Bi-Fluid Nozzle Atomization for High-Viscosity Liquid Extinguishers
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Solution Overview
Problem
Existing spray devices struggle with effective atomization of high-viscosity liquids across a wide range of temperatures, particularly when cold, leading to poor extinguishing performance due to increased droplet size and evaporation time, causing the extinguishing agent to impact cold surfaces instead of evaporating at the fire zone.
Innovation Solution
A spray device that combines a liquid with combustion gas to create turbulence, using a bi-fluid nozzle for internal or external mixing, which reduces viscosity and enhances atomization by dispersing the liquid into fine droplets, with a pyrotechnic gas generator providing hot gases to aid in heating and efficient mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the extinguishing agent is stored in a reservoir and expelled under gas pressure, then the agent can be delivered to the ejection member, but the viscosity and density increase when cold, resulting in poor atomization and larger droplet size
Solution Approach 1:
The ejection member is designed with multiple small orifices arranged in a matrix pattern, dividing the liquid flow into numerous fine streams that are further broken up by gas injection, creating uniform fine droplets even at low temperatures
Solution Approach 2:
A second gas circuit is introduced as an intermediary medium that mixes with the liquid in the ejection member, providing aerodynamic shear forces that break the liquid into fine droplets and improve atomization when the liquid is cold and viscous
2Productivity
If the liquid is sprayed without heating, then the device can operate in a wide temperature range, but the evaporation time increases and droplets may impact cold surfaces before evaporating
Solution Approach 1:
The problem of insufficient evaporation is solved by transitioning from a single-function nozzle to a bi-fluid nozzle that adds a gas dimension, creating turbulence and extending the liquid-gas interaction time and surface area for heat transfer and evaporation
Solution Approach 2:
The ejection member modifies the physical parameters of the liquid by introducing gas mixing that changes the flow regime from laminar to turbulent, increasing the surface area and residence time for evaporation to occur before droplet impact
3Reliability
If a single-fluid nozzle is used, then the device structure is simple, but the atomization of high-viscosity liquids is poor and droplet size is large
Solution Approach 1:
The ejection member creates dynamic interaction between liquid and gas flows, using the relative motion and shear forces between the two phases to achieve effective atomization that adapts to varying liquid viscosities and temperatures
Solution Approach 2:
Gas is introduced as an intermediary substance that facilitates the breakdown of liquid into fine droplets through mixing and shear forces, enabling effective atomization of high-viscosity liquids without requiring complex mechanical atomization devices
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
Ensures good atomization and efficient delivery of the extinguishing agent even at high viscosity, improving the extinguishing efficiency by ensuring the agent evaporates effectively at the fire zone, thereby enhancing fire extinguishing capabilities.
Implementation Method 1
the two circuits, respectively of liquid and gas, joining together to create turbulence inside the ejection member or at the outlet thereof
Implementation Method 2
Under the effect of aerodynamic shear, the liquid is separated into microdroplets
Implementation Method 3
as the gas supplying the ejection member is hot, since coming from a pyrotechnic gas generator, it makes it possible to heat the liquid with which it is mixed in order to reduce its viscosity
Implementation Method 4
the combustion gases generated by the pyrotechnic gas generator being very mainly made up of CO2, N2, H2O (g)
Data Source
Figure 1~2B
Figure 3~4
Figure 5~6
AI summary
A device for atomising (100) a liquid (L), comprises a container (10) containing the liquid to be atomised (L), at least one liquid ejection member (20), in communication with said container (10), and a pyrotechnic gas generator (30) for pressurising the liquid inside said container and propelling said pressurised liquid out of said container. According to the invention, the ejection member (20) is, at least in one operating mode, in communication with the gas generator (30) in such a way as to be able to be supplied with the gas generated by said generator (30).