Basic working principle of Air-conditioning system and their major components

:Basic Principle of Air-conditioning system:

What is Air-conditioner?

Air conditioning is the process of Conditioning and controlling the properties of air, for provide human comfort at the desired temperature of air should be 22°C to 26°C and humidity should be 40% to 60%. It means an air conditioner in a room works by collecting hot air from a given space, processing it to release cool air into the same space where the hot air had originally been collected.In a simple way that working condition and comfort for human being improve by Air-conditioner. Fundamental rule of any air-conditioning system is evaporator keep it more cool than room temperature and condenser keep it more hot than surrounding temperature.

Ton of Refrigeration (TR) :

This term is used to indicate the capacity of refrigeration & air-conditioning system and is equal to heat removal required to freeze one metric Tonne of water at 0 Deg C (32 Deg F) into ice in 24 hours,ie. heat removal rate of

* 2000 lb - weight of one metric tonne of water

= ( 2000 lb) x (144 Btu/lb) / 24 hrs.

= 12000 Btu/hr

= 3024 kcal/hr

= 3.52 kilowatt(KW)

* 144 Btu/lb - Latent heat of solidification of water at 32 Deg F

Please note that ton in ton of refrigeration should be spelled only as Ton.

Unit of Heat : To measure the amount of heat called as heat unit termed as calorie in the metric system and "British Thermal unit (BTU) in the British (FPS) system.

Refrigeration Cycle :

Air-conditioning system works on principle of refrigeration cycle,called in another name is "Vapour-compression system" We have discussed fundamental points of air-conditioning system,now we will discussed vapour compression cycle.

Figure 1

First of all understand the term Evaporation. Evaporation is the process by which water changes from a liquid to a gas or vapour. We have taken example like that how cold your skin felt,when spread by liquid spirit at Doctor's clinic before an injection? It felt cold,because the spirit evaporated (changed from liquid state to vapour state) very rapidly and when it evaporated it's needed heat to change it's state. Where did this heat come from? It came from the liquid itself and your skin with which it was in contact.

Refrigeration Cycle-Figure 2

The main purpose of vapour compression cycle is to remove heat from the refrigerant by putting it into a stage of reuse.

Image Source-Google

The various stages are mentioned below-

a) Compression

b) Condensation

c) Expansion

d) Evaporation

Refrigerant :
The Refrigerant is generally a gas which circulate through different stages to extract the heat from the substances. Various type of refrigerant used as air-conditioning system are R-22,R410A,R134,R-32 or any eco-friendly refrigerant.R-410A is better than R-22 and R-32 also most common used in industry.Nowadays Many leading manufacturers such as Daikin,Mitsubishi, Panasonic and Carrier are promoting R-32 refrigerant for their premium models.

Refrigerant type R-410A

Application of vapour compression refrigeration cycle :

Vapour compression refrigeration cycle employed for following purposes-

Domestic refrigerator
Water cooler
Air-conditioner
Ice Plant
Cold Storage etc.

Types of air-conditioning system :

There are many types of air-conditioning available in market.Such as-

Window Air-conditioning system

Split Air-conditioning system

Centralized Air-conditioning system

Package Air-conditioning system

Types of Air-conditioning system 1

Types of Air-conditioning system 2

There is so much discussion regarding air-conditioning system,but most commonly used nowadays is split air conditioner in domestic purpose,such as office,home etc. Previously window AC used in many places,but now it does not used anymore,due to too much noisy and also window is blocked due to AC installation.Instead of window AC,split AC has come. But it has some limitation that split ac available in market upto 3Ton cooling capacity.

Photo Courtesy Google image

Major components of air-conditioning system :

According to the type of installation,all air conditioners consist of four major components that are listed below-

1. Evaporator:

It is also know as "Cooling coil".It is a type of heat exchanger coil which is responsible for collecting heat from inside a room through a refrigerant gas where the liquid refrigerant absorbs heat through a blower and evaporates to become gas at suction line of compressor,refer figure 1 & 2.On the other side liquid refrigerant is coming from the condenser is injected through a meeting device called capillary or expansion valve into the cooling coil which is comprises of bundle of tubes.Evaporator is part of a indoor unit of split air-conditioner.

Evaporator coil-Indoor unit of Split AC

2. Compressor:

As we already discussed the refrigerant gas travels from evaporator and enter into compressor,wherein compressed the gases takes place and lower temperature and pressure convert into high pressure and temperature. Said temperature will be more than atmospheric temperature,so that heat can be eject to atmosphere through fan. As we know under atmospheric temperature and pressure the refrigerant is in gaseous form and we have learn also when liquid evaporate to become gas.So change of state from gas to vapour form by raising its pressure and liquid refrigerant travels to condenser.Compressor is the part of a outdoor unit of split air-conditioner.Nowadays scroll type compressor used in air-conditioning system instead of reciprocating type.

3. Condenser :

Condenser coil also known as heating coil. The condenser receives the vaporized refrigerant from the compressor, converts it back to liquid and heat can be reject to outside through fan and refrigerant change state from vaporize gas to liquid. So convert into low temperature and high pressure liquid refrigerant. It’s also located on the outside unit of the split AC.

Condenser Coil

4. Expansion Valve :

After passing through condenser coil liquid refrigerant passing through Drier,wherein moisture can be absorbed through silica gel & filter refrigerant as indicated in figure 2. Then low temperature & high pressure refrigerant passing travel through expansion valve,wherein refrigerant transform into low pressure & low temperature and moving towards evaporator. Expansion valve also known as throttling device. In this way air condition cycle is continue and provide us air-conditioning.

Danfoss Expansion Valve

If anyone ask you that what does it mean by air-conditioning system comfortable. You may say following bellow points for their better understanding-

Generally best recommend for chosen copper tube in both side at condenser and evaporator for air conditioning system. Because cooper is a best heat transfer coefficient higher than aluminium alloy. So better heat transfer coefficient means better heat exchange. But cost wise copper is slightly higher than aluminium.
We discussed a lot about Air-conditioning system,furthermore many books are available in market for detail study.

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