Low Temperature Stirling Engines



Theory 5 - Output work of engines with ideal Stirling cycle

Thermodynamic cycle work

The thermodynamic work available during one complete cycle is given by integration of the P(V) curve in the the PV diagram (area of the internal surface of the cycle).

thermodynamic work

The ideal Stirling cycle is composed of two isothermal curves Ph(V) = nkBTh/V and Pc=nkBTc/V and two isochore segments (V=cste). Therefore the work Wthermo_ideal is given by :

Ideal cycle work

where n is the number of molecules, kB is the Boltzman constant and r is the compression ratio Vmax/Vmin

 

Mechanical cycle work applied to the shaft (optimally buffered engines)

The work available as output of the engine is the product of the thermodynamic cycle work by the mechanical efficiency discussed in the previous chapter.

Wshaft_ideal = Emeca_ideal * Wthermo_ideal

Graph for one mole of gas and mechanism effectiveness E = 0.7, the engine is optimally buffered:

Mechanical cycle work








Theory index

Theory 1 - Generic schematic
Theory 2 - Buffer pressure
Theory 3 - Mechanism effectiveness
Theory 4 - Optimal buffer pressure of the ideal Stirling Cycle
Theory 5 - Output work of engines with ideal Stirling cycle
Theory 6 - Pressurization of ideal Stirling cycle engines
Theory 7 - Crossley cycles engines
Theory 8 - Various losses in real engines





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