Fuel Cell Circulation Pump Noise Suppression via Timing Coordination
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Solution Overview
Problem
In fuel cell systems, the condensation of water vapor in discharge gas leads to liquid water accumulation in the hydrogen circulation flow path, causing noise vibrations and increased rotational load on the hydrogen circulation pump, which can be exacerbated by high-speed operation intended to blow away the water, resulting in resonance with pressure pulsations and operating noise.
Innovation Solution
A fuel cell system with a controller that coordinates the injection of fuel gas and the operation of the circulation pump to either operate at a preset RPM without injecting fuel gas or inject fuel gas at a lower RPM, and adjusts the injection cycle and quantity to prevent resonance-induced noise vibrations, ensuring effective drainage of liquid water while minimizing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the circulation pump is operated at high rotating speed to discharge liquid water from the circulation flow path, then water drainage efficiency is improved, but operating noise increases and resonance with pressure pulsations occurs
Solution Approach 1:
The controller performs water drainage operation at high pump speed before the injection timing occurs. By advancing the water discharge action to occur prior to fuel injection, the system achieves effective water removal from the circulation flow path while avoiding the resonance problem that occurs when high-speed pumping coincides with injection-induced pressure pulsations
Solution Approach 2:
The controller operates the circulation pump at high speed only during specific periodic intervals (before injection timing) rather than continuously. This periodic high-speed operation maintains water drainage effectiveness while limiting the duration of high noise generation, thereby reducing overall operating noise and avoiding sustained resonance conditions
2Productivity
If the circulation pump is operated at high rotating speed, then liquid water is effectively discharged, but pressure pulsations and operating noise resonate to generate noise vibrations
Solution Approach 1:
The system performs water discharge as a preliminary action before the injection process begins. The controller increases pump speed to discharge water from the circulation flow path and maintains this high speed until the injection timing occurs, ensuring water removal is completed before resonance-prone conditions are established
Solution Approach 2:
The controller preemptively discharges water from the circulation flow path before injection-induced pressure pulsations occur. By removing the liquid water that would otherwise resonate with incoming pressure waves, the system prevents the generation of noise vibrations rather than merely mitigating them after they occur
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 effectively suppresses noise vibrations due to resonance between pressure pulsations and operating noise, ensuring efficient water drainage and reduced noise disturbances, particularly during vehicle startup and low-speed operations, while maintaining sufficient fuel gas supply.
Implementation Method 1
the circulation pump is operated at an RPM preset for blowoff of water to discharge water residing on the circulation flow path
Implementation Method 2
pressure pulsations in the hydrogen supply flow path or the hydrogen circulation flow path will be occurred
Implementation Method 3
the rotating speed of the hydrogen circulation pump is increased independently of running of the fuel cell so as to blow away the liquid water residing on the hydrogen circulation flow path
Data Source
AI summary
When a first timing at which a fuel gas is injected to a fuel gas supply flow path by an injector and a second timing at which water residing on a circulation flow path is discharged by controlling rotating speed of a circulation pump coincide with each other, a controller performs either: (i) a first process of operating the circulation pump at a preset RPM without injecting the fuel gas to the fuel gas supply flow path by the injector; or (ii) a second process of injecting the fuel gas to the fuel gas supply flow path by the injector and operating the circulation pump at an RPM lower than the preset RPM.