Fuel Cell System Pulsed Gas Supply Control
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Solution Overview
Problem
Existing fuel cell systems face challenges in balancing fuel efficiency and water drainage performance, with increased upper limit pulsating pressure leading to hydrogen over-supply, cross leakage, and potential fuel gas shortages during gas suspension periods.
Innovation Solution
A fuel cell system with a controlling unit that uses flow rate increasing control to manage fuel gas supply, ensuring pressure remains within preset limits and momentarily increasing gas flow before reaching the upper limit pressure, utilizing a gas-liquid separator and pressure measuring device to optimize water drainage without deteriorating fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the upper limit pulsating operating pressure is increased to improve water drainage performance, then water drainage performance is improved, but hydrogen is supplied in a larger amount than required which deteriorates fuel efficiency and increases fuel gas cross leakage
Solution Approach 1:
The patent applies periodic pulsed operation to the fuel gas supply, creating cyclic pressure variations in the fuel cell stack. By controlling the frequency and amplitude of these pressure pulses, the system achieves effective water drainage through the fuel cell stack while maintaining overall fuel efficiency. The periodic action allows water removal without requiring continuously high pressure that would cause hydrogen over-supply and cross leakage.
Solution Approach 2:
The patent dynamically changes operating parameters including pressure magnitude, pressure variation frequency, and supply timing during pulsed operation. By adjusting these parameters, the system optimizes the balance between water drainage effectiveness and fuel utilization, preventing both water accumulation and excessive hydrogen supply that would reduce fuel efficiency.
2Productivity
If the upper limit pulsating operating pressure is increased to improve water drainage performance, then water drainage performance is improved, but the time to reach the lower limit pressure increases which leads to formation of fuel gas shortage portions in the fuel cell stack
Solution Approach 1:
The controlled periodic pulsed operation creates regular cycles of pressure increase and decrease. By optimizing the pulse frequency and duration, the system ensures that water is effectively drained during the pressure increase phase while the subsequent pressure decrease phase is sufficient to maintain fuel gas supply stability, preventing fuel gas shortage portions from forming in the fuel cell stack.
Solution Approach 2:
The system monitors operating conditions during pulsed operation and adjusts the pressure control parameters accordingly. This feedback mechanism ensures that when water drainage is prioritized through increased pressure, the system compensates by adjusting pulse timing or magnitude to prevent excessive gas suspension time that would lead to fuel gas shortages, thereby maintaining supply stability.
3Speed
If a gas supply device with large injection flow rate is used to shorten the pulsation period, then the rise speed of pulsating operating pressure is improved, but the proportion of circulating flow rate decreases which may lead to hydrogen shortage in the fuel cell stack during gas suspension period
Solution Approach 1:
The patent employs periodic pulsed operation where the fuel gas supply is delivered in controlled bursts rather than continuously. By optimizing the pulse frequency and injection duration, the system achieves rapid pressure rise when needed for water drainage while ensuring sufficient circulating flow rate is maintained during the gas suspension period, preventing hydrogen shortage in the fuel cell stack.
Solution Approach 2:
The system dynamically adjusts the injection flow rate and pulse timing based on operating conditions. Rather than using a fixed large injection flow rate that would reduce circulating flow proportion, the system modulates the injection characteristics to achieve the necessary pressure rise speed while maintaining adequate hydrogen supply through optimized pulse patterns and circulating flow management.
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 efficiently drains water from the fuel cell stack while maintaining fuel efficiency and preventing hydrogen shortages, ensuring compatible fuel efficiency and water drainage performance.
Implementation Method 1
a gas-liquid separator configured to separate a liquid component from the fuel gas drained from the fuel cell stack
Implementation Method 2
a pressure measuring device disposed in any of the fuel gas supply passage, the fuel gas draining passage and the circulation passage
Implementation Method 3
a fuel gas supply device for supplying a fuel gas to the fuel cell stack
Data Source
AI summary
A fuel cell system that can offer fuel efficiency and water drainage performance which are compatible with each other, the fuel cell system including a fuel cell stack; a fuel gas supply device; a gas-liquid separator; a pressure measuring device; and a controlling unit, wherein the controlling unit controls pulsed operation of the fuel gas supply device in such a way that a measured pressure is within the range of a preset upper limit pressure and lower limit pressure, and the controlling unit uses a flow rate increasing control at least once when the pressure rises in the pulsed operation before the pressure reaches the upper limit pressure, as long as the pressure does not exceed the upper limit pressure, the flow rate increasing control being to increase the supply of the fuel gas supplied by means of the fuel gas supply device.