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STUDY OF DETERMINATION OF CALORIFIC VALUE OF FUELS BY USING BOMB
CALORIMETER
AIM: -To study determination of Calorific Value of Fuels by using Bomb calorimeter.
APPARATUS: - Oxygen Cylinder, Solid fuel (Benzoic Acid), Digital Meter, Stop watch, Tablet Gun & Calorimeter, etc.
DIAGRAM:
To start with, about 1 gm of fuel sample is accurately weighed into the crucible and a fuse wire (whose weight is known) is stretched between the electrodes. It should be ensured that wire is in close contact with the fuel. To absorb the combustion products of Sulphur and nitrogen 2 ml of water is poured in the bomb. Bomb is then supplied with pure oxygen through the valve to an amount of 25 atmospheres. The bomb is then placed in the weighed quantity of water, in the calorimeter. The stirring is started after making necessary electrical connections, and when the thermometer indicates a steady temperature fuel is fired and temperature readings are recorded after 1/2 minute intervals until maximum temperature is attained. The bomb is then removed; the pressure slowly released through the exhaust valve and the contents of the bomb are carefully weighed for further analysis.
The heat released by the fuel on combustion is absorbed by the surrounding water and the calorimeter.
From the above data the calorific value of the fuel can be found in the following way:
Let
Wf = Weight of fuel sample (kg),
W = Weight of water (kg),
C = Calorific value (higher) of the fuel (kJ/kg),
We = Water equivalent of calorimeter (kg),
T1 = Initial temperature of water and calorimeter,
T2 = Final temperature of water and calorimeter,
Tc = Radiation corrections, and
Cpw = Specific heat of water.
Heat released by the fuel sample = Wf × C
Heat received by water and calorimeter
= (Ww + We) × Cpw× [(T2 – T1) + Tc].
Heat lost by fuel Sample = Heat gained Water and Calorimeter
Wf × C = (W + We) × c × [(T2 + T1) + Tc]
[Value of c is 4.18 in SI units and unity in MKS units.]
OBSERVATIONS:
Water equivalent of calorimeter (kg),= 1.1 Kg
Weight of water (kg),= 1.6Kg
Specific heat of water (Cpw)= 4.187 KJ/Kg K
Weight of fuel sample (kg),: 1gm
Weight of fuse wire:0.26 gm
Higher calorific value of Nickel fuse wire (HCVfw )=4108.70KJ/Kg
Initial temperature is T1=26.70C
OBSERVATIONS TABLE:
CALCULATIONS:
Observed rise in temperature= T2-T1
Cooling rate: CR
CR=
Cooling correction: Tc
True rise in temperature = Observed rise in temperature + Cooling Correction
= (T2-T1) + Tc
Heat released by fuel= Wf X HCV
Heat released by fuse wire = Wmf X HCVfw
Calorific value of fuel
RESULT:
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