1. THERMODYNAMICS

2. introduction The word Thermodynamics derived from two Greek ideas:
Therme meaning hot or heat
Dynamikos meaning power and now the study of matter in motion.
Thermodynamics is the study of heat related to matter in motion.
Without thermodynamic engines-petrol engine, gas turbine, steam turbine etc-modern industrial society could not survive

3. Working Substance
The working substances are in general fluids that can rapidly expand and compressed.
Common example are steam and air
Pure Substance
substances which has the same consistent composition throughout
steam and water or mixture of steam and water
Macroscopic and Microscopic Analysis
If the property of particular substance such as pressure, volume and temperature are analyzed then the analysis is said to be macroscopic.
If the analysis is made in which the behavior of the individual atoms and molecules of a substance are under investigation then it is said to be microscopic.

4. Properties and State
In the macroscopic analysis of a substance any character of the substance which can be observed or measured is called as property of the substance
Example of property is pressure, volume temperature
The type of property which is dependent upon the physical and chemical structure of the substance is called as internal or thermostatic property
If a value can be assigned to the property then it is said to be a point function
its value can be plotted on a graph
Properties which are independent of mass, such as temperature, pressure are called as intensive properties
Property which is dependent of mass such as volume and energy in its various form are called extensive property

5. Property that can vary independently in called as independent property
Such as temperature and pressure
A knowledge of the various thermostatic properties of a substance defines the state of the substance
Property which includes the function of time , rate at which some interaction occur, is referred to as a transport property
Specific Quantity
When ever we will discuss the property of unit mass of a substance , word specific is used to prefix the property
Such as volume occupied by unit mass of the substance

6. Temperature
Temperature describes the degree of hotness or coldness of the body
Freezing and boiling point of pure water are designated 32 0F and 212 0F respectively on Fahrenheit scale.
In Celsius scale this come to 0 0C and 100 0C respectively
Other scales in use are Kelvin and Rankine scale
T=T
Where t= temperature in Celsius
T=temperature in Kelvin

7. Pressure
Defined as force per unit area
P=F/A (N)
Phase
When substance is same throughout its mass
Solid, liquid , vapor (or gas)
If two phases exist together then the substance is in the form of two-phase mixture
Example can be when liquid transformed into vapors
In a single phase substance is said to be homogeneous
If it is in two phase is said to be heterogeneous

8. Process
When the state of a substance is changed by means of an operation or operations
Cycle
If processes are carried out on a substance such that at the end the substance returned to its original state
Constance Temperature Process
Process carried out such that the temperature remains constant throughout the process
Constance Pressure Process
Process carried out such that the pressure remains constant throughout the process
Constance Volume Process

9. Energy
Capacity a body or substance possesses which can result in the performing work
Work is defined as the result of moving a force through a distance
Transfer of energy because of the temperature difference is called as heat transfer
Two forms of energy
Potential Energy
Kinetic Energy
One due to position of the body and other due to motion of the body

10. Work and Pressure-Volume Diagram
Used to describe corresponding changes in volume and pressure in a system
PV diagrams, originally called indicator diagrams
Work done= force * distance
=PA*L
Now we can write
AL=volume swept by piston
=(V2-V1)
So we can write as
Work done= P (V2-V1) Nm=Joule=J

11. This P-V diagram shows the expansion in the thermal engine
The area of each small rectangle represents the work done
Sum of all the areas of these rectangles almost represents the area under the graph
That can be seen as total work done
Work done=

12. Example Question
A fluid in a cylinder is at a pressure of 700kN/m2. It is expanded at constant pressure from volume 0.28m3 to a volume of 1.68m3. Determine the work done.
Solution
W=P(V2-V1)
=700*103( )
=9.8*105 J

13. BIogas