Hot air engine

Illustration of a low temperature differential (LTD) hot air engine. 1. Power piston, 2. Cold end of cylinder, 3.Displacer piston 4. Hot end of cylinder Q1. Heat in, Q2. Heat out.

A hot air engine[1] (historically called an air engine or caloric engine[2]) is any heat engine that uses the expansion and contraction of air under the influence of a temperature change to convert thermal energy into mechanical work. These engines may be based on a number of thermodynamic cycles encompassing both open cycle devices such as those of Sir George Cayley[3] and John Ericsson[4] and the closed cycle engine of Robert Stirling.[5] Hot air engines are distinct from the better known internal combustion based engine and steam engine.

In a typical implementation, air is repeatedly heated and cooled in a cylinder and the resulting expansion and contraction are used to move a piston and produce useful mechanical work.

  1. ^ "An Inquiry into the Hot Air Engines of the 19th Century". hotairengines.org.
  2. ^ Robert Sier (1999). Hot air caloric and stirling engines. Vol.1, A history (1st Edition (Revised) ed.). L.A. Mair. ISBN 0-9526417-0-4.
  3. ^ "Cayley's life and Air Engines". hotairengines.org.
  4. ^ "Ericsson's life and Air Engines". hotairengines.org.
  5. ^ "Stirling's life and Air Engines". hotairengines.org.