Bomb calorimeter – Parts, Diagram, Working, Formula

Calorimeter- Introduction 

What is Calorimeter?

A calorimeter is an object used for calorimetry or the process of measuring the heat of chemical reactions or physical changes as well as heat capacity. Differential scanning calorimeters, isothermal micro calorimeters, titration calorimeters, and accelerated rate calorimeters are among the most common types. A simple calorimeter just consists of a thermometer attached to a metal container full of water suspended above a combustion chamber. It is one of the measurement devices used in the study of thermodynamics, chemistry, and biochemistry.

The different calorimeters types are given below:

  • Adiabatic Calorimeters
  • Reaction Calorimeters
  • Bomb Calorimeters (Constant Volume Calorimeters)
  • Constant Pressure Calorimeters
  • Differential Scanning Calorimeters

Definition of Bomb Calorimeters:

The calorific value of solid and liquid fuels is determined in the laboratory by ‘Bomb calorimeter’ It is so named shape resembles that of a bomb.Fig shows the schematic sketch of the bomb calorimeter.

Construction of Bomb Calorimeters :

The calorimeter is made of austenitic steel which provides considerable resistance to corrosion and enables it to withstand high pressure. In the calorimeter use of a strong cylindrical bomb in which combustion occurs. The bomb has two values at the top. One supplies oxygen to the bomb and the other releases the exhaust gases. A crucible in which a weighed quantity of fuel sample is burnt is arranged between the two electrodes as shown in fig. The calorimeter is fitted with a water jacket that surrounds the bomb To reduce the losses due to radiation calorimeter is further provided with a jacket of water and air. A stirrer for keeping the temperature of water uniform and a thermometer the temperature up to the accuracy of 0.001 degree C is fitted through the lid of the calorimeter.

Calorimeter Diagram 

Bomb calorimeter diagram
Bomb calorimeter diagram

Working of Bomb Calorimeters:

The calorimeter is made of austenitic steel which provides considerable resistance to corrosion and enables it to withstand high pressure. In the calorimeter use of a strong cylindrical bomb in which combustion occurs. The bomb has two values at the top. One supplies oxygen to the bomb and the other releases the exhaust gases. A crucible in which a weighed quantity of fuel sample is burnt is arranged between the two electrodes as shown in fig. The calorimeter is fitted with a water jacket that surrounds the bomb To reduce the losses due to radiation calorimeter is further provided with a jacket of water and air. A stirrer for keeping the temperature of water uniform and a thermometer the temperature up to the accuracy of 0.001 degree C is fitted through the lid of the calorimeter. 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.

Bomb Calorimeter Formula :

Dulong’s formula used to calculate the theoretical calorific value of fuel if the ultimate analysis is available and the calorific value of elementary combustibles is known.

Theoretical calorific Value of fuel = 33800 C + 144500 ( H2 – ( O2/8 ) ) +9300  kJ/kg

Where C, H2 O2 & S repents the mass of carbon, hydrogen, oxygen, and sulfur in kJ/Kg


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Sachin Thorat

Sachin is a B-TECH graduate in Mechanical Engineering from a reputed Engineering college. Currently, he is working in the sheet metal industry as a designer. Additionally, he has interested in Product Design, Animation, and Project design. He also likes to write articles related to the mechanical engineering field and tries to motivate other mechanical engineering students by his innovative project ideas, design, models and videos.

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