Air handling units. Equipment components. Air filtration. Advantages.

Ventilation is the process of replacing the exhaust air in a room, which is saturated with carbon dioxide, with fresh air. Ventilation happens:

- natural (ventilation);

- mechanical (forced air exchange with the help of specialized equipment).

Advantages of using special fresh air supply equipment (supply and exhaust units) in everyday life:

1. 24 hours a day – freshness, comfortable sleep, no unpleasant odors and stale air.
2. Silence. Not every person lives in a private house and the problem of open apartment windows in the summer, especially at night, is familiar to everyone.
Domestic air handling units have a very simple design, which consists of a housing, two fans (supply and exhaust), a heat exchanger and a filtration system.

A heat exchanger is a device with the help of which the heat that is in the room (exhaust warm air) is transferred to the fresh air that enters the room, thereby saving up to 90 % on air heating! energy for the operation of ventilation equipment in winter. The recuperator is also called a heat exchanger.

Types of recuperators:

- lamellar;

- rotary;

- glycolic.

Rotary and glycol heat exchangers are not found in domestic ventilation systems.

A rotary heat exchanger is a «wheel» containing many small plates inside, which are heated by the heat of the exhaust air, and due to the constant rotation of the rotor, the warm part of the wheel turns to the supply air, where heat is transferred. The efficiency of a rotary heat exchanger reaches 93 %, and at high air flow rates (from 10,000 m³/h), it usually has a more pleasant price.

A glycol heat exchanger consists of two heat exchangers that are «closed» to each other, and a mixture of glycol and water constantly circulates between them (glycol is an antifreeze liquid). One heat exchanger is located on the extract air side, the other on the supply air side. It is used in medicine and some technologies where air flow is prohibited (mixing of supply and exhaust air), for example, operating rooms. The efficiency of such a heat exchanger is low, up to 30 %.

The plate heat exchanger is the most common type of heat exchanger. In 99 % of cases, it is who is used in domestic air handling units.

The device separates the air flows with the help of many plates, which carry out heat transfer.

There are several types differing in shape and material.

Conventional square-shaped plate heat exchangers have an efficiency of up to 65 % (at maximum temperature difference and low air velocity).

Hexagonal heat exchangers have a large area without taking up much more space, the efficiency is much better – up to 90 %.

The choice of heat exchanger material is also important:

- budgetary – «paper» recuperators, a mixture of paper and cellulose. They are quite effective (up to 75 %), but they are afraid of hitting a large amount of water, short-lived.

- expensive – aluminum recuperators. The most reliable, almost eternal recuperators, but not the most efficient (up to 65 %).

- the golden mean – plastic recuperators, which, with proper operation and piping, will last no less than aluminum ones, have an efficiency of up to 80 %, and are not afraid of water. Such a heat exchanger can be safely removed from the installation, washed, allowed to dry and installed back. The only thing to consider when using is protection from too hot air.

Air filtration.

Most air handling units are equipped with a pre-filter to protect the internal elements from getting into them large particles or the same leaves. In some cases, manufacturers equip a more serious filtration system, up to H13 (the maximum degree of air filtration), and electrostatic filters that purify the air from the finest dust (up to 0.01 microns), including soot and tobacco smoke. Installations with such a filtration system, in addition to the task of air exchange, perform the function of air purification.