Skip to main content

WHAT IS A CHILLER? | MAIN TYPES OF CHILLERS | MAJOR COMPONENTS

WHAT IS A CHILLER?


  • A Chiller is a machine that removes heat from a liquid (usually water or glycol mix) via vapor-compression or absorption refrigeration.
  • The chilled water is circulated through AHUs or FCUs to absorb heat from the building, making it a central part of HVAC systems.

MAIN TYPES OF CHILLERS

1. Based on Heat Rejection:

⭐Air-Cooled Chiller

  •  Heat is rejected to ambient air via condenser fans.
  • No cooling tower needed.
  • Higher power consumption (low efficiency).
  • Used where water availability is limited (like UAE rooftops).

⭐Water-Cooled Chiller

  •  Heat is rejected to condenser water, then to a cooling tower.
  • Higher efficiency and longer lifespan.
  • Requires more maintenance (cooling towers, water treatment).
  • Ideal for large-scale commercial or industrial applications.
2. Based on Refrigeration Cycle: 

→Vapor Compression Chiller

  •  Commonly used.
  • Uses mechanical compressor (screw, scroll, centrifugal).

→Absorption Chiller

  •  Uses heat source (steam, hot water, gas) to generate cooling.
  • Uses lithium bromide-water cycle.
  • No compressor; eco-friendlier but less efficient.


MAJOR COMPONENTS

1. Evaporator

  • Where chilled water is cooled.
  • Heat absorbed from building's water loop.
2. Compressor

  • Pumps refrigerant from evaporator to condenser.

⭐Types of compressor:

  •  Scroll: Small systems. 
  •  Screw: Medium-large systems. 
  •  Centrifugal: Very large capacity, high efficiency.
3. Condenser

  • Rejects heat from refrigerant to air/water. 
  • Water-cooled chillers use cooling tower loop.

4. Expansion Valve (TXV or EXV)

  • Controls refrigerant flow into evaporator.
  • Lowers pressure and temperature of refrigerant.
5. Refrigerant

  • Common types: R134a, R123, R410A, R717 (ammonia), R1234ze (low-GWP).
  • Transfers heat from chilled water to environment.

CHILLER SYSTEM COMPONENTS (HVAC INTEGRATION)

⇒ Primary Chilled Water Loop

  •  Carries chilled water from chiller to AHUs/FCUs and back. 

⇒ Secondary Loop (in decoupled system)

  •  Isolates distribution pumps from chiller pumps.

⇒ Condenser Water Loop (only for water-cooled)

  •  Carries heat from chiller condenser to cooling tower.


⚙ OPERATION SEQUENCE (TYPICAL WATER-COOLED CHILLER)

1. CHW return (from building) → Evaporator → CHW supply. 

2. Heat absorbed → refrigerant evaporates. 

3. Compressor raises refrigerant pressure/temp. 

4. Condenser removes heat via cooling tower water. 

5. Expansion valve lowers pressure → back to evaporator.


⚠ KEY CONSIDERATIONS IN SELECTION

⇒ Capacity (TR or kW) 

⇒ Efficiency: COP, kW/TR, IPLV, NPLV ⇒ Type of compressor 

⇒ Ambient conditions 

⇒ Cooling medium availability (air vs. water) 

⇒ Initial cost vs. life-cycle cost 

⇒ Space availability (rooftop vs. plant room)

Comments

Post a Comment

Popular posts from this blog

VALVES USED IN A CHILLER SYSTEM AND THE TYPICAL VALVE PACKAGE

  VALVES USED IN A CHILLER SYSTEM AND THE TYPICAL VALVE PACKAGE 1.Chilled Water Side Valves ⇒Isolation valve (manual/electric actuated). ⇒ Installed on CHW supply and return lines.  ⇒ Used to isolate chiller for maintenance. 2. Balancing Valve (Manual or Automatic)  ⇒ Ensures correct flow rate to/from chiller.  ⇒ Helps maintain Delta T and proper flow distribution.  ⇒ Located after evaporator outlet (return line). 3. Differential Pressure Bypass Valve (if 2-way valves in system)  ⇒ Prevents excess pressure build-up when terminals shut.  ⇒ Maintains flow through chiller. 4. Flow Switch  ⇒ Senses chilled water flow across evaporator.  ⇒ Safety interlock: trips chiller if flow is lost.  ⇒ Usually paddle type or electronic. 5. Air Vent Valve (Manual or Automatic)  ⇒ Removes air pockets.  ⇒ Placed at high points of piping and chiller headers. 6. Drain Valve  ⇒ For flushing, cleaning, and maintenance.  ⇒ Located at low poin...
Post a Comment
Read more

HVAC MEP Thumb Rules & Formulas (With Examples)

  HVAC MEP Thumb Rules & Formulas (With Examples) 1. Heat Load Calculation  Formula: Q = Area (sq.ft) x Heat Load Factor (BTU/hr per sq.ft) Example: 500 sq.ft office: Q = 500 x 30 = 15,000 BTU/hr TR = 1.25 2. CFM Calculation Formula: CFM = Sensible Heat (BTU/hr) / (1.08 x Delta T) Example: 12,000 BTU/hr, Delta T = 20°F CFM = 556 3. AHU/FCU Sizing Rule: 1 TR = 400 CFM 2 TR Airflow = 800 CFM 4. Duct Sizing Velocity Limits: Main: 1400-1800 FPM 800 CFM @ 1000 FPM 0.8 sq.ft 14"x10" 5. Chilled Water Flow Rate Formula: GPM = BTU/hr / (500 x Delta T) Example: 24,000 BTU/hr GPM = 4.8 6. Pipe Sizing 1" pipe: 8-12 GPM 2" pipe: 30-40 GPM 35 GPM Use 2" 7. Chiller Sizing Formula: TR = BTU/hr / 12,000 Example: 60,000 BTU/hr → 5 TR 8. Cooling Tower Sizing Rule: Heat Rejection = 1.25 x Load 10 TR → Tower = 12.5 TR 9. Pump Head Calculation Formula: Power (kW) = (Q x H x 9.81) / (Efficiency x 1000) Example: Q = 5 L/s, H = 20 m, Efficiency = 0.75 Power 1.31 kW 10. Fresh Air Re...
Post a Comment
Read more

Type of Heat Exchanger

 There are several types of heat exchangers used in HVAC systems, including: 1. Coil Type:     - Chilled water coils     - Hot water coils     - DX (direct expansion) coils     - Evaporator coils     - Condenser coils 2. Shell and Tube Type:     - U-tube heat exchangers     - Straight tube heat exchangers 3. Plate Type:     - Plate and frame heat exchangers     - Plate and shell heat exchangers 4. Finned Tube Type:     - Finned tube heat exchangers 5. Spiral Type:     - Spiral heat exchangers 6. Regenerative Type:     - Regenerative heat exchangers 7. Adiabatic Type:     - Adiabatic wheel heat exchangers 8. Run-Around Coil Type:     - Run-around coil heat exchangers These heat exchangers are used in various applications, including: - Air conditioning - Heating - Ventilation - Refrigeration - Heat recovery - Industrial processes Each type of hea...
2 comments
Read more