Stoddard engine

Thermodynamics
The classical Carnot heat engine
Branches Classical Statistical Chemical Equilibrium / Non-equilibrium
Laws Zeroth First Second Third
Systems State Equation of state Ideal gas Real gas State of matter Equilibrium Control volume Instruments Processes Isobaric Isochoric Isothermal Adiabatic Isentropic Isenthalpic Quasistatic Polytropic Free expansion Reversibility Irreversibility Endoreversibility Cycles Heat engines Heat pumps Thermal efficiency
System properties Note: Conjugate variables in italics Property diagrams Intensive and extensive properties Functions of state Temperature / Entropy (introduction) Pressure / Volume Chemical potential / Particle number Vapor quality Reduced properties Process functions Work Heat
Material properties Property databases Specific heat capacity  Compressibility  Thermal expansion
Equations Carnot's theorem Clausius theorem Fundamental relation Ideal gas law Maxwell relations Onsager reciprocal relations Bridgman's equations Table of thermodynamic equations
Potentials Free energy Free entropy Internal energy Enthalpy Helmholtz free energy Gibbs free energy
History Culture History General Heat Entropy Gas laws "Perpetual motion" machines Philosophy Entropy and time Entropy and life Brownian ratchet Maxwell's demon Heat death paradox Loschmidt's paradox Synergetics Theories Caloric theory Theory of heat Vis viva ("living force") Mechanical equivalent of heat Motive power Key publications "An Experimental Enquiry Concerning ... Heat" "On the Equilibrium of Heterogeneous Substances" "Reflections on the Motive Power of Fire" Timelines Thermodynamics Heat engines Art Education Maxwell's thermodynamic surface Entropy as energy dispersal
Scientists Bernoulli Carnot Clapeyron Clausius Carathéodory Duhem Gibbs von Helmholtz Joule Maxwell von Mayer Onsager Rankine Smeaton Stahl Thompson Thomson Waterston
Book:Thermodynamics

Elliott J. Stoddard invented and patented two versions of the Stoddard engine, the first in 1919 and the second in 1933. The general engine classification is an external combustion engine with valves and single-phase gaseous working fluid (i.e. a "hot air engine"). The internal working fluid was originally air, although in modern versions, other gases such as helium or hydrogen may be used.

One potential thermodynamic advantage of using valves is to minimize the adverse effects of "unswept volume" in the heat exchangers (sometimes called "dead volume"), which is known to reduce engine efficiency and power output in the valveless Stirling engine.

The 1919 Stoddard engine

The generalized thermodynamic processes of the 1919 Stoddard cycle are:^[1]

1. Adiabatic compression
2. Isobaric heat-addition
3. Adiabatic expansion
4. Isobaric heat-removal

The engine design in the patented was using a scotch yoke.

The 1933 Stoddard engine

In the 1933 design,^[2] Stoddard reduced the internal volume of the heat exchangers maintaining the same generalized thermodynamic processes as the 1919 cycle.

Gallery

Stoddard engine diagrams
The 1919 Stoddard Engine  The 1933 Stoddard Engine

References

Weblinks

Wikimedia Commons has media related to Stoddard engine.