Liquid Atomization into Sub-Micron and Nano-Droplets

Nataliya Dvoskin, Center for Energy and Numerical Simulations, Mechanical Engineering, Shamoon College of Engineering, Beer Sheva, Israel
Gedalya Mazor, Center for Energy and Numerical Simulations, Mechanical Engineering, Shamoon College Of Engineering, Beer Sheva, Israel
Maksim Mezhericher, Center for Energy and Numerical Simulations, Mechanical Engineering, Shamoon College Of Engineering, Beer Sheva, Israel
Izhak Ladizhensky, Center for Energy and Numerical Simulations, Mechanical Engineering, Shamoon College Of Engineering, Beer Sheva, Israel

Liquid atomization is useful in many applications, such as engineering, science, pharmaceutics, medicine, forensics and others. Fine micron and sub-micron droplets have developed surfaces offering high heat and mass transfer rates combined with increased bioavailability. Traditional liquid-atomization methods and devices like various types of nozzles, rotating discs, droplet generators and nebulizers are well-known and have been extensively studied . Some other methods like microfluidic nozzle and flash-evaporation atomizer have recently been reported.

The main advantages of the invention are simplicity, cheapness, versatility in generating micron and submicron droplets, ability to obtain narrow droplet-size distributions, working in wide range of liquid viscosities and densities, absence of clogging, ability to achieve high atomization capacities, suitability for pharmaceutical and biological materials, and environmental friendliness.

The present liquid-nebulization method exploits the physical phenomenon of disintegration of bubbles and thin liquid films into fine micron and submicron droplets. In several tested prototypes, the bubbles generated within a liquid (water, salt water) have been subsequently destroyed by applying a mechanical impulse (pressure of a compressed air) once coming over the liquid surface. The main characteristics of the generated mist have been experimentally measured by means of the laser diffraction technique under various conditions for each prototype. One of the prototypes demonstrated the minimum arithmetic and Sauter mean droplet diameters less than 1 μm. The influence of atomizing air pressure, air and liquid temperatures, level of liquid in vessel on flow rates and size of generated droplets has been investigated. It was found that simultaneous increase in temperature of both the liquid and the atomizing air lead to substantial enlarge of the flow rate of the produced mists of fine droplets.

Keywords: atomization, bubble, droplet, liquid film, mist, nebulization