13prop_gases

# 13prop_gases - p c v = γ since h = u pv = u RT then dh/dT...

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PROPERTIES OF GASES Equation of State For a perfect gas: pv = RT where p is pressure, N/m 2 , Pa, or kPa v is specific volume, m 3 /kg T is absolute temperature, ° K R is the gas constant, J/kgK or kJ/kgK and R = R /M where R is the Universal Gas Constant = 8.3144 kJ/kmole K M is the molecular weight, e.g. for air M air = 28.96 kg/kmol, R air = 0.2871 kJ/kgK . Other Properties At moderate temperatures and pressures the properties internal energy and enthaply are assumed to be independent of pressure. u = u(T ,M) or for a particular gas u = u(T) and h = h(T ,M) or h = h(T) specific heats: c v = du/dT, c p = dh/dt, and c
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Unformatted text preview: p / c v = γ since h = u + pv = u + RT, then dh/dT = du/dT + R. Thus c p = c v + R and c p- c v = R, or R = c p ( γ-1)/ γ . Second Law Tds = dh -v dp ∴ ds = dh/T -v dp/T = dh/T - R dp/p for an isentropic process ds = 0 ∴ dh/T = R dp/p. This expression may be integrated to give 1 2 ln * 2 1 p p R T dT c s T T p = ∫ For the special case where the specific heats remain constant this equation may be written as: γ 1 1 2 1 2 1 2 − = = p p p p T T p c R s DVB modified from Prof. Carmichael version: Page 1 10/12/2004...
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## This note was uploaded on 02/24/2012 for the course MECHANICAL 2.611 taught by Professor Davidburke during the Fall '06 term at MIT.

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