Air Handling Unit (AHU) - what is it exactly?

Air Handling Unit (AHU) is a ventilation unit used in ventilation and air conditioning systems. The most important task of an AHU is to ensure a good indoor climate. It does this by treating and distributing air to the correct temperature, humidity and purity.

In this article we will look at AHUs in offshore and maritime use.

An AHU can include functions such as air filtration, heating, cooling, ventilation and humidity control. In order to maintain a healthy and comfortable indoor climate, the AHU is an important component.

The HVAC (Heating Ventilation and Air Conditioning) industry uses ventilation units, which are an important part of the entire ventilation system.

What does an Air Handling Unit contain?

An AHU has many components, which play important roles in ensuring it functions optimally. Here are some examples of what is found inside an AHU, and how it works:

1. Fresh air intake: Air from outside is drawn in through an intake, where it passes through a filter. It can be fresh air from outside or recirculated air from indoors, or a mixture of fresh air and recirculated air.
2. Filter: The AHU has one or more filter stages, ranging from coarse to HEPA (High Efficiency Particulate Air), which clean the air by removing dust, pollen and particles. This ensures that clean air is circulated in.
3. Heating and cooling: After filtration, the air can be treated to achieve the desired temperature. The air passes through heat exchangers (coils) that either heat or cool the air, depending on whether heating or cooling is required in the AHU. This can be done with water-borne systems (hot/cold water) or electric heating elements. All cooling coils must have a droplet separator to avoid moisture transport.
4. Fan system: One or more fans in the unit move the air through the system and send it into the ventilation ducts, to circulate around the ventilation unit. The fans can vary in speed to adjust the airflow based on demand.
5. Humidity control (humidification/dehumidification): The AHU may also have a section that controls the humidity. The humidification system adds moisture if the air is too dry, while the dehumidification system removes excess moisture from the air.
6. Air recirculation: Some AHUs may have an indoor air recirculation section, where some of the existing air from the unit is mixed with fresh air from outside. This reduces energy costs, especially during the winter months.
7. Exhaust: After the air has been treated, it is sent through the ducts to different sections of the ventilation system (air diffusion terminal elements). The precise air flow is controlled by dampers that ensure that the duct system is balanced. At the same time, used air is exhausted (often via exhaust fans) from the AHU to maintain proper air quality.

How is an Air Handling Unit used in the offshore industry?

The offshore industry requires high quality units that will operate for many years in a harsh environment. Certifications are often required for the areas where the AHU will be placed. This is to increase safety and operational efficiency in challenging environments.

An example of a challenging environment was when Nordic Steel and Novenco Marine & Offshore delivered two Air Handling Units to the production vessel Johan Castberg, in the Barents Sea. Novenco's complex design was manufactured and assembled by Nordic Steel in Bryne.

To withstand arctic weather conditions, the ventilation units were a fully welded weatherproof construction, with tailored technical details to prevent icing. They were manufactured in acid-resistant steel, a type of stainless steel that is highly resistant in corrosive environments, such as in maritime environments or the oil and gas industry.

Read more about the project here.

Can be produced on request

Nordic Steel has all the certifications to supply equipment that the oil and gas industry needs. All production is delivered with full documentation.

Air Handling units can be manufactured in all sizes. For more information, you can read about Novenco's Air Handling Units here , or contact us on our website.

Sources: Novenco Marine & Offshore