4 Responses to Weekend Project: Fire Piston

  1. Orpheline on said:

    I thought compressing air generated heat because it increases the friction of the air molecules ‘gainst one another; is that not so?

    • trevyn on said:

      Friction in the air molecules may be part of the reason for the heating. The other reason is that a given volume of gas has a certain amount of heat energy in it (related to the temperature), and if the gas is compressed the same amount of energy is pushed into a smaller volume, resulting in a higher temperature. Refrigeration operates (more or less) on this principle.

      Given the speed with which the air is compressed, it’s hard to say to what degree each effect contributes to heating the air without figuring out some numbers and doing some calculations (for which I lack the necessary thermodynamics knowledge).

      As a side note, both effects would take place no matter how fast the air was compressed, but in this case it has to be compressed as quickly as possible because it’s always losing heat to the outside environment (the system is not adiabatic).

  2. chris on said:

    Kip Kay is the Billy Mays of Make.

  3. 500 degrees (°C ? °F ? °K ?) seems a lot for a plastic tube … Is it one shot ?

    Kip Kay seems totally unimpressed by the fact that Rudolf Diesel was inspired by a Malaysian fire making technique, but I think it’s totally awesome !

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