Calorific value

Calorific Value Definition

“Calorific value refers to the amount of heat produced by unit volume of a substance by complete combustion.”

What is the Calorific value?

Calorific value is the amount of heat energy present in food or fuel and which is determined by the complete combustion of specified quantity at constant pressure and in normal conditions. It is also called calorific power. The unit of calorific value is kilojoule per kilogram i.e. KJ/Kg.

Water vapour is generated in the combustion process and the heat should be recovered by using certain techniques. If the heat contained in the water vapour could be recovered then it has high calorific value. If heat contained in the water vapor could not be recovered when it has low calorific value.

The efficiency of fuel or food mainly depends on the calorific value. If the value is high, its efficiency will also be high. If the value is low, its efficiency would also decrease. Calorific value is directly proportional to its efficiency.

Also Read: Carbohydrates

Calorific Value of Fuel

Here is the detailed list of fuels and their calorific values:

calorific value

Calorific Value of Fuel

Fuel  Calorific Value Of Fuel( Approximately)
Cow Dung 8000
Wood 22000
Coal 33000
Biogas 40000
Diesel 45000
kerosene 45000
Petrol 45000
Methane 50000
LPG 55000

LPG has more calorific value when compared to diesel, petrol, and kerosene.

A detailed list of foods and their calorific values:

The calorific value of food indicates the total amount of energy, a human body could generate during its metabolism which is expressed in Kilojoules per 100  grams or 100 ml. The calorific value of food is generally expressed in kilocalories i.e. kcal.

The below table shows the type of food and its calorific value:

Category of food  Quantity(Grams)   Calorific value (Approximately)
Kilojoules(KJ) Kilocalories(Kcal)
Dietary fibre   1       8       2
Polyhydric Alcohols   1     10       2.4
Alcohols   1    29      7
Carbohydrates   1    17     4
Protein   1   17     4
Fats   1   37      9

Fats have more calorific value when compared to carbohydrates, protein, alcohols, roughage and other biomolecules involved in the maintenance and metabolic processes.

Importance of Calorific Value

It is very important to have a knowledge of the calorific value of fuel to carry out our day-to-day activities. This knowledge helps us to determine the amount of energy we transport. The gas shippers and suppliers require this information to bill gas consumers. It also helps to determine transportation charges of gas shippers and suppliers.

The human body requires calories to carry out daily activities. Without calories, the body would stop working and the cells in the body would die. But, if people consumed only a specific amount of calories each day, they would lead a healthy life. Too high or too low calorie consumption eventually leads to health problems.

Also Read: Balanced Diet

Learn more about the calorific value and calorific value of fuel and other related concepts @ BYJU’S Biology

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