Question

During the flash evaporation of a liquid refrigerant from a pressurized cylinder to atmospheric pressure, the cylinder gets cooled significantly because of this. What is this temperature reduction process called, what is the detailed science behind it?

Answer 1

Hi
In the case of the flash vaporization of a liquid refrigerant from pressurized cylinder to the normal atmospheric pressure the process occurring is called throttling process.

The proces is very fast and as when the molecules are close to each other they keep colliding to each other but when at low pressure they are kept apart they don't have significant collision and thus the cooling of cylinder takes place.

Let us understand the process of throttling proces in little detailed -

It happens when there is a sudden decrese in the cross sectional area of the flowing gas and thus the velocity changes and this creates a sudden drop in the pressure.

This process is irreversible adiabatic ideally.

Also there is no change in the enthalpy of the proces and thus this is isoenthalpic process as well.

It is done to bring the gas at a state so that it can be condensed in the vapor refrigeration cycle.

Hope this helps.

Thanks