A thin-walled tube with a diameter of 6 mm and length of 2 0 m is used to carry exhaust gas from a smoke stack to the laboratory in a nearby building for analysis. The gas enters the tube at 2 00 ° C and with a mass flow rate of 0.00 3 kg / s . Autumn winds at a temperature of 15 ° C blow directly across the tube at a velocity of 5 m / s . Assume the thermophysical properties of the exhaust gas are those of air. (a) Estimate the average heat transfer coefficient for the exhaust gas flowing inside the tube. (b) Estimate the heat transfer coefficient for the air flowing across the outside of the tube. (e) Estimate the overall heat transfer coefficient U and the temperature of the exhaust gas when it reaches the laboratory.
A thin-walled tube with a diameter of 6 mm and length of 2 0 m is used to carry exhaust gas from a smoke stack to the laboratory in a nearby building for analysis. The gas enters the tube at 2 00 ° C and with a mass flow rate of 0.00 3 kg / s . Autumn winds at a temperature of 15 ° C blow directly across the tube at a velocity of 5 m / s . Assume the thermophysical properties of the exhaust gas are those of air. (a) Estimate the average heat transfer coefficient for the exhaust gas flowing inside the tube. (b) Estimate the heat transfer coefficient for the air flowing across the outside of the tube. (e) Estimate the overall heat transfer coefficient U and the temperature of the exhaust gas when it reaches the laboratory.
Solution Summary: The author calculates the average heat transfer coefficient for exhaust gas flowing in the tube based on table A-4 "Thermo physical properties of air at atmospheric pressure".
A thin-walled tube with a diameter of 6 mm and length of
2
0
m
is used to carry exhaust gas from a smoke stack to the laboratory in a nearby building for analysis. The gas enters the tube at
2
00
°
C
and with a mass flow rate of
0.00
3 kg
/
s
. Autumn winds at a temperature of
15
°
C
blow directly across the tube at a velocity of
5 m
/
s
. Assume the thermophysical properties of the exhaust gas are those of air.
(a) Estimate the average heat transfer coefficient for the exhaust gas flowing inside the tube.
(b) Estimate the heat transfer coefficient for the air flowing across the outside of the tube.
(e) Estimate the overall heat transfer coefficient U and the temperature of the exhaust gas when it reaches the laboratory.
oyfr
3. The figure shows a frame under the
influence of an external loading made up
of five forces and two moments. Use the
scalar method to calculate moments.
a. Write the resultant force of the
external loading in Cartesian vector
form.
b. Determine the
& direction
of the resultant moment of the
external loading about A.
15 cm
18 cm
2.2 N-m
B
50 N
45°
10 cm
48 N.m
250 N
60 N
20
21
50 N
25 cm
100 N
A
118,
27cm 5, 4:1
Assume the Link AO is the input and revolves 360°, determine a. the coordinates of limit positions of point B, b. the angles (AOC) corresponding to the limit positions
oyfr
3. The figure shows a frame under the
influence of an external loading made up
of five forces and two moments. Use the
scalar method to calculate moments.
a. Write the resultant force of the
external loading in Cartesian vector
form.
b. Determine the
& direction
of the resultant moment of the
external loading about A.
15 cm
18 cm
2.2 N-m
B
50 N
45°
10 cm
48 N.m
250 N
60 N
20
21
50 N
25 cm
100 N
A
118,
27cm 5, 4:1
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