[shahab mataji]

what does" self refrigeration" mean?
is there any industrial application for that?
how we can design equipment for that?

[eugenedakin]

Hello shahab mataji,

Self refrigeration is where refrigeration occurs 'naturally'.

An example of this is a building floor slab which is in the earth. The floor slab is usually cooler than the ambient air. This is usually passive refrigeration.

I hope this helps,

Eugene

[mbeychok]

Whenever a liquid at some given pressure is introduced (through a control valve or other restriction) to a lower pressure, it "flashes" (partially vaporizes) and the resulting vapor and liquid are both reduced to the boiling point temperature of the liquid at the lower pressure. That is known as "auto-refrigeration" and it is the basis of all vapor-compression refigeration systems (using refrigerants such as ammonia, propane, butane, etc.).

See these articles for more details:

Flash evaporation
Vapor-compression refrigeration