Fuel Cell Gas-Liquid Separator for White Fog Suppression
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Solution Overview
Problem
Existing fuel cell systems face issues with white fog and water splashing when discharging water and fuel gases, particularly when mounted on vehicles, as the flow rate of cathode off-gas can vary, leading to inadequate dilution and potential fuel economy decreases.
Innovation Solution
A fuel cell system with separate anode and cathode gas-liquid separators, controlled liquid surface levels, and specific flow passages to mix and discharge gases and liquids separately, preventing white fog and water splashing by ensuring the anode liquid is discharged from the lower portion of the anode gas-liquid separator and mixing the separated gases and liquids before discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If water is discharged from the fuel cell along with the cathode off-gas, then the water can be removed from the system, but white fog occurs and water splashing becomes problematic
Solution Approach 1:
The patent divides the off-gas flow into separate anode and cathode streams, each with its own gas-liquid separator. This segmentation allows independent control of water discharge from each side, preventing the mixing that causes white fog and splashing while maintaining effective water removal from both anode and cathode off-gases.
2Object-affected harmful factors
If the flow amount of cathode off-gas is increased to dilute water, then white fog becomes thinner, but the total volume of gas increases and fuel economy decreases
Solution Approach 1:
The patent extracts liquid water from the anode off-gas using a dedicated gas-liquid separator before the gases are mixed. By removing the water component separately, the system achieves effective water discharge without requiring excessive cathode off-gas flow for dilution, thus maintaining fuel economy while preventing white fog.
3Device complexity
If the liquid surface level of the anode gas-liquid separator is not controlled, then the structure is simpler, but fuel gas may be discharged to the drainage system
Solution Approach 1:
The patent implements feedback control by monitoring the liquid surface level in the anode gas-liquid separator and adjusting the liquid discharge accordingly. This ensures the liquid surface remains at an optimal level to prevent fuel gas from being carried into the drainage system, while avoiding overly complex control mechanisms.
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 suppresses white fog and water splashing, maintains fuel economy by diluting fuel gases, and prevents liquid from entering the drainage system, ensuring efficient discharge and reduced environmental impact.
Implementation Method 1
an anode gas-liquid separator which is connected to the first flow passage and which separates the anode off-gas into a separated anode gas and a separated anode liquid
Implementation Method 2
a cathode gas-liquid separator which is connected to the second flow passage and which separates the cathode off-gas into a separated cathode gas and a separated cathode liquid
Implementation Method 3
a first connection portion where the third flow passage and the fifth flow passage are connected to each other and the separated anode gas and the separated cathode gas are mixed
Implementation Method 4
a second connection portion where the fourth flow passage and the sixth flow passage are connected to each other and the separated anode liquid and the separated cathode liquid are mixed
Data Source
AI summary
To make it possible to suppress the occurrence of white fog and water splashing in a fuel cell system and to discharge gas and liquid to the outside of the system while diluting fuel gas, a fuel cell system is provided wherein each of an anode off-gas passage and a cathode off-gas passage is provided with a gas-liquid separator, an exhaust passage and a drain passage are separated, a gas in the anode off-gas is mixed with a gas in the cathode off-gas and are discharged together, and a liquid in the anode off-gas is mixed with a liquid in the cathode off-gas and are discharged together. The liquid surface level of the gas-liquid separator provided in the anode off-gas passage is controlled by a controller so that the liquid surface level does not become zero when liquid is discharged. As a result, in the gas-liquid separator, it is possible to prevent the gas in the anode off-gas from flowing into the drain side. Thus, the occurrence of white fog or water splashing can be suppressed by separately providing the exhaust system and the drain system. Additionally, it is possible to dilute the fuel gas by mixing the anode exhaust gas with the cathode exhaust gas in the exhaust system.