What is Kool gas defrost?
Hot gas defrost is where superheated discharge gas is directed into the evaporator, and “Kool gas” is a trademarked name for a defrost that directs saturated vapor from the top of the receiver unto the evaporator. That is to allow that gas to flow through the evaporator and back into the liquid line.
How does a hot gas defrost system work?
The hot gas defrost process uses the superheated vapor from the compressor discharge (on high pressure and high temperature) as the heat source. This vapor is diverted on a third system line, bypassing the condenser and the expansion valve, and directed through the unit cooler coil, warming it from the inside.
What is drop leg temperature?
Subcooling is defined as the point at which liquid is cooled below it’s condensing temperature. Example: At 100° F condensing and 0° F subcooling, 47% of the refrigerant’s BTU capacity is lost through the TXV on an evaporator operating at a -25° F SST.
Why do you have to defrost an evaporator?
During a defrost, water is formed on the evaporator as the ice melts. Once the defrost terminates, the water must be allowed to drain from the coil. This drip time prevents moisture from being blown off the coil and refreezing on the cold product, or other surfaces in the room.
What is reverse cycle defrost?
The reverse-cycle defrosting (RCD) is the common method of frost removal. A bypass solenoid valve was used to bypass the thermostatic expansion valve to decrease the defrosting time of the RCD cycle and to relieve the shutdown caused by the low-pressure protection .
How is ice melted with off cycle defrost?
OFF CYCLE DEFROST With the refrigeration cycled off, allowing the air in the refrigerated space to continue to circulate through the evaporator tube/fins will raise the evaporator surface temperature, melting the frost.
Which freezer defrost system is more efficient hot gas or electric?
Which freezer defrost system is more efficient hot gas or electric? Hot gas is more efficient because the compressor can generate the same amount of Btus as electric heaters, but with less electrical energy.
What is drop leg in refrigeration?
It’s a small horizontal receiver tank about 5-6 dropleg pipe diameters by 2-3 feet long with two top inlets and one top outlet with a dip tube. These are handy when the condenser is located below the receiver. Condensers have already been Split for Heat Reclaim.
Can the condenser maintain a pressure below?
Basically it becomes harder and harder to maintain perfect sealing condition in a condenser as the pressure reduce below 1 atmosphere. Now as the temperature of condensing steam decrease with decrease in pressure; various challenge arise to maintain the same heat exchange between the medium.
What terminates a defrost cycle?
The defrost cycle can also be terminated by a pressure switch, where a pressure control is used as the defrost termination switch. When it senses a pressure that will ensure all the ice is removed from the evaporator, it will close and terminate defrost.