What is the method used in hot gas defrosting?

Hot gas defrosting utilizes high-pressure gas that is piped through the evaporator. In this method, the refrigerant gas, which has been heated up and is under high pressure, is directed into the evaporator coils. This increases the temperature of the coils, allowing any accumulated frost or ice to melt efficiently.

The process is beneficial because it effectively raises the temperature of the evaporator without requiring a complete shutdown of the refrigeration system. This results in a faster and more efficient defrosting process, maintaining the overall productivity and energy efficiency of the refrigeration cycle. By leveraging the existing refrigerant during its gas phase, the system can return to normal operation more quickly, minimizing downtime.

The other methods suggested, such as releasing gas directly into the atmosphere or circulating low-pressure gas, do not provide the necessary heating effect on the evaporator or serve the purpose of effective defrosting. Thus, piping high-pressure gas through the evaporator is the correct and efficient approach for hot gas defrosting.