Thermodynamic Properties Of Refrigerants

In this article, I will share with you the thermodynamic properties of refrigerants and explain to you how they affect a refrigeration system.


Refrigerants are an essential part of a refrigeration system as they help in transferring the absorbed energy around the refrigeration cycle.


The function of these refrigerants will be efficient if they will have certain properties.


Refrigerants have three types of properties which are as namely;

  • Chemical properties.
  • Thermodynamic properties.
  • Physical properties.


The fundamental properties that I will talk about in these articles are the thermodynamic properties.


With that much said, let me share with you these properties.


Thermodynamic properties of refrigerants

1. Critical temperature.

The critical temperature and pressure of the refrigerant should be very high as possible above the condensing temperature to have a great heat transfer at a constant temperature.


The refrigeration cycle depends on absorption and heat transferring around the cycle.


When the critical temperature of the refrigerant is very high, then the heat transfer will also be high and this will bring about the efficiency of the refrigeration system.


If the refrigerant has a lower critical temperature, then this means there will be no great heat transfer and this will affect the refrigeration system cycle.


This will also cause the refrigeration system to consume a lot of power to ensure the critical temperature is high enough for sufficient heat transfer.


2. Critical pressure.

Critical pressure is another thermodynamic property that refrigerants should have.


The refrigeration system also largely depends on the pressure of the refrigerant system.


High or low critical pressure in the refrigeration system will affect its performance.


This means that the critical pressure of the refrigerant should be moderate and positive high pressure for the refrigeration cycle to be effective.


If the critical pressure in the refrigeration system will be too high, it will cause the system to be heavy.


This will make the refrigeration system lag, and this will cause inefficiency for it.


If the critical pressure of the refrigerant is too low, this will cause air leakages into the refrigeration system.


If there will be air leakages in the refrigeration system, this means it will not work effectively as it’s impossible to compress air.


This will eventually lead to refrigeration system failure.


You might like this: Causes Of Vapour Compression Refrigeration System Failure +Solutions


3. Specific heat.

The specific heat of the refrigerant in the refrigeration system should be as small as possible to ensure that irreversibilities associated with throttling are small.


Also, the specific heat of the refrigerant should be small, as this will enhance the sub-cooling of the liquid.


If there is no sub-cooling of the liquid refrigerant, then this will affect the whole refrigeration cycle.


The liquid refrigerant will enter the evaporator having high specific heat, thus absorbing the latent heat of vaporization will not happen and this will not bring about the cooling effect as expected.


If you want to know more about the refrigeration cycle, don’t forget to read the article below.


You might like this: Vapour Compression Refrigeration System: Components And Working Principle


Specific heat of the vapour refrigerant should be high as possible so that a small absorption of latent heat of vaporization can cause enough superheating of the refrigerant as it enters the compressor.


For the refrigeration cycle to be super-efficient then only a slight temperature change should have a high super-heating effect on the vapour refrigerant.


This will make the refrigeration effect high.


4. Enthalpy of vaporization.

The enthalpy of vaporization of the refrigerant should be higher to minimize the area under super-heat and area reduction because of throttling.


The enthalpy of vaporization is essential for the energy transferring around the refrigeration cycle.


If the enthalpy of vaporization will be lower, this means the refrigeration system will have to use much power to increase the enthalpy of the refrigerant.


And this will make the area under super-heat higher when drawing the T-S and P-H graphs.


The higher value of enthalpy of vaporization lowers the required flow rate of refrigerant per ton of refrigeration.


A ton of refrigeration is simply the rate of heat transfer that results in a cooling effect.


If the flow rate of refrigerant required to flow is the refrigeration system per ton of refrigeration will lower because of high enthalpy of vaporization, it will cause a reduced quantity of the refrigerant used.


Which is a good thing on the economic side of things.


Higher enthalpy of vaporization will also result in efficiency in the refrigeration system.


5. Conductivity.

The conductivity of the refrigerant should be higher enough to minimize the size of evaporators and condensers.


If the refrigerant has a higher conductivity, the need for big evaporators in the refrigeration system will not be necessary since the absorption and transfer of heat in the refrigeration system will be efficient.


The moment the refrigerant will have poor conductivity, the size of evaporators will have to be bigger to increase the surface area of heat absorption.


In cooling, this property also plays a big part in that, as the condensers will also have to be big enough to maximize the cooling of the refrigerant.


6. Compression ratio.

The compression ratio of the refrigerant in the refrigeration system should be as low as possible.


The higher compression ratio of the refrigerant will cause leakages of the refrigerant.


Do you know what happens when there is a leakage of the refrigerant because of its compression ratio? When there is a leakage of the refrigerant, the entire system of refrigeration will be inefficient, because energy transfer in the system will be low.


For the refrigerant to be effective, all these thermodynamic properties should be present.


If you have questions leave your comment in the comment section.


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