Fuel Cell Cold-Start Protection Using Predictive Purge and Warm-Up
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Solution Overview
Problem
Conventional fuel cell protection systems in vehicles are inadequate in cold environments, as they remove hydrogen protection during stack purge events, leading to increased degradation when starting without hydrogen protection, and fail to minimize unprotected starts without compromising fuel cell safety.
Innovation Solution
A controller-driven system that estimates and manages the fuel cell stack's temperature to prevent overheating and protect the fuel cell from freezing conditions by either purging the stack with heated air or warming it before startup, depending on the estimated ambient temperature and next start-up time, using a cooling system that operates without starting the fuel cell when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the cooling system blows air through the fuel cell stack to remove water (stack purge event), then water removal and freezing protection is improved, but hydrogen protection is removed causing increased degradation
Solution Approach 1:
The system performs a preliminary warm-up of the fuel cell stack before shutdown in cold conditions, storing thermal energy in the stack and coolant. This preliminary heating action ensures that when the stack is later purged to remove water, the residual heat prevents freezing while maintaining hydrogen protection, thus resolving the contradiction between freezing protection and degradation prevention
Solution Approach 2:
The system cushions against the harmful effect of cold temperatures by pre-heating the fuel cell stack and coolant before shutdown. This creates a thermal buffer that protects the stack during subsequent purge events, allowing water removal without exposing the fuel cell to degradation from cold starts or loss of hydrogen protection
2Object-affected harmful factors
If the cooling system is turned on without starting the fuel cell to warm the stack, then freezing protection is improved, but energy consumption increases
Solution Approach 1:
The system utilizes the cooling system's circulation capability to continuously pump coolant through the fuel cell stack, transferring thermal energy from the coolant to the stack. This continuous thermal transfer warms the stack without requiring full fuel cell operation, providing freezing protection while minimizing energy consumption by using existing system components
Solution Approach 2:
The system uses its own cooling system to provide heating functionality, allowing the coolant circulation pump to transfer heat from the coolant to the fuel cell stack. This self-service approach eliminates the need for separate heating equipment, reducing overall energy consumption while maintaining freezing protection
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
Effectively minimizes fuel cell degradation by maintaining hydrogen protection and reducing the number of unprotected starts, ensuring the fuel cell's integrity in freezing conditions while optimizing vehicle operations.
Implementation Method 1
a cooling system for the fuel cell that controls the temperature of the fuel cell that is responsive to the controller... functions to control the temperature of the fuel cell preventing the fuel cell from over-heating when the fuel cell is operating and warming the fuel cell upon start-up
Implementation Method 2
The cooling system may purge the fuel cell by blowing heated air through the through the fuel cell stack to remove water from the fuel cell stack
Data Source
AI summary
A protection system for a fuel cell is provided that has two different modes of operation. The protection system includes a fuel cell, a cooling system for the fuel cell that controls the temperature of the fuel cell responsive to a controller. The controller is operable in a first mode of operation when a time T for the next start-up is not known and a second mode of operation when the time T for the next start-up is known. In the first mode, a time TF is the time an estimated future ambient temperature is estimated to fall to near freezing wherein at TF the cooling system purges the fuel cell. In the second mode, at TF the cooling system turns on without starting the fuel cell. The controller turns of the cooling system when the fuel cell stack is warmed to a nominal temperature.