1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
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

You might be interested in
A 150 MVA, 24 kV, 123% three-phase synchronous generator supplies a large network. The network voltage is 27 kV. The phase angle
Aleks04 [339]

Answer:

the generator induced voltage is 60.59 kV

Explanation:

Given:

S = 150 MVA

Vline = 24 kV = 24000 V

X_{s} =1.23(\frac{V_{line}^{2}  }{s} )=1.23\frac{24000^{2} }{1500} =4723.2 ohms

the network voltage phase is

V_{phase} =\frac{V_{nline} }{\sqrt{3} } =\frac{27}{\sqrt{3} } =15.58kV

the power transmitted is equal to:

|E|=\frac{P*X_{s} }{3*|V_{phase}|sinO } ;if-O=60\\|E|=\frac{300*4.723}{3*15.58*sin60} =34.98kV

the line induced voltage is

|E_{line} |=\sqrt{3} *|E|=\sqrt{3} *34.98=60.59kV

7 0
3 years ago
A 75- kw, 3-, Y- connected, 50-Hz 440- V cylindrical synchronous motor operates at rated condition with 0.8 p.f leading. the mot
Thepotemich [5.8K]

78950W the answer

Explanation:

A 75- kw, 3-, Y- connected, 50-Hz 440- V cylindrical synchronous motor operates at rated condition with 0.8 p.f leading. the motor efficiency excluding field and stator losses, is 95%and X=2.5ohms. calculate the mechanical power developed, the Armature current, back e.m.f, power angle and maximum or pull out torque of the motor

A 75- kw, 3-, Y- connected, 50-Hz 440- V cylindrical synchronous motor operates at rated condition with 0.8 p.f leading. the motor efficiency excluding field and stator losses, is 95%and X=2.5ohms. calculate the mechanical power developed, the Armature current, back e.m.f, power angle and maximum or pull out torque of the motor

5 0
3 years ago
The dam cross section is an equilateral triangle, with a side length, L, of 50 m. Its width into the paper, b, is 100 m. The dam
lisabon 2012 [21]

Answer:

Explanation:

In an equilateral trinagle the center of mass is at 1/3 of the height and horizontally centered.

We can consider that the weigth applies a torque of T = W*b/2 on the right corner, being W the weight and b the base of the triangle.

The weigth depends on the size and specific gravity.

W = 1/2 * b * h * L * SG

Then

Teq = 1/2 * b * h * L * SG * b / 2

Teq = 1/4 * b^2 * h * L * SG

The water would apply a torque of elements of pressure integrated over the area and multiplied by the height at which they are apllied:

T1 = \int\limits^h_0 {p(y) * sin(30) * L * (h-y)} \, dy

The term sin(30) is because of the slope of the wall

The pressure of water is:

p(y) = SGw * (h - y)

Then:

T1 = \int\limits^h_0 {SGw * (h-y) * sin(30) * L * (h-y)} \, dy

T1 = \int\limits^h_0 {SGw * sin(30) * L * (h-y)^2} \, dy

T1 = SGw * sin(30) * L * \int\limits^h_0 {(h-y)^2} \, dy

T1 = SGw * sin(30) * L * \int\limits^h_0 {(h-y)^2} \, dy

T1 = SGw * sin(30) * L * \int\limits^h_0 {h^2 - 2*h*y + y^2} \, dy

T1 = SGw * sin(30) * L * (h^2*y - h*y^2 + 1/3*y^3)(evaluated between 0 and h)

T1 = SGw * sin(30) * L * (h^2*h - h*h^2 + 1/3*h^3)

T1 = SGw * sin(30) * L * (h^3 - h^3 + 1/3*h^3)

T1 = 1/3 * SGw * sin(30) * L * h^3

To remain stable the equilibrant torque (Teq) must be of larger magnitude than the water pressure torque (T1)

1/4 * b^2 * h * L * SG > 1/3 * SGw * sin(30) * L * h^3

In an equilateral triangle h = b * cos(30)

1/4 * b^3 * cos(30) * L * SG  > 1/3 * SGw * sin(30) * L * b^3 * (cos(30))^3

SG > SGw * 4/3* sin(30) * (cos(30))^2

SG > 1/2 * SGw

For the dam to hold, it should have a specific gravity of at leas half the specific gravity of water.

This is avergae specific gravity, including holes.

6 0
3 years ago
In poor weather, you should __ your following distance
Ratling [72]

Answer:

I think reduce your following distance

5 0
3 years ago
Read 2 more answers
Two identical 3 in. major-diameter power screws (single-threaded) with modified square threads are used to raise and lower a 50-
sp2606 [1]

Answer:

Check the explanation

Explanation:

Kindly check the attached images below to see the step by step explanation to the question above.

6 0
3 years ago
Other questions:
  • At a certain elevation, the pilot of a balloon has a mass of 120 lb and a weight of 119 lbf. What is the local acceleration of g
    6·1 answer
  • Two cars A and B leave an intersection at the same time. Car A travels west at an average speed of x miles per hour and car B tr
    9·1 answer
  • The Emergency Stop Button icon on the Inputs toolbar can be used to press or release the Emergency Stop button on the CNC machin
    10·1 answer
  • If a machine uses LESS effort to overcome a given resistance force (if Fe is less than FR), it has an actual mechanical advantag
    13·1 answer
  • dentify a semiconducting material and provide the value of its band gap) that could be used in: (a) (1 point) red LED (b) (1 poi
    10·1 answer
  • Zack's new home is progressing well, and the foundation work is finished. The general contractor stops by Zack's present home to
    11·1 answer
  • Hello, so I have a watch and I don't know where the plugin for the charger is, or what brand it is. Please do help and please DO
    11·1 answer
  • I love touching the atmospheres crest
    8·1 answer
  • Does anyone know the answer to this
    5·2 answers
  • A pipe fitter would fabricate which one of the following systems?
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!