Fuel Cell Exhaust Water Separation With Venturi Hydrogen Dilution
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Solution Overview
Problem
Existing fuel cell systems face challenges in efficiently separating and collecting water from gas streams, particularly from exhaust air, which is typically discharged into the environment, leading to potential membrane drying and system damage.
Innovation Solution
A device comprising a water separator configured as a riser with a water tank, enhanced by a condensation-promoting element and a Venturi nozzle, integrated into the exhaust air path, which separates and collects water via gravity and secondary flow, preventing hydrogen accumulation and optimizing water vapor condensation using a cooled internal surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If water is separated and collected from exhaust air, then water availability for humidification is improved, but device complexity increases
Solution Approach 1:
The water separation device is divided into functionally independent modules: a water separator (riser) for gravity-based liquid water separation, a water tank for collection and storage, and a gas-to-gas membrane humidifier for water vapor transfer. This segmentation allows each component to perform its specific function efficiently while enabling flexible integration into the fuel cell system.
Solution Approach 2:
The water tank serves multiple functions: it collects liquid water from the water separator, stores water for later humidification use, and acts as a chamber for the membrane humidifier where water is transferred to the gas stream. This multi-functionality reduces the need for separate components and minimizes overall device complexity.
2Quantity of substance
If exhaust air is discharged into the environment, then system simplicity is maintained, but water loss increases
Solution Approach 1:
Instead of discarding the exhaust air containing valuable water directly to the environment, the system recovers water from the exhaust stream through the water separator and membrane humidifier. The separated water is collected in the water tank and reused for cathode humidification, thereby recovering a valuable resource that would otherwise be lost.
Solution Approach 2:
The exhaust air, which initially represents a loss of water and energy, is converted into a beneficial resource. By integrating the water separation and recovery device, the exhaust air becomes a source of water for humidification, turning a waste stream into a valuable input for maintaining fuel cell performance.
3Reliability
If water is not humidified, then device complexity is reduced, but fuel cell reliability deteriorates
Solution Approach 1:
The fuel cell system essentially serves itself by recovering water from its own exhaust air and using it for cathode humidification. The water separator and membrane humidifier create a closed-loop system where the fuel cell's waste product (water in exhaust air) is reused to maintain its own operation, reducing dependence on external water sources.
Solution Approach 2:
The gas-to-gas membrane humidifier acts as an intermediary device that facilitates water transfer from the liquid phase in the water tank to the gas phase in the cathode air stream. This intermediary component enables efficient humidification without direct contact between liquid water and the fuel cell, protecting the fuel cell while ensuring adequate moisture supply.
4Quantity of substance
If hydrogen accumulates in water tank, then safety risk increases, but water collection efficiency is improved
Solution Approach 1:
The Venturi nozzle extracts hydrogen gas from the water tank by creating a low-pressure zone that draws hydrogen out through a separate outlet. This extraction mechanism removes the harmful hydrogen accumulation while allowing the water collection function to continue uninterrupted, as the hydrogen removal is achieved through a separate flow path.
Solution Approach 2:
The Venturi nozzle utilizes pneumatic principles to remove hydrogen from the water tank. By creating a pressure differential through restricted gas flow, the system automatically draws hydrogen out without requiring mechanical pumps or complex control systems, maintaining water collection efficiency while eliminating safety risks.
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 device effectively separates and collects water for reuse in humidifying the air supply, enhancing fuel cell system efficiency and preventing system damage by recycling water and diluting hydrogen, thus improving operational reliability and efficiency.
Implementation Method 1
Liquid water contained in the gas flow is thereby—driven by gravity—separated and directed into the water tank via the outlet
Implementation Method 2
an element that promotes the condensation of water vapor in the water separator is arranged between the gas inlet and the gas outlet
Implementation Method 3
a Venturi nozzle is connected upstream of the gas inlet, which is connected to the water tank in the area of a cross-sectional constriction via a riser. In this way, a secondary flow may be generated with the aid of which gas that enters the water tank with the separated water is drawn in via the riser
Implementation Method 4
the fixtures of the water separator and/or the water tank are hollow at least in certain areas and can be exposed to ambient air. In this way, the cooling of the gas stream that promotes condensation can be achieved
Data Source
AI summary
The invention relates to a device (1) for separating and collecting water from a gas stream, comprising a water separator (2), configured as a riser, and a water tank (3) which is arranged below the water separator (2), wherein the water separator (2) has, at its lower end, an outlet (4) which opens into the water tank (3), a lateral gas inlet (5), and a gas outlet (6) which is arranged at its upper end.The invention also relates to a fuel cell system (20) with a corresponding device (1) and to a method for operating a fuel cell system (20).