A fire piston, sometimes called a fire syringe or a slam rod fire starter, is a device of ancient Southeast Asian origin which is used to kindle fire. In Malay it is called “gobek api” . It uses the principle of the heating of a gas (in this case air) by rapid and adiabatic compression to ignite a piece of tinder, which is then used to set light to kindling.
source.image: Warped
Youtube channel Warped made a See-through fire piston and filmed it in slow motion so we can see how exactly a diesel engine ignites, the fire piston is the exact same principle that diesel engines use. It was very interesting to see combustion happen from simply compressing air.
Rapid compression of a gas increases its pressure and its temperature at the same time. If this compression is done too slowly the heat will dissipate to the surroundings as the gas returns to thermal equilibrium with them. If the compression is done quickly enough, then there is no time for thermal equilibrium to be achieved. The absolute temperature of the gas can suddenly become much higher than that of its surroundings, increasing from the original room temperature of the gas to a temperature hot enough to set tinder alight.
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The air in the cylinder acts both as a source of heat and as an oxidizer for the tinder fuel. The same principle is used in the diesel engine to ignite the fuel in the cylinder, eliminating the need for a spark plug as used in the gasoline engine.
