Mist Generating Nozzle with Segmented Fluid Passages
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Solution Overview
Problem
Existing mist generating apparatuses, such as WO '764, face limitations in achieving uniform droplet size and distribution due to reliance on external aerosol creation and single annular gas streams, leading to unpredictable variations in droplet size and distribution.
Innovation Solution
The apparatus features a design with inner and outer working fluid passages circumferentially spaced around an inner transport fluid passage, a second mixing chamber, and a communicating passageway with a nozzle that employs a convergent-divergent nozzle structure to enhance atomization through turbulence and shear forces, ensuring a homogenous mist generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single annular gas stream is used to carry droplets, then the apparatus structure is simple, but droplet distribution homogeneity deteriorates
Solution Approach 1:
The single annular gas stream is segmented into multiple working fluid passages (inner and outer passages) that are circumferentially spaced around the transport fluid passage. This segmentation allows for more uniform droplet distribution while maintaining manageable structural complexity through modular passage design.
Solution Approach 2:
The gas stream arrangement transitions from a single two-dimensional annular stream to a three-dimensional configuration with multiple working fluid passages distributed both radially (inner and outer passages at different distances from the transport fluid passage) and circumferentially. This multi-dimensional arrangement enhances droplet distribution homogeneity.
2Device complexity
If aerosol is created externally upstream, then the apparatus is simpler, but droplet size control precision deteriorates
Solution Approach 1:
The apparatus performs preliminary atomization actions within its structure through the interaction of transport fluid and working fluid in multiple passages before the final spray stage. This preliminary action enables better droplet size control while the apparatus remains relatively simple in design.
Solution Approach 2:
The invention controls droplet size by changing parameters such as the velocity and distribution of the transport fluid, the configuration of working fluid passages, and the pressure differential between fluids. These parameter adjustments enable precise droplet size control without requiring complex external aerosol generation equipment.
3Area of stationary object
If working fluid passages are positioned radially outward, then gas stream coverage is improved, but droplet distribution uniformity deteriorates
Solution Approach 1:
The working fluid delivery system is segmented into multiple passages positioned at different radial distances (inner and outer passages) and circumferential locations. This segmentation ensures both wide gas stream coverage and uniform droplet distribution by preventing concentration in any single radial zone.
Solution Approach 2:
Different working fluid passages are positioned at different radial locations to create local variations in droplet injection points. The inner passages provide coverage near the center while outer passages extend coverage to the periphery, with each location optimized for its specific zone to achieve overall uniformity.
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 achieves a consistent and uniform mist with smaller droplet sizes, as evidenced by performance data showing Dv90 and Df90 values, indicating 90% of the liquid is in droplets smaller than specified sizes, improving droplet distribution and homogeneity.
Implementation Method 1
The transport fluid and working fluid are mixed together in a mixing chamber. The mixing of the two fluids creates turbulence and shear forces which atomise the working fluid
Implementation Method 2
The mixing of the two fluids creates turbulence and shear forces which atomise the working fluid
Implementation Method 3
The transport fluid then passes through a nozzle which accelerates it to a high velocity. The aerodynamic forces created by the high velocity transport fluid further atomise the working fluid
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3
AI summary
An improved apparatus for generating a mist is provided. The apparatus has at least one working fluid supply conduit (66) having an inlet in fluid communication with a supply of working fluid and an outlet in fluid communication with a first mixing chamber. The apparatus also includes a plurality of transport fluid passages (60a,60b), each of which has an inlet adapted to receive a supply of transport fluid and an outlet in fluid communication with the mixing chamber. Downstream of the mixing chamber is a nozzle (72) having an inlet (74) in fluid communication with the mixing chamber, an outlet (78), and a throat portion (76) intermediate the nozzle inlet (74) and outlet (78). The throat portion (76) of the nozzle (72) has a cross sectional area which is less than that of either the nozzle inlet (74) or the nozzle outlet (78). The provision of a plurality of transport fluid passages flowing into the mixing chamber, and the nozzle downstream of the mixing chamber, enhance the atomisation of the working fluid to generate the mist.