Where did you get that information? I want to learn more....

Minh-Thanh, any text book on thermodynamics (I got my start designing a model turbo-jet engine made from automobile turbo-charger rotor parts, same approach as Kurt Schreckling and Thomas Kamps, so have a collection of turbine engine text books which also cover the thermodynamics)

you'll have to get familiar with these equations

first from high school

PV = nrT, or Pressure x Volume = constant x Temp for a given amount of gas

then the formulas they (sadly) don't teach you in high school

P x V^(gamma) = constant, for a given amount of gas

the exponent gamma depends on the molecular structure of the gas, 1.667 for monatomic gases like argon, 1.4 for diatomic gases like N2 and O2, 1.333 for triatomic gases like H20 steam and C02

finally there's the energy equations

E[compression] = T[in] x Cp x ( PR^((gamma-1)/gamma) - 1)

E[expansion] = T[in] x Cp x ( 1 - PR^((1-gamma)/gamma) )

here Cp is coefficient of heat (heat req per deg of temp change)

and from these equations you can derive these "ratio" equations

TR = PR ^ ((gamma-1)/gamma TR = VR ^ (1-gamma)

VR = PR ^ (-1/gamma) VR = TR ^ (1/(1-gamma))

PR = TR ^ (gamma/(gamma-1)) PR = VR ^ (-gamma)

Note that the "compression ratio" we describe our piston engines with is VR, the volume ratio, here in thermodynamics, "compression ratio" is not the pressure ratio, the actual pressure is much higher than the compression.

you'll probably want to consult a text book to be sure you get all the units right,

in addition all the "ratio" formulas and any that involves an exponent require

Temp units that start at "absolute zero" and Pressure units that start at "absolute vacuum". IE zero degrees is absolute zero and zero pressure is a vacuum.

I use degrees Kelvin (293 = room temp), Bar is convenient for pressure (1 = sea

level atmospheric pressure), and if you want the energy to come out in MKS

Joules then Cp = 1000.

welcome to the journey !!!