The ppt is especially designed for engineering students. The lecture explains about fuels, its types, characteristics and in the last we have discussed about measurement of calorific value using Bomb calorimeter.

1. Dr. Shivendra Singh
Assistant Professor
NET-JRF, PhD (IIT Indore)
1
Engineering Chemistry
Fuels

2. 1. To acquire knowledge of different types of fuels
and about calorific value.
2. To acquire required knowledge about Bomb
calorimeter.
Objectives
Outcomes
Students will gain the basic knowledge of fuels.
They can understand the basic properties of fuels
and measurement of calorific values.

3. 1. Introduction- Importance of fuels in industry
2. Classification of fuels
3. Comparison of solid, liquid & gaseous fuels
4. Properties/Characteristics of fuels
5. Calorific value of a fuel
6. Determination of calorific value by Bomb Calorimeter
Outlines

4. Fuels: Most widely-used sources of energy in the world today.
Most fuels are natural substances such as petro fuel, diesel, and
natural gas, which are either extracted straight from the earth or
produced by refining substances such as petroleum.
The energy produced by burning fuel has many applications;
1. Powering vehicles, ships & airplanes
2. Providing electricity for homes and industries.
Some common fuels are;
Wood, Coal, Petroleum, Kerosene, Diesel, Natural gases
Definition (Fuel): Any combustible substance which during
combustion gives large amount of industrially or domestically
useful heat.
Introduction

5. A. On the basis of their occurrence:
1) Natural / Primary Fuels: Found in nature. Eg Wood, Coal,
Petroleum, Natural gas etc.
2) Artificial / Secondary Fuel: Prepared artificially generally from
primary fuels. Eg. Petrol, Coal gas, kerosene etc.
B. On the basis of physical state of aggregation:
1) Solid: Eg Wood, Coal etc.
2) Liquid: Eg. Petrol, kerosene etc.
3) Gas: Eg. Natural gas, coal gas, bio gas, water gas etc.
Classification

6. SN Fuel Characteris0cs Solid Fuel Liquid Fuel Gaseous Fuel
1 Cost Cheap Costly than solids Costly
2 Storage Easy In a closed container Leak proof container
3 Risk of fire hazards Least Greater Very high
4 CombusDon rate Slow Quick Very rapid
5 CombusDon control Not easy Controlled Possible by controlling air supply
6 Ash Always produced No issue No issue
7 Smoke Produced If high carbon; then
produced
Not produced
8 W/W calorific value Least Higher Highest
9 Thermal efficiency Least Higher Highest
Advantages
Easy to transport High CV, burn without dust Burn without any smoke, clean in
use
Moderate igniDon
temp
Easy to transport High CV
Classification

7. 1. High calorific value
2. Moderate igniDon temperature
3. Low moisture content
4. Low non-combusDble ma[er content
5. Moderate rate of combusDon
6. Harmless combusDon products
7. Low cost
8. Easy to transport
9. Low storage cost
10. Controllable combusDon
11. Uniform size
12. Fuel should burn in air with efficiency without much smoke
Characteristics of good fuel

8. 1. High calorific value: “Total quanDty of heat liberated from
combusDon of a unit mass (or volume) of the fuel in air or
oxygen.”
2. Moderate igni0on temperature: “Lowest temperature to
which the fuel must be pre-heated so that it starts burning
smoothly.” Moderate igniDon temp is ideal.
3. Low moisture content: Moisture reduces its heaDng value.
Low moisture is ideal.
4. Low non-combus0ble maGer content: Ash or clinker aeer
combusDon. Low is preferred.
5. Moderate rate of combus0on: “Moderate ideal”.
Characteristics of good fuel

9. 6. Harmless combus0on products: Not pollute the atmosphere.
7. Low cost:
8. Easy to transport:
9. Low storage cost:
10. Controllable combus0on:
11. Uniform size: “Combus0on is regular”.
12. Fuel should burn in air with efficiency without much smoke.
Characteristics of good fuel

10. Calorific Value of a fuel: “The total quanDty of heat liberated from the
combusDon of a unit mass (or unit volume) of the fuel in air or oxygen”.
Units of heat:
1. Calorie: Amount of heat required to increase the temp of 1 gm of water
through 1 °C.
2. Kilocalorie (Kilogram cen0grade units): (METRIC SYSTEM) 1 Kg of water
through 1°C. (1KCal = 1,000 Cal)
3. Bri0sh Thermal Unit (BTU): (ENGLISH SYSTEM) Amount of heat required to
increase the temp of 1 pound of water through 1 °F.
(1 BTU = 252 Cal = 0.252 Kcal)
4. Cen0grade Heat Unit (CHU): Amount of heat required to increase the temp
of 1 pound of water through 1 °C.
(1KCal = 3.968 BTU = 2.2 CHU)
Calorific value and Units

11. Higher or Gross Calorific Value (HCV): Hydrogen is found to be
present in almost all fuels and when the calorific value of
hydrogen-containing fuel is determined experimentally, the
hydrogen is converted into steam.
If the products of combusDon are condensed to the room
temperature, the latent heat of condensa0on of steam also gets
included in the measured heat, which is then called “higher or
gross calorific value”.
Defini0on of HCV: “The total amount of heat liberated, when unit
mass (or unit volume) of the fuel has been burnt completely and
the products of combusDon are cooled to room temperature”
Calorific value and Units

12. Lower or Net Calorific Value (LCV): In actual use of any fuel, the water
vapors and moisture escape as such along with hot combusDon gases.
Since they are not condensed. Hence a lesser amount of heat is
available.
LCV = HCV – Latent heat of water vapors
Since 1 parts by mass of hydrogen produces 9 parts by mass water
Hence, LCV = HCV – mass of hydrogen x 9 x Latent heat of steam
(The latent heat of steam is 587 Kcal/Kg or 1,060 BTU/lb of water
vapors formed at room temperature)
LCV: “The net heat produced, when unit mass or unit volume of the fuel
is burnt completely and the combusDon products are allowed to
escape.”
H2 + ½ O2 -----à H2O
2 gm 18 gm
1 gm 9 gm
Calorific value and Units

13. For Solid or Liquid Fuel:
ü Calorie/gram
ü Kcal/Kg
ü BTU/lb
Rela0ons:
ü 1 Kcal/Kg = 1.8 x BTU/lb
ü 1 Kcal/m3 = 0.1077 x BTU/Ft3
ü 1 BTU/Ft3 = 9.3 Kcal/m3
For Gaseous Fuels:
ü Kcal/Cubic meter (Kcal/m3)
ü BTU/Cubic Feet (BTU/f3)
Ib is an abbreviation of the latin word “libra” means
“balance or scales”
Calorific value and Units

14. 1. By Bomb Calorimeter: For solid and liquid fuels.
2. By Boy’s Gas Calorimeter
3. By Junker’s Gas Calorimeter
By Bomb Calorimeter
1. Principle: A known mass of fuel is burnt and the quanDty of heat
produced is absorbed in water & measured. Then the quanDty of
heat produced by burning a unit mass of the fuel is calculated.
2. Construc0on:
3. Working:
4. Calcula0ons:
5. Correc0on:
Determination of calorific value

15. 2. Construc0on:
Bomb calorimeter

16. 3. Working:
1. Weighed amount of the fuel in a crucible. Crucible is supported over the
ring.
2. A fine Mg wire, touching the fuel sample is then stretched across the
electrodes.
3. The Bomb lid is Dghtly screwed and Bomb filled with oxygen to 25-30
atmospheric pressure.
4. The Bomb is then lowered into copper calorimeter, containing a known
mass of water.
5. The iniDal temperature of water is noted. The electrodes are then
connected to 6 Volt ba[ery and circuit is then completed.
6. The sample burns and heat is liberated which is transformed to water.
7. Now Calorific value can be calculated;
Bomb calorimeter

17. 4. Calcula0ons: Let x = mass of gms of fuel sample taken in crucible;
W = Mass of water in the calorimeter (in gms)
w = water equivalent in gms of calorimeter, sDrrer, thermometer etc
(= weight of apparatus x specific heat = W’ x S)
T1 = iniDal temp of water in calorimeter
T2 = final temp of water in calorimeter
L = Higher (gross) calorific value of fuel in cal/gm
Hence Heat liberated by burning of fuel = x L Cal
And heat absorbed by water = W x S x (T2-T1)
And heat absorbed by apparatus = W’ x S x (T2-T1) = w(T2-T1)
Bomb calorimeter

18. Hence total heat absorbed by water, apparatus etc.
= [W x 1 x (T2-T1) + w x 1 x (T2-T1)] = [(W+w) x 1(T2-T1) Cal
Since specific heat of water = 1 cal/gm °C & 1 cal=4.186 J
xL = (W+w) (T2-T1)
Or HCV of fuel (L) = (W+w) (T2-T1)/x cal/gm
Bomb calorimeter

19. Let H = % of hydrogen in the fuel
Then gms of hydrogen present in 1 gm fuel = 1 x H/100
Since hydrogen is converted into steam,
H2 + ½ O2 -----------à H2O
2 gm 18 gm
1 gm 9 gm
So, weight of water produced from 1 gm H2 = 9 gm
Weight of water produced from H/100 H2 (or 1 gm fuel) = 9 x H/100
= 0.09 H gm
Moreover, Latent heat of steam = 587 cal/gm
Hence, Heat taken by water in forming steam (or Latent heat of water
vapors formed) = 0.09 H x 587 cal
Hence, LCV = (HCV – 0.09 H x 587) cal/gm
Bomb calorimeter

20. Summary
1. Introduction- Importance of fuels in industry
2. Classification of fuels
3. Comparison of solid, liquid & gaseous fuels
4. Properties/Characteristics of fuels
5. Calorific value of a fuel
6. Determination of calorific value by Bomb Calorimeter

21. For any querry
drshivendrasinghiiti@gmail.com