CO2 Nozzle Screen Filtration for Surface Damage Prevention
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Solution Overview
Problem
Conventional CO2 snow cleaning nozzles produce large CO2 pellets that can damage surfaces and introduce contaminants, known as 'adders,' which are deposited during the cleaning process, due to agglomeration and inadequate filtration.
Innovation Solution
The nozzle design incorporates a screen member to filter out CO2 pellets larger than a specific size, combined with rigorous cleaning processes such as purification and baking to minimize residual contamination, ensuring only controlled-sized CO2 particles reach the workpiece, and includes features like screens with varying perforations and an electrically isolated design to manage particle size and electrostatic charges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CO2 nozzle design is used, then CO2 snow cleaning capability is achieved, but large CO2 pellets are produced that can damage surfaces
Solution Approach 1:
The patent changes the physical parameters of CO2 delivery by transitioning from liquid CO2 to CO2 snow (solid-gas mixture) with controlled particle size distribution. The nozzle design controls temperature, pressure, and phase composition to produce particles within a specific size range that prevents surface damage while maintaining cleaning effectiveness.
Solution Approach 2:
The patent applies local quality by creating a non-uniform particle size distribution within the CO2 plume, with a controlled mix of particle sizes where smaller particles perform cleaning and larger particles are limited in quantity. The nozzle design creates different zones within the plume with different particle characteristics.
2Productivity
If CO2 snow is used for cleaning, then particle removal capability is achieved, but contaminants accumulate on barrel walls forming adders
Solution Approach 1:
The patent applies preliminary action by pre-cleaning and pre-purifying the nozzle barrel before operation. The barrel undergoes rigorous cleaning processes including solvent cleaning, ultrasonic treatment, and thermal treatment to remove all potential contaminant sources before CO2 snow delivery begins, preventing adder formation from the outset.
Solution Approach 2:
The patent maintains an inert atmosphere within the barrel by using purified CO2 environment and preventing contamination from external sources. The sealed design and purification processes create an inert environment that prevents contaminant accumulation on barrel surfaces.
3Quantity of substance
If liquid CO2 is expanded through orifice, then phase transfer to gas and pellets occurs, but inadequate filtration allows large pellets to pass
Solution Approach 1:
The patent controls the phase transfer parameters by adjusting pressure, temperature, and expansion conditions to produce a controlled distribution of particle sizes. The orifice design and downstream conditions are optimized to generate predominantly small particles while limiting large pellet formation.
Solution Approach 2:
The patent employs dynamic control of the CO2 expansion process, adjusting operational parameters in real-time to maintain optimal particle size distribution. The system can adapt flow rates, pressure, and temperature to control the phase transfer dynamics and resulting particle characteristics.
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 solution effectively reduces the risk of surface damage and contamination by trapping large CO2 particles and contaminants, ensuring precise control over particle size, velocity, and flux, thereby enabling safe and effective cleaning without residue or damage.
Implementation Method 1
Liquid carbon dioxide flows through the orifice to phase transfer into gaseous carbon dioxide and carbon dioxide pellets in the passageway
Implementation Method 2
a screen member constructed and arranged for interrupting flow of the carbon dioxide pellets greater than a select size from being emitted from the passageway of the barrel
Implementation Method 3
CO2 molecules can coalesce or agglomerate onto a CO2 assembly. This agglomeration of the CO2 molecules occurs during passage through the orifice
Data Source
AI summary
A nozzle for providing carbon dioxide for cleaning is disclosed. The nozzle includes a reservoir for receiving liquid carbon dioxide, a barrel defining a passageway therethrough, the passageway extending to an outlet of the barrel, an orifice effecting fluid communication between the reservoir and the passageway, and a screen member constructed and arranged for interrupting flow of the carbon dioxide pellets greater than a select size from being emitted from the passageway of the barrel. Liquid carbon dioxide flows through the orifice to phase transfer into gaseous carbon dioxide and carbon dioxide pellets in the passageway. An internal diameter of the passageway is smaller than an internal diameter of the reservoir.