Manson engine

The Manson engine is a hot air engine that was first described by A. D. Manson in the March 1952 issue of Newnes Practical Mechanics-Magazines.^[1] Manson engines can be started in either direction (clockwise or anti-clockwise).^[2] It has a stepped piston. The front part acts as a displacer and the back part acts as a work piston (the displacer and the work piston move as a single component).^[3][1] The engine only requires three moving parts: piston,^[3] piston rod, and crank.

Animation

Photo

The engine is double acting,^[1] using both the expansion of the warmed air and atmospheric pressure overcoming the reducing pressure of the cooling air to do work.^[3][4][5]

The engine currently has no commercial or practical applications. The engines are built mainly as desk toys, physics demonstrations, and novelties.^[2]

Functioning mechanism

Drawing based on the original design^[1]

ideal PV-Diagramm^[6][7]

• Phase 1 (cooling down the work medium, suction stroke)
  • when the Piston is moved toward the heat source, the hot gas inside the engine is moved to the cool side of the cylinder.
  • the gas is cooled there, resulting in pressure dropping below atmospheric, further moving the piston toward the heat source.
• Phase 2 (top dead centre)
  • When the piston reaches top dead centre, the inlet valve is open, releasing the vacuum.
  • the flywheel keeps the piston moving
• Phase 3 (heating up the work medium, expansion stroke)
  • when the piston is moving away from the heat source, the air is pushed toward the heat source.
  • the air is then heating up, resulting in the air expanding and the piston being further pushed away from the heat source
• Phase 4 (bottom dead centre)
  • when the piston reaches bottom dead centre, the exhaust valve is open, releasing the build up pressure and hot air.
  • the flywheel keeps the piston moving

Differences from Stirling engines

Stirling engines are typically closed systems, while Manson engines are open systems.^[3][5][8][2] The displacer and work piston of the Manson engine have zero phase angle.^[4]

Variations

Manson-Ruppel-Engine^[9]

• Manson-Guise Engine

The valves and gas paths are considered by some to be complicated to manufacture, so various variants exist with improved, modified, or simplified valves and gas paths.^[9][10]