# Lec 6 - (v,T specific heat ratio k or γ = c p/c v c v and...

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Lec 6 Internal Energy, Enthalpy, h and u and Specific Heats c v and c p In many applications the quantity, Internal Energy U added to the product PV appears so often it has been given its own symbol H that is called enthalpy . H = U + pV (extensive prop.) H on a unit mass basis is: h = u + pv (intensive prop.) H on a per mole basis is: v p u h + = (intensive prop.) Units for H are kJ and Btu, same as for U, E, KE, PE, W, Q, i.e. energy Specific Heats c v and c p definitions: (for pure, simple, compressible subst.) Units: kJ/(kg*K), kJ/(kmol*K), Btu/(lb * °R), Btu/(lbmol * °R)

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c v = c v (v,T) or c v = c v (p,T) c p = c p (p,T) or c p = c p
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Unformatted text preview: (v,T) specific heat ratio: k or γ = c p /c v c v and c p for Incompressible Substances: For I.S. u(v,T) → u(T) ( ) dT du T c c v v = = So then H(p,T) = u(T) + pv If T and p for the system changes what is the change in u and h, U and H? For many liquid and solids c can be taken as constant so, c v and c p For Ideal Gases Like for solids and liquids for an ideal gas: u = u(T) only so as a consequence for ideal gases c v and c p For ideal gases are then Specific heat functions are available if your model needs more accuracy Using Ideal Gas Tables (M&S) Tables A-22 and A-23...
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## This note was uploaded on 10/05/2011 for the course ME 2124 taught by Professor Uzgoren during the Spring '08 term at Virginia Tech.

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Lec 6 - (v,T specific heat ratio k or γ = c p/c v c v and...

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