Fuel Cell Exhaust Gas Recirculation Using a Jet Pump
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Solution Overview
Problem
Existing fuel cell systems face limitations in high-temperature tolerance and efficiency due to the use of recirculation fans, which are sensitive to temperature and consume excessive electrical energy.
Innovation Solution
A fuel cell system employing a recirculation section with a jet pump that recirculates exhaust gas, eliminating the need for additional conveying apparatus and allowing for a wider operating temperature range, improved efficiency, and reduced maintenance, by mixing recirculated exhaust gas with a primary flow within the jet pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a recirculation fan is used to recirculate exhaust gas, then the exhaust gas can be recirculated to generate a reducing atmosphere, but the fan has limited operating temperature range and requires additional cooling
Solution Approach 1:
The patent replaces the mechanical recirculation fan with a jet pump that uses fluid dynamics (the Venturi effect) to recirculate exhaust gas. The jet pump utilizes the kinetic energy of a primary fluid stream to entrain and move the exhaust gas, eliminating mechanical moving parts that are sensitive to high temperatures. This substitution resolves the contradiction by enabling high-temperature operation without requiring additional cooling systems for the recirculation device.
Solution Approach 2:
The patent employs pneumatic principles by using a jet pump that operates on the Venturi effect, where a high-velocity primary fluid stream creates a pressure difference to entrain and recirculate exhaust gas. This pneumatic approach replaces the mechanical fan system, allowing the recirculation device to operate reliably at high temperatures without mechanical components that would require cooling.
2Productivity
If a recirculation fan is used to recirculate exhaust gas, then the exhaust gas can be recirculated, but the fan consumes excessive electrical energy
Solution Approach 1:
The patent replaces the electrically-driven mechanical fan with a jet pump that uses fluid kinetic energy to achieve recirculation. The jet pump converts the kinetic energy of a primary fluid stream into momentum to entrain and move the exhaust gas, eliminating the need for electrical energy consumption associated with mechanical fans. This resolves the contradiction by maintaining recirculation effectiveness while dramatically reducing energy input requirements.
Solution Approach 2:
The jet pump system is self-driven by the kinetic energy of the primary fluid stream, requiring no external electrical power source. The system uses its own operational parameters (the flow and velocity of the primary fluid) to create the suction and recirculation effect, making it energy-autonomous and eliminating the excessive electrical energy consumption problem of electric fans.
3Ease of operation
If a recirculation fan is used, then exhaust gas recirculation is achieved, but the fan components are sensitive to temperature and require additional cooling
Solution Approach 1:
The patent substitutes the temperature-sensitive mechanical fan with a jet pump that has no moving parts and is inherently resistant to high temperatures. The jet pump relies on fluid dynamics principles that remain effective across a wide temperature range, eliminating the need for cooling systems and expanding the operational temperature range of the exhaust gas recirculation device.
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 system achieves enhanced temperature tolerance, increased efficiency, and improved functional reliability by utilizing a jet pump to recirculate exhaust gas, creating a reducing atmosphere without additional gas introduction, thus optimizing system performance.
Implementation Method 1
A jet pump comprises at least two inlets and at least one outlet for connection to lines that convey fluid or other components. A jet pump functions in such a way that a primary flow flows from a first inlet of the jet pump to the outlet of the jet pump. A secondary flow is fed to the primary flow through a second inlet of the jet pump. The primary flow experiences a pressure drop and acceleration in the jet pump. On account of the suction effect of the primary flow, the secondary flow is also accelerated, the flows mix and then exit mixed through the outlet of the jet pump.
Data Source
AI summary
The present invention relates to a fuel cell system (100) comprising at least one fuel cell stack (1) having at least one cathode section (K) and at least one anode section (A), an air supply section (2) for supplying air (2) to the anode section (A) of the fuel cell stack (1), an exhaust air section (4) for discharging exhaust air (5) from the anode section (A) of the fuel cell stack (1), as well as a supply section (7) for supplying at least one main medium (6) to the cathode section (K) of the fuel cell stack (1), an exhaust gas discharge section (9) for discharging exhaust gas (8) from the cathode section (K) of the fuel cell stack (1), as well as a pump (12) for delivering the at least one main medium (6), the exhaust gas discharge section (9) being fluidically connected via a recirculation section (14) to the supply section (7) downstream of the pump (12) in order to recirculate exhaust gas (8), the recirculation section (14) being connected via a jet pump (16) to the supply section (7) in order to introduce recirculated exhaust gas (8) as the secondary flow (20) of the jet pump (16) into the at least one gaseous main medium (6) as the primary flow (18) of the jet pump (16). The invention also relates to a method for recirculating exhaust gas (8) in a fuel cell system (100).