AHU is an air handling device used in HVAC systems. Widely used in industrial buildings. This device helps to exchange heat and is often used in heating systems, ventilation systems, air conditioning systems.
So what is AHU? What is the structure and operating principle of the Ahu system? Why is this system so trusted? Follow the article below of P69 Mechanical Factory to get more information!
What is AHU system?
The AHU system stands for Air Dealing with Unit. The air handling unit is a heat exchanger and humidifying heat treatment device.
Ahu air conditioning system creates clean air. Commonly used in HVAC systems or industrial workshops. Use the Ahu system for places with high requirements for clean rooms such as pharmaceuticals, cosmetics, electronic sciences, etc.
Today, AHU systems are commonly used in commercial buildings. High-class hotels, large commercial centers with central chiller systems.
You can also understand that ahu air conditioning system is a pre-treatment device like PAU in places such as corridors or large halls, etc.
AHU Structure
The AHU system is usually composed and assembled from many coordinated modules as follows: Mixing chamber, Dust filter, heat exchanger system and fan box.
– On the mixing chamber with 2 doors attached to the regulating valve part.
– One door to get fresh air and the other one to connect to the air return line.
– The main control system includes thermostats, three-way actuator valves, .. Department of sound and vibration reduction, air supply pipe, …
– The dust filter of the AHU air conditioning system often uses many different types of filters. Such as synthetic fibers can be pleated or use a fabric bag (filter bag) design.
Over a long period of development, now clean room AHU system with more and more complex and sophisticated structure.
The structure of the AHU will depend on the requirements of each project. However, they all have a common structure with the following departments include:
– Fan
– Heater (Heater)
– Cooler
– Air filter
– Protective case
AHU Classification
In fact, AHU is divided into 2 types: Water-powered system and AHU system running on direct refrigerant gas.
Water AHU
It is a heat exchanger using cold water and air. This system includes temperature, humidity sensors, chiller and 3-way actuator valve. The cold water passes through the copper tubes and the air through the centrifugal fan.
When the room temperature is greater than the set temperature. Then the 3-way valve opens to let cold water flow through the heat exchanger. Until the temperature drops below the reaching temperature. Then the 3-way valve will close. Cold water flows to the bypass to the chiller equipment.
AHU direct refrigerant gas (DX AHU)
It is a heat exchanger that uses refrigerant gas to pass through copper pipes. The air is blown through by the suction of the centrifugal fan. When the air is supplied to the use area, it usually passes through the pre-filter and the filter bag. In case it is necessary to use for a room with high cleanliness, use an additional HEPA filter.
When applied in an external pressure clean room. AHU’s supply fan usually uses a centrifugal fan that can pressurize the fan up to 1000Pa. To precisely adjust the right amount according to the need. And the design needs to use VCDs to help the fan reach the maximum capacity.
Through the use of cold-water valve controls. And the fan speed to control the outlet air temperature.
AHU System Principle of Operation
In fact, the AHU indoor unit is a heat exchanger used to treat air moisture. The air passing through the AHU air conditioning system will be treated to adjust the temperature and humidity levels by thermodynamic principles.
The operation of the AHU system
Cold water will move inside the heat exchanger tube assembly, the airflow will move across the outside. The air is cooled and blown by the fan through the air channel system to the rooms and areas.
The AHU fan is usually a belt-driven centrifugal fan.
– When the temperature inside the room or the area to be cooled is higher than the set temperature. Then the 3-way valve will open to let chilly water flow through the heat exchanger to cool the airflow.
– When the airflow makes the temperature inside the room or in that area lower than the set temperature, the 3-way valve will close, the cold-water flow will follow the bypass to return to the chiller.
– Meanwhile, the air before entering the AHU indoor unit will be filtered through the pre-filter, usually in the form of a coarse filter and bag filter (This department should be cleaned on a regular basis).
– In case if higher cleanliness is required, a HEPA filter can be used.
– The ambient air after passing through the filter will contact the heat exchanger inside the AHU system to create cold air.
– Then it will enter a circulation chamber, finally, the cold air will be blown through the ducts and then to the room, or areas where the air conditioner is used.
– The outlet air temperature will be adjusted by the chilled water valve and depends on the fan speed.
However, most AHU air conditioning systems are not completely authentic. AHU systems are mainly used for the pre-treatment of air flows.
– In order to handle the humidity in an authentic way, people often install additional FCU systems in each specific area.
What is the effect of AHU air conditioning system?
AHU system is usually connected to an HVAC system. This technique is applied in almost all machining industries. Or building areas that require high cleanliness.
The AHU system currently has 2 types and depending on the installation location, we can choose the appropriate type:
– Horizontal AHU type when mounted to the ceiling.
– The vertical type of AHU system is purchased at the time of foundation laying.
Advantages of AHU central air conditioning system
AHU central air conditioners have sandwich panels. The outer metal layer is galvanized inside to give the panel rigidity. The structure of the product is reinforced with an aluminum profile. Fixed with bolts results in a solid and light structure. High heat insulation and good rust resistance increase the durability of the product.
AHU central air conditioning system is manufactured and designed according to Labyrinth’s exclusive patent. The connection of the frame and panel through the joints of negative and positive plates helps insulate heat. Reduces corners to limit air leakage to the outside.
The PU insulation is sandwiched between the panels in a sandwich style. A special insulation method to insulate all internal metal surfaces of the AHU from the outside air. The cold bridge should be eliminated. As a result, the system does not have condensate on the surface and minimizes energy consumption.
The AHU air conditioning system is designed in a modular form. Applies to both length and width. With a flexible and solid structure, it will be suitable for different conditions of the building. Wind flow reaches from 564 m3/h – 15000m3/h. 3000 m3/h 3000 m3/h – 50,000 m3/h. With 3 different ESPs, it will create flexibility and be able to suit many different projects.
AHU central air conditioning system has low noise due to solid structural panels. The blower is statically and dynamically balanced and spring-loaded. The components are closely coordinated to reduce vibration and reduce noise when the device is in operation.
With ARI certificate. This is the high standard for heat exchanger design and manufacture. Calculated based on professional software. Central air conditioning system AHU is designed to meet the test in the laboratory. And real-life applications to the highest HVAC standards.
NOTES
Currently, 3-way valve technology is mostly using actuators. For smooth control of cold-water valves. Because it is an old technology because they can accurately control the opening % of the chilled water valves.
Today, high-pressure fans are replaced by 3-speed fans. With small SHU (FUCU) or VSDs (Variable Speed Drive). Used for fans with large capacity.
The outlet air temperature is controlled by the chilled water valve fan speed.
Most AHUs are not exactly accurate. And pre-treatment of the airflow is the main task of the AHUs. People often install FCUs to have the exact humidity in each area to help achieve the desired effect.
As society becomes more and more modern, the demand for air conditioners is increasing day by day. Therefore, you must know which type of air handling equipment is most appropriate. Let P69 Mechanical Factory help you learn about AHU system and AHU working principal diagram.
Contact information P69 Mechanical Factory
Address: Km 18, Thang Long Boulevard, Thach That Quoc Oai Industrial Park, Hanoi
Office: No. 06/165C, Xuan Thuy, Cau Giay, Hanoi
Phone: 09666 86 969
Hotline: 0989 188 982
Email: kd1@cokhip69.com.vn
Linkedin: https://www.linkedin.com/in/nhamaycokhip69/
Website: https://cokhip69.com.vn/
Youtube: https://www.youtube.com/channel/UCfvFIhhuJ4ANAO0glUPSTAg/ab
