We were
discussing the basic of engineering thermodynamics in our previous post i.e.
Thermodynamics system, boundary and surrounding, we have also seen the various classes
of thermodynamics system there.
Today we will focus here the concept of thermodynamic
equilibrium in this post and also we will see here the properties of the
system.
Thermodynamic system will be considered in
thermodynamic equilibrium, if system is meeting the condition of the three
important types of equilibrium as mentioned below.
- Mechanical Equilibrium
- Thermal Equilibrium
- Chemical equilibrium
Mechanical Equilibrium
A system will be considered in the state of
mechanical equilibrium if there is no unbalanced force within the system or
between system and its surrounding. Pressure must be same at each point within
the system and should not vary with respect to time.
If there is presence of unbalanced force within the
system or between system and its surrounding, then system will not be
considered in the state of mechanical equilibrium and in this situation only
system or system and its surrounding will go through state change for securing
the state of mechanical equilibrium.
Thermal Equilibrium
In order to consider a system in the state of
thermal equilibrium, temperature must be same at each point within the system
and should not vary with respect to time. If system is not meeting this
criterion, in that situation system will go through state change for securing
the state of thermal equilibrium.
Chemical equilibrium
In order to consider a system in the state of
chemical equilibrium, if there is no chemical reaction taking place within the
system and chemical composition of the system is not changing with respect to
time.
Any thermodynamic system must meet the above
equilibrium state to be considered as system in the state of thermodynamic
equilibrium. A thermodynamic system will be considered in the state of
non-equilibrium, if system is not meeting anyone above equilibrium state.
Now let us see the properties of a thermodynamic
system
Thermodynamics properties
There are basically two types of properties of
thermodynamics system
Intensive property
Any property that will not be dependent over the
mass of the system will be termed as intensive property. Intensive property
will exist at a point in space. Pressure, temperature and density will be the
good example of intensive property.
Extensive property
Any property that will be dependent over the mass of
the system will be termed as extensive property. Volume will be the good
example of extensive property.
There is another important type of intensive
property i.e. specific property. Specific property will always comes in per
unit mass such as specific volume. Specific volume indicates the volume per
unit mass and its unit will be cubic meter/kg in SI system.
We will discuss another topic in thermodynamics in
our next post.
Do you have any suggestions? Please write in comment
box.
Image courtesy: Google
Reference
Engineering thermodynamics by R.K Rajput
Engineering thermodynamics by P.K Nag
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