Two-Fluid Atomizing Nozzle Annular Gap Droplet Control

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Solution Overview

Problem

Existing two-component atomizing nozzles often produce large droplets at the nozzle edge due to liquid films adhering to the walls and forming beads, which contribute significantly to the mean droplet size, leading to operational disruptions and inefficiencies in processes like evaporative cooling.

Innovation Solution

Incorporating an annular gap surrounding the outlet opening, where compressed gas exits at high speed directly at the edge, drawing out the liquid film into a thin lamella and breaking it into fine droplets, while maintaining a fine droplet spectrum in the jet core without increasing energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If liquid is sprayed through conventional two-component nozzles, then liquid distribution is achieved, but large droplets form at the nozzle edge due to liquid films adhering to walls

Engineering Contradiction:
Improveliquid distributionVSAvoiddroplet size uniformity
Core Design Contradiction:
Quantity of substanceVSManufacturing precision

Solution Approach 1:

The nozzle design segments the liquid flow path by introducing an annular gap that divides the liquid film into multiple thinner streams. The liquid film that would normally adhere to the wall is interrupted and redistributed through the gap structure, preventing the formation of large cohesive droplets at the nozzle edge.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention introduces a dimensional element by creating an annular gap structure that adds a radial dimension to the liquid-gas interaction. This gap allows compressed gas to act on the liquid film from multiple angles, breaking it up into finer droplets rather than allowing it to form a single large droplet at the edge.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If high-pressure single-component nozzles are used to achieve fine droplets, then droplet size is reduced, but flow cross section is limited and coarse particles cannot be sprayed

Engineering Contradiction:
Improvedroplet sizeVSAvoidcapability to spray coarse particles
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The invention merges the advantages of high-pressure atomization with the capacity for coarse particle handling by combining a two-component nozzle structure with an annular gap design. The larger flow cross section of the two-component design accommodates coarse particles, while the annular gap creates the fine droplet spectrum through enhanced liquid film disruption.

Inventive Principle:
Principle #5Merging (Combining)

3Quantity of substance

If liquid films are allowed to form on nozzle walls, then liquid distribution occurs, but large edge droplets form that cause operational disruptions

Engineering Contradiction:
Improveliquid distributionVSAvoidoperational continuity
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The invention converts the harmful effect of wall-adhering liquid films into a beneficial atomization mechanism. By introducing the annular gap, the liquid film that would normally cause large droplet formation is instead disrupted and atomized into fine droplets, turning a reliability problem into an effective atomization feature.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

4Manufacturing precision

If compressed gas flow rate is increased to break up liquid films, then droplet size is reduced, but energy consumption increases

Engineering Contradiction:
Improvedroplet sizeVSAvoidenergy consumption
Core Design Contradiction:
Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The annular gap structure performs preliminary action by pre-disrupting the liquid film before it reaches the nozzle exit. The gap geometry itself begins the atomization process by creating thin liquid lamellae, which reduces the additional energy required from compressed gas to achieve fine droplet sizes.

Inventive Principle:
Principle #10Preliminary action

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 design reduces the maximum droplet size to approximately one-third, significantly improving the droplet spectrum and reducing construction volume requirements in applications like evaporative coolers, with the same energy consumption, and allows for efficient atomization with 10-40% of the atomizing air.

Implementation Method 1

the annular gap and the trailing edge are designed in such a way that the compressed gas exits the annular gap at high speed directly in the area of the trailing edge and draws out the liquid film at the trailing edge to form a very thin liquid lamella

Methodology Applied
Scientific EffectAerodynamic forces:

Implementation Method 2

which is then broken up into fine droplets

Methodology Applied
Scientific EffectShear stress: Shear Stress

Implementation Method 3

The liquid which wets the wall in the mixing chamber 7 is driven towards the nozzle mouth as a liquid film 20 by the shear stress and pressure forces

Methodology Applied
Scientific EffectPressure forces: Pressure Gradient

Data Source

PatentEP2444161B1Atomizing nozzle for two substances
Publication Date: 2015.12.16 WURZ DIETER
  • EP2444161B1 patent drawingFigure 1
  • EP2444161B1 patent drawingFigure 2~2a
  • EP2444161B1 patent drawingFigure 3

AI summary

Two-fluid atomizing nozzle for spraying a liquid using a pressurized gas. The invention relates to a two-fluid atomizing nozzle for spraying a liquid using a pressurized gas, comprising a mixing chamber, a liquid inlet opening into the mixing chamber, a pressurized gas inlet opening into the mixing chamber, and an outlet opening downstream of the mixing chamber. According to the invention, an annular gap surrounding the outlet opening is provided for the high-velocity escape of pressurized gas. Applications include, for example, flue gas cleaning.