Variable Flow Rate Fuel Ejector for Hydrogen Recirculation

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Solution Overview

Problem

Existing fuel cell systems face inefficiencies due to the need for mechanical pumps to recirculate hydrogen, which are energy-intensive, prone to corrosion, and limited in their ability to maintain optimal flow rates, especially in large systems like vehicle power systems.

Innovation Solution

A variable flow rate ejector system utilizing a primary nozzle, needle, and motor to control the flow of hydrogen gas, allowing for supersonic entrainment and recirculation of low-pressure hydrogen, with a stepper motor and impact-absorbing elements to manage flow rates and pressures effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If positive displacement mechanical pumps are used to recirculate hydrogen, then hydrogen recirculation is achieved, but energy consumption increases and corrosion risk worsens

Engineering Contradiction:

Improvehydrogen recirculation capabilityVSAvoidenergy consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent replaces the mechanical pump system with a fluid dynamic ejector system that uses high-pressure hydrogen jet to create suction and recirculate low-pressure hydrogen through entrainment, eliminating mechanical moving parts and lubrication requirements

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention uses pneumatic principles where a high-pressure primary hydrogen stream creates a low-pressure region that entrains and recirculates low-pressure secondary hydrogen, achieving pump function through fluid dynamics rather than mechanical displacement

Inventive Principle:

Principle #29Pneumatics and hydraulics

2Productivity

If positive displacement mechanical pumps are used to recirculate hydrogen, then hydrogen recirculation is achieved, but corrosion resistance worsens

Engineering Contradiction:

Improvehydrogen recirculation capabilityVSAvoidcorrosion

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent eliminates mechanical pumps with moving parts that are susceptible to corrosion by using a purely fluid dynamic ejector system with no lubrication requirements and fewer material compatibility constraints

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention extracts and removes the mechanical pump component entirely from the hydrogen recirculation system, replacing it with a passive fluid dynamic device that has no moving parts to corrode or require lubrication

Inventive Principle:

Principle #2Taking out (Extraction)

3Device complexity

If fixed geometry ejectors are used, then simple structure is achieved, but flow rate adaptability worsens

Engineering Contradiction:

Improveejector structureVSAvoidflow rate range

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent incorporates a variable geometry mechanism with a movable needle that can adjust the primary nozzle opening area, allowing the ejector to adapt to different flow rate requirements and operating conditions while maintaining a relatively simple overall structure

Inventive Principle:

Principle #15Dynamics

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 enhances fuel cell efficiency by maintaining optimal flow and pressure between the gas outlet and inlet, reducing energy consumption and minimizing corrosion risks, while allowing for precise control of hydrogen recirculation to match the fuel cell's reaction rate.

Implementation Method 1

transmit a flow of the first fluid through the primary nozzle opening

Methodology Applied

Scientific EffectSupersonic flow: Jet

Implementation Method 2

supersonic entrainment and recirculation of low-pressure hydrogen

Methodology Applied

Scientific EffectEntrainment: Entrainment

Implementation Method 3

The needle is sized to create a gap between the tapered portion of the needle and the primary nozzle opening. The motor is coupled to axially move the needle in order to vary a size of the gap

Methodology Applied

Scientific EffectVariable geometry flow control: Valve

Implementation Method 4

The first impact-absorbing element is positioned to contact the first stop portion or the needle, respectively, when the needle is fully retracted from the primary nozzle opening by the motor

Methodology Applied

Scientific EffectImpact absorption: Impact Force

Data Source

PatentUS10746197B2Devices, systems, and methods for variable flow rate fuel ejection

Publication Date: 2020.08.18 UNIVERSITY OF DELAWARE

AI summary

Variable flow rate fuel ejectors, and methods of use therefore, are disclosed. One variable flow rate ejector includes a primary nozzle, a needle, a motor, a first stop portion, and a first impact-absorbing portion. The primary nozzle is connected to a first inlet chamber to receive a first fluid and transmit a flow of the first fluid through the primary nozzle opening. The needle is disposed to create a gap between the tapered portion of the needle and the primary nozzle opening. The motor is coupled to axially move the needle to vary a size of the gap. The first stop portion delimits the axial movement of the needle in a direction of retraction of the needle from the primary nozzle opening. The first impact-absorbing element is positioned to contact the first stop portion or the needle, respectively, when the needle is fully retracted from the primary nozzle opening.