What is the Best AC Compressor: Rotary or Reciprocating? 

An air conditioner needs the functioning of certain components. There are five most essential components of an AC – compressor, evaporator, condenser, thermostat, and blowing unit. Bear with us, these technical terms may sound intimidating, but if you want to enjoy all the benefits from your AC, you need to understand the functioning of the units.

In this article, we will discuss only the AC compressors and learn about their type, pros, and cons of some compressors, and assess which compressor will suit you the best. To begin with, let us understand what a compressor in an AC actually is:

What is a Compressor?

A compressor is nothing but a mechanical machine inside the AC responsible for maintaining the continuous and optimum flow of the refrigerant liquid between the evaporator and the condenser.

AC CoilTubes that helps to transfer the refrigerant. Typically comes in copper and aluminium. 
CondenserMachine outside the room to release the heat.
EvaporatorMachine inside the room to absorb the heat from the room.
Refrigerant fluidSubstance used in the heat cycle that flows inside the coil.

Now, understand it this way:

1. The fundamental principle of an AC is quite simple, keep the condenser hotter than the environment and evaporator cooler than the room temperature. The air conditioner comes with two connected coils that help to flows the refrigerant fluid. One coil is inside the room (evaporator), and one coil is outside the room (condenser).

2. The refrigerant fluid in the coil absorbs the heat from the evaporator and ejects it through the condenser. However, there is another system that is involved in this entire process – an AC compressor.

3. The task of a compressor is to increases the pressure of the refrigerant for the best heat exchange. When the refrigerant is collected in the compressor, it is in the low-pressure vapor state. It is then compressed, and the volume of the gas starts decreasing, this increases the temperature as well as the pressure.

4. This entire process results in converting the low-pressure vapor into high-pressure vapor. It is then passed on to the condenser which condenses the gas into a liquid and releases the heat to the environment.

5. It is clear how important a compressor is in the air conditioning unit. However, there are different types of compressors available in the Indian market, and the question that comes into mind is – do all compressors work in the same way or some are more efficient? Well, let’s find out in our next section.

Types of AC Compressors

As we have learned that a compressor acts as a heart in an air conditioner unit, let us now look at the different types of AC compressor and understand how they function.

Essentially, there are five different types of AC compressor, namely:

  • Centrifugal Compressor
  • Reciprocating Compressor
  • Rotary Compressor
  • Screw Compressor
  • Scroll Compressor

However, in India, most air conditioners unit integrates either Rotary Compressor or Reciprocating Compressor so, it is quite important for you to understand the difference between these two types of compressors.

Rotary AC Compressor: 

In this type, the housing of the compressor is cylindrical in shape. Inside the housing, there are multiple adjustable rotators which in technical terms are called vanes or rotary blades.

These vanes are attached to the cylindrical shaft, which is positioned off-centered inside the housing. Now, this housing has an inlet and an outlet that collects and releases the refrigerant, respectively.

The inlet, in the shaft, is located where there is more space in the cylinder wall to collect the low-pressure gas/refrigerant. And, the outlet is located where space is minimum.

Now, as the shaft rotates, the blade/vanes start rotating while maintaining contact with the cylindrical wall. As this happens, the vanes create chambers of varying sizes within the cylinder.

The low-pressure gas enters through the inlet in the largest chamber and as the vanes rotate they get retracted which makes the chamber smaller and smaller. This process compresses the low-pressure gas and is pushed out through the outlet towards the condenser.

Reciprocating AC Compressor:

The other common type of AC compressor is the Reciprocating Compressor. It compresses the refrigerant in a cylinder with the help of a piston. To understand it better, you can think of this compressor as an automobile engine.

Inside the cylinder, you will find two-valves, one is the suction valve, and the other is the discharge valve, and both are responsible for compressing the refrigerant. The piston is connected with a crankshaft, and when this mechanism brings the piston downward, the suction valves open, and the refrigerant is sucked in.

The piston sucks all the refrigerant from the suction valve until the compartment is filled. Next, the piston goes upwards, and at this stroke, the suction valves close. As the piston goes upwards, the volume of the gas gets compressed, and there is an increase in the pressure.

When the pressure is optimum in the cylinder, it (pressure) opens the discharge valve, and all the compressed gas is released out from the compartment. The piston then comes downwards and closes the discharge valve and continues the cycle.

Rotary Compressor Advantages & Disadvantages

Rotary AC Compressor uses rotary blades inside the cylindrical walls to compress the low-pressure gas and increase the pressure. As this is a mechanical device, there are some advantages and disadvantages that you will often find:

Advantages:

  • These compressors are small and do not make too much noise which makes them a perfect option for places where noise is a major concern.
  • The functioning of the rotary compressor is quite simple; this means lesser components and lesser maintenance cost.
  • Rotary compressors consume less energy and oil but can reach up to 90% mechanical efficiency.
  • They are free of vibration and pulsation.

Disadvantages:

  • The discharge pressure of the gas is lower than Reciprocating Compressor.
  • They are comparatively expensive than other compressors.

Reciprocating Compressor Advantages & Disadvantages

Reciprocating Compressors uses a piston to compress the low-pressure gas inside the cylinder, but these compressors also come with their own pros and cons, let’s find out.

Advantages:

  • These compressors could use multiple pistons and cylinders, which makes them one of the most efficient AC compressors.
  • Reciprocating compressors could easily work in high pressure.
  • They are affordable and have an unmatchable efficiency.

Disadvantages:

  • They require special attention and maintenance.
  • Vibration and noise are very common.
  • The out-coming air temperature is higher than other compressors.

Which one should you buy: Rotary or Reciprocating

As we have learned the difference between the Rotary and Reciprocating along with the advantages and limitations, it must be clear to you, which will suit you better. However, if you are still sceptical about your choice, let us clear it for you.

If you are planning to buy an air conditioner for a smaller area or want it to run continuously for hours, then go for an AC that has a rotary compressor. They are small and do not make noise. Also, they are a good option for commercial and industrial offices. Besides that, the machine will run at a slower speed which will result in durability and low maintenance. However, these benefits may come at a higher price.

On the flip side, if you want an air conditioner that is going to be used on an irregular basis, in your house, for instance, then it is advisable to opt for an AC with a reciprocating compressor. Air conditioners with reciprocating compressors are not only efficient but are cheaper than rotary compressors. The downsides may be – higher maintenance costs.

Conclusion

Air conditioners are designed to maintain room temperature along with removing the humidity and airborne particles that could otherwise affect your health. There are a lot of components in an AC unit that plays a vital role in this function. One of these parts is an AC compressor.

An air conditioner compressor compresses the low-pressure refrigerant gas and converts it into a high-pressure gas, ultimately maintaining the heat cycle. There are two common types of ac compressors – rotary and reciprocating compressors.

The Rotary compressor uses adjustable vanes that help in compressing the refrigerant. These compressors are smaller and do not make noise or vibrations. If you want an AC that would be running continuously for long hours, then consider buying an AC with a rotary compressor. They are good for industries, offices, or commercial buildings.

Reciprocating compressors use a piston and a cylinder to compress the refrigerant gas and are more efficient than a rotary compressor. They are much suitable for a small space like your house. These compressors are affordable and could easily work in high pressure.

We have given our best to provide every piece of information on both rotary and reciprocating compressors. Eventually, you will be the one making the choice so make sure to read the functioning, pros, and cons of each type for a better experience. Good luck!

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