Skip to main content

Inside an Advanced Air Handling Unit (AHU): Complete Air Treatment Process Explained

 Inside an Advanced Air Handling Unit (AHU):

Complete Air Treatment Process Explained


Designing a high-performance HVAC system-especially for critical environments like pharmaceuticals, cleanrooms, or healthcare-requires precise control over air quality, temperature, and humidity.


Here's a step-by-step breakdown of how air is processed inside a modern Air Handling Unit (AHU):


1. Return & Fresh Air Intake

The process begins with a combination of Return Air (RA) from the space and Outdoor Air (OA). These streams enter through the intake plenum, where the return fan helps maintain proper airflow balance.


2. Mixing Section

Fresh and return air are mixed in controlled proportions to maintain indoor air quality while optimizing energy efficiency.


3. Pre-Filtration Stage

Air passes through pre-filters and intermediate filters, removing dust and larger particles-protecting downstream components and improving system life.


4. Energy Recovery Coil (Optional)

An energy recovery system transfers heat between exhaust and incoming air streams, reducing overall energy consumption.


5. Heating Coil Section

If required, air is preheated to maintain desired conditions, especially in colder climates.


6. Humidification (Optional)

A humidifier adds moisture to the air to maintain required relative humidity levels-critical for product quality and comfort.


7. Cooling Coil Section

Air is cooled and dehumidified as it passes through the cooling coil, removing excess heat and moisture.


8. Dehumidifier Unit

For applications requiring tight humidity control, a dedicated dehumidifier ensures precise moisture removal beyond standard cooling.


9. Re-Cooling & Reheating

Air may undergo re-cooling and reheating to fine-tune temperature and humidity-this is essential for achieving exact environmental conditions.


10. Supply Fan Section

The conditioned air is then pushed by the supply fan toward the final stage.


11. Final Filtration

High-efficiency filters (HEPA/ULPA, if required) ensure the air meets strict cleanliness standards before entering the controlled space.


12. Supply Air (SA)

Finally, clean, conditioned air is delivered to the room, maintaining the desired environment.



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

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...
1 comment
Read more

HVAC common unit converter chart

 Here's a comprehensive HVAC unit converter chart: Volume Flow Rate 1.CFM (Cubic Feet per Minute) to CMH (Cubic Meters per Hour):  1 CFM ≈ 1.699 CMH 2.CFM to m³/s (Cubic Meters per Second):  1 CFM ≈ 0.000472 m³/s Airflow Velocity 1.FPM (Feet per Minute) to m/s (Meters per Second):  1 FPM ≈ 0.00508 m/s 2.m/s to FPM:  1 m/s ≈ 196.85 FPM Energy and Power 1.BTU/h (British Thermal Units per Hour) to kW (Kilowatts):  1 BTU/h ≈ 0.000293 kW 2.Tons of Refrigeration to kW:  1 Ton ≈ 3.517 kW Pressure 1.Inches of Water Gauge (in wg) to Pascals (Pa):  1 in wg ≈ 249.08 Pa 2.PSI (Pounds per Square Inch) to kPa (Kilopascals):  1 PSI ≈ 6.895 kPa Temperature 1.°F (Fahrenheit) to °C (Celsius):  °C = (°F - 32) × 5/9 2.°C to °F:  °F = °C × 9/5 + 32 Additional Conversions Length 1.Inches to Millimeters:   1 inch = 25.4 mm 2.Feet to Meters:  1 foot = 0.3048 meters Area Square Feet to Square Meters:  1 sq ft = 0.0929 sq m Volume Gallons to L...
Post a Comment
Read more