Production of Carbon Dioxide Snow by Flash-Atomization for Material Cleaning Process

Abstract

This paper investigates the production of CO2 snow by flash-atomization of liquid carbon dioxide for material cleaning process. The evolution of flash-atomization processes was recorded by means of high-speed shadowgraph. Results shows that the degree of superheat condition of liquid CO2 greatly influence the atomization modes, bobbles growth rate and concentration, and thus result in difference spray angle, spray pattern, and the structure of liquid jet which is suitable for different material cleaning applications. It is found that the spray angle first slowly increases with increase in the degree of superheat (ΔT) under external flash atomization processes. It is increased drastically as the spray transform from external-flashing to internal-flashing mode. Finally the spray angle is decreased again because of the decrease of mass flowrate due to the internal flashing processes . Moreover, the spray angle is increased as the length-to-diameter ratio (L/D) is increased. This is due to the higher bobble growth rate in terms of different pressure distribution and bobble growth time. It is also found that the external-flashing disappears at higher L/D because of the heat transfer to the liquid carbon dioxide. It is concluded that the superheated condition is useful in the control of the spray angle for material cleaning processes.

Experimental Investigation of High-Pressure Liquid Ammonia Injection under Non-Flash Boiling and Flash Boiling Conditions

“…The spray tip velocity decreased normally with the increase in P amb . The separation of P amb is more distinct under average velocity, which is calculated as Equation (17). The average spray tip velocities in the acceleration and stable stages are shown in Figure 13.…”

“…The expansion caused by flash boiling changes spray characteristics significantly. Liquid CO 2 can also be superheated in high ambient pressure, in which the explosion of bubbles improves atomization [17][18][19]. However, atomization quality decreases with the interaction of sprays of multi-hole GDI injectors, causing the spray collapse phenomenon [20][21][22][23][24].…”

Agglomeration Processes and Mechanisms of CO2Snow Inside a Tube

“…Carbon dioxide (CO 2 ) snow jets are widely used in medical and industrial applications, such as cryogenic therapy , food processing, pharmaceutical granulation, particle removal, and surface cleaning (Yang et al 2007;Kang et al 2010;Liu et al 2011;Shen et al 2012). In semiconductor fabrication, CO 2 snow cleaning has unique eco-friendly organic and particle removal abilities that are better than those of traditional surface cleaning methods, such as ultra-sonic cleaning, mega-sonic cleaning, and brush scrubbing (Sherman et al 1991;Sherman 2007).…”