Page 82 - DJJ20063- Thermodynamics 1
P. 82
DJJ20063- Thermodynamics 1
3.0 FIRST LAW OF THERMODYNAMICS AND ITS PROCESSES
3.1 Relate the concept of the first law of thermodynamics.
The first law of thermodynamics is simply a statement of conservation of energy principle
and it asserts that total energy is a thermodynamic property. Energy can neither be
created nor destroyed; it can only change forms. This principle is based on experimental
observations and is known as the First Law of Thermodynamics. The First Law of
Thermodynamics can therefore be stated as follows:
When a system undergoes a thermodynamic cycle then the net heat supplied to the
system from its surroundings is equal to the net work done by the systems on its
surroundings.
……The First Law of Thermodynamics
In symbols,
dQ = dW (3.1)
where represents the sum of a complete cycle.
3.1.1 Describe forms of energy.
The various forms of energy which the fluid can have are as follows:
a) Potential energy
If the fluid is at some height Z above a given datum level, then as a result of its
mass it possesses potential energy with respect to that datum. Thus, for unit mass
of fluid, in the close vicinity of the earth,
Potential energy = g Z
9.81 Z
73 | P a g e
