What is Air Conditioning?


Air conditioning is part of the terminology that we often use - HVAC.

A complete set of equipment should be able to alter air temperature and humidity, circulate and mix air, as well as filter and purify air.

Nevertheless, the equipment can be used to serve any of the functions specified, separately.

By TS Mohamed Rasied

It is a subset of HVAC (heating, ventilation and air conditioning). The ultimate purpose of HVAC, is to provide comfort for our everyday living.

Let's go through some explanation on "H" and "V" part, before going into "AC" section.

The "H" part in HVAC, stands for heating.

This heating is associated with radiators, furnaces, fire place stoves and electric heating. Radiators are fed with hot water from boilers, fire place and stoves provides radiant heat by burning wood or coal, furnaces heat up a given space by means of fossil fuel burning, and electric heaters use the principle of electrical resistance to generate heat.

Heating is used mainly in very cold areas.

"V" stands for ventilation in HVAC.

Ventilation topic relates to air circulation and movement between an open space, and an enclosed space. It is possible to achieve this by means of natural occurrence, or by means of forced ventilation. Equipment that aid ventilation include chimneys, blowers, eductors, and ventilators.

Purpose of ventilation is for safety of occupant in a space, as well as comfort. It is especially useful in case of fire.

Finally, "AC" is a short form of, air conditioning.

Contrary to popular belief, it is not just about refrigerant filled air conditioners. The word "conditioning" itself, suggests that, air conditioners should condition the air, to reach comfort level of occupants in a room.

The equipment should do any, or a combination of the following, to reach comfort level,

  • Alter air temperature by means of cooling or heating,

  • Alter air humidity,

  • Circulate and mix air,

  • Filter and purify air

Not only that, air conditioners can be coupled with heating, and ventilation - especially with central air conditioners. Into details,

Alter air temperature by means of cooling or heating

Equipment, which can alter air temperature, by means of cooling is known as air conditioner. It is called a heat pump, if it is used for heating.

However, a heat pump is suitable for heating, only if the temperature do not go down to extremes. As such, a supplementary heating equipment (the "H" part) will be used - be it a heating strip, furnace, or radiator.

A mechanical cycle air conditioner, is an equipment with compressor, condenser, expansion valve, evaporator, and tubes, filled with refrigerant.

Alter air humidity

A conventional mechanical ACs can alter humidity. When it is used for cooling, it will also dehumidify. A heat pump will alter relative humidity as it heats up the air.

However, there are equipment built specifically for humidification, and dehumidification. These are humidifiers, and dehumidifiers.

A humidifier will add in water vapour into air, to cool down hot and dry climate areas. A dehumidifier, will be very useful in very mild air temperatures, with high humidity. Humidifier's parts are same to an air conditioner, but the construction is different, such that air will be cooled, moisture removed, and reheated before discharging it to the room.

Circulate and mix air

Stale and stagnant air is no good for you health - let alone the uncomfortable feeling. Air circulation can be achieved with the simplest equipment - fans. Air draft will continuously displace warm air near your skin, and aid evaporation and hence, provide skin cooling by means of evaporation.

Air circulation for whole building, would require ducts and blowers. This combination is used mainly with central air conditioners. Conditioned air will be circulated to designated areas. It is also designed to take in fresh air, and expel some of used air, for ventilation purposes - the "V" part.

Filter and purify air

Most conditioning equipment, is fitted with filter as a package, or separate installation. Main reason - to filter out dust in air.

Air purification can be achieved by means of activated carbon (for odour removal), UV light (for removing germs), and HEPA filters (high efficiency particulate air).

AC is essential in our life, especially in extreme temperature areas, or even for the sake of air circulation and purification.

TS Mohamed Rasied,
Provides information on air conditioners and air conditioning in her site,
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