Fuel Cell Manifold Mixed Gas Flow Path Ice Prevention
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Solution Overview
Problem
Fuel cell systems face challenges in achieving high heat exchange efficiency and preventing ice formation from water in the fuel off-gas from entering the fuel cell stack, as the existing systems do not effectively manage the temperature and ice introduction.
Innovation Solution
A fuel cell system design that includes a mixed fuel gas flow path within a plate-like manifold where the fuel off-gas and new fuel gas are merged, allowing the mixed gas to flow along the manifold's inner surface, increasing heat exchange efficiency and preventing ice formation by extending the flow path and utilizing nearby heat sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the point of merger between fuel off-gas and new fuel gas is provided in the manifold, then the heat exchange efficiency is improved, but water in the fuel off-gas may freeze and produce ice that enters the fuel cell stack
Solution Approach 1:
The patent extends the fuel off-gas circulation passage from a three-dimensional space into the planar direction along the inner surface of the manifold. This dimensional change creates a longer flow path (extending from central to edge portions of the manifold) that allows the gas to absorb more heat from the manifold walls, thereby preventing water freezing while maintaining efficient heat exchange.
Solution Approach 2:
The patent pre-heats the fuel off-gas by circulating it through the manifold's internal passage before it reaches the point of merger with new fuel gas. This preliminary heating action ensures that the temperature of the fuel off-gas is maintained above the freezing point of water, preventing ice formation upstream of the merger point while still allowing efficient heat recovery.
2Device complexity
If the distance from the point of merger to the fuel cell stack is short, then the system complexity is reduced, but ice produced from frozen water in the fuel off-gas may be introduced into the fuel cell stack
Solution Approach 1:
The patent introduces the manifold's internal passage as an intermediary heating zone between the fuel off-gas source and the fuel cell stack. This intermediary structure provides a controlled environment where the fuel off-gas can be pre-heated before merging with new fuel gas, preventing ice formation without requiring additional complex heating devices or increasing the overall distance to the stack.
3Temperature
If the fuel off-gas is further heated by heat generated by the fuel cell stack, then the temperature is increased, but the heat exchange efficiency is insufficient
Solution Approach 1:
Instead of heating the fuel off-gas by placing the merger point close to the hot fuel cell stack, the patent inverts the approach by using the cooler manifold walls as the heat source. The fuel off-gas flows along the inner surface of the manifold, absorbing heat from the manifold walls rather than from the stack directly, which reverses the conventional heating direction and achieves better heat exchange efficiency.
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 configuration significantly enhances heat exchange efficiency and reliably prevents ice from entering the fuel cell stack by maintaining a lower temperature and utilizing nearby heat sources to melt ice, improving both efficiency and operational reliability.
Implementation Method 1
a fuel cell that includes a stack body including a plurality of cells for generating electric power through electrochemical reaction between a fuel gas and an oxidant gas
Implementation Method 2
the mixed fuel gas flows in a direction along the inner surface of the substantially plate-like manifold... increasing heat exchange efficiency
Implementation Method 3
utilizing nearby heat sources to melt ice, improving both efficiency and operational reliability
Data Source
AI summary
A fuel cell system according to the present invention comprises a fuel gas supply system that supplies a fuel gas from a fuel supply source to a fuel cell that includes a stack including a plurality of cells, and a fuel off-gas circulation system that resupplies fuel off-gas to the stack. The fuel off-gas circulation system includes: a mixed fuel gas flow path formed such that a mixed fuel gas containing the fuel off-gas and the fuel gas flows in a direction along an inner surface of a manifold installed in the stack; and a point of merger where the fuel off-gas and the fuel gas merge with each other to produce the mixed fuel gas, the point of merger being arranged on one surface side of the manifold. With such configuration, the heat exchange efficiency of the fuel off-gas and the fuel gas can be increased, and ice resulting from water in the fuel off-gas can be prevented from flowing into the fuel cell stack.