Working Principles of Air Conditioners, Maintenance, and Precautions.
By KnowledgeVeto Monday, June 03, 2024 17:30
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The Thermodynamic rules serve as the foundation for the air conditioning principle. An air conditioner runs on the refrigeration cycle. Specific refrigerants are required as the working fluid in the refrigeration cycle.
An air conditioner undergoes four processes: compression, condensation, expansion, and evaporation. An air conditioner typically consists of four key components: the compressor, the heat exchanger, the fan, and the expansion valve.
An air conditioner works similarly to a pump, collecting heat from a room and releasing it outside. This method employs a mechanism containing refrigerant gas, heat exchanger coils, and a compressor. The operation of air conditioning units is based on a fundamental physics principle: the absorption of heat as a liquid turns into a gas. In essence, air conditioners move heat from the inside of a room to the outside. Let's look at how this complicated gear works to keep you comfortable.
Picture 1.0 (Working Principal of Air Confitioner)
Key Components Of An Air Conditioner
Refrigerant
The refrigerant is the most crucial component of every air conditioner. It is the gas that circulates through the unit's heat exchanger coils, absorbing heat from within a room and discharging it outside. The refrigerant circulates within the air conditioner in a cycle of evaporation and condensation, helping to reduce the temperature inside a space. The most prevalent refrigerants are HCFCs (hydrochlorofluorocarbons) like R-22, HFCs (hydrofluorocarbons) like R410A and R32, and HCs (hydrocarbons) like R290.
Evaporator
An evaporator is essentially a heat exchanger coil that collects heat from the inside of a room using refrigerating gas. This component is known as an evaporator because it is where the liquid refrigerant absorbs heat (from the room) and turns into a gas. These metals are often made of copper or aluminum and are chosen for their outstanding heat conduction qualities. The evaporator has copper/aluminum tubes through which the refrigerant flows, as well as fins attached to the tubes to improve heat transfer between the refrigerant and the outside air.
Compressor
As the name implies, this component compresses the refrigerant gas to a high-pressure, high-temperature state. The compressor works as a pump, collecting refrigerant gas from the evaporator (or the unit inside the room), compressing it to increase both pressure and temperature, and then delivering the high-pressure/high-temperature gas to the condenser outside the room.
Let's understand in more clear and easy way:
Air conditioners keep us cool by transporting heat outdoors through a cycle that uses a specific refrigerant. Here's a breakdown of the procedure:
Air conditioners provide a comfortable indoor environment through a smart cycle of refrigerant compression, heat release, expansion, and cooling.
Condenser
A condenser is another heat exchanger located outside the room. It gets its name from the fact that it is where heated gas condenses to form liquid. When the high-pressure/high-temperature gas reaches the condenser, a fan blows ambient air over the heat exchanger, cooling the refrigerant gas and converting it to liquid. This technique allows the refrigerant to release the heat it has absorbed from the room. Condensers, like evaporators in construction, are often constructed of copper or aluminum. However, they are housed in a separate unit from the room.
Expansion Valve
An expansion valve, a necessary component of air conditioning machines, is located between a condenser and an evaporator. It controls the amount of refrigerant flowing toward the evaporator. The expansion valve converts high-pressure liquid refrigerant from the condenser to low-pressure, low-temperature liquid. The low-pressure/low-temperature liquid is then sent to the evaporator, where the cycle resumes.
These are the primary components of an air conditioner. Let's take a look at how they work together to make an air conditioner function properly.
Details study of Expansion Valve
The expansion valve is located in the liquid line running from the condenser to the evaporator's inlet.This is a basic component of the refrigeration system that regulates refrigerant flow.It reduce the pressure & temperature of the refrigerant coming from the condenser as per the demand of the system. And also helps to regulate the flow( Metering ) of refrigerant as per the load on the Evaporator.
Expansion valves do not directly affect the evaporation temperature. Instead, they control superheating by regulating the mass flow of refrigerant into the evaporator while maintaining the pressure differential between the high and low pressure sides. The evaporation temperature relies on the capacity of the compressor and the features and efficiency of the evaporator.
The word "low side" refers to a system component that operates at low pressure, such as an evaporator. The term "high side" refers to a system component that operates at high pressure, such as the condenser.
Basically Two types of expansion devices :-
1.Variable Restriction Type.
2. Constant Restriction Type.
1. Variable Restriction Type:The opening region of flow varies based on the type of control. Three popular types include: A. Automatic Expansion Valve (Pressure Control).
B. A thermostatic expansion valve.
C. Float valves.
i) High side Float valve This keeps the liquid at a consistent level in the condenser.
ii) Low-side float valve. This keeps the liquid at a steady level in the Evaporator.
2. Constant Restriction Type: Capillary Tube with limited diameter bore.
The Automatic Expansion valve responds to pressure variations in the evaporator when the load increases or decreases.This valve maintains a steady pressure throughout the varying load on the evaporator, hence managing the amount of refrigerant flowing into it.It is made up of a needle valve, a seat, a diaphragm, and a spring, as illustrated in the image.
The two opposing forces govern the opening of the valve in the seat.
A. Tension in the spring
B. Pressure in the evaporator acting on the diaphragm.
Once the spring has been adjusted for the desired evaporator pressure and load, the valve will operate automatically in response to changing evaporator load circumstances.
Assume the spring is initially set to maintain a pressure of 1.5 bar in the evaporator at a certain load. If the pressure drops below 1.5 bar owing to a decrease in load, the spring pressure will exceed the evaporator pressure, causing the valve to open wider and increase the flow of refrigerant. If the pressure in the evaporator rises above 1.5 bar owing to increased load, the evaporator pressure exceeds the spring tension, causing the valve to close. This lowers the volume of refrigerant flow in the evaporator.
AC: Operating Principle Of The Air Conditioner
To sum up, here is a 4 step process by with an air conditioner works:
The refrigerant begins as a low pressure, low temperature liquid in the house's evaporator coil. It absorbs heat from the indoor air. The cooled air is then pumped throughout the home. Meanwhile, the refrigerant absorbs heat and transforms from a liquid to a low-pressure gas.
This gas is then delivered to a unit outside the home. A compressor is used to increase the pressure and temperature of this gas refrigerant.
It is then transferred to the condensation coil where the heat previously received from your home is discharged into the outside air. A fan circulates air over the condenser, cooling and turning the refrigerant back into a high pressure liquid.
The refrigerant is subsequently transferred back into the home (indoor unit) via the expansion valve, restarting the cycle. Heat from inside your home is thus moved outside, cooling the interior.
An air conditioner is not a magical instrument; it does not generate cooled air. It only exploits some physical and chemical phenomena extremely effectively to transport heat from the room to outside.
What happens when you turn on the air conditioner?
Also refer above Picture 1.0
When you switch on an air conditioner and set the desired temperature, say 20 degrees Celsius, the thermostat included in it will detect a difference in temperature between the room air and the temperature you have set.
The above-mentioned technique is repeated until the necessary temperature is obtained. In short, an air conditioner sucks in warm air, cools it, and then pushes it back into the room until there is no more warm air to cool.
Originally Air Conditioner wast not invented for Human comfort!!!
As much as we rely on air conditioning, it's surprising that it wasn't originally created for human comfort. The first contemporary air conditioning system was designed to solve specific challenges in a publisher's production processes! It's incredible to think that a machine designed to enable large-scale newspaper production could one day become a vital component of every modern household.
1. Low Temperature, Low Pressure vapor.
2. High Temperature, High Pressure vapor.
3. High Temperature, High Pressure Liquid.
4. Low Temperature, Low Pressure Phase-2.
Step-by-Step Explanation of How Compressor Works
When the air conditioner is turned on, the compressor absorbs low-pressure refrigerant gas from the evaporator coil. It then compresses the gas, increasing its temperature and pressure dramatically. The new high-pressure gas flows to the condenser coil, where it releases heat and condenses into a liquid before continuing through the system.
After releasing heat in the condenser coil, the high-pressure liquid refrigerant passes through an expansion valve, resulting in a large pressure decrease. As the refrigerant enters the evaporator coil, it undergoes a pressure decrease, transforming into a low pressure gas. As it goes through the evaporator coil, the refrigerant absorbs heat from the interior air and cools it before being sucked back into the compressor to repeat the cycle.
