The following are some of the most common types of ventilation systems:
1) Mechanical Ventilation System (MVSS): These are used in factories, offices, hospitals and other industrial environments where there is no space for air circulation.
They are very efficient and they provide good quality of life to workers. However, it is not possible to have them in every room or even in all rooms.
2) Natural Ventilation System (NVS): NVS consists of two parts: 1) the fan itself and 2) the filter.
The fan is installed at the top of the room to be ventilated. Its main job is to suck air from the bottom of the room.
The electronic filter filters out all pollutants and expels them outside. This kind of ventilation is common in nature. It has been successfully implemented in buildings, especially in those with a lot of glass.
3) Cross Ventilation: This is a traditional form of ventilation where fresh air is brought into the building through one side and vented out from another side.
The most common is when one side of the building faces the wind and the other faces the open space such as a courtyard. This is by far the cheapest and most common form of ventilation.
4) Quarter Ventilation: this is a modern type of cross ventilation.
In this system, there are four sides to the building which are open. The air is allowed to flow through the building freely in any direction.
5)Night Ventilation: the system works at night, when the temperature has dropped to a comfortable level. At night, the system opens all windows in the building to allow for a through circulation of air.
6) Day-night Ventilation: this is a modern system which takes advantage of both day and night ventilation. At night when the temperature has dropped, the system opens all windows to allow for a through ventilation of air.
During the day, the windows are closed and the system works as an air-conditioning unit.
7) Cross-flow system: In this system, there is a fan which pushes the air from one end of the room to the other end.
It doesn’t have any supply or exhaust.
8) Balanced-Pressure System: it is a little similar to cross-flow system.
In this system, there are two exhaust fans and two supply fans. The exhaust from the first supply fan is vented out through one of the exhaust fans while the second exhaust fan vents out through the second supply fan.
This system provides even distribution of air throughout the room.
9) Energy-recovery system: in this system, the exhaust air is channeled back to the room.
The air is first warmed up using heat transfer mechanism and then vented back into the room. This system is very efficient and can reduce energy consumption by up to 40 percent.
10) Down Draft System: this system is widely used in restaurants and bakeries. It involves the use of a vertical exhaust fan which sucks out all air and pollutants from the room.
It is connected to the supply system through a duct.
There are several advantages and disadvantages of using fans and ventilators. Fans are extremely cheap.
They are very affordable and one can be acquired for as little as ten U.S dollars. They are also very light and can be placed anywhere in a room. On the other hand, they are less efficient in removing pollutants as compared to ventilators and they have to be turned on all the time. For this reason, they increase the electricity bills. Ventilators, on the other hand, are more efficient as they have filters and can be turned on when needed. They are also heavy and are more expensive.
They can also be a hazard to children if not placed at a high enough place.
There are several types of filters widely used in ventilators and fans.
1) The most common is the electrostatic filter.
It is made up of a thin layer of wire mesh to which copper or aluminum foil is attached. When the air is forced through this filter, some of the particles become charged thereby making it easier for the oppositely charged foil to attract them.
This type of filter is usually found in computers and AC units.
2) The second type is the filter which uses ions.
In this system, air is forced through a wire mesh substrate to which a small amount of mercury is added. The charged ions formed as a result of this process capture the small particles in the air.
3) The third type is the filter which uses activated carbon.
The air in this system is forced to flow over a block of activated carbon. Pollutants get trapped on the porous surface of the carbon.
4) The fourth type is the filter which uses gases.
This system uses gases such as ammonia and propane to clean the air. The air passes through the filter and the pollutants stick to it.
5) The fifth type is the filter which uses steam.
This system heats up the air and the pollutants become less volatile and fall down as dust.
6) The sixth type is the filter which uses membranes.
These filters use a thin layer of synthetic membrane that allows air to pass through but not the pollutants. It is most commonly used in the medical industry.
1) EC technology: EC technology stands for electrostatic.
In this method, air is forced through a wire mesh to which an electric charge has been applied. The oppositely charged dust then sticks to the mesh.
2) ION technology: in this method, air passes through a wire mesh substrate to which an electrical charge is applied.
Since the air itself is neutral, the only way it can flow through is if a negative charge develops on one side and a positive charge on the other. Any dust in the air becomes charged as it passes through, and the oppositely charged dust then clumps together.
3) HEPA technology: stands for high-efficiency particulate arrestance.
Air is forced through a very fine mesh of metal, plastic, or synthetic materials. The mesh is so fine that all but the smallest particles can pass through it.
This method can be used on its own or in combination with any of the other methods.
4) Gas phase technology: in this method, air is forced through a container of gas such as ammonia or propane.
The pollutants become less volatile and fall down as dust.
5) Hotwire technology: this method is sometimes used in the medical industry.
It uses a network of wires that are heated by electric current passing through them. The pollutants become less volatile.
6) Mechanical filtration: this method uses a fan to force air through a series of filters.
Sources & references used in this article:
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Basic concepts in mechanical ventilation by C Carbery – Journal of perioperative practice, 2008 – journals.sagepub.com
Concept of operations for triage of mechanical ventilation in an epidemic by JL Hick, DT O’Laughlin – Academic Emergency Medicine, 2006 – Wiley Online Library
Classification of hybrid ventilation concepts by P Wouters, N Heijmans, C Delmotte, L Vandaele – IEA Annex, 1999 – researchgate.net
A non-ventilated solar façade concept based on selective and transparent insulation material integration: An experimental study by M Čekon, R Slávik – Energies, 2017 – mdpi.com
Pilbeam’s mechanical ventilation: physiological and clinical applications by JM Cairo – 2015 – books.google.com
Unplanned extubations in the adult intensive care unit: a prospective multicenter study by T Boulain… – American journal of …, 1998 – atsjournals.org