توضیحات

Introduction

A multi-zone air handling unit is a type of central air handler that can simultaneously supply air to several zones or spaces at different temperatures. This system is typically used in buildings where various areas require independent cooling or heating, but installing multiple separate air handling units would not be cost-effective.

Main Components

1. Fan (Forward or Backward Curved)
2. Air Filters (Bag filters, Polyester filters, HEPA, etc.)
3. Cooling Coil (Chilled Water or DX)
4. Heating Coil (Hot Water, Steam, or Electric)
5. Zone Dampers
6. Electrical Panel and Control System
7. Air Mixing Chamber
8. Double-skin Insulated Casing and Frame

Technical Specifications

1) Air Flow Capacity

• Unit: CFM
• Typical range: 1,500 to 60,000 CFM (depending on application)
• Capacity is determined based on: Cooling/Heating load/ Number of zones/ Ventilation rate (ACH)

2) Number of Zones

• Typically 2 to 8 zones
• Each zone is equipped with: Independent motorized damper / Zone thermostat / Dedicated duct

3) Fan Section

Fan Types:

• Forward Curve Centrifugal Fan
• Backward Inclined / Airfoil Centrifugal Fan (higher efficiency)

Technical Specifications:

• Airflow capacity: based on unit CFM
• Static pressure: 2 to 6 inches WC
•  Impeller material: galvanized steel or aluminum
• Electric motor:

• Power: 0.75 to 50 kW
• Speed: 900–1750 RPM
• Insulation class: F
• Protection rating: IP55

4) Cooling Coil

Types:

• Chilled Water Coil
• DX Coil (Direct Expansion) for AC or refrigerant-based chillers

Specifications:

• Tube material: Copper
• Fins: Aluminum with anti-corrosion coating
• Rows: 4, 6, or 8 rows
•  Working pressure: 300 psi
• Cooling capacity: 5 to 200 tons of refrigeration

5) Heating Coil

Types:

• Hot Water Coil
• Steam Coil
• Electric Heater (for cold climates)

Specifications:

• Copper or steel tubes
• Aluminum fins
•  Steam working pressure: up to 7 bar
•  Hot water temperature: 70–90°C

6) Multi-Zone Damper System

Each zone includes:

• Aluminum or steel damper
•  Profiled blades with rubber sealing
• Motorized damper (On/Off or Modulating)
•  Compatible with PI/PLC/BMS controls

Function:

• Regulates the mixing ratio of hot and cold air
• Provides independent temperature control for each zone

7) Filtration Section

Typical filter arrangement:

1. Aluminum Pre-filter
2. Bag Filter – 60% to 95% efficiency
3. HEPA Filter for hospital-grade units

Features:

• Filtration classes: G4, F7, F9, H13
• Typical pressure drop: 50 to 250 Pa

8) Casing & Structure

• Casing Material: Galvanized sheet, thickness 1–1.5 mm / Stainless steel optional
• Insulation: Double-skin panels / Polyurethane or rockwool insulation /Thickness: 25–50 mm
• Features: Acoustic insulation / Reduced energy loss / Vibration control

9) Control and Automation System

• Central control or BMS integration
• Zone temperature control
• Temperature & pressure sensors
• VFD (inverter) for fan speed control
• Optional humidity control (Humidifier/Dehumidifier)

10) Noise Level

• Typically 65 to 85 dB
• Noise reduction via: Inlet/outlet silencers / Internal acoustic insulation /Airfoil fans

11) Humidification/Dehumidification (Optional)

• Electric or steam humidifier
• DX or rotary dehumidifier
• Used in hospitals, laboratories, and clean rooms

12) Standards

The AHU must comply with international standards:

• ASHRAE 62.1 – Ventilation & Indoor Air Quality
• ASHRAE 90.1 – Energy Efficiency
• AMCA 210 – Fan Performance Testing
• AHRI 430 – Coil Performance Testing
• ISO 16890 – Air Filters
• EN 1886 – Mechanical Strength & Construction of AHU Cabinets