CO2 Snow Jet Expansion Channel for Higher Cleaning Momentum
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Solution Overview
Problem
Existing CO2 snow blasting devices do not achieve a high enough cleaning effect and are not operated economically.
Innovation Solution
The expansion channel is designed with multiple channel sections arranged in series, featuring localized changes in cross section that create pressure jumps and turbulence, enhancing the momentum of CO2 snow particles and increasing their abrasiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If liquid CO2 is expanded through a conventional expansion channel, then CO2 snow is formed, but the cleaning effect is insufficient and operating costs are high
Solution Approach 1:
The expansion channel is divided into multiple channel sections (first, second, third channel sections) with different cross-sectional areas arranged in series. This segmentation allows the CO2 to undergo staged expansion with pressure jumps at each transition, enhancing snow particle momentum and cleaning effect while improving operational efficiency
Solution Approach 2:
Different channel sections have different cross-sectional areas to create localized pressure jumps and turbulence at specific positions. The first channel section has a larger cross-sectional area than the second, which is larger than the third, creating optimal conditions for snow crystal formation and acceleration at different stages of expansion
2Force
If the expansion channel cross section is reduced, then CO2 snow particles gain momentum, but the channel design becomes more complex
Solution Approach 1:
The expansion channel is segmented into multiple sections with progressive cross-sectional reductions. This segmentation transforms a single complex pressure reduction into multiple manageable stages, each creating controlled turbulence and momentum enhancement without requiring overly complex single-stage design
Solution Approach 2:
The cross-sectional area parameter of the expansion channel is systematically changed across different sections. By progressively reducing the cross-sectional area from the first to the third channel section, the design achieves momentum enhancement through controlled parameter variation rather than complex geometric features
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 configuration results in a higher cleaning effect by increasing the momentum of CO2 snow particles, reducing the need for additional acceleration by the outer jet, and enhancing the formation of larger snow crystals, thus improving efficiency and reducing operating costs.
Implementation Method 1
a step-by-step phase conversion from liquid CO2 to gaseous CO2 takes place with simultaneous cooling of the mixture. If the pressure falls below the triple point of CO2 (5.185 bar), the remaining liquid phase is at least partially converted into solid CO2 in the form of snow crystals
Implementation Method 2
The pressure drops from the outlet pressure at the inlet opening to ambient pressure (usually 1 bar) at the outlet opening over a length of the expansion channel. As the pressure falls, a step-by-step phase conversion from liquid CO2 to gaseous CO2 takes place with simultaneous cooling of the mixture
Implementation Method 3
The resulting CO2 snow crystals are entrained by the CO2 gas accelerated as a result of expansion and are accelerated and discharged together with the CO2 gas as CO2 gas/CO2 snow mixture from the outlet opening
Implementation Method 4
a nozzle (26) for generating an outer jet (28) which surrounds and accelerates the CO2 gas/CO2 snow mixture (8) discharged from the outlet opening (22) of the expansion channel (6)
Implementation Method 5
Abrasion through momentum transfer (accelerated CO2 snow crystals transfer pressure and shear forces when they hit the surface)
Implementation Method 6
Abrasion through momentum transfer (accelerated CO2 snow crystals transfer pressure and shear forces when they hit the surface)
Implementation Method 7
Embrittlement of impurities through rapid cooling (sublimation point of CO2 snow at atmospheric pressure: −78.5° C.)
Implementation Method 8
Chemical dissolution of impurities, e.g. of adsorption compounds (in the course of the impact of CO2 snow crystals on a surface, CO2 can be converted into a supercritical state; in this state, CO2 is a good chemical solvent)
Implementation Method 9
Impurities are thrown away by an increase in volume (approx. 500 times) during the sublimation of CO2 from the solid phase into the gas phase
Data Source
AI summary
The invention relates to a device for generating a CO2 snow jet, comprising an expansion channel (6) which extends in a flow direction (14) for generating a CO2 gas/CO2 snow mixture based on liquid CO2, said expansion channel having an inlet opening (18) for supplying liquid CO2 and an outlet opening (22) for discharging the CO2 gas/CO2 snow mixture. The device also comprises a nozzle for generating an outer jet which surrounds and accelerates the CO2 gas/CO2 snow mixture discharged from the outlet opening of the expansion channel. The expansion channel has multiple channel sections (36a, 36b, 36c, 36d, 36e) arranged one behind the other in the flow direction, wherein the expansion channel cross section (40) that lies on a plane orthogonal to the flow direction changes locally in a particular transition or transition region (38a, 38b, 38c, 38d, 38e, 38f) between the channel sections, and the expansion channel (6) cross section (46d) at the upstream end (48d) of a particular channel section (36d) is larger than the expansion channel (6) cross section (46c) at the upstream end (48c) of the channel section (36c) arranged upstream of said channel section (36d) in the flow direction (14).