Dual-Nozzle Ejector Heating for Fuel Cell Moisture Freezing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In fuel cell systems, moisture generated within the fuel cell stack can freeze in the ejector, blocking the flow of fuel and off gases, especially in subfreezing environments, and adding a heating unit to prevent freezing increases the ejector's size and complexity.
Innovation Solution
A fuel cell system design with a dual-nozzle ejector and a strategically placed heating unit, where the heating unit is positioned on the side of the smaller-diameter nozzle to prevent freezing while minimizing the overall size increase, using a heat conduction member and a cooling pipe for efficient heat exchange, and an auxiliary heating unit for additional support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heating unit is added to the ejector to prevent moisture freezing, then the reliability is improved, but the device complexity and size increase
Solution Approach 1:
The heating unit is integrated into the ejector structure by utilizing the existing smaller-diameter nozzle as the heating element. The nozzle serves dual functions: fuel injection and heat generation, eliminating the need for a separate heating component and reducing overall device complexity
Solution Approach 2:
The smaller-diameter nozzle is designed to serve multiple purposes: it functions as both a fuel injection nozzle and a heating element. This multi-functionality allows the same component to address both fuel delivery and moisture prevention, thereby avoiding additional complexity
2Reliability
If a heating unit is added to the ejector to prevent moisture freezing, then the reliability is improved, but the external size increases
Solution Approach 1:
The heating function is merged with the existing nozzle structure rather than being added as a separate external component. This integration ensures that the heating unit does not increase the external dimensions of the ejector beyond what is already required for the nozzle itself
3Manufacturing precision
If the diameter of the injection port is reduced to improve mixing, then the manufacturing precision is improved, but the reliability decreases due to increased freezing risk
Solution Approach 1:
The heating unit is activated to prevent moisture freezing before it can block the smaller-diameter injection port. This preliminary protective action counteracts the increased freezing risk that results from using a reduced diameter for improved mixing precision
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 inhibits moisture freezing in the ejector without significantly increasing the system's size, ensuring continuous operation in subfreezing conditions by prioritizing heating of the smaller nozzle and utilizing efficient heat exchange mechanisms.
Implementation Method 1
The heating unit is configured to heat the ejector
Implementation Method 2
a heat conduction member sandwiched between the ejector and the heating unit, and the heat conduction member may be configured to be deformed in accordance with shapes of the ejector and the heating unit
Implementation Method 3
the gas pipe and the cooling pipe may have a structure in which heat exchange is performed between the cooling medium and the fuel gas
Implementation Method 4
The fuel cell is configured to generate power due to a chemical reaction between fuel gas and oxidant gas
Data Source
AI summary
A fuel cell system includes a fuel cell that generates power due to a chemical reaction between fuel gas and oxidant gas, and an ejector that includes a first nozzle and a second nozzle having injection ports with different diameters, respectively, the injection ports injecting the fuel gas. The ejector introduces off gas recirculated from the fuel cell to the fuel cell together with the fuel gas. The fuel cell system also includes a heating unit that heats the ejector. The diameter of the injection port of the second nozzle is smaller than that of the first nozzle, and the heating unit is arranged on the side of the second nozzle of the ejector out of the first nozzle and the second nozzle.