Izentropski proces

U termodinamici, izentropski proces ili izoentropijski proces (ισον = "jednak" (grčki); εντροπία entropija = "nered"(grčki)) je proces u kojem se, u svrhu inženjerske analize i proračuna, može pretpostaviti da se proces odvija od početka do kraja bez porasta ili opadanja entropije sistema, tj., entropija sistema ostaje konstantna.^[1][2] Može se dokazati da je bilo koji povratni adijabatski proces izentropski proces.

Tabela izentropskih relacija za idealan plin

${\displaystyle {\frac {p_{2}}{p_{1}}}}$	${\displaystyle =\,\!}$	${\displaystyle \left({\frac {T_{2}}{T_{1}}}\right)^{\frac {\gamma }{\gamma -1}}}$	${\displaystyle =\,\!}$	${\displaystyle \left({\frac {\rho _{2}}{\rho _{1}}}\right)^{\gamma }}$	${\displaystyle =\,\!}$	${\displaystyle \left({\frac {V_{1}}{V_{2}}}\right)^{\gamma }}$
${\displaystyle {\frac {T_{2}}{T_{1}}}}$	${\displaystyle =\,\!}$	${\displaystyle \left({\frac {p_{2}}{p_{1}}}\right)^{\frac {\gamma -1}{\gamma }}}$	${\displaystyle =\,\!}$	${\displaystyle \left({\frac {\rho _{2}}{\rho _{1}}}\right)^{(\gamma -1)}}$	${\displaystyle =\,\!}$	${\displaystyle \left({\frac {V_{1}}{V_{2}}}\right)^{(\gamma -1)}}$
${\displaystyle {\frac {\rho _{2}}{\rho _{1}}}}$	${\displaystyle =\,\!}$	${\displaystyle \left({\frac {T_{2}}{T_{1}}}\right)^{\frac {1}{\gamma -1}}}$	${\displaystyle =\,\!}$	${\displaystyle \left({\frac {p_{2}}{p_{1}}}\right)^{\frac {1}{\gamma }}}$	${\displaystyle =\,\!}$	${\displaystyle {\frac {V_{1}}{V_{2}}}}$
${\displaystyle {\frac {V_{2}}{V_{1}}}}$	${\displaystyle =\,\!}$	${\displaystyle \left({\frac {T_{1}}{T_{2}}}\right)^{\frac {1}{\gamma -1}}}$	${\displaystyle =\,\!}$	${\displaystyle {\frac {\rho _{1}}{\rho _{2}}}}$	${\displaystyle =\,\!}$	${\displaystyle \left({\frac {p_{1}}{p_{2}}}\right)^{\frac {1}{\gamma }}}$

dobiveno iz:

${\displaystyle pV^{\gamma }={\text{konstanta}}\,\!}$

${\displaystyle pV=mR_{s}T\,\!}$

${\displaystyle p=\rho R_{s}T\,\!\,\!}$

gdje je:

${\displaystyle p\,\!}$ = pritisak

${\displaystyle V\,\!}$ = zapremina

${\displaystyle \gamma \,\!}$ = omjer specifičnih toplota = ${\displaystyle C_{p}/C_{v}\,\!}$

${\displaystyle T\,\!}$ = temperatura

${\displaystyle m\,\!}$ = masa

${\displaystyle R_{s}\,\!}$ = plinska konstanta specifičnog plina = ${\displaystyle R/M\,\!}$

${\displaystyle R\,\!}$ = univerzalna plinska konstanta

${\displaystyle M\,\!}$ = molekularna masa specifičnog plina

${\displaystyle \rho \,\!}$ = gustoća

${\displaystyle C_{p}\,\!}$ = specifična toplota pri konstantnom pritisku

${\displaystyle C_{v}\,\!}$ = specifična toplota pri konstantnoj zapremini

Reference

• Van Wylen, G.J. and Sonntag, R.E. (1965), Fundamentals of Classical Thermodynamics, John Wiley & Sons, Inc., New York. Library of Congress Calatog Card Number: 65-19470

Zabilješke

1. Van Wylen, G.J. and Sonntag, R.E., Fundamentals of Classical Thermodynamics, Section 7.4
2. Massey, B.S. (1970), Mechanics of Fluids, Section 12.2 (2^nd edition) Van Nostrand Reinhold Company, London. Library of Congress Catalog Card Number: 67-25005

Također pogledajte

• Adijabatski proces
• Izentalpijski proces
• Politropski proces