Fuel Supply Pulse Control for Low-Flow Ejector Circulation
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Solution Overview
Problem
The existing fuel cell systems fail to improve the circulation efficiency of the ejector during low output power driving due to inconsistent fuel supply flow rates, which are not adequately addressed by switching control modes based on internal pressure alone.
Innovation Solution
The fuel cell system employs pulse control for the fuel supply unit when the required supply flow rate is below a maximum circulation efficiency threshold and switches to proportional control when the flow rate exceeds this threshold, using multiple nozzles with different flow rates to maintain efficient circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the fuel supply unit is driven by proportional control to maintain steady fuel supply, then the fuel supply stability is improved, but the circulation efficiency of the ejector deteriorates during low flow rate conditions
Solution Approach 1:
The fuel supply unit is driven by pulse control to intermittently supply fuel to the ejector, creating periodic high velocity fuel flow that enhances the circulation efficiency of off-gas during low flow rate conditions while maintaining overall supply stability through controlled pulsing
2Quantity of substance
If the fuel supply flow rate is reduced during low output power driving, then the fuel consumption is optimized, but the circulation efficiency of the ejector deteriorates due to slow flow velocity
Solution Approach 1:
By using pulse control to intermittently supply fuel at high velocity bursts rather than continuous low flow, the system maintains effective ejector circulation efficiency while reducing overall fuel consumption during low output power driving conditions
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 enhances the circulation efficiency of the ejector by maintaining fuel flow velocity and preventing reductions during nozzle transitions, ensuring consistent fuel supply to the fuel cell.
Implementation Method 1
an ejector provided in the fuel supply passage... The circulation efficiency of an ejector indicates the circulation performance of off-gas (i.e., fuel not used in the fuel cell) to the ejector
Data Source
AI summary
A fuel cell system wherein a fuel supply unit is driven by pulse control when a required supply flow rate of fuel to a fuel cell is less than a flow rate at maximum circulation efficiency at which the circulation efficiency of an ejector is the maximum value when the fuel supply unit is driven by proportional control, and the fuel supply unit is driven by the proportional control when the required supply flow rate of the fuel to the fuel cell is greater than or equal to the flow rate at the maximum circulation efficiency.