Mollier diagram: Everything you need to know

Over the years and the various inventions that were made by mankind, the coolant stands out, it is a liquid that is responsible for preventing the heating of various engines and also fulfills the function of being able to cool the air, such as the air conditioners.

What is the Mollier Diagram?

The Mollier Diagram, It is based on a table in which the condition of the refrigerant can be seen in its thermodynamic state and in any cycle. Studies have been carried out that show the different transformations that the refrigerant undergoes and conclusions have been drawn from it.

Mollier’s diagram was created in 1904, when Richard Mollier plotted total heat against entropy. At the 1923 thermodynamics meeting held in Los Angeles, he agreed to name any thermodynamic diagram in his honor a Mollier diagram.

There are several things that the mollier diagram contains, one of them is Isobars, these are known to be parallel lines that have the same pressure value, these are perpendicular to the axis of the ordinates, this was one of the diagrams most important to humanity.

Another fundamental component in the Mollier diagram are the Isotherms that in the subcooled liquid zone are parallel to the ordinate and inside the mixing bell they are parallel to the abscissa, and in the zone of superheated steam they descend in a curved form.

How to Read the Pressure-Enthalpy Diagram or Mollier Diagram?

It is important for a person to get a specialist who can explain the mollier diagram, since it is somewhat complex to read if you do not have some knowledge about the laws of thermodynamics.

In order to do so, some knowledge of the area of ​​thermodynamics, Since everyone cannot read a pressure-enthalpy diagram or Mollier diagram that easily, but here are some principles that are taken into account before doing so:

  • The horizontal lines are the lines of constant pressure.
  • The vertical lines are the lines of constant “enthalpy”.
  • The two steps above are understood as the amount of heat present in one kilo of refrigerant.

Once these principles are clear, we only need to apply a simple formula in order to obtain our result and know what we are looking for and where we are looking for it, to know which formula to use, just follow these steps:

  • The formula is H= U+PV/J
  • H= enthalpy.
  • U= thermal energy.
  • P= absolute pressure.
  • V= specific volume.
  • J = equivalent mechanical energy.

By implementing this formula and looking at the diagram, we will know what is the enthalpy that we are looking forthe other values ​​will be given by said diagram and in this way be able to obtain the result that is wanted to know in what state the refrigeration is.

How is the Mollier Diagram Developed?

In the evolution of industrial machinery, various changes were seen that served to improve the operation of said machinery, one of the most seen was the refrigerant, to control and learn more about what the refrigerant did Mollier diagram was created.

It is somewhat complex to carry out, it is necessary to take into account all the factors that it carries such as Isobars, Isotherms, among others, but the fundamental basis of said diagram only consists of some parts, here we show you what are they and how is it done a molier diagram:

  • On the axis of ordered the pressure value is recorded in (Pub) for Ph diagrams in YESscale graduated axis logarithmic.
  • On the axis of abscissas the enthalpy value in unit mass is recorded in [kJ/kg] or [kcal/kg].
  • An inverted “U” shaped saturation curve which determines if the compound is in a state of: supercooled liquid, saturated liquid, mixed liquid–steamsaturated steam or superheated steam (red color).

What is an enthalpy diagram?

At the beginning of the industrial revolution, great control had to be taken over various areas and various theories and new inventions had to be made to make the machinery work bettermany systems, theories and diagrams were created, one that stands out from the majority is the enthalpy diagram.

It is very important to always have to carry out a study using an enthalpy diagram, to know what the conditions in which a piece of equipment is, because if there is a lack of refrigerant, the equipment will be damaged.

This diagram could provide knowing how much was the level of overheating suffered by various systems, and be able to counteract that heat with cold using the well-known refrigerants or ventilation systemswhich are responsible for cooling the equipment.

In this way, it was possible to continue evolving for a long period of time, since they did not suffer from heat failure, and in this way billing hand increased, because they could use the equipment persistently without it getting damaged as quickly.

What is the Function of Enthalpy Diagrams?

The enthalpy diagram is one that is responsible for the graphic representation of the enthalpy (quantity that a thermodynamic system generates or absorbs) of a certain substance whether liquid, solid or gas. This diagram expresses enthalpy as a function of temperature and pressure.

By making an enthalpy diagram, the person could know the exact amount of coolant that you have and how that refrigerant acts on the temperature and pressure that you have on said refrigerant container, in this way to evaluate the performance of the machine.

It should be known that in this area it is very important to know what are the functions that must be fulfilled in order to know well what the functions of a enthalpy diagramsince if a mistake is made by making one, the machinery and employees are at risk.

What is Enthalpy in a Refrigeration System?

Enthalpy is a magnitude of thermodynamics that is symbolized with the letter H, the change in enthalpy expresses a measure of the amount of energy absorbed or yielded by a thermodynamic system, or the amount of energy that it exchanges in the environment.

In this way, the person can observe how the energy change takes place and be able to know what the result of it will be, that is, if it is very strong it runs the risk of being damaged and if it is very weak something is wrong. little wrong with the system.

Thus, the equipment can be repaired if it presents any of these complications, it is possible to repair the equipment, but if it is not possible, it is best to change it to avoid future problems with employees and ensure their safety.

So the enthalpy in the refrigeration system it is so important since it allows the equipment to cool down, before it was impossible to develop this, but now all the equipment has this cooling system.

How is an Enthalpy Diagram Formed?

It is very important to know what are the principles by which an enthalpy diagram is formed, in order to know the level of refrigeration that is in the systemand in this way to know the amount of refrigerant there is.

One of the most fundamental things is to keep in mind that about 6 more functions are needed to be taken into account to be able to carry out this mollier diagram, here we show you the 6 types of traces:

  • isobars: Straight parallel equal pressure values ​​coincide. These are perpendicular to the ordinate axis.
  • isenthalpic: Parallel lines that coincide with equal mass enthalpy values. These are perpendicular to the abscissa axis.
  • isotherms: That in the subcooled liquid zone they are parallel to the ordinate and inside the mixing bell they are parallel to the abscissa, and in the superheated steam zone they descend in a curved shape
  • Isochores: They are the curves that coincide the points with the same specific volume and they are also parallel to each other for different values. At YES is expressed in [m³/kg].
  • isentropic: they are curves that coincide the values ​​of equal entropy in the system. At YES are measured in [kJ/kg K] or [kJ/kg°C]. Parallel to each other and with a high slope (yellow color).
  • Nine curves of «steam title» or «steam quality» that indicate the percentage in mass of steam content in the liquid-vapor mixture. These curves, existing only inside the mixing hood, are coincident at their upper end plus their lower end is relatively equidistant from the adjacent one, and so on.

It is important to know these 6 principles, since without them you would not be able to know how the enthalpy diagram is structured, and thus be able to evaluate the condition of the equipment and know what can be done with them.

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