High-pressure homogenizers work with a low-viscous dispersions. Such devices operate in a continuous mode.
Homogenizers of high pressure are divided into counter jet dispersers, axial nozzle systems and radial diffusers. Jet dispersers collide two or more jets at high speed. The pressure of homogenization and the flow rate of substances can be adjusted by changing the gap width (with the help of flap-valve).
In axial nozzle systems the liquid moves through a nozzle at high pressure that creates cavitation and turbulent flow conditions. These two schemes are combined joining a nozzle and valves.
The main feature of jet dispersers and axial nozzle systems is the absence of moving elements, which allows to create a higher pressure in comparison with the radial diffusers.
Homogenization under high pressure creates turbulent flow condition, cavitation and shear forces. The resulting emulsion droplet size is determined by pressure, temperature, flow rate, dispersed phase concentration,which in turn depends on the valve design of a homogenizer.
High-pressure homogenizers can be used to produce so-called nano-emulsions, with a droplet diameter 100 nm or less. At the same time, such homogenizers are not recommended for preparation of emulsions with dispersed phase having a high viscosity. This is due to a greater diameter of the droplets.