A long plastic rod of 30-mm diameter ( k = 0.3 W/m ⋅ K and ρ c p = 1040 kJ/m 3 ⋅ K ) is uniformly heated in an oven as preparation for a pressing operation. For best results. the temperature in the rod should not be less than 200 ° C . To what uniform temperature should the md be heated in the oven if, for the worst case, the rod sits on a conveyor for 3 min While exposed to convection cooling with ambient air at 25 º C and with a convection coefficient of 8 W/m 2 ⋅ K? A further condition for good results is a maximum-minimum temperature difference of less than 10 ° C . Is this condition satisfied? If not, what could you do to satisfy it?
A long plastic rod of 30-mm diameter ( k = 0.3 W/m ⋅ K and ρ c p = 1040 kJ/m 3 ⋅ K ) is uniformly heated in an oven as preparation for a pressing operation. For best results. the temperature in the rod should not be less than 200 ° C . To what uniform temperature should the md be heated in the oven if, for the worst case, the rod sits on a conveyor for 3 min While exposed to convection cooling with ambient air at 25 º C and with a convection coefficient of 8 W/m 2 ⋅ K? A further condition for good results is a maximum-minimum temperature difference of less than 10 ° C . Is this condition satisfied? If not, what could you do to satisfy it?
Solution Summary: The author explains that to justify the condition of temperature difference of 10 ° C, the biot number can be calculated according to the approximate calculation.
A long plastic rod of 30-mm diameter
(
k
=
0.3
W/m
⋅
K
and
ρ
c
p
=
1040
kJ/m
3
⋅
K
)
is uniformly heated in an oven as preparation for a pressing operation. For best results. the temperature in the rod should not be less than
200
°
C
.
To what uniform temperature should the md be heated in the oven if, for the worst case, the rod sits on a conveyor for 3 min While exposed to convection cooling with ambient air at
25
º
C
and with a convection coefficient of
8
W/m
2
⋅
K?
A further condition for good results is a maximum-minimum temperature difference of less than
10
°
C
.
Is this condition satisfied? If not, what could you do to satisfy it?
The 8-mm-thick bottom of a 220-mm-diameter pan may be made from aluminum (k = 240 W/m · K) or copper (k = 390 W/m · K). When used to boil water, the surface of the bottom exposed to the water is nominally at 110°C. If heat is transferred from the stove to the pan at a rate of 600 W, what is the temperature of the surface in contact with the stove for each of the two materials?
Plot the temperature distribution along the fin using the following data:
k = 168 W/m.K, h = 12 W/m2.K, a = 0.05 m, b = 0.01 m. Vary x from 0 to 0.1 m in increments of 0.01 m.
Consider a heat engine with a piston chamber that has a diameter of 30 mm, a cold reservoir at 285 K and hot reservoir at 350 K. It is also equipped with a metal can cylinder that has a volume of 0.0002 m3. How many moles of air are present in the system if the metal cylinder is in the cold tank and the measured pressure and the total air volume are 104160 and 0.00015 m3, respectively?
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First Law of Thermodynamics, Basic Introduction - Internal Energy, Heat and Work - Chemistry; Author: The Organic Chemistry Tutor;https://www.youtube.com/watch?v=NyOYW07-L5g;License: Standard youtube license