Consider Problem 6.17. The stationary plate, ambient air, and surroundings are at T ∞ = T sur = 20 ° C the rotating disk temperature is T s = 80 ° C , what is the total power dissipated from the disk’s top surface for g = 2 mm , Ω = 150 rad/s for the case when both the stationary plate and disk are painted with Parsons black paint? Over time, the paint on the rotating disk is worn off by dust in the air, exposing the base metal, which has an emissivity of ε = 0.10 . Determine the total power dissipated from the disk’s worn top surface.
Consider Problem 6.17. The stationary plate, ambient air, and surroundings are at T ∞ = T sur = 20 ° C the rotating disk temperature is T s = 80 ° C , what is the total power dissipated from the disk’s top surface for g = 2 mm , Ω = 150 rad/s for the case when both the stationary plate and disk are painted with Parsons black paint? Over time, the paint on the rotating disk is worn off by dust in the air, exposing the base metal, which has an emissivity of ε = 0.10 . Determine the total power dissipated from the disk’s worn top surface.
Solution Summary: The author explains the electrical power that must be dissipated from the disk. The emissivity of the heater is epsilon =0.1
Consider Problem 6.17. The stationary plate, ambient air, and surroundings are at
T
∞
=
T
sur
=
20
°
C
the rotating disk temperature is
T
s
=
80
°
C
, what is the total power dissipated from the disk’s top surface for
g
=
2
mm
,
Ω
=
150
rad/s
for the case when both the stationary plate and disk are painted with Parsons black paint? Over time, the paint on the rotating disk is worn off by dust in the air, exposing the base metal, which has an emissivity of
ε
=
0.10
. Determine the total power dissipated from the disk’s worn top surface.
When viscous dissipation is appreciable, the energy balance of a convective system must include the viscous effects of the fluid, so a third term is added to the energy balance:
A slide bearing (pillow block) can be idealized as a static plate and a plane that moves parallel to it. The rotary axis of such a system has a diameter of 100 mm and rotates at 3600 rpm inside the bearing, which has a gap between the plates of 0.5 mm. The system is lubricated by oil, with a density of 800 kg / m, a viscosity of 0 01 kg / ms and a thermal conductivity of 0:14 W / mk. The top and bottom surfaces of the bearing are at 60 ° C. Considering the viscous effects of the oil, determine a) The maximum temperature of the oil. FC b) Bottom plate heat flux per unit length W / m Write down all assumptions made
An air current moving vertically upward at 5 m/s carries raindrops of various sizes.
Calculate the velocity of a 2-mm-diameter drop and determine whether it is rising or falling. Repeat this exercise for a 0.2-mm-diameter drop. Assume standard atmospheric
pressure and air temperature 20 ̊C. Air density = 1.20 kg/m3 also determine the precipitation intensity if the surface
temperature is 20˚C. By what percentage is the precipitation intensity reduced by
lowering temperature from 30 to 20˚C. Calculate the rate of release of latent heat in the
thunderstorm through condensation of water vapour.
4.2. The ball catathermometer factor (F) is 620, time while the spirit column drops from 38 to 350C in 100 seconds and the air temperature is 260C. Determine the air movement speed for the industrial section with these parameters.
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