TechFriday(How it Works): Air Conditioners

Photo Credit: allareaappliancellc

Many of us, especially those living in the warm & hot regions, have air conditioners (AC) installed in our houses and offices. Even our cars has for long been using AC’s also. Some of us might have wondered how it works. How does it actually make our rooms and cars so cool?!
Wanna know why? Just read on!

How Air Conditioners Work

The working process of an air conditioner can be likened to that of a refrigerator. The only difference is that the refrigerator cools a small, insulated compartment while AC’s cools larger spaces like your rooms, offices and cars. To understand how it works, it is important we know what it’s made of.

Main Components of AC’s

There are two common types of air conditioners: window systems and split systems. The window system is single device that is normally hung on walls by inserting them in a fitting window on the wall.
A split system carries two units; the indoor unit and the outdoor unit. As the name implies the indoor unit is placed in the house and the outdoor unit placed outside.

But regardless of the types, air conditioners mainly consist of four parts;

• The Compressor
• The Condenser
• The Expansion Valve
• The Evaporator

The compressor and condenser are located in the outside part of the AC (outdoor unit for split systems) i.e outside the house while the evaporator is located inside part of it (indoor unit).

Compressor

The compressor can be regarded as the heart of the air conditioner. Its basic function is to circulate the refrigerant necessary for heat exchange through the coils of the condenser and evaporator, and to apply energy to the refrigerant. It is consumes most of the electrical power used for running AC’s.
A refrigerant is a substance used in refrigeration and cooling. It undergoes phase transitions from a liquid to a gas and back again. Examples of refrigerants are HFCs (Hydrofluorocarbons) e.g R-410A, HCFCs (Hydrochlorofluorocarbons) e.g R-22 and HCs (Hydrocarbons) e.g R-290 and
R-600A).

The compressor compresses the gaseous refrigerant which raises the refrigerant’s temperature and changes it to a high pressure gas.

Condenser

As the name implies, a condenser is used for condensing the gaseous substances into a liquid by cooling it. It receives vaporized refrigerants from the compressor, condenses it to liquid and releases the heat outside.

The Expansion Valve

This is located between the condenser and the evaporator. It controls the amount of refrigrant entering the evaporator.

Evaporator

The evaporator works in an opposite like manner to the condenser. It evaporates/vaporizes the refrigerant from liquid state to gas and absorbs the heat from the area to be cooled.

Working Principle of the Air Conditioner

.Photo Credit: Tamilmani - Quora

Since we now know the different major parts of the air conditioner and what they do, we can put it all together to describe the working principle of air conditioners.

The basic principle air conditioners employ is the collection of hot air from an area, process that hot air with the aid of a refrigerant and some coils, and then releases it as cool air back to the area hot air was collected from.

The hot air is drawn through a grille located at the base of the inside part of the air conditioner (indoor unit for split systems) and allowed to flow over some chiller pipes through which the refrigerant (coolant) is flowing. The refrigerant absorbs the heat and vaporizes to become a hot gas. The hot refrigerant gas then flows into the compressor which compresses (squeezes) it and the molecules in the liquid are packed closely together which gives a rise in the temperature and energy of the gas.

The gas, which now possesses a high pressure and temperature, travels to the condenser which then condenses it to become a liquid and become cool because the heat in it is dissipated as hot gas through some metal fins/plates. These metal fins work like the radiator on a vehicle and help to dissipate the heat more quickly. This is aided with the help of an electric fan which blows air past them.

The liquid makes its way to the evaporator through an expansion valve (a minuscule narrow hole which regulates the flow of liquid refrigerant into the evaporator), where it absorbs heat and change phase from a liquid into a low-pressure gas. The cooled air is then delivered to the house through ducting. The refrigerant then flows back to the compressor where the cycle starts over again.
There is a fan that’s connected to the evaporator, and it circulates air around the inside of the property and across the fins of the evaporator.

This process continues until the air inside the area reaches the desired temperature that was set in the air conditioner and stops with the aid of a thermostat. The process continues again when the thermostat senses that the temperature in the given area is different, in this case higher, than the one set by the user.

I hope you found this interesting, enlightening and useful. You can please follow me for more of my FridayTech series and other of my posts.

Thank You.

References

• Quora - How does an air conditioner work?
• Scienceabc - How does an air conditioner work
• Explain that stuff - Air Conditioners