Thermal efficiency

• Thermal Efficiency

  Heat engines are any device that absorbs heat (Q) and convert part of that energy to mechanical work and then the remaining heat (waste) is released into a low-temperature sink.

  Q(in) = Work done + Q(out)

  Work done = Q(in) - Q(out)
• Heat engines: Steam turbine

  1)High temprature steam is directed across the blade of a turbine, causing it to spin

  2)The spinning motion converts the heat (Q) from the steam into mechanical work

  3)This 'mechanical work' can be used to generate electricity or power machinery.

  
  

  Some heat is lost (cannot reach 100% efficiency) to the surroundings.
• Efficiency (η) = Work done / Q(in)

  -> η = 1 - Q(out) ÷ Q(in)
• Carnot Efficiency

  The maximum efficiency that a heat engine may have operating between the two temperatures. Also known as the 'maximum theoretical efficiency'