What is AHU?
AHU (Air Handling Unit) is a heat exchanger and humidifier, which cleans the air commonly used in HVAC systems. AHU is used for places where there is a high demand for cleanrooms such as pharmaceuticals, cosmetics, electronic technology,…. Today, AHU systems are heavily popular in commercial buildings, large commercial centers with central chiller systems.
The structure of AHU
AHU is usually assembled from many modules as follows: Mixing chamber, Dust Filter, heat exchanger and fan box. On the mixing chamber there are 2 doors attached to the adjustment valve, one door for fresh wind, one door connected to the wind recovery line.
Dust filters often use a variety of filters such as synthetic fibers that can be folding or fabric bag-style designs (bag filter).
AHU is designed to fit each building differently, but all types of AHU have a common structure including:
– Air filter
– Protective cover
AHU Operating Principles
AHU is essentially a heat exchanger to handle air humidity. The air passing through AHU will be processed to regulate temperature and humidity using thermophysical principles.
Cold water moves inside the heat exchanger cluster, the air moves across the outside, the air is cooled and blown by the fan according to the wind channel system to the rooms and areas. AHU fans are usually belt-driven centrifuges.
*AHU’s operating principles:
When the temperature in the room, or the area to be cooled is greater than the set temperature, the 3-fall valve will open for cold water to flow through the heat exchanger to cool the airflow until the airflow makes the temperature in the room or area lower than the set temperature, the new 3-fall valve closes, Cold water flows through the bypass to chiller. Meanwhile, the air before being introduced into the AHU is filtered through a prefilter unit, usually coarse filtration and bag filter (Should be regularly cleaned). In case of higher cleanliness, use hepa filter. The environmental air after passing through the filter will come into contact with the heat exchanger inside the AHU to create cold air, which will then enter a circulatory chamber, eventually the cold air is blown through the wind pipes and then to the room, or the air-conditioned area.
The output air temperature is regulated by cold water valves and fan speeds. However, in most AHUs that are not absolutely accurate, AHUs are mainly used to preliminarily process airflow. To handle the humidity correctly, it is common to install fcu in each area.
AHU has two forms: Horizontal and vertical. Depending on the location of the installation, we can choose the appropriate type. When setting the background, select the type of standing, when the nap is mounted on the ceiling, select the horizontal type.
Thus, it can be understood that AHU is simply a heat exchanger to cool the air flow through with a fan system, heater and a refrigerator to cool a room, or an area.