Fuel Cell Exhaust Port Recirculation Structure
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Solution Overview
Problem
Conventional exhaust gas dilution systems for fuel cell vehicles require complex additional structures to manage hydrogen concentration, often leaving un-diffused hydrogen in exhaust gases due to reliance on external air, which can lead to ignition and explosion risks.
Innovation Solution
An exhaust port structure with a re-circulation fluid passage and mixing pipe that recirculates hydrogen-rich exhaust gas back into the exhaust pipe, mixing it with external air before release, reducing hydrogen concentration through a venturi nozzle and expanded pipe sections to minimize back pressure and enhance safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If external air is used to dilute exhaust gas, then hydrogen concentration is reduced, but additional complex structures are required to draw in external air
Solution Approach 1:
The exhaust gas itself serves as the dilution medium by recirculating it through the re-circulation fluid passage. The system uses its own exhaust gas rather than requiring external air, eliminating the need for additional air intake structures and actuators while still achieving hydrogen concentration reduction through mixing and diffusion processes
Solution Approach 2:
The re-circulation fluid passage acts as an intermediary channel that facilitates the mixing of fresh exhaust gas with residual exhaust gas. This intermediary structure enables concentration dilution without requiring direct connection to external air sources, simplifying the overall system architecture
2Quantity of substance
If external air is used to dilute exhaust gas, then hydrogen concentration is reduced, but exhaust gas may still contain un-diffused hydrogen concentration
Solution Approach 1:
The re-circulation fluid passage enables continuous mixing and diffusion of hydrogen throughout the exhaust gas stream. By continuously recirculating and mixing the gas rather than relying on a single external air injection event, the system ensures complete diffusion of hydrogen concentration throughout the exhaust before it is discharged
Solution Approach 2:
The system performs preliminary mixing and diffusion of hydrogen in the re-circulation fluid passage before the exhaust gas is finally discharged. This preliminary action ensures that hydrogen is thoroughly mixed and diffused in advance, preventing un-diffused hydrogen from reaching the discharge point
3Quantity of substance
If purge valve and crossover are used, then hydrogen is exhausted, but considerable amount of hydrogen is lost
Solution Approach 1:
Instead of simply discarding hydrogen through the purge valve and crossover, the system recovers it by recirculating the hydrogen-rich exhaust gas back through the re-circulation fluid passage. This allows the hydrogen to be mixed and diffused before final discharge, reducing the overall loss of hydrogen while still achieving safe exhaustion
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
Effectively reduces hydrogen concentration in exhaust gases during initial starting and hydrogen purge, enhancing safety by minimizing hydrogen levels and eliminating the need for separate actuators, while maintaining fuel cell performance.
Implementation Method 1
hydrogen is re-circulated into the exhaust pipe through the re-circulation fluid passage and mixed with the external air through the mixing pipe
Implementation Method 2
reducing hydrogen concentration through a venturi nozzle and expanded pipe sections to minimize back pressure
Data Source
AI summary
An exhaust port structure of a fuel cell vehicle includes a re-circulation fluid passage mounted on an upper portion of an exhaust pipe so as to be arranged parallel to the exhaust pipe, and a mixing pipe mounted on an end of the exhaust pipe and through which external air is suctioned. When a concentration of hydrogen in exhaust gas exceeds a reference value, hydrogen is re-circulated into the exhaust pipe via the re-circulation fluid passage and mixed with external air through the mixing pipe before being exhausted to outside. As a result, during starting and hydrogen purge to remove hydrogen from a fuel cell, the gas with high hydrogen concentration exhausted from the fuel cell and exhausted out of the vehicle can have reduced hydrogen concentration through the re-circulation fluid passage and the mixing pipe.