cold room after defrosting
Product knowledge

Why is hot gas defrost an effective way to defrost evaporators?

When we understand how hot gas defrosting works, we will understand that hot gas defrosting is the most energy efficient method.

How is hot gas defrost work?

  1. The evaporator becomes a condenser.

High-pressure hot gas from the compressor’s discharge side is carefully transferred into the evaporator during the hot gas defrosting, where it condenses back to its liquid condition.


  1. Use the latent heat of the refrigerant.

 The condensation process releases a lot of energy. This is equal to the mass flow of hot gas entering the evaporator multiplied by the latent heat of vaporization of the refrigerant. The heat released during condensation is called “latent heat” because during condensation there is no change in temperature. If the condensation pressure is kept constant, the condensation process will be carried out at a constant temperature. The heat released during condensation is much greater than the heat released when the superheated gas is cooled without condensing (called “sensible” cooling).

  1. The condensed refrigerant liquid is “recovered” and flows back into the evaporator.

During defrost, the condensed refrigerant liquid from the evaporator is expanded into the wet suction pipe and returned to the low-pressure receiver (LPR) or medium pressure receiver (MPR), where it is “recovered” and pumped directly back to the evaporator.

  1. Hot gas defrost is like a heat pump “moving” heat.

Heat pumps move heat “up” by collecting energy at low-temperature levels in the evaporator, compressing the evaporated refrigerant to a higher pressure, and then releasing energy at higher temperature levels during condensation. The process would be 7 to 8 times more energy efficient than burning fossil fuels or electricity directly to produce the same heating effect. In the same way that the heat for hot gas defrosting is actually “moved” to the defrost evaporator by compression at a refrigerant pressure and temperature sufficient to melt the frost, the heat used for hot gas defrosting is actually moved from Collected in refrigerated space.


No need to consume electricity when defrosting, hot gas defrosting is very energy efficient! When electricity bills are getting more and more expensive, hot gas defrosting can effectively help reduce the electricity bill for cold storage operations.

CRYO provides the cold room solution for refrigeration equipment with hot gas defrost, which is make it more energy efficient, to cut down your electricity bill. Contact us Now!