Page 106 - Mechanical Engineers' Handbook (Volume 4)

1 Introduction 95

ƒ specific Helmholtz free energy (u Ts), J/kg
F force vector, N
g gravitational acceleration, m/s 2
g specific Gibbs free energy (h Ts), J/kg
h specific enthalpy (u Pv), J/kg
2
K isothermal compressibility, m /N
m mass of closed system, kg
˙ m mass flow rate, kg/s
m i mass of component in a mixture, kg
M mass inventory of control volume, kg
M molar mass, g/mol or kg/kmol
n number of moles, mol
N 0 Avogadro’s constant
P pressure
Q infinitesimal heat interaction, J
˙
Q heat transfer rate, W
r position vector, m
R ideal gas constant, J/(kg K)
s specific entropy, J/(kg K)
S entropy, J/K
S gen entropy generation, J/K
S ˙ gen entropy generation rate, W/K
T absolute temperature, K
u specific internal energy, J/kg
U internal energy, J
v specific volume, m /kg
3
v specific volume of incompressible substance, m /kg
3
V volume, m 3
V velocity, m/s
W infinitesimal work interaction, J
˙
W lost rate of lost available work, W
˙
W sh rate of shaft (shear) work transfer, W
x linear coordinate, m
x quality of liquid and vapor mixture
Z vertical coordinate, m
coefficient of thermal expansion, 1/K
ratio of specific heats, c /c v
P
‘‘efficiency’’ ratio
I first-law efficiency
II second-law efficiency
relative temperature, C

SUBSCRIPTS
() ƒ saturated liquid state (f ‘‘fluid’’)
() g saturated vapor state (g ‘‘gas’’)
() s saturated solid state (s ‘‘solid’’)
() in inlet port
() out outlet port
() rev reversible path
() H high-temperature reservoir