Fuel Cell Power Plant By-Pass Circuit for Sub-Freezing Operation
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Solution Overview
Problem
Fuel cell water freezing in sub-freezing ambient conditions disrupts reactant stream flow, leading to performance issues and aborted starts in transportation vehicles, as existing solutions like fuel fired heaters and antifreeze solutions are costly and inefficient.
Innovation Solution
A fuel cell power plant operating system with a temperature sensor and on/off switching device by-pass circuit that maintains fuel cell operation below a predetermined freeze-safe temperature, allowing heat generation to prevent water freezing and ensure liquid water balance, directing electric current to an auxiliary load until the system reaches a safe operating temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fuel cell operation is shut down in sub-freezing conditions, then operator control is maintained, but fuel cell water freezes and blocks reactant stream flow paths
Solution Approach 1:
The system applies preliminary anti-action by detecting sub-freezing temperatures and preventing shutdown operations before freezing can occur. The control system monitors temperature and blocks the shutdown sequence when conditions indicate freezing risk, thereby preventing the harmful effect of frozen water blocking reactant streams while maintaining operator control during safe operations
Solution Approach 2:
The control system acts as an intermediary between the operator's shutdown request and the fuel cell operation. It mediates by evaluating temperature conditions and either permitting or blocking the shutdown command, thus protecting the fuel cell from freezing while respecting operator intent during safe conditions
2Temperature
If fuel cell operates in sub-freezing ambient conditions, then heat is generated to prevent freezing, but water may still freeze in pores and flow channels during short duration operation
Solution Approach 1:
The system employs feedback by continuously monitoring fuel cell temperature and using this information to control shutdown operations. The temperature sensor provides real-time data to the control system, which adjusts its decision-making regarding shutdown permission based on whether the temperature is above or below the freezing threshold, ensuring water remains liquid during operation
Solution Approach 2:
The system takes preliminary action by establishing temperature monitoring and control logic before freezing can occur. The control system is pre-configured to recognize sub-freezing conditions and prevent shutdown operations that would lead to freezing, acting in advance to maintain water in liquid state during short duration operations
3Reliability
If complicated heating systems or antifreeze solutions are used, then freezing protection is improved, but system complexity and cost increase
Solution Approach 1:
The system applies self-service by using the fuel cell's own operational characteristics (temperature generation during normal operation) to prevent freezing. Rather than adding external heating systems or antifreeze solutions, the invention relies on the fuel cell's inherent thermal properties and control logic to maintain water in liquid state, thereby achieving freezing protection without increasing system complexity
Solution Approach 2:
The invention extracts the essential freezing protection function from complex external systems and implements it through simple control logic. By removing the need for fuel fired heaters, electrical heaters, or antifreeze solutions, and replacing them with a temperature-based shutdown control system, the patent achieves freezing protection while dramatically reducing device complexity
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
Prevents ice formation in catalyst layers and reactant flow paths, ensuring stable fuel cell operation and safe shutdown by maintaining water in a liquid state until a freeze-safe temperature is reached, thereby minimizing disruptions and extending start-up reliability in cold conditions.
Implementation Method 1
Fuel cells are well known and are commonly used to produce electrical power from hydrogen containing reducing fluid fuel and oxygen containing oxidant reactant streams
Implementation Method 2
rely exclusively upon heat generated by an operating fuel cell upon start-up of the fuel cell to prevent fuel cell product water from freezing
Implementation Method 3
A temperature sensor is secured to the fuel cell for sensing temperatures adjacent an electrolyte of the fuel cell
Implementation Method 4
directing electric current to an auxiliary load until the system reaches a safe operating temperature
Data Source
AI summary
The fuel cell power plant operating system (10) includes an on/off switching device by-pass circuit (60) to sustain operation of a fuel cell (12) whenever the fuel cell (12) on/off switching device (58) is turned off while a fuel cell operating temperature is below a predetermined freeze-safe operating temperature. The by-pass circuit (60) operates the fuel cell (12) until the fuel cell (12) temperature reaches or exceeds the freeze-safe temperature to thereby prevent fuel cell (12) product water from becoming ice in and adjacent fuel cell catalysts (26, 40).