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

Working Substance The working substances are in general fluids that

can rapidly expand and compressed. Common example are steam and airPure Substance substances which has the same consistent

composition throughout steam and water or mixture of steam and waterMacroscopic 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.

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

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

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-273.15 Where t= temperature in Celsius

T=temperature in Kelvin

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

Process When the state of a substance is changed by means of an

operation or operationsCycle If processes are carried out on a substance such that at

the end the substance returned to its original stateConstance Temperature Process Process carried out such that the temperature remains

constant throughout the processConstance Pressure Process Process carried out such that the pressure remains

constant throughout the processConstance Volume Process Process carried out such that the pressure remains

constant throughout the process

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 energy1. Potential Energy2. Kinetic Energy One due to position of the body and other due to

motion of the body

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

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=

2

1

V

V

PdV

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(1.68-0.28) =9.8*105 J