Homogenizer- Principle, Procedure, Parts, Types, Uses, Examples


A homogenizer is a device that uses mechanical forces to blend, emulsify, disperse, and dissolve liquid-liquid and solid-liquid systems. The purpose of homogenization is to reduce particle size, breach the cell wall and/or cell membrane, destroy pathogens, and facilitate stable emulsions and dispersions. A classical example of this is the homogenization of milk, which distributes and shrinks the milk fat globules so that they are evenly dispersed throughout the remaining milk.

The principle of homogenization is based on three fundamental physical phenomena: shearing, cavitation, and turbulence. These phenomena work together to produce homogenizing action by breaking down the particles and droplets in the mixture.

  • Shearing: The primary cause of shearing in fluids is friction between fluid molecules brought on by viscosity. Large particles and droplets are reduced in size by the shear forces. A big particle or droplet experiences shearing when it becomes trapped between fluid layers moving at different speeds .
  • Cavitation: Cavitation occurs when a fluid has a significant pressure reduction. A pump that introduces the fluid under higher pressure typically has a homogenizer valve upstream. This allows cavities to form from tiny vapor pockets briefly. Shockwaves are generated when these cavities collapse or implode, breaking the particles and droplets in the mixture .
  • Turbulence: When the fluid reaches a high velocity, it becomes turbulent. The fluid moves erratically as a result of the high velocity. These unsteady movements are a form of energy dissipation in which the fluid’s kinetic energy is transformed into internal energy in the form of eddy currents and a small amount of heat. The particles are reduced in size by the eddies created .

Different types of homogenizers use different mechanisms to create these physical forces. Some common types of homogenizers are mechanical homogenizers, high-pressure homogenizers, and ultrasonic homogenizers . These will be discussed in detail in the following sections.