational costs.
Implementation Method 1
evaporative cooling in the cathode
Implementation Method 2
phosphoric acid (PA), or H3PO4, can be depleted from the cathode by entrainment with the water mist
Data Source
AI summary
The invention of the current application is directed to a cooling spray system and method for a high temperature proton exchange membrane (HTPEM) fuel cell including a HTPEM fuel cell including a cathode and an anode, a liquid sprayer, and a storage vessel containing a mixture of water and electrolyte. The storage vessel is in fluid communication with the liquid sprayer and the liquid sprayer is positioned to spray the mixture of water and electrolyte into the air supply of the cathode.