Why is a Vapour compression refrigeration more effective than the air refrigeration?

Option 2 : (COP)air < (COP)vap.c.

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Concept:

• The Vapour compression cycle consists of phase change from gas to liquid in condenser and the compressor pumps liquid phased refrigerant.
• Making it more efficient as compression work per unit of mass flow is low. It is generally used in refrigeration purposes and air conditioning in buildings.
• The Air cycle uses air as a working fluid and doesn't have phase change in any part of the cycle. Meaning air always remains in the gas state.
• Hence the fluid circulation per KW of cooling is very high. Also, the compression work is more.
• One of the very few applications that satisfy its suitability is air conditioning in aircraft.

So (COP)air < (COP)vap.c

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Vapor-compression cooling can be found in virtually any home, such as in air conditioners that remove heat from our homes and in refrigerators that store our food. The history of vapor-compression goes back to 1805 where Oliver Evans, an American inventor, described a closed vapor-compression refrigeration cycle for producing ice. The first working vapor-compression refrigeration system was built in 1834 by another American who was living in the UK, Jacob Jenkins. This blog post will explain how this vapor-compression refrigeration cycle works and how it can be applied, or you can watch the video explanation, here.

Vapor-compression cycle refrigeration is a process that uses the physics of phase change heat transfer and the unique properties of a refrigerant to transfer heat from a relatively cold source to a hot medium. Simply stated, refrigeration systems efficiently move heat from a cold source to a hot heat sink (normally air). The components in the basic refrigeration system are the compressor, condenser, expansion valve, and evaporator.

The heart of the system is the compressor. The compressor takes in a low temperature, low pressure refrigerant vapor, and compresses it into a high temperature, high pressure vapor. This high temperature/pressure vapor then enters the condenser where heat is removed to either air or water. As the heat is removed, the energy stored in the high pressure gas is released and the refrigerant gives up its latent heat as it reverts to a hot liquid.

This hot, high temperature liquid then exits the condenser and enters the expansion valve, where it undergoes a pressure drop causing some of the hot gas to vaporize. This lowers the temperature of the refrigerant stream. The refrigerant at the exit of the expansion valve is a low temperature two-phase fluid.

This two-phase fluid enters the evaporator where it is exposed to the heat source. The heat from the source boils off the refrigerant through phase change heat transfer, and the low temperature, low pressure gas enters the compressor, completing the cycle.

It is useful to understand the refrigerant cycle in the quadrant shown in Figure 1. The high pressure, high temperature upper half allows the refrigerant to become significantly hotter than ambient air, forcing heat transfer into a habitually hot environment.

The low temperature, low pressure half of the cycle allows the refrigerant to absorb heat from a source that is not as hot as the environment. The compressor does the work to raise the pressure, and the expansion valve assures that adequate pressure is retained in the condenser for heat transfer.

The vapor compression cycle can be used to cool air, liquid, or cold plates. All that is required to accomplish this is to modify the evaporator to accommodate the systems that are being cooled. To create an air cooling system, the evaporator acts as a refrigerant to an air heat exchanger. The air cooling system is used in buildings, automobiles, and in electronics enclosures where air cooled rack-mounted equipment is being cooled.

To cool liquid, the evaporator again acts as a refrigerant, this time to a liquid heat exchanger, with the pumped liquid being cooled by the evaporating refrigerant. The liquid cooled system is used for systems such as lasers, electronics, and medical devices that are designed for liquid cooling.

A third alternative for cold plate cooled devices is to run the refrigerant directly through the cold plate. With the evaporator as the cold plate, the devices being cooled have the advantage of phase change heat transfer with minimal temperature rise.

Vapor-compression cooling is adaptable, efficient, and effective at cooling. Watch “How Vapor Compression Cooling Works” to learn more.

Hello Everyone, In this article, we will study the Difference between Vapour compression and the Absorption Refrigeration System in detail. And at the end of the article, you will be able to download a PDF of this article.

Lets start,

What is Vapour compression Refrigeration System?

The Vapour compression Refrigeration System is a refrigeration system in which we use R12 as a refrigerant and this system needs high-grade energy (mechanical energy or Electrical Energy) for the operating compressor.

The working of the Compression refrigeration system in brief: The refrigerant is drawn from the evaporator and sends to the compressor, here it is compressed adiabatically to high temperature and high pressure. Now it is sent to the condenser for cooling at constant pressure.

After that, The high-refrigerant is expanded through an expansion valve, and here the temperature and pressure decrease. Now in the evaporator, it absorbs heat at constant pressure and cools the space. And further, the cycle is repeating.

Now come to Vapour Absorption Refrigeration System,

What is Vapour Absorption Refrigeration System?

The Vapour Absorption Refrigeration System is a refrigeration system in which we use ammonia (NH3) or water as a refrigerant and here Low-grade energy sources (waste heat from furnaces, exhaust steam) and Solar power used for running a vapor absorption system.

Here in the diagram you can see the components of both the refrigeration system.

Difference between Vapour compression and Absorption Refrigeration System:

I have listed more than 15 point on the Difference between Vapour compression and Absorption Refrigeration System:

Vapour compression Refrigeration System	Vapour Absorption Refrigeration System
The Vapour compression refrigeration system has parts like Compressor, receiver, condenser, refrigerant control device, and evaporator. Whereas,	Vapour Absorption Refrigeration has Parts like condenser absorber, generator, rectifier, and evaporator.
Here when the operation is going it produces noise.	There is very less in noise or you can say it is quiet in operation.
The refrigerant we use here is Chlorofluorocarbons, Hydrocarbons, and Hydrochlorofluorocarbons. Or you can say R12 refrigerant is used.	In the Absorption system, we use refrigerant is Ammonia or water.
Here the charging of these refrigerants is very simple. Whereas	In this case, charging is very difficult.
The supply of energy is low.	Here the supply of energy is high.
The compression system occupies more space and It is less efficient.	The Absorption system occupies less space and It is more efficient comparatively the Compression refrigeration system.
Vapour compression refrigeration system required to operate by prime movers like electric Motor, Petrol engine or Diesel Engine.	But here It is required to operate by heat energy like kerosene oil, gas, or electric heater.
The compressor is used and The flow of gas depends upon the compressor only. Whereas	In the Absorption system, the flow of gas depends upon the generator’s working and Gravity.
The mechanical energy is supplied as input here.	The heat energy is supplied here as input.
Here the chances of wear and tear because the compression system has many moving parts.	Here the chances of wear and tear are very less because the Absorption system has not any moving parts.
Here the refrigerant is being compressed for working operation.	In the Absorption system, refrigerant is being absorbed and heated.
The operationg cost is high becasue here we compressor and it consumes more work.	The operationg cost is Less because of less heat energy is required.
The coefficient of Power (COP) is high in the compression system.	The coefficient of Power (COP) is low in the Absorption system.
Maintenance is more.	Less Maintenance.
The compressor system is not used for large capacity work as it is limited. Whereas	This system is used for large-capacity works.
The leakage chance is more because of high pressure.	The leakage chance is very less or negligible because of low pressure.

Vapour compression vs Vapour Absorption Refrigeration System

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