Fuel Cell Anode Recirculation Pump Control via Pressure Drop
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Solution Overview
Problem
Current fuel cell systems lack direct controllability of anode hydrogen concentration and recirculation rate due to the absence of suitable hydrogen concentration sensors and flow rate sensors, especially in humid environments, leading to inefficiencies and potential system instability from nitrogen cross-over.
Innovation Solution
A method to control the speed of the recirculation pump in the anode recirculation loop by measuring pressure drop, temperature, and gas density, calculating the volume flow and hydrogen percentage, and adjusting the pump speed to maintain a predetermined ratio of fresh hydrogen to recirculated gas without relying on hydrogen concentration or flow sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If recirculation pump speed is increased to maintain proper hydrogen concentration, then hydrogen distribution uniformity is improved, but system complexity increases due to lack of direct sensors
Solution Approach 1:
The patent replaces mechanical/electronic sensors with a mathematical model that uses readily available measurements (pressure drop, temperature, pump speed) to calculate hydrogen concentration and recirculation rate. This substitution eliminates the need for complex sensor systems while achieving the same control objective.
Solution Approach 2:
The patent introduces a mathematical model as an intermediary between the physical system and the control decision. The model translates easily measurable parameters (pressure, temperature, pump speed) into meaningful control variables (hydrogen concentration, recirculation rate) that would otherwise require complex sensors to measure directly.
2Loss of energy
If recirculation rate is increased to reuse hydrogen, then system efficiency is improved, but measurement capability deteriorates due to absence of suitable sensors
Solution Approach 1:
The patent replaces unavailable hydrogen concentration sensors and flow rate sensors with a mathematical model that calculates these parameters from readily available measurements including pressure drop across the pump, temperature, and pump speed, enabling precise measurement without specialized sensors.
Solution Approach 2:
The system uses its own existing measurements (pressure, temperature, pump speed) to determine the recirculation rate and hydrogen concentration, making the system self-measuring without requiring external specialized sensors that would add complexity and cost.
3Measurement precision
If pressure drop measurement is used to calculate volume flow, then measurement capability is improved, but system reliability is affected by humid environment
Solution Approach 1:
The patent introduces a mathematical model as an intermediary that processes the pressure drop measurement along with temperature and pump speed data to calculate volume flow. This model compensates for the effects of humid environment on the measurements, maintaining reliability without requiring specialized humidity-resistant sensors.
Solution Approach 2:
The patent replaces direct flow measurement sensors that would be vulnerable to humid environment with a calculation-based approach using pressure drop, temperature, and pump speed measurements, which are more reliable in humid conditions when processed through the mathematical model.
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 allows for accurate control of the recirculation rate, maintaining optimal hydrogen levels and reducing nitrogen dilution, thereby enhancing fuel cell system efficiency and stability by ensuring the proper mixture of fresh and recirculated hydrogen.
Implementation Method 1
measuring the pressure drop across the recirculation pump
Implementation Method 2
calculating a volume flow of the recirculated gas through the anode side of a fuel cell stack as a function of a calculated pressure drop across the anode side of the stack, the percentage of hydrogen in the recirculated gas, the measured temperature and the measured pressure
Data Source
AI summary
A system and method for controlling the speed of a recirculation pump in an anode recirculation loop of a fuel cell system based on a predetermined ratio of fresh hydrogen to recirculated anode gas. The system uses a model to determine the volume flow of the recirculated gas through a fuel cell stack to determine the recirculation rate based on a measured temperature of the recirculated gas, a measured pressure drop across a recirculation pump, a pressure drop across the anode inlet and outlet of the stack, a percentage of hydrogen in the recirculated gas, and the density of the recirculated gas.