Fuel Cell Coolant Control for Cold Start Oxidizing Gas Temperature
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Solution Overview
Problem
Conventional cold start control methods for fuel cell systems cause the air supplied to the fuel cell to become cold due to heat exchange with a cold coolant, leading to frozen electrolyte membrane water and difficulty in generating electricity.
Innovation Solution
A fuel cell system with a coolant circulation controller that starts or stops coolant circulation based on detected temperatures to maintain the air temperature above the minimum required for electricity generation, preventing excessive cooling and ensuring the fuel cell can operate at cold start-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the coolant circulation is started at cold start-up to cool the oxidizing gas, then the temperature control of the fuel cell is improved, but the oxidizing gas becomes too cold causing water in the electrolyte membrane to freeze
Solution Approach 1:
The patent applies preliminary action by detecting the temperature of the oxidizing gas before it enters the fuel cell and controlling the coolant circulation accordingly. The coolant circulation is started only when the oxidizing gas temperature exceeds a predetermined value, preventing the gas from becoming too cold and causing freezing of water in the electrolyte membrane while still providing cooling when needed.
2Reliability
If the coolant circulation is stopped at cold start-up to prevent excessive cooling, then the electricity generation is enabled, but the temperature of the oxidizing gas cannot be controlled when it becomes too high
Solution Approach 1:
The patent implements feedback control by continuously detecting the temperature of the oxidizing gas and adjusting the coolant circulation based on the detected temperature. When the temperature exceeds a predetermined threshold, the coolant circulation is started to cool the gas; when the temperature is below the threshold, the circulation is stopped to prevent excessive cooling. This closed-loop control ensures both electricity generation capability and temperature control.
3Temperature
If the coolant flow rate is increased to improve cooling efficiency, then the temperature control is enhanced, but the oxidizing gas temperature drops below the minimum required for electricity generation
Solution Approach 1:
The patent applies dynamics by making the coolant flow rate adjustable based on the detected oxidizing gas temperature. The coolant circulation controller dynamically adjusts the flow rate to match the cooling demand: increasing flow rate when temperature is high and decreasing it when temperature is low, thereby maintaining optimal temperature for electricity generation while providing effective cooling when needed.
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 prevents the air from becoming too cold, allowing the fuel cell to generate electricity at cold start-up and protecting components from excessive temperature increases, thus ensuring reliable operation.
Implementation Method 1
an aftercooler cooling the oxidizing gas supplied to the fuel cell by heat exchange with a coolant
Data Source
AI summary
A fuel cell system of the present invention includes: a fuel cell (1) supplied with fuel gas and oxidizing gas to generate electricity; a fuel gas supply unit supplying the fuel gas to the fuel cell (1); an oxidizing gas supply unit supplying the oxidizing gas to the fuel cell (1); an aftercooler (7) cooling the oxidizing gas supplied to the fuel cell (1) by heat exchange with a coolant; an oxidizing gas temperature detector (16, 17) detecting temperature of the oxidizing gas; and a coolant circulation controller (21a) starting circulation of the coolant when the detected temperature of the oxidizing gas exceeds a predetermined value. The predetermined value is set to a value of not higher than a minimum electricity generation temperature of the fuel cell (1), and a circulation timing and flow rate of the coolant for the aftercooler (7) are controlled such that the supplied oxidizing gas does not become cold. This enables the fuel cell (1) to generate electricity at cold start-up.