The basic principle of a fog machine is to heat a liquid, usually water and glycol or mineral oil, to create a vapor that is expelled through a nozzle. The heat source can be an electric heating element or a flame. However, the generated fog is often too hot and not dense enough, which is where refrigeration comes in.
Refrigeration is used to cool the fog before it is expelled through the nozzle. This cooling process causes the water vapor to condense, creating a dense, cool fog. The refrigeration unit, which is typically a small compressor and a heat exchanger, cools the fog by removing heat from it.
One of the key advantages of using refrigeration in a fog machine is that it allows for greater control over the density and temperature of the fog. This is important for many applications, such as in stage performances, where the fog must be thick and cool enough to be visible, but not so thick that it obscures the performers. Additionally, refrigeration also allows for a longer hang time of the fog, which can be beneficial in certain applications.
In conclusion, refrigeration is an essential component of a fog machine that allows for greater control over the density and temperature of the generated fog. It also enables longer hang time of the fog, which is important for many applications such as stage performances and special effects in movies.