FrontMatter.qxd 6/15/04 4:06 PM Page xv
Symbols
English Letter Symbols
A
A
A
Af
ADPI
B
b
C
C
C
C
C
C
Cd
Cd
Cp
Cv
COP
c
cfm
clo
D
D
DD
db
DR
d
E
EDT
ET
F
area, ft2 or m2
apparent solar irradiation for zero
air mass, Btu/(hr-ft2) or W/m2
absorptance of fenestration layer,
dimensionless
absorptance of fenestration,
dimensionless
air distribution performance index,
dimensionless
atmospheric extinction coefficient
bypass factor, dimensionless
concentration, lbm/ft3 or kg/m3
unit thermal conductance, Btu/(hrft2-F) or W/(m2/C)
discharge coefficient,
dimensionless
loss coefficient, dimensionless
fluid capacity rate, Btu/(hr-F) or
W/C
clearance factor, dimensionless
overall flow coefficient,
dimensionless
draft coefficient, dimensionless
pressure coefficient, dimensionless
flow coefficient, dimensionless
coefficient of performance,
dimensionless
specific heat, Btu/(lbm-F) or J/(kgC)
volume flow rate, ft3/min
clothing thermal resistance, (ft2-hrF)/Btu or (m2-C)/W
diameter, ft or m
diffusion coefficient, ft2/sec or m2/s
degree days, F-day or C-day
dry bulb temperature, F or C
daily range of temperature, F or C
bulb diameter, ft or m
effective emittance, dimensionless
effective draft temperature, or C
effective temperature, F or C
configuration factor, dimensionless
F
F
F
F(s)
f
ft
FP
G
G
g
g
gc
H
H
H
h
h
h
hp
i
IAC
J
JP
J (s)
quantity of fuel, ft3 or m3
radiant interchange factor,
dimensionless
conduction transfer function
coefficient, dimensionless
wet surface function,
dimensionless
friction factor, dimensionless
Darcy friction factor with fully
turbulent flow, dimensionless
correlating parameter,
dimensionless
irradiation, Btu/(hr-ft2) or W/m2
mass velocity, lbm/(ft2-sec) or
kg/(m2-s)
local acceleration due to gravity,
ft/sec2 or m/s2
transfer function coefficient,
Btu/(hr-ft) or W/C
dimensional constant, 32.17 (lbmft)/(lbf-sec2) or 1.0 (kg-m)/(N-s2)
heating value of fuel, Btu or J per
unit volume
head, ft or m
history term for conduction transfer
functions, Btu/(hr-ft2) or W/m2
height or length, ft or m
heat-transfer coefficient, Btu/(hrft2-F) or W/(m2-C) (also used for
mass-transfer coefficient with
subscripts m, d, and i)
hour angle, degrees
horsepower
enthalpy, Btu/lbm or J/kg
interior solar attenuation
coefficient, dimensionless
Joule’s equivalent, 778.28 (ftlbf)/Btu
correlating parameter,
dimensionless
wet surface function,
dimensionless
xv
FrontMatter.qxd 6/15/04 4:06 PM Page xvi
xvi
Symbols
Ji (s)
j
K
K
Kt
k
k
L
L
Le
LMTD
l
l
M
M
MRT
m
m
N
N
Nu
NC
NTU
P
P
P
Pr
PD
p
p
Q
wet surface function,
dimensionless
Colburn j-factor, dimensionless
color correction factor,
dimensionless
resistance coefficient,
dimensionless
unit-length conductance, Btu/(ft-hrF) or W/(m-C)
thermal conductivity, (Btu-ft)/(ft2hr-F), (Btu-in.)/(ft2-hr-F), or
(W-m)/(m2-C)
isentropic exponent, c p/cv,
dimensionless
fin dimension, ft or m
total length, ft or m
Lewis number, Sc/Pr,
dimensionless
log mean temperature difference, F
or C
latitude, deg
lost head, ft or m
molecular mass, lbm/(lbmole) or
kg/(kgmole)
fin dimension, ft or m
mean radiant temperature, F or C
mass, lbm or kg
mass flow rate or mass transfer
rate, lbm/sec or kg/s
number of hours or other integer
inward-flowing fraction of
absorbed solar heat gain
Nusselt number, hx/k,
dimensionless
noise criterion, dimensionless
number of transfer units,
dimensionless
pressure, lb/ft2 or psia or N/m2 or
Pa
heat exchanger parameter,
dimensionless
circumference, ft or m
Prandtl number, µc p/k,
dimensionless
piston displacement, ft3/min or
m3/s
partial pressure, lbf/ft2 or psia or Pa
transfer function coefficient,
dimensionless
volume flow rate, ft3/sec or m3/s
q
q
q
R
R
R
R
R
R
Rf
Rb
Re
Rf
r
rpm
S
S
Sc
Sh
SC
SHF
SHGC
s
T
T
t
t*
U
u
V
V¯
v
v
heat transfer, Btu/lbm or J/kg
heat flux, Btu/(hr-ft2) or W/m2
heat transfer rate, Btu/hr or W
gas constant, (ft-lbf)/(lbm-R) or
J/(kg-K)
unit thermal resistance, (ft2-hrF)/Btu or (m2-K)/W
heat exchanger parameter,
dimensionless
fin radius, ft or m
thermal resistance, (hr-F)/Btu or
C/W
gas constant, (ft-lbf)/(lbmole-R) or
J/(kgmole-K)
front reflectance of fenestration,
dimensionless
back reflectance of fenestration,
dimensionless
Reynolds number V D ¯ /µ,
dimensionless
unit fouling resistance, (hr-ft2F)/Btu, or (m2-C)/W
radius, ft or m
revolutions per minute
fin spacing, ft or m
equipment characteristic, Btu/(hrF) or W/C
Schmidt number, /D,
dimensionless
Sherwood number, hmx/D,
dimensionless
shading coefficient, dimensionless
sensible heat factor, dimensionless
solar heat gain coefficient,
dimensionless
entropy, Btu/(lbm-R) or J/(kg-K)
absolute temperature, R or K
transmittance of fenestration,
dimensionless
temperature, F or C
thermodynamic wet bulb
temperature, F or C
overall heat transfer coefficient,
Btu/(hr-ft2-F) or W/(m2-C)
velocity in x direction, ft/sec or m/s
volume, ft3 or m3
velocity, ft/sec or m/s
specific volume, ft3/lbm or m3/kg
transfer function coefficient,
dimensionless
FrontMatter.qxd 6/15/04 4:06 PM Page xvii
Symbols
v
W
W
W
WBGT
w
w
w
X
X
velocity in y-direction, ft/sec or m/s
humidity ratio, lbmv/lbma or
kgv/kga
equipment characteristics, Btu/hr
or W
power, Btu/hr or W
wet bulb globe temperature, F or C
skin wettedness, dimensionless
work, Btu, or ft-lbf, or J
transfer function coefficient,
dimensionless
normalized input, dimensionless
fraction of daily range
X
x
x
x, y, z
Y
Y
Z
conduction transfer function
coefficient, Btu/(hr-ft2-F) or
W/(m2-K)
mole fraction
quality, lbmv/lbm or kgv/kg
length, ft or m
normalized capacity, dimensionless
conduction transfer function
coefficient, Btu/(hr-ft2-F) or
W/(m2-K)
conduction transfer function
coefficient, Btu(hr-ft2-F) or
W/(m2-K)
Subscripts
a
a
a
a
as
as
ASHG
avg
B
b
b
b
c
c
c
c
c
c
c
c
c
CL
cl
D
D
d
d
d
d
d
dry
e
transverse dimension
air
average
attic
adiabatic saturation
denotes change from dry air to
saturated air
absorbed solar heat gain from
fenestration
average
barometric
branch
longitudinal dimension
base
cool or coil
convection
ceiling
cross section or minimum free area
cold
condenser
Carnot
collector
convection
cooling load
center line
direct
diameter
dew point
total heat
diffuse
design
downstream
dry surface
equivalent
e
e
e
es
ext
f
f
f
f
f
fg
fl
fl
fr
g
g
g
g
H
h
h
h
h
h
i
i
i
in
is
j
l
l
m
xvii
sol-air
equipment
evaporator
exterior surface
exterior surface
film
friction
fin
fictitious surface
frame
refers to change from saturated
liquid to saturated vapor
fluorescent light
floor
frontal
refers to saturated vapor
glazing
globe
ground
horizontal
heat
hydraulic
head
heat transfer
hot
j-factor for total heat transfer
inside or inward
instantaneous
inside
inside surface
exterior surface number
latent
liquid
mean
FrontMatter.qxd 6/15/04 4:06 PM Page xviii
xviii
m
m
ND
n
o
o
o
oh
P
p
p
R
R
r
r
s
s
s
s
s
s
s
sc
s-g
shd
SHG
Symbols
mass transfer
mechanical
direct normal
integer
outside
total or stagnation
initial condition
humid operative
presure
constant pressure
pump
reflected
refrigerating
radiation
room air
stack effect
sensible
saturated vapor or saturated air
supply air
shaft
static
surface
solar constant
surface-to-ground
shade
solar heat gain from fenestration
s-sky
SL
sl
t
t
t
t
TSHG
u
u
V
v
v
v
w
w
w
wet
x
x
Z
1, 2, 3
1, 2, 3
8
surface-to-sky
sunlit
sunlit
temperature
total
contact
tube
transmitted solar heat gain from
fenestration
unheated
upstream
vertical
vapor
ventilation
velocity
wind
wall
liquid water
wet surface
length
extraction
Zenith angle
state of substance at boundary of a
control volume
a constituent in a mixture
free-stream condition
Greek Letter Symbols
α
α
α
α
ß
ß
γ
∆
δ
δ
ε
ε
φ
η
θ
θ
θ
angle of tilt from horizontal, deg
absorptivity or absorptance,
dimensionless
total heat transfer area over total
volume, ft-1 or m-1
thermal diffusivity, ft2/sec or m2/s
fin parameter, dimensionless
altitude angle, deg
surface solar azimuth angle, deg
change in a quantity or property
boundary layer thickness, ft or m
sun’s declination, deg
heat exchanger effectiveness,
dimensionless
emittance or emissivity,
dimensionless
solar azimuth angle, deg clockwise
from north
efficiency, dimensionless
angle, deg
angle of incidence, deg
time, sec
θ
µ
µ
ν
ρ
ρ
Σ
σ
σ
τ
ϕ
ϕ
ψ
ψ
current time
degree of saturation, percent or
fraction
dynamic viscosity, lbm/(ft-sec) or
(N-s)/m2
kinematic viscosity, ft2/sec or m2/s
mass density, lbm/ft3 or kg/m3
reflectivity or reflectance,
dimensionless
angle of tilt from horizontal, deg
Stefan–Boltzmann constant,
Btu/(hr-ft2-R4) or J/(s-m2-K4)
free flow over frontal area,
dimensionless
transmissivity or transmittance,
dimensionless
fin parameter, dimensionless
relative humidity, percent or
fraction
surface azimuth angle, deg
clockwise from north
fin parameter, dimensionless