Condensers: Condenser Functions and Splits

 How the Condenser Rejects Heat:

• Three Phases of Heat Rejection:
  1. Desuperheating:
     • Removal of sensible heat from discharge vapors to cool them down to their condensing temperature.
     • Occurs in the first 10-15% of the condenser.
  2. Condensation:
     • Change of refrigerant from vapor to liquid form, removing latent heat absorbed in the evaporator.
     • The majority of the condenser's length is used for this phase.
  3. Subcooling:
     • Cooling of liquid refrigerant below its condensing temperature, removing additional sensible heat.
     • Occurs in the last 5-10% of the condenser.

Example:

• Desuperheating: Discharge vapors at 175°F are cooled down to 125°F (condensing temperature).
• Condensation: No temperature change during this phase.
• Subcooling: Liquid refrigerant subcools from 125°F (saturation temperature) to 115°F, resulting in 10°F subcooling.

Condenser Split:

• Definition: The temperature difference between the condensing temperature (saturation temperature) and the air entering the condenser.
• Example:
  • If condensing temperature is 105°F and air entering is 75°F, the condenser split is 30°F.
• Air-Cooled Condensers and Condenser Splits:
  • Low Efficiency Systems: Typically have a 30°F condenser split (e.g., if air enters at 95°F, condensing temperature is 125°F).
  • High Efficiency Systems: Have a 20°F condenser split (e.g., 95°F air entering, 115°F condensing temperature).

Common Rules of Thumb for Condenser Splits:

• Standard Refrigeration & Air Conditioning (up to 10 SEER): 30°F condenser split.
• Commercial Freezers: 20-25°F condenser split.
• High Efficiency Air Conditioners & Heat Pumps: 15-20°F condenser split.
• Remote Refrigeration Condensers (rooftop or outdoor): 10-30°F condenser split.

Examples of Condenser Split in Different Systems:

• Older Rooftop Air Conditioning Unit: 30°F split.
• Freezer: 20°F split.
• High Efficiency Air Conditioner or Heat Pump: 20°F split.
• Remote Unit: 10-30°F split.