fundamentals of engineering supplied-reference handbook - Ventech!

Mean Effective Pressure (mep)
W�
ns
mep = , where
V n N
d
c
ns = number of crank revolutions per power stroke,
nc = number of cylinders, and
Vd = displacement volume per cylinder.
mep can be based on brake power (bmep), indicated power
(imep), or friction power (fmep).
Volumetric Efficiency
where
η
v
2m�
a =
ρ V n N
a
d
c
(four-stroke cycles only)
m� a = mass flow rate of air into engine (kg/s), and
ρa = density of air (kg/m 3 ).
Specific Fuel Consumption (SFC)
m�
f 1
sfc = = ,
W�
ηHV
kg
Use ηb and Wb � for bsfc and ηi and Wi � for isfc.
Gas Turbines
Brayton Cycle (Steady-Flow Cycle)
J
213
w12 = h1 – h2 = cP (T1 – T2)
w34 = h3 – h4 = cP (T3 – T4)
wnet = w12 + w34
q23 = h3 – h2 = cP (T3 – T2)
q41 = h1 – h4 = cP (T1 – T4)
qnet = q23 + q41
η = wnet /q23
Steam Power Plants
Feedwater Heaters
MECHANICAL ENGINEERING (continued)