The top surface of a heated compartment consists of very smooth (A) and highly roughened (B)portions, and the surface is placed in an atmospheric airstream. In the interest of minimizing total convection heat transfer from the surface, which orientation, (1) or (2), is preferred? If T s = 100 ° C, T ∞ = 20 ° C, and u ∞ = 20 m/s, what is the convection heat transfer from the entire surface for this orientation?
The top surface of a heated compartment consists of very smooth (A) and highly roughened (B)portions, and the surface is placed in an atmospheric airstream. In the interest of minimizing total convection heat transfer from the surface, which orientation, (1) or (2), is preferred? If T s = 100 ° C, T ∞ = 20 ° C, and u ∞ = 20 m/s, what is the convection heat transfer from the entire surface for this orientation?
The top surface of a heated compartment consists of very smooth (A) and highly roughened (B)portions, and the surface is placed in an atmospheric airstream. In the interest of minimizing total convection heat transfer from the surface, which orientation, (1) or (2), is preferred? If
T
s
=
100
°
C,
T
∞
=
20
°
C,
and
u
∞
=
20
m/s,
what is the convection heat transfer from the entire surface for this orientation?
A 10-cm-diameter, 30-cm-high cylindrical bottle contains cold water at 3°C. The bottle is placed in windy air at 27°C. The water temperature is measured to be 11°C after 45 min of cooling. Disregarding radiation effects and heat transfer from the top and bottom surfaces, estimate the average wind velocity.
The passenger compartment of a minivan traveling at 50 mi/h in ambient air at 1 atm and 80°F is modeled as a 4.5-ft-high, 6-ft-wide, and 11-ft-long rectangular box. The airflow over the exterior surfaces is assumed to be turbulent because of the intense vibrations involved. Determine the drag force acting on the top and the two side surfaces of the van and the power required to overcome it.
A 10-cm shaft rides in a 10.03-cm sleeve and 12-cm long, the clearance space (assumed to be uniform) being filled with lubricating oil (? = 0.11 ?? − ?). Calculate the rate at which heat is generated when the shaft turns at 100 rpm in Watts (W). (Rate of energy = Frictional force/resistance x Velocity)
INTERNATIONAL EDITION---Engineering Mechanics: Statics, 14th edition (SI unit)
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