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nadya68 [22]
3 years ago
15

Pressurized steam at 450 K flows through a long, thin-walled pipe of 0.5-m diameter. The pipe is enclosed in a concrete casing t

hat is of square cross section and 1.5 m on a side. The axis of the pipe is centered in the casing, and the outer surfaces of the casing are maintained at 300 K. What is the heat loss per unit length of pipe
Engineering
1 answer:
iris [78.8K]3 years ago
7 0

Answer:

Heat loss per unit length of pipe = q' = 1363.47 W/m

Explanation:

Heat loss per unit length would be in terms of W/m.

Assumptions:

• steady-state conditions

• negligible steam side convection resistance, pipe wall resistance and contact resistance (T1 = 450 K)

• constant properties

The thermal conductivity for concrete must be found.

Referring to the table of thermal conductivity of some common materials, the value for stone concrete will be used, which is 1.7.

The heat rate can be expressed as:

q = SkΔT₁₋₂ = Sk(T₁ − T₂)

The proper shape factor is needed for the solution and is found from the list of shape factors. The shape factor must be for a circular cylinder of length L centered in a square solid of equal length and is:

S = 2πL  ÷ [ln (1.08w/D) ]

Then,

q' =   q  ÷ L

The full equation is:

q' =   2πk(T₁ − T₂)  ÷ [ln (1.08w/D) ]

Substituting known values:

q' =   2π(1.7 W/mK)*(450 K − 300 K)  ÷ [ln [1.08(1.5 m)/0.5 m] ]

q' = 1363.47 W/m

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Two thousand pieces will flow through from the first machine A to the final machine F based on the given sequence of operations.
Vlad1618 [11]

The total number of trips that the vehicle has to make based on the given sequence of operation is 120 trips.

<em>"Your</em><em> </em><em>question is not complete, it seems to be missing the following information;"</em>

The sequence of operation is A - E - D - C - B - A - F

The given parameters;

  • <em>number of pieces that will flow from the first machine A to machine F, = 2,000 pieces</em>
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  • <em>the capacity of the vehicle = 1 unit load</em>

<em />

The given sequence of operation of the vehicle;

A - E - D - C - B - A - F

<em>the vehicle makes </em><em>6 trips</em><em> for </em><em>100</em><em> unit </em><em>loads</em>

The total number of trips that the vehicle has to make, in order to transport the 2000 pieces of the load given, is calculated as follows.

100 unit loads ----------------- 6 trips

2000 unit loads --------------- ?

= \frac{2000}{100} \times 6\\\\= 120 \ trips

Thus, the total number of trips that the vehicle has to make based on the given sequence of operation is 120 trips.

Learn more here:brainly.com/question/21468592

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Answer:

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