How does a bomb calorimeter work?

How does a bomb calorimeter work? | DDS Calorimeters

In short, the process of a calorimeter involves measuring the heat of a fuel sample when burned under stable temperature conditions to evaluate the heating energy of the fuel sample. The fuel sample can be a solid or liquid, but not a gas.

Our calorimeters require approximately 0.5g of sample matter (i.e. food) weighed in a crucible. We need to have the weight entered with four decimal places (i.e. 0.4972g) . Place crucible inside the stainless steel container ("the bomb vessel") and fill bomb vessel with 30 bar (435psi or 30 atm) of pure oxygen.

How does a bomb calorimeter work? | DDS Calorimeters

Place the filled bomb vessel inside the calorimeter and close the lid. The bomb vessel is now sealed and isolated from outside temperature influences. Once the bomb vessel temperature has stabilized in the bomb well, the sample is then ignited.

An electrical ignition charge instantly heats the ignition wire, which in turn burns the attached firing cotton. The burning cotton thread falls into the fuel sample below causing the sample to ignite.

How does a bomb calorimeter work? | DDS Calorimeters

During the burning of the fuel sample, the crucible can momentarily rise to above 1000 Deg C with the pressure spiking to 3 x the initial pressure. With in seconds, the heat of the reaction starts to dissipate into the bomb vessel and the pressure starts to subside.

To accurately measure the temperature of the vessel, sensitive high resolution temperature sensors are used, measuring every 6 seconds for the duration of the determination.

Once the determination is complete, typically within 4 minutes ( depending on which model you have), the calorimeter calculates the Calorific Value ( CV ) of the fuel sample. At this point in time, the bomb vessel is removed from the bomb well to be cooled. Typically the bomb vessel is now between 8 to 14 Deg C higher in temperature.

Once the bomb vessel is sufficiently cooled in a cooler, it can be reused again.

How does a bomb calorimeter work? | DDS Calorimeters


Combustion Calorimeters measure the heat released from a combustible solid-liquid substance. This is done by weighing a precise measure of the sample substance into a crucible, placing the crucible inside a "bomb" (a sealed metal cylinder called a vessel), filling the vessel with oxygen and igniting the substance.

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Traditionally water is used in adiabatic and isothermal combustion calorimeters. It is used as a heat sink, as a transfer medium, or as a transport medium. In short : A calorimeter will combust a weighted sample in a steel cylinder and measures the resulting temperature increase. From the temperature increase it calculates the calorific value. Somewhere in the process...

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