A flat-plate solar collector, consisting of an absorber plate and single cover plate, is inclined at an angle of τ = 60 ° relative to the horizontal. Consider conditions for which the incident solar radiation is collimated at an angle of 60° relative to the horizontal and the solar flux is 900 W/m 2 . The cover plate is perfectly transparent to solar radiation ( λ ≤ 3 μ m ) and is opaque to radiation of larger wave lengths. The cover and absorber plates are diffuse surfaces having the spectral absorptivities shown. The length and width of the absorber and cover plates are much larger than the plate spacing L . What is the rate at which solar radiation is absorbed per unit area of the absorber plate? With the absorber plate well insulated from below and absorber and cover plate temperatures T a and T c of 70°C and 27°C, respectively, what is the heat loss per unit area of the absorber plate?
A flat-plate solar collector, consisting of an absorber plate and single cover plate, is inclined at an angle of τ = 60 ° relative to the horizontal. Consider conditions for which the incident solar radiation is collimated at an angle of 60° relative to the horizontal and the solar flux is 900 W/m 2 . The cover plate is perfectly transparent to solar radiation ( λ ≤ 3 μ m ) and is opaque to radiation of larger wave lengths. The cover and absorber plates are diffuse surfaces having the spectral absorptivities shown. The length and width of the absorber and cover plates are much larger than the plate spacing L . What is the rate at which solar radiation is absorbed per unit area of the absorber plate? With the absorber plate well insulated from below and absorber and cover plate temperatures T a and T c of 70°C and 27°C, respectively, what is the heat loss per unit area of the absorber plate?
Solution Summary: The author explains the absorbed solar radiation and heat loss per unit area of the plate and the cover plate. The kinematic viscosity of air is given by t_a=70°
A flat-plate solar collector, consisting of an absorber plate and single cover plate, is inclined at an angle of
τ
=
60
°
relative to the horizontal.
Consider conditions for which the incident solar radiation is collimated at an angle of 60° relative to the horizontal and the solar flux is
900
W/m
2
. The cover plate is perfectly transparent to solar radiation
(
λ
≤
3
μ
m
)
and is opaque to radiation of larger wave lengths. The cover and absorber plates are diffuse surfaces having the spectral absorptivities shown.
The length and width of the absorber and cover plates are much larger than the plate spacing L. What is the rate at which solar radiation is absorbed per unit area of the absorber plate? With the absorber plate well insulated from below and absorber and cover plate temperatures Taand Tcof 70°C and 27°C, respectively, what is the heat loss per unit area of the absorber plate?
A shaft is loaded in bending and torsion such that Ma = 70 N·m, T₁ = 45 N · m, M =
55 N. m, and T = 35 N m. For the shaft, S₁ = 700 MPa and S = 560 MPa, and a fully
corrected endurance limit of S₂ = 210 MPa is assumed. Let K = 2.2 and K = 1.8. With a
Se
design factor of 2.0 determine the minimum acceptable diameter of the shaft using the
a) DE- Goodman
b) DE-Morrow
c) DE-Gerber
d) DE-SWT
The feed flow rate to an adiabatic continuous stirred tank reactor (CSTR) in which an exothermicreaction is occurring is increased from 1000 to 1400. kg/h, causing the outlet temperature to change as shown:a) Briefly explain on a physical basis why the temperature in this system oscillates after a step increasein the inlet flow rate. Be clear, complete, and concise. c) You know that this oscillating response cannot be that of two first order processes with real timeconstant acting in series. Assuming the reaction is first order and the CSTR operates with constant holdup,derive the block diagram with all transfer functions indicating how the temperature would respond to the feedflow rate step change (W’(s) as input and T’(s) as output). An intermediate variable in this block diagram willbe the concentration of A in the reactor, represented by CA’(s). d) A correct result for part c) will include a feedback loop in the block diagram, indicating the responsein T to a change in w is not…
Spur gears
Note : Exam is open notes &tables / Answer all questions.
Q.1. The press shown for Figure.1 has a rated load
of 22 kN. The twin screws have double start Acme
threads, a diameter of 50 mm, and a pitch of 6 mm.
Coefficients of friction are 0.05 for the threads and
0.08 for the collar bearings. Collar diameters are 90
mm. The gears have an efficiency of 95 percent and a
speed ratio of 60:1. A slip clutch, on the motor shaft,
prevents overloading. The full-load motor speed is
1720 rev/min.
(a) When the motor is turned on, how fast will the
press head move? (Vm= , Vser. =
)
(5M)
(b) What should be the horsepower rating of the
motor? (TR=, Tc= Pser. =
"
Bronze
bushings
Foot
Motor
Bearings
watt, Pm= watt, Pm= h.p.) (20M)
2['s
Fig.1
Worm
Collar
bearing
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