How Air Conditioners Work

Latent Heat of Vaporization

• Sweating cools us down because sweat evaporates, taking heat away from our skin.
• This process is known as Latent Heat Of Vaporization.
  • The larger the Latent Heat Of Vaporization, the more heat is taken away.
• Air conditioners use refrigerants with high Latent Heat Of Vaporization for effective cooling.

Principles of Air Conditioning

• Evaporation: Transition of liquid to gas through heat absorption.
• Condensation: Transition of gas to liquid by releasing heat.
• Refrigerants: Substances with high Latent Heat Of Vaporization used in air conditioners for cooling.

Components of an Air Conditioner

• Compressor:
  • Acts like the heart, circulating and compressing refrigerant to high temperature and pressure.
• Condenser:
  • Converts refrigerant from gas to liquid by taking away its heat.
• Expansion Valve:
  • Narrow section where refrigerant pressure and temperature drop.
• Evaporator:
  • Cools the refrigerant, which steals heat from the room and evaporates.
• Fans:
  • Impeller type fans are used for space efficiency in indoor units.

Process Flow of Refrigerant

1. Compressor: Compresses gaseous refrigerant raising its pressure and temperature.
2. Condenser: Cools the refrigerant from gas to liquid form.
3. Expansion Valve: Drops the refrigerant’s pressure and temperature.
4. Evaporator: Cooled refrigerant absorbs heat from the room and evaporates.

Detailed Functions

• In the compressor:
  • Traditionally used a piston, more commonly using scroll type now.
  • Scroll compressors are more space-efficient, less noisy, and reduce vibration.
• In the condenser:
  • The refrigerant’s temperature is reduced from about 80°C to 50°C, converting from gas to liquid.
• In the expansion valve:
  • Connected to sensible heat storage which detects temperature changes and regulates refrigerant flow.
• In the evaporator:
  • Fans circulate the room air over refrigerant pipes for cooling.
  • Excess condensed water is stored and drained.