BASIC THERMODYNAMICS

THERMODYNAMICS:

1. It is the science of the relations between heat,
Work and the properties of the systems.

2. How to adopt these interactions to our benefit?
Thermodynamics enables us to answer this
question.




                                 Definitions

* In our study of thermodynamics, we will choose a small part of
the universe to which we will apply the laws of thermodynamics.We call this subset a SYSTEM. 

* The thermodynamic system is analogous to the free body
diagram to which we apply the laws of mechanics, (i.e.
Newton’s Laws of Motion). 

* The system is a macroscopically identifiable collection of matter
on which we focus our attention (eg: the water kettle or the
aircraft engine).

*  The rest of the universe outside the system close enough
to the system to have some perceptible effect on the
system is called the surroundings.
 
*   The surfaces which separates the system from the
surroundings are called the boundaries as shown in fig
below (eg: walls of the kettle, the housing of the engine).

system & surroundings:

                                             *Type of system*

1.Closed system-
 in which no mass is permitted to cross the
system boundary i.e. we would always consider a system
of constant mass.We do permit heat and work to enter or
leave but not mass.
2.Open System-
in which we permit mass to cross the system
boundary in either direction (from the system to surroundings
or vice versa). In analysing open systems, we typically look at
a specified region of space, and observe what happens at the
boundaries of that region.
Most of the engineering devices are open system.

3.Isolated System-
in which there is no interaction between
system and the surroundings. It is of fixed mass and
energy, and hence there is no mass and energy transfer
across the system boundary.