# Calorific Value of the IC Engine Fuels

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## Importance of Calorific Value

The term calorific value of the IC engines fuels is very important term. The fuels for the IC engines are selected on the basis of the calorific value of the fuel. If the fuel has higher calorific value it will have tendency to produce more power in the engine. The fuels with less calorific value tend to burn inefficiently thus causing lots of exhaust and air-pollution. Let us see this very important term of the fuels.

## Calorific Value of the IC Engine Fuels

The calorific value of the fuel is also called as the heat value of the fuel. It is defined as the amount of heat released by burning of unit quantity of the fuel. The calorific value is an important characteristic of the fuel. The unit of measurement of the calorific value is the same as the energy.

In SI system calorific value is measured as J/kg (Joule per kg), in MKS system it is measured as Kcal/kg and in British units it is measured as Btu. The calorific value of the fuel can be measured by a devise called as Bomb Calorimeter.

## Types of Calorific Value of the Fuel

There are two types of the calorific value of the fuels, these are:

1) Gross calorific value or higher heating value of the fuel: The gross calorific value of the fuel is defined as the amount of heat released by burning the specified amount of fuel at 25 degree Celsius and bringing the products of combustion back to the original temperature of 25 degrees. The gross calorific value of the fuel takes into account the latent heat of vaporization of water in the combustion products.

2) Net calorific value or lower heating value of the fuel: The net calorific value of the fuel is defined as the amount of heat released from the fuel by burning specified quantity of the fuel at 25 degree Celsius and bringing the products of combustion to a temperature of 150 degree Celsius. In the net calorific value it is assumed that the latent heat of vaporization of water in the fuel is not recovered. The gross calorific value of the fuel is always higher than the net calorific value of the fuel.

The higher is the calorific value of the fuel more is the heat generated by its combustion in the engine of the automobiles and eventually more is the power generated by the engine. Hence fuels with high calorific value are always preferred for the automobiles. Further, the low calorific value of the fuels also means that there will be more exhaust from the engine, which has tendency to create more air-pollution.