Ch:1Ch:1INTRODUCTONINTRODUCTON

PRIME MOVERS DEFINATION

Prime movers is a device which use the energy from natural sources and convert in to mechanical works.

Before the development of machine man had to depend on his own physical strength and on animal, mainly horse.

So when was the mechanical system was invented at that time unit of power is horse power.

Technically, it is a group of machines that transform energy from thermal, electrical, or pressure into mechanical form for use in different sources for some mechanical work. Engines and turbines are examples.

Sources of energy used by Prime movers. Burning of fuels:

It is the most important topics of energy. heat energy is librated when fuel is burnt.

Different fuels have different calorific value based on on heat is given out.

The heat energy converted in to mechanical work by using heat energy.

River water:

River water is another useful and widely used another sources.

Water potential energy convert in to the kinetic energy when it reaches the prime movers.

River water is also used to generate the steam in the boiler and its used in the steam turbine.

Atoms:

Using atoms as a source of energy is recent development. It is also widely use energy source. heat energy produce by fission of the atoms.

Wind and solar energy:

It is the renewable energy sources of energy.

this is the freely available energy sources.

Sources of energy to run prime movers

Sources of energy

Thermal Non Thermal

water

Tidal power wind

fuel Nuclear Geothermal Bio-gas Solar energy

External combustion engine Internal combustion engine

Reciprocating steam engine Stem

turbineClosed cycle gas turbine

Reciprocating I.C engine Open cycle

gas turbine

Definitions

Force :A body of mass m subject to a force F undergoes an acceleration a that has the same direction as the force and a magnitude that is directly proportional to the force i.e., F = ma.

Weight:It is the force exerted by gravityw = m x g (N)Weight of an object is not constant. It depends on the gravitational force

Mass : Mass is the quantity of matter. It depending force acting on it. Mass of the body is same weather the body is on the moon or the earth.

Pressure: Pressure is the ratio of force to the surface area over which it is exerted.

Pressure : )(

)(2mm

n

Area

Force

211mm

npascal

Breaker power : Power delivered by the engine is break power.

Energy : It is defined as the capacity of doing work.

Energy conservation

Energy cannot be destroyed or created it can change from its State. This conversion may be completed or partial

High grade energy:

Energy that can completely converted in to the work.

Low grade energy:

energy of which only certain portion can be converted in to the work.

Specific heat : energy is required to rise the temperature of unit mass of a substance by one degree is know as its specific heat.

Which is denoted by (c)

Unit of specific heat is kj / kg k

)()(

)(

KTKgm

KJQC

TCmQ

Melting point: The point it where the solid converted in to the liquid when heat is added.

Boiling point: The point it where the liquid converted in to the vapour when heat is added.

Critical point: It is the temperature above which only one phase is existing. i.e vapour

Tripple pointIt is the temperature at which all the three phases solid, liquid and vapour are in equilibrium. Below this point only two phase are existing solid and vapour.solid is directly converted into the vapour.This process called sublimation

Types of systems

Open system

a system where matter or energy can flow into and/or out of the system.

Heat mass

Closed system :

where energy can enter or leave but matter may not.

i.e pressure cooker Isolated system :

In these system energy and mass can not across the boundary.

i.e thermos flask

Enthalpy : It is the combination of the (u+pv)

it is defined enthalpy and is given symbol.

it is denote by (H).

H= u + pv

Efficiencies

Brake power of an engine (b.p):

It is the power available for work at the output shaft of the engine.

Indicated power (i.p) :

It is the power developed in its engine cylinder Friction power : i.p = b.p + Friction power

Mechanical efficiency :

owerindicatedp

braekpowermech

Steady flow energy equation (SFEE)

11vp

entery

z1

z2Datum lineq

w

Enter

P1 v1

U1 c1

EXIT

P2 V2

U2 C2

P1 and p2 – Pressure at the entry and exit.

V1 and v2 – volumes at the enter and exit m3 / kg

U1 and u2 – internal energy at the entry and exit kj/kg.

C1 an c2 – velocity at the entry and exit m/s

Potential energy : This is because of the height of the fluid from the datum.

P.E = z kj/kg Kinematics energy : it is the energy because of the

motion of the fluid.

K.E =

kgkjcgc

/2

1 2

Internal energy : Internal Energy is the energy stored in a system at the molecular Level.

Which is denoted by the (u) and the unit is kj/kg

Flow and displacement work : Flow work at the entry = p1v1

Flow work at exit = p2v2

Heat received by the system = q kj/kg External work done by the system = w kj/kg. By the law of conservation of energy we have

Total energy entering at the system = Total energy leaving the system

wgc

cvpuzq

gc

cvpuz

22

2222

21

1111 22

wgc

cvpuzq

gc

cvpuz

22

2222

21

1111 22

First Law of Thermodynamics : The first law of thermodynamics is often

called the Law of Conservation of Energy. This law suggests that energy can be transferred from one system to another in many forms. Also, it can not be created or destroyed.

Zeroth law of thermodynamics:

If two bodies are thermal equilibrium with third body and they are also thermal equilibrium with each other .

Second law of thermodynamics:

Two statement for 2nd law of thermodynamics

1. Kelvin Plank Statement.

2. Clausius statement.

Kelvin Plank Statement :

it is impossible for any device that operate on a cycle to receive heat from a single source and produce a net amount of work.

Clausius statement :

It is impossible to construct a device that operates in a cycle and produce no effect other than the transfer of heat a lower temp. body to a higher temp. body.