Combination of steam and ultrasound kills bacteria within just 1-2 seconds

Combined steam-ultrasound treatments usually last no longer than just two seconds

At such fast rates, disinfection with steam and ultrasound combined reaches up to 7-8 logs on non-food products and up to 2-4 logs on certain food products. The catalyzing effect of ultrasound accelerates heat transfer to the surface of any object. This results in an instant increase in temperature on the surface. The disinfection treatment is halted before heat penetrates the product and causes unwanted thermal damages.

The “catalyzing” effect of ultrasound disrupts heat restricting air layers that protects the bacteria on the surface

The zone of air closest to the surface serves as a protective mantel, restricting vapour and heat exchange across the surface, a layer often referred to as the laminar sublayer.

surface with laminar layer without ultrasound

Ultrasound sets the air of the laminar zone in a state with intensified molecular oscillations, resulting in a destruction of the protective characteristics of the laminar sublayer. Hot steam is then able to reach microstructures and pits in the surface. The continuous pumping of new steam creates a fast, substantial flux of heat to the surface structure.

surface laminar layer with ultrasound

Microorganisms are killed more rapidly with steam-ultrasound compared to steam treatment without ultrasound

The small size of microorganisms make them particularly sensitive to the concentrated steam treatment. Microbial reduction or elimination happens so quickly, that the depth of heat entrance into the surface of the product is kept at a minimum. The treatment can be stopped before the surface is thermally damaged. The processing time in a SonoSteam treatment are for some applications even shorter than one second.

Play the video to see how the ultrasound and steam works when combined

Real simulation of ultrasound waves disrupting the heat restricting laminar boundary air layer

This video is a real simulation and it shows how effective the ultrasound waves disrupts the heat-restricting stagnant air right above any object.

The green and yellow areas shows the velocity  of the fast moving airflows just above the surface of the object. The closer air is to the surface, the slower is the velocity due to the friction with the surface. The dark blue area is stagnant air  also knows as the laminar sublayer. The laminar sublayer is heat restricting and takes out energy from the steam treatment but when combined to the ultrasound, the ultrasound waves can disrupt the laminar sublayer and thereby improve heat transfer to the surface.

The time rate in this video is significantly reduced in order to show the pulsing ultrasound waves.  The sound waves push the boundary layer aside and allow heat to reach the surface rapidly.

Learn more about the benefits of the SonoSteam treatment