Fuel Cell Gas Temperature Control for Ice Prevention
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Solution Overview
Problem
In fuel cell systems, reducing the flow rate of cooling water to facilitate early warm-up in sub-zero temperatures leads to slowed temperature increase of anode gas, potentially causing ice formation and passage closure during startup, which hampers the circulation of gases and delays warm-up.
Innovation Solution
A fuel cell system with a gas temperature increase control unit that adjusts the refrigerant flow rate in the heat exchanger to prevent freezing by increasing the flow rate before ice formation occurs, ensuring early warm-up and preventing passage closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the flow rate of cooling water is reduced to facilitate early warm-up of the fuel cell, then the warm-up speed of the fuel cell is improved, but the temperature increasing rate of the anode gas is slowed down
Solution Approach 1:
The control unit predicts the temperature of the anode gas before it enters the heat exchanger and takes preliminary action by adjusting the cooling water flow rate to the heat exchanger. When the predicted temperature is below a predetermined threshold, the control unit increases the cooling water flow rate to the heat exchanger (not to the fuel cell) to heat the anode gas in advance, preventing ice formation while maintaining fast fuel cell warm-up.
Solution Approach 2:
The cooling water circulation system is divided into two separate paths: one path supplies cooling water to the fuel cell for warm-up, and another path supplies cooling water to the heat exchanger for anode gas heating. This segmentation allows independent control of each path's flow rate, enabling the system to optimize both fuel cell warm-up speed and anode gas temperature increase simultaneously.
2Loss of time
If the flow rate of cooling water to the heat exchanger is reduced, then the fuel cell warm-up is accelerated, but ice formation in the flow passage increases
Solution Approach 1:
The control unit continuously monitors the temperature of the anode gas and uses this feedback to dynamically adjust the cooling water flow rate to the heat exchanger. Based on the detected temperature and predicted future temperature, the control unit automatically increases or decreases the flow rate to prevent ice formation, ensuring flow passage reliability while minimizing warm-up time.
Solution Approach 2:
The system performs preliminary heating of the anode gas by controlling the cooling water flow rate to the heat exchanger before the anode gas enters the flow passage. This advance action prevents ice formation in advance, maintaining flow passage operability without extending warm-up time.
3Productivity
If the flow rate of cooling water is reduced for early warm-up, then the warm-up efficiency is improved, but the temperature of anode gas supplied from the tank becomes lower than freezing point
Solution Approach 1:
The heat exchanger acts as an intermediary device between the cooling water system and the anode gas. By controlling the cooling water flow rate to the heat exchanger, the system indirectly heats the anode gas without directly heating the fuel cell. This intermediary approach allows independent optimization of anode gas temperature and fuel cell warm-up efficiency.
Solution Approach 2:
The system segments the thermal management functions by separating the cooling water supply to the fuel cell from the cooling water supply to the heat exchanger. This segmentation enables the heat exchanger path to be optimized for anode gas heating while the fuel cell path is optimized for rapid warm-up, resolving the temperature conflict.
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 effectively prevents freezing of gas circulation components while enabling early fuel cell warm-up, ensuring continuous operation and efficient power generation.
Implementation Method 1
a heat exchanger configured to exchange heat between the refrigerant increased in temperature by the fuel cell and the gas supplied to the gas supply passage
Implementation Method 2
a refrigerant supply apparatus configured to supply refrigerant for cooling the fuel cell to the fuel cell
Data Source
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AI summary
A fuel cell system includes a gas supply passage configured to supply one of the anode gas and the cathode gas to the fuel cell, a refrigerant supply apparatus that supplies refrigerant for cooling the fuel cell to the fuel cell, a heat exchanger that exchanges heat between the refrigerant increased in temperature by the fuel cell and the gas supplied to the gas supply passage. The fuel cell includes a component that circulates the one of the anode gas and the cathode gas discharged from the fuel cell to the fuel cell, and a warm-up control unit that controls a flow rate of the refrigerant to a predetermined flow rate for warming up the fuel cell when the fuel cell is warmed up. The fuel cell system includes a gas temperature increase control unit increases the flow rate of the refrigerant to be supplied to the heat exchanger on the basis of a temperature of the gas circulated by the component or a parameter related to the temperature when the flow rate of the refrigerant is controlled by the warm-up control unit.