Split AC working principle/Split air conditioning system

Split air conditioning system:

  • It is known as the Split AC because it consists of two parts.
1) Indoor unit:
  •  It is known as indoor unit because it is always installed inside the room and provides cooling.
2) Outdoor unit:
  • It is known as the outdoor unit because it is always installed outside the room.
Split AC working principle/Split AC system

Parts of the Indoor Unit:

  • Evaporator coil: It is used as a cooling coil. When room air passes over the evaporator, it absorbs heat from the room air which leads it to cool.
  • Blower: It is used to extract the hot air from the room and this hot air comes in contact with the evaporator, which helps to reduce the temperature of the hot air after that it is supplied to the room with the help of blower.
  • Air filter: It is used to remove the dust particle from the air. It is fitted in between the return air grill and evaporator.
  • Front Panel: It has two parts.
           a) Return air grill: Through this path, the blower is able to extract the hot air from the room.
           b) Supply grill: Through this path, blower supplies cool air to the room.
  • Drain Tray: When hot air passes through evaporator continuously, condensation forms and it falls down. To avoid shutdowns and condensation leaks in air condition, we use drain tray and here it collects condensation water and it is thrown outside with the help of drain pipe.
  • Control panel: Using the control panel, we can switch ON/OFF the system and also increase/decrease the temperature according to our comfort zone.

Parts of the outdoor part:

  • Compressor: It is used to increase the pressure and temperature of the refrigerant. It is also known as the heart of the refrigeration cycle.
  • Condenser: It is used to reject the heat to the atmosphere, due to this both pressure and temperature of refrigerant decreases.
  • Propeller fan: It passes ambient air through the condenser which takes heat outside to the atmosphere.
  • Expansion Device: It is used to decrease the pressure.

 Types of split AC:

  • 1) High wall unit
  • 2) Ceiling mounted unit
  • 3) Floor mounted unit

Working principle of Split AC:

Note: In split AC, indoor and outdoor are connected through copper pipe.

Basically, it works in two different processes.

  • 1) Refrigeration cycle process
  • 2)Air circulation process.

Refrigeration process:

When we switch on the unit using the thermostat, the compressor starts to compress the refrigerant then the temperature and pressure of the refrigerant increases and it flows to the condenser. Condenser rejects heat and converts vapor refrigerant to liquid refrigerant. Then it passes to the expansion device, here temperature decreases due to a sudden decrease in pressure. Then this low temperature and pressure liquid refrigerant pass to evaporator inside the copper tube. As we know indoor and outdoor is connected by copper pipe and expansion device is fitted in outdoor (to avoid noise expansion device is fitted in outdoor). When low-temperature liquid refrigerant passes through the copper pipe then there are chances it will convert into vapor refrigerant because the copper pipe is open to the surrounding. If it happens then liquid refrigerant can’t reach to the evaporator. Hence we use insulation to cover copper pipe to avoid this. Low temperature and low-pressure liquid refrigerant enters the evaporator and it absorbs heat from the room and it converts liquid refrigerant into vapor refrigerant. Then this vapor refrigerant goes to compressor. In this way, this cycle continues the process.

Air circulation process:

This process of the split AC consists of the following parts,

In this process, One blower is fitted behind the evaporator. It sucks the hot air from the room which first passes over the evaporator and then gets chilled. Then cooled air is supplied to the room with the help of a blower.

Propeller fan is fitted behind the condenser. It sucks the atmospheric air and blows it over the condenser. Condenser gives up the heat to the atmospheric air.

Advantage of split AC:

  • Low initial cost.
  • Less noise and easy to install.
  • Good alternative as compared to a ducted system.
  • Each system is totally independent and has its own control.

Disadvantage of split AC:

  • There is a limitation in the distance between the indoor and outdoor units.
  • Limited air is thrown which can lead to possible cold/hot spots.
  • Maintenance is within the occupied space.
  • Impact on large building aesthetics because too many outdoor units will spoil the appearance of the building.

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