Intro to Chillers : Introduction to Water Chillers

 Basics of Chillers:

• Function: Absorb heat using refrigerant from a water solution, sometimes containing glycol as an antifreeze.
• Operation: If using glycol, can operate below freezing; with just water, operates above freezing.
• Refrigeration System: The evaporator absorbs heat from the water or glycol solution, which is then pumped to remote cooling coils in air handlers within a building.
• Primary Refrigerants: R134a, R22, R123.
• Secondary Refrigerant: Water-glycol solution, which acts as the coolant sent to remote cooling coils.

Flooded Evaporators:

• Structure: A vessel or tank with liquid refrigerant covering the entire water tubing.
• Operation:
  • Warm water or glycol returns from remote coils, passes through water tubes, and is conditioned by the refrigerant boiling in the evaporator.
  • Liquid refrigerant is metered into the evaporator, maintaining a level above the water tubes to ensure effective heat absorption.

Centrifugal Chillers:

• Components:
  • Compressor motor driving the centrifugal compressor.
  • Impeller inside the compressor compresses vapors.
  • Evaporator (chiller barrel) at the bottom.
• Operation:
  • Suction comes off the top, vaporized refrigerant enters the centrifugal compressor, and chilled water is pumped to remote cooling coils.

Water-Cooled Condensers:

• Structure: Shell and tube type, similar to the evaporator.
• Operation:
  • Cooler water from the cooling tower circulates through the tubes, absorbing heat from discharge gases.
  • Discharge vapor condenses to liquid, subcooling occurs within the vessel.
• Diagram: Shows tube bundles, discharge vapor entering at the top, and liquid refrigerant exiting at the bottom.

Process:

• Water Flow: Cooler water returns from the cooling tower, absorbs heat from the refrigerant, and returns warmer to the cooling tower.
• Refrigerant Flow: Liquid refrigerant exits the condenser, passes through the metering device, and returns to the evaporator to absorb more heat.