Introduction to Refrigeration Systems: Simple A/C System

 Basic AC System Overview:

• Components: Compressor, Metering Device, Evaporator (tank), Condenser (tank).
• Focus: High and low side pressures, superheat, and subcooling.

Understanding Refrigeration Systems:

• Repetition and Visualization:
  • Learning requires multiple exposures, reading, and diagramming.
  • Gradual understanding through consistent study and visual aids.

Simple R22 AC System Diagram:

• Key Temperatures and Pressures:
  • Ambient Air: 95°F (outside air).
  • Return Air: 75°F (inside air).
  • High Side Pressure: 278 PSIG, Saturation Temperature: 125°F.
  • Low Side Pressure: 69 PSIG, Saturation Temperature: 40°F.

High Side of the System:

• Compressor:
  • High pressure, high temperature vapor refrigerant (175°F).
• Condenser:
  • Cooled by 95°F ambient air.
  • Refrigerant cools to 125°F (saturation temperature), then condenses to liquid.
  • Further cooling to 115°F (subcooling by 10°F).

Metering Device Analogy:

• Toll Booth Comparison:
  • High side refrigerant queues like traffic at a toll gate.
  • Metering device controls flow, allowing refrigerant to enter the low side in small amounts.

Low Side of the System:

• Evaporator:
  • 40°F droplets of refrigerant enter the evaporator tank.
  • 75°F return air heats the refrigerant, causing it to evaporate.
  • Once vaporized, refrigerant superheats to 50°F (10°F superheat).

Superheat and Subcooling:

• Superheat:
  • Temperature above the saturation point (example: 40°F to 50°F).
• Subcooling:
  • Temperature below the saturation point (example: 125°F to 115°F).

Diagram Takeaways:

• High side (compressor to metering device): High pressure, high temperature.
• Low side (metering device to evaporator): Low pressure, low temperature.
• Superheat and subcooling measurements indicate the efficiency of the system.