AHU (Air Handling Unit) is an important device in the air handling system of buildings. It helps regulate and maintain air quality in living and working spaces. If you do not know What is AHU?, operating principle as well as structure of What is AHU?, let's Tan Long Find out through this article.
Find out what AHU is?
What is AHU? AHU (Air Handling Unit) is a device that has the function of exchanging heat and treating heat and humidity, creating clean air, often used in HVAC system. The role of AHU What is that? AHU plays an important role in this system, widely used in factories, buildings, hospitals, hotels, and many other places.
AHU air handling and circulation throughout a building system. This equipment is usually designed for outdoor use, typically on a roof, and is also known as a rooftop unit. (RTU).
About the structure, AHU is a large metal box that contains components such as a ventilator, heating coil, cooling coil, heat recovery system, air filter rack or chamber, muffler, mixing chamber, and dampers.
Classification of AHU or Air Handling Unit
Air Handling Unit (AHU) There are two main types: AHU running water and AHU direct refrigerant
Water AHU
- How it works: Use cold water through copper pipe and centrifugal fan for heat exchange.
- Control system: Humidity and temperature sensors, three-way valves and chiller.
- Cooling process: The three-way valve opens when the room temperature is greater than the set temperature, allowing cold water to flow through the heat exchanger; the valve closes when the temperature reaches the required level.
Direct Refrigeration AHU (DX AHU)
- How it works: Use refrigerant gas in copper tube and centrifugal fan for heat exchange.
- Air filter: Pre-filter and bag filter to treat air before supplying it to the use area; required HEPA filter system for clean room
- Fan: High static pressure centrifugal fan, using VSD to regulate air volume and temperature.
What is the structure of AHU?
Parts included Air Handling UnitWhat is an AHU system has been answered above, the following is the structure of this system, they are often assembled from many modules, including:
- Mixing chamber: There are two control valve ports: one for fresh air intake and one for return air.
- Air filter: Make sure the air is clean.
- Heat exchanger: Including heating system and condenser to regulate air temperature.
- Fan box: Contains fan for air circulation.
- The main control system includes: thermostat, three-way actuator, sound and vibration damper, air supply pipe,…
Normally, AHU Designed according to the requirements of each project, but the general structure usually includes: condenser, fan, heater, air filter and protective cover.
Details and uses of each part of AHU
What is AHU protective cover?
Is an aluminum profile frame that creates an insulating layer, often designed with rounded corners to prevent dust from sticking from the outside.
Fan
Using centrifugal fan with double layer structure, with standard insulation layer. For AHU For outdoor installation, the fan is equipped with additional insulation and anti-corrosion tape to suit the environment.
Anti-vibration device
Helps reduce vibration and noise from high-capacity fans during operation, helping the system operate smoothly.
Heating system
Also known as Heater, consisting of copper (or aluminum) coils to exchange heat directly in the air stream, ensuring consistent heating or cooling.
Air filter
Ceramic coarse filter, fine filter and filter HEPA (if required). This filter removes dust particles and contaminants, producing clean air.
Heating resistor
Moisture and heat treatment in AHU system, ensuring the air reaches the desired humidity and temperature.
Condensing local moisture separator
Pre-cool the air and remove moisture before the air enters the main evaporator.
Central control
Transmit control signals and receive feedback signals from devices, helping the system operate accurately.
Operating principle of AHU system
- Air Cooling: The three-way valve opens to allow cold water to flow through the heat exchanger when the temperature of the area to be cooled is higher than the set level.
- Temperature control: When the set temperature is reached, the three-way valve closes, cold water flows through the Bypass line to the Chiller.
- Air filter: Air is filtered through a coarse and bag filter, or a HEPA filter in environments requiring high cleanliness.
- Heat exchanger: Air comes into contact with the heat exchanger, creating cold air.
- Air distribution: Cold air is blown through the HVAC system's ductwork to the area that needs cooling.
- Fan adjustment: The output air temperature level depends on the fan speed, adjusted by the cold water valve.
AHU system Pre-treat the air, using the FCU system to control humidity precisely when needed.
Parameters when choosing AHU for HVAC system
Normally, air conditioning system suppliers will have a technical department to support customers in choosing. AHU equipment suitable for project requirements.
The designer plays the most important role in choosing AHU. If they do not understand the specifications and choose available equipment, the performance of the system may be reduced.
Some Basic specifications for AHU include:
- Total Capacity: kW
- Sensible Capacity: kW
- Supply Air Volume: l/s
- Coil Entering Air Temperature: °C (DB-WB)
- Coil Leaving Air Temperature: °C (DB-WB)
- Fresh Air Volume: l/s
- Fresh Air Temperature: °C (DB-WB)
- External Static Pressure: Pa
- Cooling/Heating Water Flow: l/s
- On-Off Coil Water Temp: °C
- Main Filter Type: Panel/Bag/Hepa Filter
- Supply Fan Power: kW
Common locations for installing Air Handling Unit systems
What is AHU? Answered, so where is this system usually installed? AHU Commonly used in medium to large commercial and industrial buildings, often located in basements, rooftops, or other floors. They may serve a specific area or purpose such as a restroom.
Old high-rise buildings often have a AHU large on the roof, but this design is inefficient because there is no return duct. Nowadays, many AHU Smaller with airtight slots are more commonly used, requiring a return pipe to regulate pressure.
In industrial plants, AHU usually placed on the technical ceiling.
Common applications of AHU
What is the function of AHU?
AHU conditioning and distribution of air within a building. They take air from outside, clean it, heat it or cool it, even humidify it, and then direct it through ducts to areas within the building.
Most of the AHU All have ducts to discharge used air back to the outside environment. Some of this air can be recirculated to save energy. Otherwise, the heat can be extracted and introduced into the fresh air stream.
Where are AHU systems commonly used?
- High-rise building
- Factory, factory
- Clean room
- Hotels, luxury facilities
- Hospitals, labs, offices, schools, etc.
- Environment requiring air treatment
Criteria for distinguishing between air handling units AHU and FCU
Usage needs
- FCU: Used in commercial buildings, small spaces, offices, local air handling.
- AHU: It is a large FCU with additional mixer and filter, used in large spaces requiring high cleanliness such as high-end commercial areas, electronic components and cosmetics factories.
Size
- FCU: Small heat exchanger, short air blowing range (under 20 meters), short air duct, fan pressure column under 200Pa.
- AHU: Large radiator, large air blowing range (over 20 meters), fan pressure column from 300Pa or more.
Noise
- FCU: Used in office, low noise due to small fan pressure column.
- AHU: High noise level, need to design additional sound absorption and soundproofing if used for office.
Heat exchanger
- FCU: Use refrigerant as HCFC freon gas, cooling water (chilled), wine water (glycol).
- AHU: Use water from chiller or similar refrigerants FCU.
Capacity
- FCU: Small capacity, suitable for small spaces.
- AHU: Large capacity, enough to provide cold air for large rooms or many rooms, or functional rooms far from the installation location.
In general, AHU and FCU They all have the same structure and operating principle, but they differ in usage needs, size, noise, heat exchange and capacity.
> Reference:
- Cold storage: Design and installation on site, quality, cheapest price
- Genuine imported pressure tank, good price, high quality
- Genuine, reputable industrial water chiller
Compare the difference in operating principles of AHU and FCU
AHU (Air Handling Unit)
- Temperature adjustment: The 3-way valve opens when the room temperature is higher than the setting, and closes when the temperature reaches the required level.
- Air filter: Air is filtered through a pre-filter, bag filter and filter HEPA (if necessary) before cooling.
- Create cold air: The air is cooled through the heat exchanger and blown into the room through the ducts.
- Fan adjustment: Fan speed and chilled water valve control outlet air temperature.
FCU (Fan Coil Unit)
- Temperature adjustment: The coil senses hot or cold steam from the central air conditioner and adjusts the air temperature.
- Design: FCU has round blow Cassette, 4-way or 1-way type.
- Fan speed adjustment: Fan speed can be adjusted for heating or cooling.
Main differences:
- AHU: Adjusted by 3-way valve, filter system, and mainly pre-treats air, suitable for large areas.
- FCU: Using thermal sensing coil, temperature adjustment via fan, suitable for small spaces.
Trends and advanced technology in AHU system
IoT Integration
AHU modern integrated IoT with smart sensors to monitor and automatically adjust temperature, humidity, and air quality, helping to increase efficiency, reduce costs, and improve air quality.
Using high performance materials
Using aluminum, stainless steel, and composite plastic materials helps reduce size, weight, and noise, increasing heat exchange efficiency and longevity.
Component Improvements
Improved fans, filters and heat exchangers save energy and reduce noise. For example, EC fan helps save energy significantly.
Optimal AI and Machine Learning Applications
AI and Machine Learning Optimize operations, analyze data to improve performance, reduce costs and prevent problems. AI predicts air demand based on history and weather conditions, helping AHUs operate more efficiently.
Conclude
AHU is an indispensable air treatment device today. This article helps you understand more about What is AHU?, its operating principles and applications, from which you can choose and apply it to your facility effectively.
