Heat engine classifications

Heat engines May Be categorized in a number of different ways. The following list is divided by attributes, rather than using a “family tree” approach which would result in much duplication. An actual engine would embody some combination of the attributes listed here. A few specific engine names are included as examples of particular attributes.

This list focuses on man-made systems that transform heat energy into mechanical energy, usually by burning a fuel in or near the engine. Systems such as solar, photovoltaic, wind, geothermal, and tidal, which capitalize on sources of energy outside the engineered system, are considered minimally here.

Thermodynamic cycle

  1. Characteristics
    1. Open / Closed
    2. Adiabatic, isothermal, isobaric
    3. Reversible / non-reversible
    4. Chamber pressure / compression ratio: none (e.g. “atmospheric”; condensing steam), fixed, variable
  2. Name
    1. Atkinson
    2. Brayton
    3. Carnot
    4. Diesel
    5. Ericsson
    6. Hirn
    7. Joule
    8. Kalina
    9. Linde-Hampson
    10. Miller
    11. Otto
    12. Rankine
    13. Stirling

Combustion location

  1. Internal
  2. External

Combustion cycles (strokes)

  1. Continuous: turboprop, fanjet, turbojet, rocket, ram/scram jet (including an experimental generator)
  2. Pulse: valved (buzz bomb), pop-pop, Savery, detonation (Lockwood-Hiller)
  3. Two stroke (Bessemer w/ crosshead; Patton w/ purge cylinder)
  4. Four stroke
  5. Five stroke
  6. Six (Mery)
  7. Eight (Aermotor)

Fuel

  1. Solid: wood, coal /coal dust / fluidized bed; gunpowder, zinc, aluminum, rubber
  2. Liquid: gasoline, diesel, coal oil, kerosene, jet fuel, bunker oil
  3. Gas: hydrogen, acetylene, coal / producer gas, wood distillate, natural gas, LP, illuminating gas

Oxidizer

  1. Air
  2. Gas: oxygen, nitrous oxide
  3. Part of fuel: nitromethane
  4. Sulphur
  5. Other: hydrogen peroxide

Combustion type

  1. Flame front propagation
    1. Continuous
    2. Cyclical
  2. Detonation

Heat sink

  1. Internal / External
  2. Medium: air, water
  3. (Primary) mode: conduction, convection, radiation

Working fluid

  1. Solid
  2. Liquid
  3. Gas: air, helium, argon
  4. Phase change: solid to liquid, liquid to gas, solid to gas
    1. Water / steam
      1. Condensing
      2. Non- condensing
        1. Freon, ammonia

Expansion

  1. Simple
  2. Compound

Ignition

  1. Compression
  2. Hot tube
  3. Flame
  4. Match
  5. Igniter
  6. Spark
    1. Make/break
    2. Hammer
    3. Magneto:
      1. Low tension, high tension
      2. Rotary, linear
      3. Continuous, impulse
    4. Battery & coil
      1. Buzz
      2. Points (timed)
      3. Electronic
      4. Piezoelectric

Chamber configuration

  1. Piston-in-cylinder
    1. Cross section: round, square, arbitrary
    2. Head of piston: hemi, flat, flow-shaping
    3. Cylinder head: flat, hemi, other
  2. Wankel, Watt, other rotary shapes
  3. Wobble / nutate (plate forms part of chamber)
  4. Turbine
  5. Rocket

Piston action

  1. Single-sided
  2. Double-sided

Linear-rotary conversion

  1. None: free piston: pile driver, pogo stick, rammer, jack hammer, Kos, rocket, gun
  2. Rack & pinion / gear & sector; with ratchet
  3. Crankshaft
    1. Single
    2. Dual: Fairbanks-Morse LST
    3. Triple: Deltic
  4. Crank Configuration
    1. Center crank
    2. Side crank
    3. Watt
    4. Epicyclic / planetary
    5. Cam
    6. Axial: swash plate

Lateral motion / force control

  1. Crosshead
  2. Trunk piston
  3. Oscillating cylinder
  4. Radial: scotch yoke, Hale

Fuel induction

  1. Hands, Shovel, conveyor, auger
  2. Evaporation
  3. Wick
  4. Chain
  5. Mixer
  6. Carburetor; fixed / variable venturi (SU)
  7. Explosion cup (HVID semi-diesel)
  8. Injection
    1. Low pressure - throttle body, manifold
    2. High pressure - combustion chamber
      1. Single
      2. Common rail
      3. Central

Valve gear

  1. None
  2. Port
  3. Flapper / reed
  4. Sleeve: Knight
  5. Rotary
  6. Poppet
  7. Slide
    1. Flat
      1. “D”
      2. Balanced
      3. Multi-ported
      4. Gridiron
      5. Oscillating cylinder
    2. Cylinder
      1. Piston / Axial (spool)
      2. Rotary:
        1. Corliss
          1. Detaching
          2. Positively-operated
        2. (Stoddard – Dayton)

Valve actuation / return

  1. Atmospheric
  2. Eccentric / crank
  3. Cam
    1. Spring return
      1. Side shaft
      2. Pushrod / rocker arm
        1. Flat
        2. T-head
        3. F-head
      3. Overhead
        1. Single cam
        2. Dual cam
    2. Desmodromic (positive actuation)
  4. Electromechanical: Solenoid

Valve timing

  1. Fixed
  2. Variable; step, continuous
    1. Timing / Phasing / Duration – intake, exhaust, both

Ignition timing

  1. Inherent: glow plug
  2. Fixed
  3. Variable; centrifugal, vacuum, electronic

Governing detection

  1. Centrifugal: Flyball, Radial weights
  2. Pendulum on valve pushrod
  3. Airflow from fan
  4. Electronic

Governing actuation

  1. None
  2. Hit-or-miss
    1. Ignition
      1. spark saver
    2. Valve
  3. Throttle
  4. Fuel metering
  5. Cylinder deactivation

Starting method

  1. None required
  2. Hand turn
  3. Hand crank
  4. Ignite in place
  5. Electric motor
  6. Air motor
  7. Compressed air
  8. Pony engine
  9. Explosive cartridge

Starting assist

  1. Match
  2. Glow plug
    1. Manifold
    2. Combustion chamber
  3. Fuel enhancer / alternate fuels: ether, gas => kerosene, diesel

Cylinder orientation

  1. Vertical
  2. Inclined
  3. Horizontal

Multi-cylinder configuration

  1. Inline
  2. Ipposed
  3. Radial
  4. Tandem
  5. Cross
  6. Duplex
  7. Angle / “V”

Speed

  1. Low
  2. Medium
  3. High

Ratio of stroke to bore size

  1. Short stroke: stroke < bore
  2. Square: stroke = bore
  3. Long stroke: stroke > bore

Not yet classified

  1. Rijke tube – Thermal-Acoustic, 1850

Influences on Engine Design

These drivers / goals / constraints / figures of merit, while not necessarily characteristics of the engines themselves, greatly influence the choice of approach to an engine design:

  1. Power
  2. Size
  3. Weight
  4. Cost
    1. Initial: build, sell, install
    2. Fuel, oil & other supplies
    3. Maintenance
    4. Disposal
  5. Reliability / longevity
  6. Available / enabling technologies:
    1. Geology: fuels, raw materials
    2. Chemistry: refining
    3. Metallurgy
    4. Manufacturing: casting, machining, fastening/joining
  7. Thermodynamics
  8. Available infrastructure
  9. Patents
  10. Ego (“Not invented here” syndrome)
  11. Perception of need
  12. Esthetics: style, appearance, smell, vibration, noise
  13. Environmental considerations
  14. Social / Moral / Ethical / Legal / Political concerns

See Also

Jonova engine

The Jonova engine / Jonova Motor is a type of rotary engine, commonly called a Wankel rotary...