A thin‐walled tube with a diameter of 12 mm and length of 25 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 200°C and with a mass flow rate of 0.006 kg/s. Autumn winds at a temperature of 15°C blow directly across the tube at a velocity of 2.5 m/s. Assume the thermophysical properties of the exhaust gas are those of air
Estimate the average heat transfer coefficient for the exhaust gas flowing inside the tube.
Estimate the average heat transfer coefficient for the exhaust gas flowing inside the tube.
1 answer:
Answer:
The average heat transfer coefficient for the exhaust gas flowing inside the tube, h = 204.41 W/m^2 - K
Explanation:
The detailed solution is attached as files below.
However, the steps followed are highlighted:
1) The average temperature was calculated as 380.5 K
2) The properties of air at 380.5 K was highlighted
3) The Prandti number was calculated. Pr = 0.693
4) The Reynold number was calculated, Re = 28716.77
5) The Nusselt umber was calculated, Nu = 75.94
6) From Nu = (hD)/k , the average heat transfer coefficient, h, was calculated and a value of 204.41 W/m^2 - K was gotten.
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Answer:
a) | v2 | , β2 ( load, bus voltage at bus 2 )
p1 , q1 ( slack, bus power at bus 1 )
b) q2 , β2
p1 and q1 ( slack, bus power at bus 1 )
Explanation:
Attached below is a schematic representation of the solution
<u>a) Identify the variables in the solution vector assume Bus 2 is a load bus</u>
The specified parameters are ; P2 and q2
while | v2 | and β2 are not specified
given that bus 2 is a load bus, bus 1 is a slack bus with ; | v1 | and β1 been specified while p1 and q1 are not specified
<em>Hence the variables in the solution </em>
<em>= | v2 | , β2 ( load, bus voltage at bus 2 )</em>
<em> p1 , q1 ( slack, bus power at bus 1 ) </em>
<u>b) Identify the variables in the solution vector ( assume Bus 2 is a PV bus )</u>
specified at Bus 2 are ; | p2 | , | v2 |
unspecified : q2 , β2
Bus 1 ( still a slack bus )
specified parameter : | v1 | and β1
unspecified : p1 and q1
<em>Hence the variables in the solution </em>
<em>= q2 , β2 </em>
<em> p1 and q1 ( slack, bus power at bus 1 ) </em>
Answer:
Shearing stresses are the stresses generated in any material when a force acts in such a way that it tends to tear off the material.
Generally the above definition is valid at an armature level, in more technical terms shearing stresses are the component of the stresses that act parallel to any plane in a material that is under stress. Shearing stresses are present in a body even if normal forces act on it along the centroidal axis.
Mathematically in a plane AB the shearing stresses are given by
Yes the shearing force which generates the shearing stresses is similar to frictional force that acts between the 2 surfaces in contact with each other.
