Fuel Cell Gas Circulation Ratio Calculation for Freezing Prevention
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Solution Overview
Problem
Conventional fuel cell systems fail to prevent freezing at the joining point of supplied and discharged gases during operation at temperatures below the freezing point, leading to potential system disruptions.
Innovation Solution
The fuel cell system sets a circulation ratio for the flow rates of supply and discharge gases based on condensation latent heat, ensuring that the combined gas temperature remains above the freezing point, thereby inhibiting freezing without the need for external heaters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the circulation ratio is increased to prevent freezing of water vapor in the circulation gas, then the temperature at the joining part is maintained above the freezing point, but the energy consumption increases due to higher gas circulation rates
Solution Approach 1:
The invention changes the circulation ratio parameter to an optimal value that balances freezing prevention with energy consumption. By calculating the specific circulation ratio based on system operating conditions, the patent achieves reliable freezing protection while minimizing unnecessary energy waste from excessive circulation rates.
Solution Approach 2:
The invention uses a calculation model that copies or simulates the thermal conditions at the joining part to determine the appropriate circulation ratio. This allows the system to predict and prevent freezing conditions without requiring actual trial-and-error adjustments, thereby optimizing energy usage while ensuring reliability.
2Reliability
If external heaters are installed at the joining part to prevent freezing, then the freezing protection is enhanced, but the device complexity and cost increase
Solution Approach 1:
The invention enables the system to prevent freezing through self-regulation of the circulation ratio without requiring external heaters or additional active heating components. The circulation control mechanism inherently maintains temperatures above freezing through proper ratio management, eliminating the need for complex heating systems.
Solution Approach 2:
The invention extracts or removes the need for external heaters by utilizing the existing circulation system's potential. By optimizing the circulation ratio, the patent achieves freezing protection using only the gas circulation mechanism already present in the system, thereby reducing device complexity.
3Use of energy by moving object
If the circulation ratio is set too low, then the energy consumption is reduced, but the water vapor in the circulation gas cools and freezes at the joining part
Solution Approach 1:
The invention establishes the minimum circulation ratio parameter threshold that prevents freezing while minimizing energy consumption. By identifying and maintaining this critical parameter value, the system achieves optimal balance between energy efficiency and reliable freezing prevention.
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 at the joining point, ensuring continuous operation by maintaining a temperature above the freezing point, thus enhancing system reliability and efficiency.
Implementation Method 1
the circulation ratio is set in consideration of condensation latent heat of water vapor in the circulation gas
Implementation Method 2
water vapor in the hydrogen off-gas is condensed in the circulation path
Data Source
AI summary
There are disclosed a fuel cell system capable of inhibiting freezing at a joining part of a supply gas and a circulation gas during a system operation, and a method for calculating circulation ratio in the system. In the fuel cell system of the present invention, the circulation gas discharged from a fuel cell meets the supply gas from a gas supply source to be supplied to the fuel cell, and a flow rate of the circulation gas with respect to that of the supply gas is set in consideration of condensation latent heat of water vapor in the circulation gas. The flow rate of the circulation gas with respect to that of the supply gas can be set by heat balance calculation at the joining part in consideration of the condensation latent heat.