Introduction to Walk-In Freezers : Walk-in Freezers and the Refrigeration Cycle

 Major Components of the Refrigeration Cycle:

1. Compressor
2. Condenser
3. Evaporator
4. Metering Device

Piping Components:

• Suction Line: Connects evaporator to compressor.
• Discharge Line: Connects compressor to condenser.
• Liquid Line: Carries high-pressure subcooled liquid refrigerant from condenser to metering device.

Refrigeration Cycle Process:

1. Compression: Compressor increases the pressure and temperature of the refrigerant, turning it into a high-pressure gas.
2. Condensation: High-pressure gas moves to the condenser coil, where it rejects heat and changes state to a liquid.
3. Metering: Liquid refrigerant flows through the liquid line to the metering device, which lowers its pressure, causing it to start evaporating.
4. Evaporation: In the evaporator coil, the refrigerant absorbs heat, changes back to a gas, and returns to the compressor through the suction line. The cycle repeats.

Refrigerant State Changes:

• Saturation: Point where refrigerant changes state. Temperature remains constant during the change.
• Superheat: Temperature of vapor above its saturation point. Measured in the evaporator and at the compressor.
• Subcooling: Temperature of liquid refrigerant below its saturation point. Indicates refrigerant amount in the condenser.

Importance of Superheat and Subcooling:

• Superheat: Indicates the amount of liquid boiling in the evaporator coil.
  • Low Superheat: More liquid in the coil (flooding), risk of compressor damage.
  • High Superheat: Evaporator coil is starved of refrigerant, risk of compressor overheating.
• Subcooling: Indicates the amount of refrigerant in the condenser.
  • No Subcooling: Insufficient refrigerant to condense into a liquid.
  • Low Subcooling: Risk of refrigerant flashing before entering the metering device.

Inspection:

• Use a sight glass in the liquid line to visually inspect for flashing refrigerant.