Calorific value is the amount of energy released when a specific quantity of a substance, typically a fuel or food, undergoes complete combustion or metabolism. It is measured in units such as kilojoules (kJ) or kilocalories (kcal). In this article, we will cover the meaning and definition of calorific value, how to calculate with the formula of calorific value, calorific values of different fuels and food items.
Table of Content
What is Calorific Value?
Calorific value is the amount of energy released when something burns or undergoes combustion. It tells how much heat is produced during this process. For example, when a piece of wood or coal is burnt, the calorific value indicates how much heat is generated. It’s like a measure of the energy we get from burning things. Different substances have different calorific values, and it helps us understand their heating or energy-producing capabilities. It is also known as calorific power, and its measuring unit is kilojoules per kilogram or KJ/Kg.
Calorific Value Definition
Calorific value is the measure of how much energy is released when a substance undergoes combustion, indicating the heat generated during the burning process.
Calorific Value of Different Fuels
The calorific value of various fuels are:
|
Fuel Type |
Calorific Value of Fuel (Approximately) |
|---|---|
|
Peat |
6000 |
|
Hardwood |
20000 |
|
Anthracite |
31000 |
|
Natural gas |
38000 |
|
Biodiesel |
42000 |
|
Jet Fuel |
43000 |
|
Gasoline |
46000 |
|
Hydrogen |
52000 |
|
Propane |
55000 |
|
Cow dung |
8000 |
|
Wood |
22000 |
|
Coal |
33000 |
|
Biogas |
40000 |
|
Diesel |
45000 |
|
Kerosene |
45000 |
|
Petrol |
45000 |
|
Methane |
50000 |
|
LPG |
55000 |
Calorific Value of Different Foods
The calorific values of various food categories are:
|
Food Category |
Calorific Value |
|
|---|---|---|
|
Cellulose |
8 KJ/gm |
2 Kcal/gm |
|
Sugar Alcohols |
10 KJ/gm |
2.4 Kcal/gm |
|
Ethanol |
29 KJ/gm |
7 Kcal/gm |
|
Starch |
17 KJ/gm |
4 Kcal/gm |
|
Amino Acids |
17 KJ/gm |
4 Kcal/gm |
|
Lipids |
37 KJ/gm |
9 Kcal/gm |
|
Protein (Generic) |
17 KJ/gm |
4 Kcal/gm |
|
Fructose (Sugar) |
17 KJ/gm |
4 Kcal/gm |
|
Glucose (Sugar) |
17 KJ/gm |
4 Kcal/gm |
|
Sucrose (Sugar) |
17 KJ/gm |
4 Kcal/gm |
|
Dietary Fiber |
8 KJ/gm |
2 Kcal/gm |
|
Olive Oil (Fat) |
37 KJ/gm |
9 Kcal/gm |
How to Calculate Calorific Value?
Two main values are used to calculate the calorific value: Gross Calorific Value (GCV) and Net Calorific Value (NCV). The Gross Calorific Value is the total heat produced during complete combustion, while the Net Calorific Value accounts for the heat used to vaporize water formed during combustion.
Calorific Value Formula
The formula for Net Calorific Value (NCV) is obtained by subtracting the Latent Heat of Water Vapors from the Gross Calorific Value (GCV). Alternatively, you can find the Gross Calorific Value by adding the Net Calorific Value to the Latent Heat of Water Vapors.
NCV = GCV – Latent Heat of Water Vapors
GCV = NCV + Latent Heat of Water Vapors
Difference Between Gross and Net Calorific Value
- Gross Calorific value is the total amount of heat produced when a certain amount of fuel burns completely. It includes all the heat released during combustion, including the heat used to turn water into steam.
- Net Calorific Value, on the other hand, is the heat produced when fuel burns, excluding the heat used to turn water into steam. It’s the useful heat available for things like generating electricity or heating.
Importance of Calorific Value
Calorific value is helpful in different fields, some of them are:
- Energy Assessment: Calorific value helps assess the energy content of various fuels, providing crucial information for energy production and consumption planning.
- Fuel Efficiency: It is a key factor in determining the efficiency of a fuel. Higher calorific values indicate more energy output per unit of fuel consumed, leading to increased efficiency.
- Combustion Analysis: Calorific values aid in understanding how efficiently a substance will burn, influencing combustion processes in industries, power plants, and for heating purposes.
- Fuel Selection: Different applications require different levels of energy. Calorific values assist in selecting appropriate fuels based on their energy content for specific uses, such as cooking, transportation, or electricity generation.
- Economic Considerations: Industries and consumers can make informed economic decisions by considering the calorific values of fuels, balancing energy requirements with cost-effectiveness.
- Environmental Impact: Knowing the calorific value is essential for assessing the environmental impact of burning fuels. It influences decisions on sustainable and cleaner energy sources.
- Cooking and Heating: In households, understanding the calorific value of cooking fuels like wood, gas, or electricity is crucial for efficient and cost-effective cooking and heating.
- Industrial Processes: Industries rely on accurate calorific values for efficient operation. This includes sectors such as metallurgy, cement production, and chemical processing.
- Renewable Energy Planning: For renewable energy sources, knowing their calorific values helps in integrating them into the energy grid and understanding their contribution to overall energy needs.
- Standardization and Regulation: Calorific values are often used in setting standards and regulations, ensuring consistency and quality in the production and use of fuels.
- Research and Development: Scientists and engineers use calorific values in research and development to innovate new energy sources, improve combustion efficiency, and create more sustainable technologies.
Read More,
Calorific Value-FAQs
What is Calorific Value and SI unit?
Calorific values is the quantity of energy released during the combustion of a fuel or other substance. The SI unit of calorific value is J kg-1.
How to Calculate Calorific Value of Fuel?
Calculating the calorific value of fuel involves burning a known quantity of the fuel and measuring the heat released. This is usually done in a controlled environment like a calorimeter.
What is the Difference Between LCV and HCV?
The difference between lower calorific value (LCV) and higher calorific value (HCV) is that LCV considers the heat released when water formed during combustion is in vapor form, while HCV includes the heat released when water is in liquid form.
What is the Unit of Calorific Value?
The unit of calorific value is expressed in joules per unit of mass, such as joules per gram (J/g) or kilojoules per kilogram (kJ/kg).
What is CV value of Coal?
Calorific value of coal is in the range of 25–35 MJ/kg.