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The thermal efficiency of a piston engine is about…

  • A
    50%
  • B
    80%
  • C
    70%
  • D
    30%

Thermal efficiency. For a heat engine, such as an internal combustion engine, thermal efficiency is the measure of how efficiently the engine converts thermal heat contained by fuel into useful work.

Thermal efficiency = (Heat converted to work ÷ Heat energy available in the fuel) × 100%.

  • The average thermal efficiency of a piston engine is approximately 33%. Most of the heat energy is lost to the atmosphere in the exhaust. The remainder heats up the engine components.

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