Combustible - GaRiMa

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22 Φεβ 2014 (πριν από 3 χρόνια και 8 μήνες)

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SCIENCE

COMBUSTION AND
FLAME

Presented By :
--

B.Kiran Kumar


(TGT BIO)


6
Chapter

COMBUSTION AND FLAME

Combustion
:
-

The chemical reaction in which
substances combines with oxygen and produce heat
and light is called

Combustion
.


Combustible

:
-

The substances which catch fire and
produce heat and light are called
Combustible.



Smoldering combustion
:

Smoldering
combustion Smoldering is the slow, low
-
temperature, flameless form of combustion,
sustained by the heat evolved when oxygen
directly attacks the surface of a condensed
-
phase
fuel. Solid materials that can sustain a smoldering
reaction include coal, cellulose, wood
.


Rapid
combustion
:

Rapid
combustion Rapid
combustion is a form of combustion, otherwise
known as a

fire, in which large amounts of heat
and

light

energy are released, which often results
in a

flame. This is used in a form of machinery
such as

internal combustion engines .

Turbulent combustion
:

Turbulent
combustion
Combustion resulting in a turbulent flame is the
most used for industrial application (e.g. gas
turbines, gasoline engines, etc.) because the
turbulence helps the mixing process between the
fuel and oxidizer
.


Microgravity
:

Microgravity
Combustion processes
behave differently in a

microgravity
environment

than in Earth
-
gravity conditions due to
the lack of

buoyancy. For example, a candle's flame
takes the shape of a sphere .



Inflammable substances
::
-
The substances which
have very low ignition temperature and can easily
catch fire with a flame
are called
Inflammable
substances

.


Rapid combustion:
-


We find that the gas burns
rapidly and produces heat and light . Such
combustion is know
as rapid combustion
.


Spontaneous combustion:
-

The types of
combustion in which a material suddenly burst into
flames, without the application to any apparent
cause is called

Spontaneous
combustion.



FLAME:


FLAME A flame is the visible (light
-
emitting), gaseous part of a

fire. It is
caused by a highly

exothermic

reaction
taking place in a thin zone . If a fire is hot
enough to

ionize

the gaseous components,
it can become a
plasma.

Fill The Table


Non

Combustible

substances

:
-

The substances
which do not catch fire and could not give heat , light
are called
non
-
combustible
substances.


Fuel:
-

The substances that undergoes Combustion

is said combustible. It also Know as
Fuel.


Ignition temperature:
-

The lowest temperature at
which a substances catches fire is called its
ignition
temperature.




LIQUID FUELS:

LIQUID
FUELS Combustion of
a liquid fuel in an oxidizing atmosphere actually
happens in the gas phase. It is the vapour that burns,
not the liquid. Therefore, a liquid will normally
catch fire only above a certain temperature: its

flash
point
.


SOLID FUELS:

SOLID
FUELS Solid fuel refers to
various types of

solid

material that are used
as

fuel

to produce

energy

and provide

heating , oih
sually released through combustion.Solid fuels
include

wood , charcoal,

peat,

coal,

Hexamine fuel
tablets, and pellets made from wood,
corn, wheat
,

rye

and other

grains .

Explosion:
-

A large amount of gas formed in the
reaction in liberated. Such a reaction is called
Explosion.

Ideal Fuel:
-


There is probably no fuel that could be
considered as an
Ideal Fuel
.


Calorific value:
-

The amount of heat energy produced
on complete combustion of 1kg of a fuel is called its
Calorific
value.




The calorific value of a fuel is expressed in a
unit called
Kilojoule per kg.



Acid rain:
-

Oxides of sulphur and nitrogen
dissolve in rain water and form acids are called

Acid
rain.







Water is commonly used to control fire.


Water cannot be used to control fires involving
electrical equipment or oils.


There is various types of combustion such as
rapid combustion, spontaneous combustion,
explosion, etc.



There are three different zones of a flame :
-



Dark Zone



Luminous Zone




Non
-
luminous Zone

Main Points

A ideal fuel is cheap, readily available, readily
combustible and easy to transport . It has high
calorific values. It does not produce gases or
residues that pollute the environment.


Fuel differ in their efficiency and cost.


Unburnt carbon particles in air are dangerous
pollutants causing respiratory problem .

Incomplete combustion of a fuel gives poisonous
carbon monoxide gas.



Key Words

o
ACID RAIN

o
CALORIFIC VALUE

o
COMBUSTION

o
DEFORESTATION

o
EXPLOSION

o
FLAME

o
FIRE EXTINGUISHER

o
IDEAL FULE

o
IGNITION TEMPERATURE

o
INFLAMMABLE TEMPERATURE

o
GLOBAL WARMING