AHU’s supply fresh air to the room. The units take air from the outside, filter it and recondition it (cooled by a cooling coil or heated by a heating coil). Where hygienic needs for air quality are lower, the air from the rooms can be re-circulated for energy saving purposes.
An Air Handling Unit (AHU) is used to re-condition and circulate air as part of a heating, ventilating and air-conditioning system. The basic function of the AHU is to take in outside air, re-condition it and supply it as fresh air to a building. All exhaust air is removed, which creates an acceptable indoor air quality. Depending on the required temperature of the re-conditioned air, the fresh air is either heated by a recovery unit or heating coil or cooled by a cooling coil.
In buildings where the hygienic requirements for air quality are lower, some of the air from the rooms can be re-circulated via a mixing chamber and this can result in significant energy savings. A mixing chamber has dampers for controlling the ratio between the return, outside and exhaust air.
AHUs connect to ductwork that distributes the conditioned air through the building and returns it to the AHU. A heat/cooling recovery exchanger is normally fitted to the AHU for energy savings and increasing capacity. An AHU designed for outdoor use, typically on roofs, is also known as a rooftop unit (RTU).
The AHU is a large metal box containing separate ventilators for supply and exhaust, heating coil, cooling coil, heating/cooling recovery system, air filter racks or chambers, sound attenuators, mixing chamber, and dampers.
Components of an AHU. As noted earlier, the main components of an AHU system are its casing or housing, the fan, the heating and/or cooling coil, filters, humidifiers, and mixing box.
Air Handling Unit: Types AHU
Airbox Modular AHU. The units consist of a frame structure with double-walled panels, which are acoustically and thermally insulated.
UTA Airbox without frame.
UTA Airbox with frame.
AHU, which is Air Handling Unit is an appliance used to circulate air. HVAC is Heating, Ventilating and Air Conditioning system. HVAC is the central unit to which AHU is connected. AHU is only a part of HVAC and as such there is hardly any difference between then two.
The AHU 180 mobile air handling unit is versatile and is particularly suitable for outdoor installation, thanks to its aluminum housing. With a maximum air volume of 20,000 m³ and an external pressure of 491 Pascal, this air handler is perfect for ventilation and fresh air.
HOW AHU CFM is calculated?
ACH = CFM x 60 / (Area x Height)
We always get CFM, but that is the volume of air per minute. To calculate air changes per hour, we have to translate that into hours. Hence the multiplication with 60 in the equation above. The volume of a room is calculated by lengthwidthheight.
As is the case with most AHU applications, controls are critical. Electric heaters provide constant heat when power is applied to the elements; therefore, a control panel is always supplied. Electric heaters in AHUs can be provided with three different types of control interfaces.
A fan coil unit (FCU) is a device that uses a coil and a fan to heat or cool a room without connecting to ductwork. Indoor air moves over the coil, which heats or cools the air before pushing it back out into the room.
Thus, a common trait is that the AHU is controlled by one room or zone thermostat only and has no terminal equipment under control. Examples of this system subset would be smaller SZ AHU room fan-coils units (FCUs), packaged DX single-zone rooftop systems (RTUs), and the ubiquitous residential split DX system.
An FCU is not as complex or extensive as an AHU. It’s a singular system that can operate on its own to circulate air in an area without ductwork. One major difference between FCUs and AHUs is that AHUs can bring in outside air and heat or cool it (i.e., conditioning).
Product category:AHU Sensors
PTH-3×02(-DF) Pressure transmitter with analogue output.
PTH-6x0x-2. Dual-input pressure transmitters.
VTH-6202 / VTH-6242. Air quality sensor.
TTH-6202. Duct temperature transmitter.
HTH-6121. Humidity transmitters.
HTH-6200. Humidity and temperature sensor.
EHP. Humidity controller.
F-NVP.
AHU (Air Handling Unit) is a heat exchanger and heat treatment device that cleans the air and is used in HVAC systems or industrial workshops. So how is the structure and working principle of AHU? Please refer to the article below.
STRUCTURE OF AHU
AHUs are designed to fit different projects, but all types of AHUs have a common structure including:
Fan
Heater
Cooler
Air filter
Protective case
AHU’s principle and process of operation
The essence of AHU is a heat exchanger to treat heat and moisture in the air. The air passing through the AHU will be treated to regulate temperature and humidity using thermodynamic principles.
When the temperature in the room, or the area to be cooled, is larger than the set temperature, the 3-way valve will open for cold water to flow through the heat exchanger to cool the air until the air flow makes the temperature inside. If the room or area is lower than the set temperature, the 3-way valve will close, and the cold water will flow through the bypass to return to the chiller.
Meanwhile, the air before entering the AHU is filtered through a pre-filter, usually a coarse filter and a bag filter (Should be cleaned regularly).
In case a higher level of cleanliness is required, use a HEPA filter as well. The ambient air after passing through the filter will contact the heat exchanger inside the AHU to produce cold air, then it will enter a recirculation chamber, finally the cold air is blown through the air ducts and then to the air ducts. room, or area using air conditioning.
The outlet air temperature is regulated by the chilled water valve and the blower speed. However, in most AHUs are not exactly absolute, AHUs are mainly used for pre-processing the airflow. In order to handle humidity accurately, people often install more FCUs in each area.
AHU is simply a heat exchanger to cool the passing air by a fan system, a heater and an indoor unit to cool the clean room.
Medium- and large-sized industrial or commercial properties use an air handling unit (AHU) to condition and distribute fresh air throughout the building. An AHU is part of the larger HVAC system (heating, ventilating, and air conditioning). The device takes air from the outdoors, cleans and conditions it, and heats or cools it as needed. Once properly conditioned, the air is forced through ductwork inside the rooms of the building.
Most AHUs include an additional duct run that pulls dirty air out of the indoor spaces and discharges it back into the atmosphere. In some cases, a portion of the stale air is recirculated into the AHU and again put through the conditioning/distribution process. Recirculating the used air is an energy-saving technique, but it is not an option in every situation.
Maintaining clean and fresh air indoors is especially important considering how much time Americans spend indoors today. In fact, the EPA estimates that most of us spend around 90% of each day inside.
AHUs are most useful in places that must house many people with limited natural ventilation sources, such as convention halls and hotel dining rooms. Units are also helpful for maintaining “clean rooms,” like laboratories and operating rooms.
In addition to managing the proper ventilation of indoor air, AHUs:
Filter and purify the interior air to maintain good indoor air quality
Control indoor temperatures
Monitor indoor humidity levels
AHUs are sometimes located in the basement of a building or on the roof.
Learning how the individual parts of an air handling unit work can help laypeople understand the system’s overall function.
Air Intake – The intake collects air from the outside to be treat and distribute indoors.
Filter – The type of filter depends on the purity requirements of the building. Air intended for a hospital surgical room requires a higher level of “cleaning” than air for a hotel conference room.
Fan – The fan expels the air from the AHU into the duct system that distributes the conditioned air.
Heat Exchangers – These devices transfer temperature between the air and the coolants used by the AHU.
The Cooling Coil – Air passes through the coils to cool before distribution. This process can cause condensation, which the AHU collects in a droplet separator.
Silencer – Special coatings are applied to the unit walls to help reduce the noise level while in operation.
Plenums – Plenums are strategically placed empty spaces within the unit where airflow is allowed to homogenize.
The ultimate goal of an air handling unit is to improve energy efficiency. Heat recovery units and specialized “run around” coils work together to pick up wasted heat and reprocess it through the AHU. This function reduces demand on the heating coils and controls energy use.
In order to save energy while cooling, indoor air mixes with outdoor air, reducing any extreme hot/cold contrast when the air reaches the cooling coil and making it possible for the unit to provide cool air with minimal energy use.
The function of AHU(Air Handling Unit)
- To properly circulate the air inside the room or working place.
- To remove the dust particles and other contamination from the air.
- To maintain Temperature.
- To maintain Humidity.
Applications and Uses of AHU
- AHUs are used in food manufacturing industries, electronic manufacturing industries, medicine manufacturing industries, etc.
- AHU has applications in Hospitals, shopping malls, Goods stores, large buildings, auditoriums, etc.
- AHUs are used in corporate buildings, Server farms, microtechnology industries.
Advantages of AHU
- AHUs are capable to maintain temperature and humidity from a medium place to large places.
- AHUs can be designed to work with a central heating and cooling system. So individual heating and cooling systems do not require for individual rooms. Central heating and cooling system can work with a no of AHUs placed in different rooms or working places.
- Temperature, Humidity, and airflow everything can be possible to control remotely with an automation system by the AHU in a building.
