How does air conditioning work?

We have been talking about air conditioners a lot recently. We have tried to cover various aspects of air conditioning and how the technology affects you.

Today, our post will go back to focusing on the basics. Let us find out how the technology actually works. Hopefully this will help you in better understanding of this common household technology and make you better equipped with information that you need before you purchase your next home air conditioner.

Air Conditioning Basic Principles

Air Conditioners schematic
Air Conditioners schematic

Air conditioning uses refrigeration technology to chill indoor air. This chilling of indoor air happens by making use of a very interesting physical law. This law states that when a liquid converts to a gas, it absorbs heat. Air conditioners make use of this law by using special compounds which are made to evaporate into gases. As they change their state from liquid to gaseous, these chemicals are able to absorb large amounts of heat from the indoor environment.

What are refrigerants

These special compounds used in air conditioning are called refrigerants. Refrigerants are chosen for their ability to change from a liquid to a gaseous state at relatively low temperatures. Imagine trying to use water as a refrigerant. Since water requires a lot of heat to change its state from liquid to gaseous, it would be very difficult to heat up the water flowing in your air conditioner to a point where it boils.

The process of refrigeration

The actual process of air conditioning happens when hot air flows over the evaporator coils of your air conditioner. The evaporator coils have the liquid refrigerant inside. The liquid refrigerant absorbs the heat from the hot air and then changes its state from a liquid to a gas. It is important the the evaporator coils of your air conditioner transmit as much of the heat from the hot air to the liquid refrigerant as they possibly can. This can be done if the material of the evaporator coils is a good conductor of heat.

You might have seen many air conditioners advertise themselves as having 100% copper coils. I hope you can now guess as to why this is important. Copper is one of the best heat conducting metals available. Silver is the absolute best but the prohibitive cost of silver makes it impossible to be used. Copper comes in at a close second in the best heat conducting metals list. An alternative metal that is used is usually aluminium mostly due to cost concerns.

Once the hot air is cooled down to a lower temperature, it is sent back into the room and thus the overall temperature of the room comes down. The refrigerant meanwhile has turned into a gas and has absorbed heat from the hot air within the room. The refrigerant is now sent to another set of coils which are called the condenser coils.

In the condenser coils, air is blown over the coils as the gaseous refrigerant is circulated through them. The air blowing over the condenser coils now absorbs heat from the gaseous refrigerant and becomes hotter. This hot air is finally dumped out into the external atmosphere.

What does a compressor do?

The cycle of refrigeration works only when the refrigerant is available in the liquid state. In this state, it can be changed into a gas by absorbing large amounts of heat from within the room intended to be cooled. Once the refrigerant changes into a gas, it has to be brought back to a liqud state. To do this, a compressor is employed.

A compressor works by forcing more and more of the gaseous refrigerant into a confined space. By doing this, the pressure within the container increases. At a sufficiently high pressure, the gaseous refrigerant changes back into a liquid. At the end of this conversion, the refrigerant is ready to be used again to absorb the extra heat from the room.

What is the role of a thermostat?

The thermostat plays an important role in your air conditioner. We all have different temperature levels at which we feel comfortable. We can set this temperature on the air conditioner by using the temperature controls. The question then remains, how does the air conditioner know when the target temperature is reached? The answer of course is that it uses the thermostat.

The thermostat is a device which signals to your air conditioner that the desired temperature has been reached. Once the theromostat is triggered, the compressor on your air conditioner slows down or completely shuts off depending on the technology present inside it. The thermostat however, is active at all times and is measuring the temperature of the air that is coming in. In case the temperature of the air coming in is measured to be higher than the set temperature, the thermostat sends out a signal again and your air conditioner gets to work in cooling the room.

In older air conditioners, the thermostat was a mechanical device. It took advantage of the property that metals expand differently due to changes in temperature. Today’s thermostats however are electronic and made of semi-conductors. This makes them much smaller than before and helps them in being more accurate as well.

How is Air Conditioning evolving

Air conditioning has been around for almost 100 years now. Despite this time period, significant innovations in the technology have been few and far between. Even then, there has been an evolution in the technology. Let’s see what are some of the most significant changes to air conditioning that have come about.

The Inverter Air Conditioner

Air Conditioners
Air Conditioners

In our mind, inverter air conditioners have been the most important upgrade to air conditioners in the past few decades. An inverter air conditioner improves upon the efficiency and effectiveness of a traditional air conditioner. In a traditional air conditioner, the compressor has two settings only – on and off. When the compressor is on, it runs at full speed and when it is off the air conditioner is not producing any more cold air.

Inverter air conditioners have improved upon this technology by making compressors run at variable speeds. With this setting, the air conditioner does not have to be completely off at any point in time and can keep your room consistently cool for a very long time.

Inverter air conditioners are fairly widely used today. If you are on the lookout for purchasing a new air conditioner, make sure you are getting an inverter air conditioner only. This way, you will get better cooling and save money on your electricity bills.

Usage of environmentally friendly refrigerants

Refrigerants are the most important chemical to be used in an air conditioner. Upto the 1980s, a class of chemicals called ChlorFluoroCarbons And HydroChloroFluoroCarbons of CFCs and HCFCs were used most frequently as refrigerants. Despite being well suited for the job of being refrigerants, both these class of chemicals have a massive flaw. They are both absolutely deadly to the ozone layer.

The ozone layer, as you must be aware is vastly important for humans, plants and animals on earth. It plays a very important role in blocking ultra-violet rays from the sun. These rays are extremely harmful for all living beings on the earth. They are known to cause skin cancer, cataracts and other ailments in human beings. The depletion of the ozone layer was discovered by NASA when they found a massive hole in the ozone layer in the 1970s.

Since then, with concerted action by countries from around the world, dangerous refrigerants have been banned. The ozone layer is also healing and it has been reported that the hole is at its smallest ever after its discovery.

Split Air Conditioners for home usage

For the longest time, the only available air conditioning unit for home usage was the window air conditioner. The window air conditioner is a large unit which has the refrigeration and the waste heat removal in the same unit. Due to its large size, these air conditioning units can only fit in windows of certain sizes and beyond. This often leads to many homes needing to be modified to fit the air conditioner.

Thanks to split air conditioners however, such costly and time consuming modifications can be avoided. The split air conditioner like its name suggest splits up the duties of the air conditioner across two different units. Cooling is done via one of the units which is placed inside the room that needs to be cooled. The waste heat expulsion is done by a separate unit. This unit is placed outside.

Due to this unique configuration, the split air conditioner has a much lower space requirement than a window air conditioner. The cooling unit of the split air conditioner can be mounted on the wall which also leads to saving of floor space and also helps in cooling the room faster, especially if the unit is placed higher up. Hot air usually rises and mounting the air conditoner high up on the wall ensures that it first tackles the hottest air within the room.

The other unit can be conveniently placed outside. This unit is the one which expels the additional heat that has been absorbed by the refrigerant. This unit is also usually more noisy so having it outside the home ensures that the audio disturbance to home occupants is minimized.

How do home air conditioners work – wrap up

So there you have it, our quick article to give you some information on home air conditioners work. We hope you found this useful. Please let us know your thoughts anywhere in the comments!

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