Fuel Cell Gas Flow Configuration and Stoichiometric Control
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Solution Overview
Problem
Fuel cells experience drying issues and reduced power generation performance when operating at high temperatures, particularly due to the counter-flow of fuel and oxidant gases, which affects the stoichiometric ratios and humidity levels, leading to inefficiencies in power output.
Innovation Solution
A fuel cell system with a control unit that adjusts the stoichiometric ratios of fuel and oxidant gases based on temperature and power output states, increasing the oxidant gas ratio in high-temperature high-output states and reducing the fuel gas ratio in such conditions to maintain optimal humidity and reduce drying, thereby enhancing power generation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the fuel gas flow rate is increased to reduce drying of the oxidant gas passage inlet, then the drying of the oxidant gas passage inlet is reduced, but the fuel gas consumption increases and power generation efficiency decreases
Solution Approach 1:
The patent dynamically adjusts the stoichiometric ratio of oxidant gas based on operating conditions (temperature and power output). In high-temperature high-output states, a higher oxidant stoichiometric ratio is used to increase oxygen partial pressure and prevent drying at the oxidant gas passage inlet, while in high-temperature low-output states, a lower oxidant stoichiometric ratio is used to reduce fuel gas consumption and improve efficiency.
2Object-affected harmful factors
If the oxidant gas stoichiometric ratio is increased in high-temperature high-output state, then the oxygen partial pressure increases and drying is reduced, but the system complexity increases due to dynamic control requirements
Solution Approach 1:
The patent implements a feedback control mechanism where the supply amount controller continuously monitors the fuel cell's temperature and power output state, then dynamically adjusts the oxidant gas stoichiometric ratio accordingly. This closed-loop control optimizes performance by increasing oxygen partial pressure and preventing drying in high-temperature high-output states while simplifying operation through automated adjustment.
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 system effectively reduces drying and improves power generation performance by optimizing gas ratios, increasing oxygen partial pressure, and maintaining adequate water production, leading to improved current density and voltage outputs even at high temperatures.
Implementation Method 1
a fuel cell including a fuel gas passage through which a fuel gas flows and an oxidant gas passage through which an oxidant gas flows
Implementation Method 2
the supply amount controller is configured to control the oxidant gas supply unit so that a stoichiometric ratio of the oxidant gas in a high-temperature high output power state is greater than a stoichiometric ratio of the oxidant gas in a high-temperature low output power state
Implementation Method 3
the high-temperature high output power state being a state where a temperature of the fuel cell is higher than a predetermined temperature
Data Source
AI summary
A fuel cell system includes: a fuel cell including a fuel gas passage through which a fuel gas flows and an oxidant gas passage through which an oxidant gas flows, an inlet of the fuel gas passage being located closer to an outlet of the oxidant gas passage than to an inlet of the oxidant gas passage, an outlet of the fuel gas passage being located closer to the inlet of the oxidant gas passage than to the outlet of the oxidant gas passage; an oxidant gas supply unit supplying the oxidant gas to the fuel cell; and a supply amount controller configured to control the oxidant gas supply unit, the supply amount controller is configured to control the oxidant gas supply unit so that a stoichiometric ratio of the oxidant gas in a high-temperature high output power state is greater than that in a high-temperature low output power state.