How Does a Hot Gas Defrost System Work?

Hot Gas Defrost Vs. Electric Defrost

“Hot Gas” is the high-temperature vapor refrigerant discharged from the compressor. Hot gas defrosting method refers to the defrost cycle which uses the compressor’s discharge gas energy to melt the frost of the evaporator unit, which is the one of the most efficient and most economic defrosting methods in refrigeration.  

The hot gas defrost system can be divided into two types: hot gas bypass defrost and reverse cycle defrost. Both of these two defrosting methods use refrigerant gas to melt the frost or ice.

The hot gas bypass defrost is one kind of hot defrost defrost used in refrigeration. As the name implies, there is a bypass line in the hot gas defrost cycle. The bypass line is installed between the compressor discharge tube and evaporator inlet, bypassing the high-temperature gaseous refrigerant at the high-pressure end to the low-pressure end of the system. The hot gas bypass defrost is controlled by an electronic hot gas bypass valve, which is a solenoid valve.

In refrigeration cycle, the hot gas solenoid valve is closed, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor, passes through the condenser, exchange the heat with the air, then the refrigerant passes through the expansion device and evaporator. The low-temperature low-pressure refrigerant absorbs heat from the commercial refrigerator, then goes back to the refrigeration compressor. Please see the refrigeration cycle below:

Refrigeration-cycle-diagram

In hot gas bypass diagram, the hot gas solenoid valve is in open state, the high-temperature high-pressure refrigerant flows through the bypass line and the solenoid valve directly, goes to the evaporator. At this time, the evaporator acts as a condenser, so the high-temperature refrigerant release the heat in evaporator to melt the frost. Please find the hot gas bypass piping schematic below:

Hot-gas-defrost-cycle

In hot gas bypass defrost cycle, the electronic hot gas bypass valve is used to control the flow of hot gas through the evaporator for defrosting.

In refrigeration cycle, the solenoid valve is closed; while in hot gas bypass defrost cycle, the solenoid valve is an open state.

The hot gas bypass defrost method is used in our small monoblock refrigeration unit, including the top mount monoblock refrigeration unit, side mount monoblock refrigeration unit.

Top mount monoblock freezing unit

Used in monoblock freezing unit for stainless steel commercial freezer for temperature -18°C~-22°C.

Side mount monoblock freezing unit

Used in monoblock freezing unit for stainless steel worktop freezer for temperature -18°C~-22°C.

The hot gas bypass defrost used in small monoblock refrigeration unit, has many advantages compared with traditional electric defrost.

  • Quick defrost
  • Energy-efficient
  • Suitable for R290 refrigeration system

The reverse cycle defrost is another kind of hot gas defrost. It achieves defrost by changing the refrigerant flow direction in refrigeration cycle, that means in reverse cycle defrost, the condenser acts as evaporator, while the evaporator acts as condenser. The hot gas defrost operation is the opposite of the refrigeration cycle.  

The refrigeration cycle consists of refrigeration compressor, condenser, filter drier, receiver, sight-glass, solenoid valve, expansion valve, evaporator, accumulator and other refrigeration parts. Please see the operation of refrigeration cycle below:

The reverse cycle hot gas defrost system consists of refrigeration compressor, condenser, Bi-flow filter drier, Bi-flow receiver, sight-glass, four-way solenoid valve, evaporator, accumulator and other refrigeration parts. The reverse cycle defrost is the opposite operation of the refrigeration cycle. Please see the reverse cycle hot gas defrost diagram below:

Reserve cycle hot gas defrost is an energy-efficient defrost method compared to electric defrost refrigeration systems. It has the advantages:

Dependable performance. The reverse cycle hot gas defrost refrigeration system provides a fast and efficient defrost performance.

Tremendous energy savings. The hot gas defrost systems can save thousands of dollars more than electric defrost every year.

Enhanced product integrity. The reverse cycle hot gas defrost system shortens the defrost time and reduces storage temperature fluctuations. The cold room temperature remains more stable.

Glen Refrigeration’s ceiling mounted monoblock refrigeration unit and wall mounted monoblock refrigeration unit, combines hot gas defrost method to provide an energy-efficient solution for commercial refrigeration.

Glen Refrigeration offers 1 HP, 2 HP, 3 HP Ceiling Mounted Monoblock Refrigeration Unit and 1 HP, 2 HP, 3 HP, 4 HP Wall Mounted Refrigeration Unit. It is a packaged refrigeration unit, integrated the outdoor unit and indoor unit together.

Ceiling mounted monoblock refrigeration unit

Used in small cold room and freezer room.

Wall mounted monoblock refrigeration unit

Used in small cold room and freezer room.

The hot gas bypass defrost and reverse cycle both use high-temperature hot gas to melt the frost. But the hot gas bypass defrost piping diagram is different from the reverse cycle defrost piping diagram. And hot gas bypass defrost don’t change the refrigerant flow direction, while the reverse cycle defrost will change the refrigerant flow direction.

In hot gas bypass defrost refrigeration cycle, a bypass tube with the hot gas defrost valve is added to the refrigeration compressor discharge line to evaporator inlet. The hot gas bypass is controlled by the hot gas defrost solenoid valve.

In refrigeration cycle, the hot gas bypass is inactive (The solenoid valve is closed). The refrigeration system cycle operates without the hot gas bypass.

In hot gas bypass defrost cycle, the hot gas bypass is active. (The solenoid valve is in an open state). When the solenoid valve is open, most of the discharge high temperature high pressure gas flows from the bypass tube to the evaporator directly.

The high temperature high pressure vapor refrigerant from the compressor that enters into the evaporator, condensate in the evaporator, transfer the heat to the evaporator coil which warms up and finally melts the ice on the evaporator surface.

The reverse cycle defrost refrigeration system has an four-way solenoid valve to change the gas flow direction. Please see the reverse cycle hot gas defrost operation below:

Electric defrost and hot gas defrost are two main defrosting methods in cold room refrigeration systems. Compared with electric defrost refrigeration system, the hot gas defrost tends to be higher efficiency and more energy saving.

Now most of the cold room refrigeration systems in the market are using electric defrosting. This type of defrost uses an electric heating tube as heat source to melt the ice. Please see the “Electric Defrost vs. Hot Gas Defrost In Commercial Refrigeration”

In order to solve the disadvantages of electric heater defrosting in cold room refrigeration system, Glen Refrigeration developed hot gas defrost refrigeration system for cold room and freezer room. Glen Refrigeration is committed to lead the commercial refrigeration market with environmental friendly and high energy efficiency condensing unit and refrigeration systems.

Glen Refrigeration has been leading the way in energy efficiency, and we offer Water-Cooled Condensing Unit, Inverter Condensing Unit, Hot Gas Defrosting Refrigeration Systems to help our partners lower energy use and costs throughout their operations.

We proudly offer Cold Room Refrigeration System with Hot Gas Defrost from 1HP to 15HP. The cold room refrigeration system is including the Cold Room Outdoor Unit and Evaporator Unit.

Hot Gas Defrost Wall Mounted Refrigeration Unit

Apart from the cold room outdoor unit and cold room indoor unit, Glen Refrigeration also offers Hot Gas Defrosting Wall Mounted Refrigeration Unit 1 HP, 2 HP, 3 HP. It is a packaged refrigeration unit, integrated the outdoor unit and indoor unit together.

Wall Mounted Refrigeration Unit (Inverter)

  • GL-BYTCN10EL (1 HP Wall Mounted Refrigeration Unit)
  • GL-BYTCN20EL (2 HP Wall Mounted Refrigeration Unit)
  • GL-BYTCN30EL (3 HP Wall Mounted Refrigeration Unit)
  • GL-BYTCN40EL (4 HP Wall Mounted Refrigeration Unit)

Are you interested in HOT GAS DEFROST REFRIGERATION SYSTEMS?

Want to discuss a project? Get a technical issue? Need a quote or more information.

For inquiries about the Hot Gas Defrost Refrigeration System, email us at info@greehvacr.com

Or feel free to call us at +86 15057108995

Or Whatsapp +86 15057108995

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