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matrenka [14]
3 years ago
13

Mercury flows inside a copper tube 9m long with a 5.1сm inside diameter at an average velocity of 7.0 m/s. The inside surface te

mperature of the tube is kept at 38 C and the mean temperature of the mercury is 66 C. Assuming that the velocity and temperature profiles are fully developed throughout, calculate the rate of heat transfer by convection. Justify any equations you may use.
Engineering
1 answer:
svp [43]3 years ago
6 0

Answer:

rate of heat transfer = 9085708.80 W

Explanation:

Given:

Inside diameter, D = 5.1 cm

                               = 5.1 x 10^{-2} m

Average velocity, V = 7 m/s

Mean temperature, T = (66+38) /2

                                    = 52°C

Therefore kinematic viscosity at 52°C is ν = 0.104 X 10^{-6} m^{2} / s

Prandtl no., Pr = 0.021

We know Renold No. is

Re = \frac{V\times D}{\nu }

Re = \frac{7\times 5.1\times 10^{-2}}{0.104\times 10^{-6}}

     = 3.432 X 10^{6}

Therefore the flow is turbulent.

Since the flow is turbulent and the ratio of L/D is greater than 60 we can use Dittua-Boelter equation.

Nu = 0.023 Re^{0.8}.Pr^{0.3}

     = 0.023 x (3.432 \times10^{6})^{0.8} x (0.021)^{0.3}

     = 1221.52

Since Nu = \frac{h.D}{k}

          h = \frac{k\times Nu}{D}

             = \frac{9.4\times 1221.52}{5.1\times 10^{-2}}

             = 225143.3

Therefore rate of heat transfer, q = h.A(T-T_{\infty }

           q= 225143.3 x 2πrh ( 66-38)

             = 225143.3 X 2π X \frac{5.1\times10^{-2}}{2}\times 9\times 28

              = 9085708.80 W

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Volgvan

Answer:

"Macro Instruction"

Explanation:

A macro definition is a rule or pattern that specifies how a certain input sequence should be mapped to a replacement output sequence according to a defined procedure. The mapping process that instantiates a macro use into a specific sequence is known as macro expansion.

It is a series of commands and actions that can be stored and run whenever you need to perform the task. You can record or build a macro and then run it to automatically repeat that series of steps or actions.

7 0
2 years ago
Assign numMatches with the number of elements in userValues that equal matchValue. userValues has NUM_VALS elements. Ex: If user
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Answer:

import java.util.Scanner;

public class FindMatchValue {

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     final int NUM_VALS = 4;

     int[] userValues = new int[NUM_VALS];

     int i;

     int matchValue;

     int numMatches = -99; // Assign numMatches with 0 before your for loop

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     for (i = 0; i < userValues.length; ++i) {

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     /* Your solution goes here */

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     for (i = 0; i < userValues.length; ++i) {

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                       numMatches++;

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8 0
3 years ago
__________ affect(s) the amount of air conditioning required.
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Answer:

Option D

All the above

Explanation:

Depending with the number of occupants in a building, the number of air conditioners required can either be increased or reduced. For instance, if the building is to be a classroom of over 50 students, 1 air-conditioner can't serve effectively. Similarly, the activity of occupants also dictate the amount of air conditioners required since if it's a gym room where occupants exercise often then the air conditioners required is different from if the room was to serve as a  lounge. The appliances that also operate in a room require that air conditioners be installed as per the heat that may be generated by the appliances.

5 0
3 years ago
A wire of diameter d is stretched along the centerline of a pipe of diameter D. For a given pressure drop per unit length of pip
JulsSmile [24]

Answer:

Part A: (d/D=0.1)

DeltaV percent=42.6%

Part B:(d/D=0.01)

DeltaV percent=21.7%

Explanation:

We are going to use the following volume flow rate equation:

DeltaV=\frac{\pi * DeltaP}{8*u*l}(R^{4}-r^{4} -\frac{(R^{2}-r^{2})}{ln\frac{R}{r}}^{2})

Above equation can be written as:

DeltaV=\frac{\pi*R^{4}*DeltaP}{8*u*l}(1-(\frac{r}{R} )^{4}+\frac{(1-(\frac{r}{R} )^{2})}{ln\frac{r}{R}}^{2})

DeltaV=\frac{\pi*R^{4}*DeltaP}{8*u*l}(1-(\frac{d}{D} )^{4}+\frac{(1-(\frac{d}{D})^{2})}{ln\frac{d}{D}}^{2})

First Consider no wire i.e d/D=0

Above expression will become:

DeltaV=\frac{\pi*R^{4}*DeltaP}{8*u*l}(1-(0)^{4}+\frac{(1-(0)^{2})}{ln0}^{2})

DeltaV=\frac{\pi*R^{4}*DeltaP}{8*u*l}

Part A: (d/D=0.1)

DeltaV=\frac{\pi*R^{4}*DeltaP}{8*u*l}(1-(0.1)^{4}+\frac{(1-(0.1)^{2})}{ln0.1}^{2})

DeltaV=\frac{\pi*R^{4}*DeltaP}{8*u*l}*0.574

DeltaV percent=\frac{(\frac{\pi*R^{4}*DeltaP}{8*u*l})-\frac{\pi *R^{4}*DeltaP}{8*u*l}*0.574}{\frac{\pi*R^{4}*DeltaP}{8*u*l} }*100

DeltaV percent=\frac{1-0.574}{1}*100

DeltaV percent=42.6%

Part B:(d/D=0.01)

DeltaV=\frac{\pi*R^{4}*DeltaP}{8*u*l}(1-(0.01)^{4}+\frac{(1-(0.01 )^{2})}{ln0.01}^{2})

DeltaV=\frac{\pi*R^{4}*DeltaP}{8*u*l}*0.783

DeltaV percent=\frac{(\frac{\pi *R^{4}*DeltaP}{8*u*l})-\frac{\pi *R^{4}*DeltaP}{8*u*l}*0.783}{\frac{\pi *R^{4}*DeltaP}{8*u*l} }*100

DeltaV percent=\frac{1-0.783}{1}*100

DeltaV percent=21.7%

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2 years ago
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the president and mr.white my history teacher lol

6 0
2 years ago
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