AHU Selection & Design – Basic Engineering Approach Air Handling Unit (AHU) is the heart of any central HVAC system. Proper selection ensures efficient cooling, air quality, and energy performance. 1️⃣ Airflow Requirement First step in AHU design is determining airflow. • Based on cooling load (TR) • Typical rule: 400–450 CFM per TR for comfort air conditioning Airflow directly affects coil size, fan capacity, and duct design. 🔹 2️⃣ Cooling Coil Selection Key parameters: • Entering air temperature • Leaving air temperature • Chilled water temperature (7°C / 12°C typical) • Air velocity across coil Proper coil design ensures good heat transfer and low pressure drop. 🔹 3️⃣ Fan Selection Fan is selected based on: • Required airflow (CFM) • Total Static Pressure (TSP) • System losses (filters, coil, duct) Common fan types: • Backward curved centrifugal fan • Plug fan (EC fan) – energy efficient modern design 🔹 4️⃣ Filtration System Filters maintain indoor air quality. Ty...
Gul Bahar Shah
Gul Bahar Shah
AHU Selection & Design – Basic Engineering Approach
Air Handling Unit (AHU) is the heart of any central HVAC system.
Proper selection ensures efficient cooling, air quality, and energy performance.
1️⃣ Airflow Requirement
First step in AHU design is determining airflow.
• Based on cooling load (TR)
• Typical rule: 400–450 CFM per TR for comfort air conditioning
Airflow directly affects coil size, fan capacity, and duct design.
🔹 2️⃣ Cooling Coil Selection
Key parameters:
• Entering air temperature
• Leaving air temperature
• Chilled water temperature (7°C / 12°C typical)
• Air velocity across coil
Proper coil design ensures good heat transfer and low pressure drop.
🔹 3️⃣ Fan Selection
Fan is selected based on:
• Required airflow (CFM)
• Total Static Pressure (TSP)
• System losses (filters, coil, duct)
Common fan types:
• Backward curved centrifugal fan
• Plug fan (EC fan) – energy efficient modern design
🔹 4️⃣ Filtration System
Filters maintain indoor air quality.
Typical configuration:
• Pre Filter – G3 / G4
• Fine Filter – F7 / F8
• HEPA Filter – Cleanroom / hospital applications
🔹 5️⃣ AHU Components
Basic AHU sections include:
• Mixing box (Fresh + Return air)
• Filters
• Cooling coil
• Drain pan
• Fan section
• Access sections
🔹 6️⃣ Modern AHU Design Trends
• EC plug fans for energy efficiency
• Double skin insulated panels
• UV & HEPA filtration for IAQ
• Smart sensors for BMS integration
📌 Proper AHU design ensures:
✔ Energy efficiency
✔ Good indoor air quality
✔ Stable temperature & humidity control
✔ Long equipment life
Proper selection ensures efficient cooling, air quality, and energy performance.
1️⃣ Airflow Requirement
First step in AHU design is determining airflow.
• Based on cooling load (TR)
• Typical rule: 400–450 CFM per TR for comfort air conditioning
Airflow directly affects coil size, fan capacity, and duct design.
🔹 2️⃣ Cooling Coil Selection
Key parameters:
• Entering air temperature
• Leaving air temperature
• Chilled water temperature (7°C / 12°C typical)
• Air velocity across coil
Proper coil design ensures good heat transfer and low pressure drop.
🔹 3️⃣ Fan Selection
Fan is selected based on:
• Required airflow (CFM)
• Total Static Pressure (TSP)
• System losses (filters, coil, duct)
Common fan types:
• Backward curved centrifugal fan
• Plug fan (EC fan) – energy efficient modern design
🔹 4️⃣ Filtration System
Filters maintain indoor air quality.
Typical configuration:
• Pre Filter – G3 / G4
• Fine Filter – F7 / F8
• HEPA Filter – Cleanroom / hospital applications
🔹 5️⃣ AHU Components
Basic AHU sections include:
• Mixing box (Fresh + Return air)
• Filters
• Cooling coil
• Drain pan
• Fan section
• Access sections
🔹 6️⃣ Modern AHU Design Trends
• EC plug fans for energy efficiency
• Double skin insulated panels
• UV & HEPA filtration for IAQ
• Smart sensors for BMS integration
📌 Proper AHU design ensures:
✔ Energy efficiency
✔ Good indoor air quality
✔ Stable temperature & humidity control
✔ Long equipment life
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