Pressurized Air-Recirculating Fuel Cell Cooling for Higher Power Density
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Solution Overview
Problem
Conventional fuel cell power systems with air cooling have a relatively low specific power per unit volume and cannot efficiently increase the pressure of reaction air without significant energy expenditure, limiting their capacity compared to liquid-cooled systems, while air-cooled systems with compression face complexity and inefficiency.
Innovation Solution
The system employs a high-pressure chamber or duct for air recirculation with a controlled valve to maintain elevated air pressure, combining air cooling and recirculation to enhance oxygen partial pressure, using a compressor and radiator to manage air flow and temperature, and eliminating the need for a humidifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If air cooling is used in fuel cell power systems, then weight is reduced and structure is simplified, but specific power per unit volume becomes low
Solution Approach 1:
The patent changes the pressure parameter of air from ambient pressure to pressurized state (2-10 bar), which increases oxygen partial pressure and enables higher specific power per unit volume while maintaining air cooling's weight and structure advantages
Solution Approach 2:
The patent introduces a compressor to pressurize air and a recirculation system with radiators to manage the pressurized cooling air, using pneumatic principles to achieve both cooling and oxygen supply functions with pressurized air
2Productivity
If reaction air is compressed to increase FC capacity, then oxygen partial pressure increases, but energy expenditures for compressing cooling air exceed energy benefit
Solution Approach 1:
The patent makes pressurized air serve dual functions: both cooling the fuel cell and providing oxygen for the electrochemical reaction. The recirculation system allows the same pressurized air to perform both functions repeatedly, eliminating the need to compress separate cooling and reaction air streams
Solution Approach 2:
The system uses the hot exhaust air from the fuel cell as part of the recirculation flow, which is then cooled by radiators and reused. This self-service approach recovers thermal energy and reduces the need for additional compression work
3Loss of energy
If conventional air cooling is used, then great volumes of air can pass through at low energy expenditures, but specific power per unit volume remains low
Solution Approach 1:
The patent changes the pressure parameter of air from ambient to pressurized (2-10 bar), which increases oxygen partial pressure and enables higher specific power per unit volume. The recirculation system maintains efficient air flow by reusing the same pressurized air multiple times
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 significantly increases the specific power output of the fuel cell system, doubling its capacity without excessive energy consumption, expands the operating temperature range, and maintains humidity without additional equipment, enhancing efficiency and reliability.
Implementation Method 1
FCPSs with air cooling (they are also called FCPSs with open cathode) are less heavy, and their structure is simpler than that of FCPSs with liquid cooling
Implementation Method 2
The system employs a high-pressure chamber or duct for air recirculation with a controlled valve to maintain elevated air pressure, combining air cooling and recirculation to enhance oxygen partial pressure
Implementation Method 3
The air pressurization module may comprise an air compressor or a sequence of compressors and at least one radiator for cooling air heated due to its compression by the compressor
Data Source
AI summary
An air pressure in fuel cells of an electric power generation system comprising a fuel cell stack (PCS) is raised with a pressurized air cooling system with recirculation to values at least two times greater than typical values for an PCS with air cooling. The FCS is either placed in a high-pressure chamber to which air is injected, or air outgoing from the FCS is redirected via a duct back to the FCS inlet and a portion of pressurized fresh air is added thereto. The chamber or the duct is provided with a radiator by means of which circulating air heat is transferred into the external environment. Air recirculation in the chamber or the duct is effected by means of fans for cooling fuel cells. Useful capacity of electric power generation systems based on fuel cells is raised significantly, the necessity of using a humidifier is excluded, and the temperature range of fuel cell operation is expanded.