Membrane Humidifier Ejector for Fuel Cell Gas Flow
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Solution Overview
Problem
Existing membrane humidifiers for fuel cell systems face challenges in efficiently humidifying tube side air due to uneven gas flow distribution, leading to reduced humidification efficiency and power generation performance.
Innovation Solution
A humidifier design that includes a membrane module with a moist air pumping part, such as a single or multi-stage ejector structure, to suction and mix moist air with tube side air, improving gas flow uniformity and humidification efficiency by directing the moist air in a radial direction within the module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a general membrane humidifier is used with forced air blowing, then the package size is reduced and no special electric power is required, but the gas flow distribution becomes uneven and humidification efficiency decreases
Solution Approach 1:
The membrane humidifier is divided into multiple hollow fiber bundles arranged in parallel, with separate air supply channels for each bundle. This segmentation allows uniform gas flow distribution across all fibers while maintaining a compact overall structure, resolving the contradiction between small package size and high humidification efficiency.
Solution Approach 2:
Different regions of the membrane humidifier are designed with locally optimized properties - the hollow fibers are arranged with specific spacing and orientation patterns to ensure uniform flow distribution in critical areas, while maintaining compact dimensions overall. This local optimization enables both small size and high efficiency.
2Productivity
If hollow fibers are densely packed to increase contact surface area, then humidification capacity is improved, but gas flow uniformity deteriorates
Solution Approach 1:
The hollow fibers are arranged in an asymmetric pattern rather than uniform dense packing, with varying spacing and orientations that promote uniform gas flow distribution while maintaining high total surface area. This asymmetric arrangement prevents flow channeling and ensures all fibers contribute effectively to humidification.
Solution Approach 2:
The problem of flow uniformity is solved by transitioning from a two-dimensional dense packing problem to a three-dimensional arrangement, where fibers are positioned at different heights and angles within the flow path. This dimensional approach allows high surface area while maintaining uniform flow access to all fibers.
3Quantity of substance
If tube side air flow rate is increased to improve humidification, then humidity of supplied air is improved, but energy consumption increases
Solution Approach 1:
The membrane humidifier utilizes the existing kinetic energy and pressure of the flowing tube side air to drive the moisture transfer process. The hollow fiber structure creates capillary forces and pressure gradients that automatically draw moisture from the cathode air to the tube side air without requiring additional energy input, achieving high humidity with minimal energy consumption.
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
Enhances the humidification efficiency of hollow fibers and the humidity of tube side air, thereby improving power generation efficiency and durability of the fuel cell stack.
Implementation Method 1
an inside of the membrane module may include a tube side air supply tube configured to form a gas flow in the same direction as the hollow fiber and one side (e.g., a first side) of the tube side air supply tube may include at least one moist air pumping part configured to suction moist air flowing to an exterior of the tube side air supply tube by a flow velocity and a flow pressure of tube side air
Implementation Method 2
A humidifier design that includes a membrane module with a moist air pumping part, such as a single or multi-stage ejector structure, to suction and mix moist air with tube side air
Implementation Method 3
supersaturation moist air including water discharged from an outlet of a fuel cell stack 20 passes through the membrane humidifier 10 to provide a moisture exchange between the supersaturation moist air and the tube side air to humidify the tube side air
Implementation Method 4
The membrane humidifier has an advantage in respect to the package size and that special electric power is not required
Data Source
AI summary
A humidifier for a fuel cell system is provided to improve humidification efficiency of a hollow fiber improving a gas flow inside a membrane module into which tube side air and moist air are introduced. The humidifier includes a membrane module in which hollow fibers are fixed inside a case in a bundle form and a first manifold and a second manifold each assembled at both ends of the case. An inside of the membrane module includes a tube side air supply tube which forms a gas flow in the same direction as the hollow fiber and one side of the tube side air supply tube includes at least one moist air pumping part configured to suction moist air flowing in an exterior of the tube side air supply tube by a flow velocity and a flow pressure of tube side air.