Fuel Cell Anode Gas Recirculation Using Jet Pumps
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Solution Overview
Problem
Conventional fuel cell systems face inefficiencies due to large construction space requirements and high electrical power consumption in recirculation blower systems, which reduce overall system efficiency and are not adaptable to dynamic load conditions typical of motor vehicles.
Innovation Solution
A compact, low-power recirculation blower system utilizing two parallel jet pumps and a magnetically controlled recirculation blower, allowing for flexible configuration and energy-efficient operation by leveraging existing fuel pressure and enabling selective engagement of the recirculation blower only when needed, with optional connection to an exhaust gas space for gas management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large flow volume recirculation blower is used to move total recirculated exhaust gas, then the recirculation function is achieved, but the construction space requirement increases and electrical power consumption increases
Solution Approach 1:
The exhaust gas recirculation system is segmented into multiple parallel jet pumps (at least two) that handle different portions of the exhaust gas flow. Each jet pump processes a fraction of the total recirculated gas, allowing the system to achieve the required total flow volume while using smaller, more compact pump units rather than one large blower.
Solution Approach 2:
The system employs jet pumps that utilize high-pressure fuel gas (already present in the fuel cell system) as the driving fluid to create suction and move exhaust gases. This pneumatic approach eliminates the need for electrically driven blowers, reducing both construction space and electrical power consumption while maintaining effective recirculation.
2Productivity
If a large flow volume recirculation blower is used to move total recirculated exhaust gas, then the recirculation function is achieved, but the electrical power consumption increases
Solution Approach 1:
The system replaces electrically driven blowers with jet pumps that use high-pressure fuel gas (already available in the fuel cell system) as the driving fluid. This pneumatic approach eliminates electrical power consumption for exhaust gas recirculation while maintaining the required flow volume, as the high-pressure fuel gas provides the necessary energy to move the exhaust gases through the system.
Solution Approach 2:
The system uses the high-pressure fuel gas that is already present in the fuel cell system to drive the jet pumps for exhaust gas recirculation. This self-service approach means the system uses its own internal resources (the pressurized fuel gas) to perform the recirculation function without requiring external electrical power, thereby reducing parasitic loads and improving overall system efficiency.
3Area of stationary object
If a compact low-power recirculation blower is used, then construction space is reduced and power consumption is reduced, but the ability to handle dynamic load conditions decreases
Solution Approach 1:
The exhaust gas recirculation system is divided into multiple parallel jet pump branches, each capable of independent operation. This segmentation allows the system to activate or deactivate specific branches based on load conditions, providing flexibility and adaptability while maintaining a compact overall structure. Each smaller jet pump unit can be independently controlled to match the recirculation requirements of varying load conditions.
4Adaptability or versatility
If multiple parallel jet pumps are used, then adaptability to various load conditions is improved, but device complexity increases
Solution Approach 1:
Each jet pump in the parallel arrangement is designed to perform the same recirculation function, making them universally interchangeable components. This multi-functionality approach allows the system to achieve adaptability through simple on/off control of identical units rather than requiring complex variable-speed drives or sophisticated control mechanisms, thereby limiting the increase in device complexity.
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
The solution minimizes energy consumption and space usage while providing adaptable and safe operation under varying load conditions, enhancing energy efficiency and safety in fuel cell systems, particularly in motor vehicles by enabling efficient gas recirculation and emergency evacuation.
Implementation Method 1
The gas originating from the anode space (3) accesses the suction connections (7a, 7b) respectively of two jet pumps (6a, 6b)
Implementation Method 2
essentially only the area of the anode space 3 is of interest, so that the cathode space 2 will not be discussed in greater detail
Data Source
AI summary
An apparatus is used for the recirculation of anode exhaust gases of a fuel cell, with a recirculation blower and at least one jet pump operated by a propulsion gas stream. The propelling medium is in this case a pressurized fuel, for example hydrogen. The anode outlet of the fuel cell is connected to the intake connection of the at least one jet pump. The outlet of the at least one jet pump is then connected to both the anode inlet and the intake connection of the recirculation blower. The output of the recirculation blower can be connected to the intake connection of the at least one jet pump.