BCIT Physics Department

Demonstration Manual


DHT02 - Pasco Compression Igniter


- To demonstrate that the compression of air inside a hollow cylinder is an adiabatic process since the compression is so fast that
there is no time for thermal energy to leave or enter the cylinder.


Method A:

Put a small piece of tissue paper into the cylinder and quickly push down on the piston. The resulting compression will cause a great enough increase in temperature to cause the tissue paper to ignite.


In a quick compression there is no time for heat to be exchanged between the air inside and its surroundings. The 15:1 adiabatic compression causes the temperature to rise approximately 600 degrees celsius (1100 degrees fahrenheit), well above the combustion temperature of paper.

The Compression Igniter serves as an excellent introduction to how diesel engines operate as they also utilize adiabatic compression, in their case to ignite fuel rather than paper.

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