How Air Conditioners Work

Now-a-days air conditioners have become very common and can be found everywhere from home, offices, shopping malls to even vehicles. Air conditioners may be luxury for some but it is an important invention for people living in warm climatic conditions and where the humidity levels are very high. Air conditioning was invented by an American genius Willis Carrier in the year 1902. Air conditioner is used to provide cool breeze in burning hot summers, they also control the humidity and the temperature. But how air conditioners work

Working principle of air conditioner

Air conditioner works on the same principle as Refrigerators does. It uses refrigeration cycle to provide cooling. Before understanding Air conditioning let’s get into some basics, we are often using the word cooling but how cooling works? Cooling, in the sense we are not cooling the room or object but instead we are removing or transferring the heat from that object or room to some other place. Each and Every matter on the earth has some heat energy in it and removing or transferring that heat from the matter makes it cool. Air conditioning systems does the same; it just transfers the heat from one place to another by using Phase Conversion technique which is achieved by refrigeration cycle.

Working principle of air conditioners

Working principle of air conditioners   (Extracted from youtube)

If you are not aware, there are two forms of heat energy:

Sensible Heat: The heat which can be measured or sensed is said to be as Sensible Heat. Like the body heat, this can be measured by a thermometer.

Latent Heat: The heat which cannot be measured is called as Latent Heat. It changes the property of an object. Consider a water vapor, if latent heat from water vapor (vapor) is removed it changes (condenses) to water (liquid), and if enough latent heat is removed from water it transform to ice (solid) or it freezes. Change of state from vapor to liquid or liquid to solid is called Phase Conversion.

The heat is transferred quickly when an object changes its state i.e., from one form to another. Air conditioning systems use refrigerants for Phase Conversion.

Components of Air Conditioner

Compressor – It compresses and converts the low pressure (temperature) refrigerant or gas to high pressure (temperature) refrigerant or gas.

Condenser – The high pressure (temperature) refrigerant enters into the condenser coils where the phase conversion process takes place i.e., conversion of high pressure refrigerant to cold liquid.

Evaporator – The cold liquid enters into the evaporator coils which absorbs heat from the air and produce cool air and one more phase conversion takes place i.e., conversion of cold liquid to vapor.

Expansion Valve – The valve is placed between the condenser and evaporator to regulate the flow of refrigerant between condenser and evaporator.

Indoor Fan – It exhausts hot room air and gives back cool air after passing through evaporator coils.

Outdoor Fan – It takes low temperature outside air and gives back high temperature air after passing through condenser coils.

How Air Conditioners work

The compressor in the air conditioner compresses the refrigerant (a gas); due to compression the gas becomes hot and develops high pressure. This high pressure refrigerant passes through the condenser where the heat from the refrigerant is absorbed and condenses it to liquid. The refrigerant has the property of changing its state even at low temperatures. As we know, when an enough amount of heat is removed from the gas it condenses to liquid.

How Air Conditioners work

How Air Conditioners work

Now the cold liquid flows through the evaporator coils, the indoor fan placed behind the evaporator coils exhausts the room or indoor air and blows that air over the evaporator coils containing the cold liquid. Thus when the hot room air passes through the cold evaporator coils, the heat from the air is absorbed by converting the cold liquid inside the evaporator coils to gas and finally we enjoy the cool air that enters into the room through indoor fan.

Now the low pressure gas enters back into the compressor and the temperature and pressure of the gas is again increased creating unwanted heat which is evacuated using outdoor fan placed behind the condenser coils and the cycle continues. This is how the air conditioners work.

Types of Air Conditioners:

Depending upon the use and requirement the air conditioners are designed. There are almost four types of air conditioners available in the market today.

  1. Window Air Conditioner
    Window Air Conditioner

    Window Air Conditioner

    It is most commonly used and will be sufficient for a single room. It is cheap when compared with other type of air conditioning systems.

  2. Split Air Conditioner
    Split Air Conditioner

    Split Air Conditioner

    It is used to cool a hall or two small rooms. As the same says, Split, the components splits into two parts. The indoor unit consists of evaporator and cooling fan, whereas the outdoor unit consists of compressor, condenser, and expansion valve.

  3. Packaged Air Conditioner
    Packaged Air Conditioner

    Packaged Air Conditioner

    It further consists of two more types. Air cooled Condenser system and water cooled condenser system. In the air cooled condenser system, the condenser is cooling using water and in water cooled, the condenser is cooled using atmospheric air. These are mostly using in Shopping Malls, Banquet halls, Restaurants, etc. The air is supplied using ducts.

  4. Central Air Conditioner
    Central Air Conditioner

    Central Air Conditioner

    It is also further divided depending upon the requirement. Like chilled water systems. These are used in Airports, High Rise buildings, Skyscraper, etc. These systems consist of Air Handling Units (A.H.U), Fan Coil Units (F.C.U), Chiller Plant, etc. In this instead of using refrigerants, cold water is used. The water is cooled at chiller plant and is supplied through pipes or ducts and a F.C.U is installed into the room which blows warm air on the pipes thus removing heat from the air and making the room cool.

What is TON in Air Conditioner?

In Air conditioner, 1 TON = 12,000 BTU. The capacity of air conditioners is rated in British Thermal Units (BTU). It is the amount of energy required to cool 0.45 Kilogram of water by 1 degree Fahrenheit.

How does air Conditioning affect the environment?

Refrigerants like Freon are causing damage to Ozone Layer. These gases when escapes reach to the upper atmosphere and making holes to ozone layer which shields the earth from harmful UV radiations. These gases are also responsible to global warming. Formerly CFCs (chlorofluorocarbons) were used as refrigerants but HCFCs (hydro chlorofluorocarbons) are used which depletes 95% less ozone layer.

How does air Conditioning affect the environment

How does air Conditioning affect the environment

The air conditioner when maintained properly can be save your life from heat stroke and hyperthermia. But these can also cause damage to your health if you use unclean filters. The use of unclean filters allows the bacteria from outside and damages your indoor air quality which in turn can cause allergies and asthma problems.

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