THERMODYNAMICS Practice Workbook

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THERMODYNAMIC FORMULAE :

FIRST LAW Q  W  U2  U1

Q  W

PROPERTIES OF PURE SUBSTANCES
Ideal gas

pV  mRT R  Ro R  Cp  Cv   Cp
M Cv

steam

v  xvg h  hf  xhfg s  s f  xsfg u  u f  x(ug  u f )

Dos  Tos  ts h  u  pv

NON FLOW PROCESS ( Ideal Gas )

Isobaric ( constant pressure)

W  P(v2  v1 )  mR(T2  T1 ) U 2  U1  mCv(T2  T1)
Q  mCp (T2  T1)
V1  V2
s2  s1  mCp ln  T2  T1 T2
T1

Isometric ( constant volume)

W 0

Q  U 2  U1  mCv(T2  T1) U 2  U 1  mCv(T2  T1 )

s2  s1  mCv ln  T2  p1  p2
T1 T1 T2

Isothermal (constant temperature)

Q  p1v1 ln  v2   p1v1 ln  p1  W  Q s2  s1  mR ln  v2   mR ln  p1 
v1 p2 v1 p2

U2  U1  0 p1V1  p2V2

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Adiabatic pv  C

Q0

W  p1v1  p2v2  mR(T2  T1) U 2  U 1  mCv(T2  T1 )

 1  1  1  1

T2   p2    v1
T1 p1 v2
s2  s1  0 

Polytropic pv  C Atau

W  p1v1  p2v2  mR(T2  T1) s2  s1  mR ln  p1   mCp ln  T1 
n 1 n 1 , p2 T2

Q    n W n1  n1
 1
T2  p2  n  v1
T1 p1 v2
 

U 2  U 1  mCv(T2  T1 )

s2  s1  mR ln  v2   mCv ln  T1 
v1 T2

Throtelling

h2  h1 ,

Wratio  Wnet thermal  T1  T2 SSC  3600
gross work T1 Wnet

 thermal  wnet  R (h1  h2 )  (h4  h3 )  carnot  Wnet
QH (h1  h3 )  (h4  h3 ) Q12

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