The handle of a ladle used for pouring molten lead is 30-cm-long. Originally the handle was made of 1.9 x 1.25 cm mild steel bar stock. To reduce the grip temperature, it is proposed to form the handle of tubing 0.15-cm-thick to the same rectangular shape. If the average heat transfer coefficient over the handle surface is 14 W/(m2 K), estimate the reduction of the temperature at the grip in air at 21°C.
GIVEN
FIND
The reduction of the temperature at the grip
ASSUMPTIONS
The lead is at the melting temperature
The handle is made of 1% carbon steel
The ladle is normally in steady state during use
The variation of the thermal conductivity is negligible
One dimensional conduction
Heat transfer from the end of the handle can be neglected
SKETCH
The ladle handle can be treated as a fin with an adiabatic end as shown below
The temperature distribution in the handle,
The only difference in the two handles is the cross-sectional area
Solid handle
The temperature of the grip is reduced 33°C by using the hollow handle.
You might also like to view...
An ordinary glass lens forms an image by ____________ of light
a. reflection b. refraction c. diffraction
The source of energy that keeps the Sun shining today is
A) nuclear fission. B) nuclear fusion. C) gravitational contraction. D) chemical reactions.
Earth is farthest from the Sun in July and closest to the Sun in January. During which Northern Hemisphere season is Earth moving fastest in its orbit?
A) Spring B) Summer C) Fall D) Winter
A 0.50-m long solenoid consists of 1 000 turns of copper wire wound with a 4.0 cm radius. When the current in the solenoid is 18 A, the magnetic field at a point 1.0 cm from the central axis of the solenoid is
a. 0.090 mT. b. 0.36 mT. c. 23 mT. d. 36 mT. e. 45 mT.