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ch4aika [34]
3 years ago
11

A thick oak wall (rho = 545 kg/m3 , Cp = 2385 J/kgK, and k = 0.17 W/mK) initially at 25°C is suddenly exposed to combustion prod

ucts at 800°C. Determine the time of exposure necessary for the surface to reach the ignition temperature of 400°C, assuming the convection heat transfer coefficient between the wall and the products to be 20 W/m2 K. At that time, what is the temperature 1 cm below the surface? (Note: use an appropriate equation for the semi-infinite wall case; compare equations 18.20 and 18.21 in the text).

Engineering
1 answer:
Nimfa-mama [501]3 years ago
8 0

Answer:

Explanation:

The detailed calculation and appropriate equation with substitution is as shown in the attached file.

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Identify the advantages of using 6 tube passes instead of just 2 of the same diameter in shell-and-tube heat exchanger.What are
liq [111]

Answer:

Please check explanation for answer

Explanation:

Here, we are concerned with stating the advantages and disadvantages  of using a 6 tube passes instead of a 2 tube passes of the same diameter:

<u>Advantages</u>

* By using a 6 tube passes diameter, we are increasing the surface area of the heat transfer surface

* As a result of increasing the heat transfer surface area, the rate of heat transfer automatically increases too

            Thus, from the above, we can conclude that the heat transfer rate of a 6 tube passes is higher than that of a 2 tube passes of the same diameter.

<u>Disadvantages</u>

* They are larger in size and in weight when compared to a 2 tube passes of the same diameter and therefore does not find use in applications where space conservation is quite necessary.

* They are more expensive than the 2 tube passes of the same diameter and thus are primarily undesirable in terms of  manufacturing costs

5 0
3 years ago
If block A of the pulley system is moving downward at 6 ft&gt;s while block C is moving down at 18 ft&gt;s, determine the relati
kramer

Answer:

Explanation:

The detailed steps and appropriate calculation with analysis is as shown in the attachment.

3 0
2 years ago
A tank with some water in it begins to drain. The function v ( t ) = 46 − 3.5 t determines the volume of the water in the tank (
olchik [2.2K]

Answer with Explanation:

Part a)

The volume of water in the tank as a function of time is plotted in the below attached figure.

The vertical intercept of the graph is 46.

Part b)

The vertical intercept represents the volume of water that is initially present in the tank before draining begins.

Part c)

To find the time required to completely drain the tank we calculate the volume of the water in the tank to zero.

0=46-3.5t\\\\3.5=46\\\\\therefore t=\frac{46}{3.5}=13.143minutes

Part d)

The horizontal intercept represents the time it takes to empty the tank which as calculated above is 13.143 minutes.

7 0
3 years ago
Identify factors that can cause a process to become out of control. Give several examples of such factors.
Oliga [24]

Answer:

Explained

Explanation:

This situation can occur because of various factors such as:

  • Gradual deterioration of lubrication and coolant.
  • change of environmental condition such as temperature, humidity, moisture, etc.
  • Change in the properties of incoming raw material
  • An increase or decrease in the temperature of the heat treating operation
  • Debris interfering with the manufacturing process.
4 0
2 years ago
Provide an argument justifying the following claim: The average (as defined here) of two Java ints i and j is representable as a
ahrayia [7]

Answer:

public static int average(int j, int k) {

return (int)(( (long)(i) + (long)(j) ) /2 );

}

Explanation:

The above code returns the average of two integer variables

Line 1 of the code declares a method along with 2 variables

Method declared: average of integer data type

Variables: j and k of type integer, respectively

Line 2 calculates the average of the two variables and returns the value of the average.

The first of two integers to average is j

The second of two integers to average is k

The last parameter ensures average using (j+k)/2

3 0
2 years ago
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