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ANTONII [103]
2 years ago
13

In an experiment, the local heat transfer over a flat plate were correlated in the form of local Nusselt number as expressed by

the correlation Nux=0.035Re0.8xPr1/3 Determine the ratio of the average convection heat transfer coefficient (h) over the entire plate length to the local convection heat transfer coefficient (hx) (h/hx = L) at x = L.
Engineering
1 answer:
zvonat [6]2 years ago
3 0

Answer:

R= 1.25

Explanation:

As given the local heat transfer,

Nu_x = 0.035 Re^{0.8}_x Pr^{1/3}

But we know as well that,

Nu=\frac{hx}{k}\\h=\frac{Nuk}{x}

Replacing the values

h_x=Nu_x \frac{k}{x}\\h_x= 0.035Re^{0.8}_xPr^{1/3} \frac{k}{x}

Reynolds number is define as,

Re_x = \frac{Vx}{\upsilon}

Where V is the velocity of the fluid and \upsilon is the Kinematic viscosity

Then replacing we have

h_x=0.035(\frac{Vx}{\upsilon})^{0.8}Pr^{1/3}kx^{-1}

h_x=0.035(\frac{V}{\upsilon})^{0.8}Pr^{1/3}kx^{0.8-1}

h_x=Ax^{-0.2}

<em>*Note that A is just a 'summary' of all of that constat there.</em>

<em>That is A=0.035(\frac{V}{\upsilon})^{0.8}Pr^{1/3}k</em>

Therefore at x=L the local convection heat transfer coefficient is

h_{x=L}=AL^{-0.2}

Definen that we need to find the average convection heat transfer coefficient in the entire plate lenght, so

h=\frac{1}{L}\int\limit^L_0 h_x dx\\h=\frac{1}{L}\int\limit^L_0 AL^{-0.2}dx\\h=\frac{A}{0.8L}L^{0.8}\\h=1.25AL^{-0.2}

The ratio of the average heat transfer coefficient over the entire plate  to the local convection heat transfer coefficient is

R = \frac{h}{h_L}\\R= \frac{1.25Al^{-0.2}}{AL^{-0.2}}\\R= 1.25

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2 years ago
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Answer:

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Explanation:

Strategy  

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∅=4°

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3 years ago
For some transformation having kinetics that obey the Avrami equation, the parameter n is known to have a value of 2. If, after
kotegsom [21]

This question is incomplete, the complete question is;

For some transformation having kinetics that obey the Avrami equation, the parameter n is known to have a value of 2. If, after 100 s, the reaction is 40% complete, how long (total time in seconds) will it take the transformation to go to 95% completion

y = 1 - exp( -ktⁿ )

Answer: the time required for 95% transformation is 242.17 s

Explanation:

First, we calculate the value of k which is the dependent variable in Avrami equation

y = 1 - exp( -ktⁿ )

exp( -ktⁿ ) = 1 - y

-ktⁿ = In( 1 - y )

k = - In( 1 - y ) / tⁿ

now given that; n = 2, y = 40% = 0.40, and t = 100 s

we substitute

k = - In( 1 - 0.40 ) / 100²

k = - In(0.60) / 10000

k = 0.5108 / 10000

k = 0.00005108 ≈ 5.108 × 10⁻⁵

Now calculate the time required for 95% transformation

tⁿ = - In( 1 - y ) / k

t = [- In( 1 - y ) / k ]^1/n

n = 2, y = 95% = 0.95 and k = 5.108 × 10⁻⁵

we substitute our values

t = [- In( 1 - 0.95 ) / 5.108 × 10⁻⁵ ]^1/2

t = [2.9957 / 5.108 × 10⁻⁵]^1/2

t = [ 58647.22 ]^1/2

t = 242.17 s

Therefore the time required for 95% transformation is 242.17 s

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what is an example of an innovative solution to an engineering problem? Explain briefly why you chose this answer.
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Answer:

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Explanation:

Innovation is nothing but the use of various things such as ideas, products, people to build up a solution for the benefit of the human. It can be any product or any solution which is new and can solve people's problems.

Innovation solution makes use of technology to provide and dispatch new solutions or services which is a combination of both technology and ideas.

One such example of an innovative solution we can see is the use of "Robots" in medical science or in any military operations or rescue operation.

Sometimes it is difficult for humans to do everything or go to everywhere. Thus scientist and engineers have developed many advance robots or machines using new ideas and technology to find solutions to these problems.

Using innovations and technologies, one can find solutions to many problems which is difficult for the peoples. Robots can be used in any surveillance operation or in places of radioactive surrounding where there is a danger of humans to get exposed to such threats. They are also used in medical sciences to operate and support the patient.  

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Drivers education - Unit 3
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Best response:

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Scenario 3: When you are in slow traffic and you hear the siren of an ambulance behind

Best response:

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  • This helps to keep the patient in the ambulance alive.
  • It also provide a clear path for the ambulance.
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  • This will exacerbate the situation. If there is no place to park on the right shoulder of the road, it is preferable to stay in the lane.

Learn more about rules of driving. at;

brainly.com/question/8384066

#SPJ1

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