What Is Air Conditioning
What is Air Conditioning
Air conditioning is the human attempt to control the climate in an enclosed area and to lower and maintain a temperature that
is comfortable to the people in that space. We use air conditioning units in business premises, public areas and our homes and also within both
our public and personal motor vehicles to help us keep cool in the hot summers. There are different terms used to describe air conditioning such
as climate control, heating and ventilation controls, aircon and A/C are the most common.
Although these systems are used in many places by many people not everyone knows how a unit works and functions to give us the desired results we
need. There are differences between the systems and components used in the units for buildings and the ones used for vehicles but the basic
principles are the same. The phases of changing a gas to a liquid and back through heat and cooling is how we achieve this. First we need to look
at the basics of the components and the science needed to accomplish this cooling and heating of the area.
Firstly is the refrigerant that is used in the heat and cooling cycles and it is this that undergoes a phase change from a gas to a liquid and
then back to a gas, this cycle repeats constantly as the refrigerant travels through the system. The most widely used refrigerants were R 12 and
R 22, R-12 being more common in automotive air conditioning and in some small refrigerators and R-22 being used widely for residential and
commercial air conditioning including refrigerators and freezers. The concerns for the deletion of the ozone layer has led to changes in the
gasses that are now used as refrigerant agents and R 12 and R 22 is being fazed out mainly because they are CFCs and harmful when released into
the atmosphere. The new blends and replacements are already in production with R 134a and R 410a at the forefront and although the other types
are still available they will be disused in the near future. The ideal properties of a refrigerant are that it is non-corrosive and safe and that
it has good thermodynamic properties.
For buildings the systems consist of two main units that are connected together where one part is indoors and one outside the building, there is
a compressor in the outdoor unit that compresses and pumps the refrigerant which changes into a high temperature and high pressure gas, as that
gas flows through the outdoor coil it loses heat and condenses into a high temperature, high pressure liquid. The liquid refrigerant travels
through copper tubing into the evaporator coil where it expands, the sudden expansion turns the refrigerant into a low temperature, low pressure
gas. Air passing through or over the evaporator is cooled as the gas absorbs the heat from the air circulating around it; the cooled air is
pushed through ducting into and around the building. The heat absorbed by the refrigerant is carried back to the condenser located outside
through copper tubing and subsequently released into the outside air. This cycle is constantly repeated to maintain the correct temperature
within the building. A thermostat is used to alter the amount of the circulation necessary for the temperature adjustment. Modern systems use
complex electronics and computer programmes to maintain a specific temperature but the basics are generally the same. As the evaporator
temperature changes condensation is produced and water forms and needs piping to direct it safely out of the system.
This is a diagram of the basics of an air conditioning and heating system used for buildings and homes.
There are many different types of units available and one popular choice for homes and apartments is the portable or window air conditioning unit
which although still has the same principles and basics is used purely for cooling purposes especially on hot summer days. These are generally
much smaller that the diagram above and quite compact in construction but have similar components less the heating facilities and are very
efficient in the cooling of warm and even hot air within a confined area such as a room.