Environmental Engineering Reference
In-Depth Information
PW
(
F
o
)
present worth of fuel cost, $
PW
(
OM
o
)
present worth of O&M cost, $
Q
a
rate of heat supplied to accumulator, kcal/ h
Q
c
rate of heat collected by solar field and evaporator condenser, kcal/ h
Q
ev
rate of heat supplied to evaporator, kcal/ h
Q
ph
rate of heat transfer in preheaters, kcal/ h
r
i
radius of pipe i, m
s
1
shadow length by neighboring absorber plate, m
s
2
shadow length of neighboring glass tube, m
s
3
shadow length of collector header box, m
temperature,
o
C
T
brine temperature,
o
C
T
b
maximum brine temperature,
o
C
T
bmax
TLC
total life cycle cost, $
overall heat transfer coefficient, kcal/ h m
2
o
C
U
V
a
wind speed, m/s
collector parameter,
o
C h m
2
/kcal
x
Greek symbols
heat conductivity of insulation material (kcal/h m
o
C)
λ
θ
incidence angle on collector plane (rad)
γ
solar azimuth angle (rad)
α
support angle of collector (rad)
τ
transmittance of glass tube
heat trasnsfer coefficient at air side, (kcal/h m
2o
C)
α
0
η
c
collector efficiency
αc
tilt angle of absorber plate with respect to collector (rad)
γ
N
solar azimuth angle measured from tilted collector plane (rad)
Subscripts
a
ambient
av
average
c
collector or condenser
c1
inlet to condenser
c2
outlet from condenser
F
block F
in
inlet
m
measured
out
outlet
w
water
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