This Timeline of heat engine technology describes how heat engines have been known since antiquity but have been made into increasingly useful devices since the seventeenth century as a better understanding of the processes involved was gained. They continue to be developed today.
In engineering and thermodynamics, a heat engine performs the conversion of heat energy to mechanical work by exploiting the temperature gradient between a hot "source" and a cold "sink". Heat is transferred to the sink from the source, and in this process some of the heat is converted into work.
A heat pump is a heat engine run in reverse. Work is used to create a heat differential. The timeline includes devices classed as both engines and pumps, as well as identifying significant leaps in human understanding.
 Pre Eighteenth century
- Prehistory - The fire piston used by tribes in southeast Asia and the Pacific islands to kindle fire.
- c. 450 BC - Archytas of Tarentum used a jet of steam to propel a toy wooden bird suspended on wire.
- c. 200 BC - Hero of Alexandria's Engine. Demonstrates rotary motion produced by the reaction from jets of steam.
- c. 900s - China develops the earliest fire lances which were spear-like weapons combining a bamboo tube containing gunpowder and shrapnel like projectiles tied to a spear.
- c 1100s - China, the earliest depiction of a gun showing a metal body and a tight-fitting projectile which maximises the conversion of the hot gases to forward motion.
- 1120 - Gerbert, a professor in the schools at Rheims designed and built an organ blown by air escaping from a vessel in which it was compressed by heated water.
- 1232 - First recorded use of a rocket. In a battle between the Chinese and the Mongols. ( see Timeline of rocket and missile technology for a view of rocket development through time.)
- c. 1500 - Leonardo da Vinci builds the Architonnerre, a steam-powered cannon.
- 1551 - Taqi al-Din demonstrates a steam turbine, used to rotate a spit.
- 1629 - Giovanni Branca demonstrates a steam turbine.
- 1662 - Robert Boyle publishes Boyle's Law which defines the relationship between volume and pressure in a gas.
- 1665 - Edward Somerset, the Second Marquess of Worcester builds a working steam fountain.
- 1680 - Christiaan Huygens publishes a design for a piston engine powered by gunpowder but it is never built.
- 1690 - Denis Papin - produces design for the first piston steam engine.
- 1698 - Thomas Savery builds a pistonless steam-powered water pump for pumping water out of mines.
 Eighteenth century
 Nineteenth century
- 1802 - Joseph Louis Gay-Lussac develops Gay-Lussac's law which describes the relationship between a gas's pressure and temperature.
- 1807 - Nicéphore Niépce installed his 'moss, coal-dust and resin' fuelled Pyréolophore internal combustion engine in a boat and powered up the river Saone in France.
- 1807 - Franco/Swiss engineer François Isaac de Rivaz built the De Rivaz engine, powered by the internal combustion of hydrogen and oxygen mixture and used it to power a wheeled vehicle.
- 1816 - Robert Stirling invented Stirling engine, a type of hot air engine.
- 1824 - Nicolas Léonard Sadi Carnot developed the Carnot cycle and the associated hypothetical Carnot heat engine that is the basic theoretical model for all heat engines. This gives the first early insight into the second law of thermodynamics.
- 1834 - Jacob Perkins, obtained the first patent for a vapor-compression refrigeration system.
- 1850s - Rudolf Clausius sets out the concept of the thermodynamic system and positioned entropy as being that in any irreversible process a small amount of heat energy δQ is incrementally dissipated across the system boundary
- 1859 - Etienne Lenoir developed the first commercially successful internal combustion engine, a single-cylinder, two-stroke engine with electric ignition of illumination gas (not gasoline).
- 1861 - Alphonse Beau de Rochas of France originates the concept of the four-stroke internal-combustion engine by emphasizing the previously unappreciated importance of compressing the fuel–air mixture before ignition.
- 1861 - Nikolaus Otto patents a two-stroke internal combustion engine building on Lenoir's.
- 1872 - Pulsometer steam pump, a pistonless pump, patented by Charles Henry Hall. It was inspired by the Savery steam pump.
- 1873 - The British chemist Sir William Crookes invents the light mill a device which turns the radiant heat of light directly into rotary motion.
- 1877 - Theorist Ludwig Boltzmann visualized a probabilistic way to measure the entropy of an ensemble of ideal gas particles, in which he defined entropy to be proportional to the logarithm of the number of microstates such a gas could occupy.
- 1877 - Nikolaus Otto patents a practical four-stroke internal combustion engine (U.S. Patent 194,047)
- 1883 - Samuel Griffin of Bath UK patents a six-stroke internal combustion engine.
- 1884 - Charles A. Parsons builds the first modern Steam turbine.
- 1886 - Herbert Akroyd Stuart builds the prototype Hot bulb engine, an oil fueled Homogeneous Charge Compression Ignition engine similar to the later diesel but with a lower compression ratio and running on a fuel air mixture.
- 1892 - Rudolf Diesel patents the Diesel engine (U.S. Patent 608,845) where a high compression ratio generates hot gas which then ignites an injected fuel.
 Twentieth century
 Twenty first century
- 2011 - Michigan State University builds the first wave disk engine. An internal combustion engine which does away with pistons, crankshafts and valves, and replaces them with a disc-shaped shock wave generator.
 See also
- The Growth Of The Steam-Engine Robert H. Thurston, A. M., C. E., New York: D. Appleton and Company, 1878.
- Thermal Engineering in Power Systems By Ryoichi Amano, Bengt Sundén, Page 40, chapter 'Brief History of energy conversion'. Volume 22 of Developments in Heat Transfer Series, International series on developments in heat transfer, v. 22, WIT Press, 2008 ISBN 1-84564-062-4, ISBN 978-1-84564-062-0
- ^ Hellemans, Alexander; et al. (1991). ""The Timetables of Science: A Chronology of the Most Important People and Events in the History of Science"". New York: Touchstone/Simon & Schuster, Inc., 1991.
- ^ Hassan, Ahmad Y. "Taqi al-Din and the First Steam Turbine". History of Science and Technology in Islam. Retrieved 2008-03-29.
- ^ "The History of the Automobile - Gas Engines". About.com. 2009-09-11. Retrieved 2009-10-19.
- ^ The Griffin Engineering Company, of Bath, Somerset University Of Bath, 15 December 2004. Accessed May 2011
- ^ Michigan State University: Wave Disk Engine U.S. Department of Energy , Advanced Research Projects Agency, March 2011