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
Vesnalui [34]
3 years ago
13

A steam pipe passes through a chemical plant, where wind passes in cross-flow over the outside of the pipe. The steam is saturat

ed at 17.90 bar and you can assume that the resistances to heat transfer inside the pipe and of the pipe itself are minimal, so that the outside surface temperature of the pipe is equal to the saturation temperature of the steam. The pipe is stainless steel and has an outside diameter of 6.75 cm and a length of 34.7 m. The air flows over the pipe at 7.6 m/s and has a bulk fluid temperature of 27 °C.
A. What is the rate of heat transfer from the pipe to the air?
B. would your answer change if the air flow direction changes to parallel flow? If so, calculate that q as well.
Engineering
1 answer:
valina [46]3 years ago
4 0

Answer:

a) the rate of heat transfer from the pipe to the air is 23.866 watts

b) YES, the rate of heat transfer changes to 3518.61 watt

Explanation:

Given that:

steam is saturated at 17.90 bar.

the pipe is stainless steel and has an outside diameter of 6.75 cm

length = 34.7 m

Air flows over the pipe at 7.6 m/s

Bulk fluid temperature of 27°C

we know that

hD/k = 0.028 (Re)^0.8 (Pr)^0.33

Outside diameter of pipe = 6.75 cm

length of the pipe = 34.7 m

velocity of air = 7.6 m/s

Cp of air = 1.005 kJ/Kgk

viscosity of air = 1.81 × 10⁻⁵ kg/(m.sec)

thermal conductivity of air = 2.624 × 10⁻⁵ kw/m.k

so as

hD/k = 0.028 (Re)^0.8 (Pr)^0.33

hD/k = 0.028 (Dvp / u)^0.8 (Cpu / k)^0.33

(h × 0.0675 / 2.624 × 10⁻⁵) = (0.028 ([0.0675 × 7.6 × 1.225] / [1.81 ×10⁻⁵])^0.8) (((1.005 × 1.81 × 10⁻⁵) / (2.624 × 10⁻⁵))^0.33))

h = 0.0414 w/m².k

a)

Now to find the rate of heat transfer Q

Q = hAΔT

Q = 0.0414 × (2π × 0.03375 × 34.7) × (105.383 - 27)

Q = 23.866 watts

therefore the rate of heat transfer from the pipe to the air is 23.866 watts

b)

Now the flow direction changes to parallel flow, then

(h × 0.0675 / 2.624 × 10⁻⁵) = (0.028 ([34.7 × 7.6 × 1.225] / [1.81 ×10⁻⁵])^0.8) (((1.005 × 1.81 × 10⁻⁵) / (2.624 × 10⁻⁵))^0.33))

h = 6.1036 w/m².k

so from the steam table, saturated steam at 17.70 bar, temperature of steam will be 105.383°C

so to find the rate of heat transfer Q

Q = hAΔT

Q = 6.1036 × (2π × 0.03375 × 34.7) × (105.383 - 27)

Q = 3518.61 watt

Therefore the rate of heat transfer changes to 3518.61 watt

You might be interested in
A piston–cylinder device contains 0.78 kg of nitrogen gas at 140 kPa and 37°C. The gas is now compressed slowly in a polytropic
DiKsa [7]

Answer:

The entropy change of nitrogen during this process. is - 0.32628 kJ/K.

Explanation:

Solution

Given that:

A piston cylinder device contains =0.78 kg of nitrogen gas

Temperature = 37°C

The  nitrogen gas constant of R = 0.2968 kJ/kg.K

At room temperature cv = 0.743 kJ/kg.K

Now,

We assume that at specific condition the nitrogen can be treated as an ideal gas

Nitrogen has a constant volume specific heat at room temperature.

Thus,

From the polytropic relation, we have the following below:

T₂/T₁ =(V₁/V₂)^ n-1 which is,

T₂ = T₁ ((V₁/V₂)^ n-1

= (310 K) (2)^1.3-1 = 381.7 K

So,

The entropy change of nitrogen is computed as follows:

ΔSN₂ = m (cv₁ avg ln T₂/T₁ + ln V₂/V₁)

= (0.78) ((0.743 kJ/kg .K) ln 381.7 K/310K + (0.2968 kJ/kg. K) ln (0.5))

= 0.57954 * 0.2080 +  (-0.2057)

= 0.12058 + (-0.2057) = -0.32628

Therefore the entropy change of nitrogen during this process. is - 0.32628 kJ/K.

6 0
2 years ago
Shear strain can be expressed in units of either degrees or radians. a)True b)- False
ExtremeBDS [4]

Answer:

true

Explanation:

shear strain is define as the ratio of change in deformation to the original length perpendicular to the axes of member due to shear stress.

     ε    = deformation/original length

         

strain is a unit less quantity but shear stain is generally expressed in radians but it can also be expressed in degree.

3 0
3 years ago
For some metal alloy, a true stress of 345 MPa (50040 psi) produces a plastic true strain of 0.02. How much will a specimen of t
Strike441 [17]

Answer:

the elongation of the metal alloy is 21.998 mm

Explanation:

Given the data in the question;

K = σT/ (εT)ⁿ

given that metal alloy true stress σT = 345 Mpa, plastic true strain εT = 0.02,

strain-hardening exponent n = 0.22

we substitute

K = 345 / 0.02^{0.22

K = 815.8165 Mpa

next, we determine the true strain

(εT) = (σT/ K)^1/n

given that σT = 412 MPa

we substitute

(εT) = (412 / 815.8165 )^(1/0.22)

(εT) = 0.04481 mm

Now, we calculate the instantaneous length

l_i = l_0e^{ET

given that l_0 = 480 mm

we substitute

l_i =480mm × e^{0.04481

l_i =  501.998 mm

Now we find the elongation;

Elongation = l_i - l_0

we substitute

Elongation = 501.998 mm - 480 mm

Elongation = 21.998 mm

Therefore, the elongation of the metal alloy is 21.998 mm

6 0
2 years ago
Birdie Par owns a company that makes golf gloves. She is thinking about introducing a new glove, which would require an addition
melamori03 [73]

Birdie's company will make a profit of $30,000 if she sells 3,000 gloves at the $15 price.

Step-by-step Solution:

Break even point= fixed cost/ selling price - variable cost

here the fixed cost is= $20,000

selling price= $15 and variable cost = $5

BEP= 20,000/ 15-5= 20,000/10= 2000 units

b. if they sell 3000 gloves, the contribution profit will be

total revenue= 3000*$15= $45,000

contribution= selling price- variable cost, 15-5= $10 per unit

the profit is= 3000*$10= $30,000

What is  variable cost?

A variable cost is one that varies in relation to either the volume of production or the number of services provided. There should be no variable costs if no production or services are provided. Variable costs should rise in tandem with increases in production or services.

To learn more about Profit Calculation, visit: brainly.com/question/28177180

#SPJ1

3 0
1 year ago
What process is used to remove collodal and dissolved organic matter in waste water ​
Juli2301 [7.4K]

Answer:

Aerobic biological treatment process

Explanation:

Aerobic biological treatment process in which micro-organisms, in the presence of oxygen, metabolize organic waste matter in the water, thereby producing more micro-organisms and inorganic waste matter like CO₂, NH₃ and H₂O.

3 0
2 years ago
Other questions:
  • A turbine produces shaft power from a gas that enters the turbine with a (static) temperature of 628 K, a velocity of 143 m/s an
    7·1 answer
  • Air as an ideal gas in a closed system undergoes a reversible process between temperatures of 1000 K and 400 K. The beginning pr
    9·1 answer
  • what should be used to feed material into a machine? A.joy stick B.push stick C. your feet D. your hands​
    14·1 answer
  • in a vehicle you're servicing the fuel pressure drops rapidly when the engine is says that one or more turned off. Technician a
    7·1 answer
  • Air at 7 deg Celcius enters a turbojet engine at a rate of 16 kg/s and at a velocity of 300 m/s (relative to engine). Air is hea
    7·1 answer
  • Identify the different engineering activities/steps in the engineering design process for each steps,summarize in 1–3 sentences
    13·1 answer
  • Help me is it a b c or d?
    14·1 answer
  • Yellow wood glue will typically also work with metal, glass, and adhesives
    13·1 answer
  • A___ remote control can be an advantage to an
    14·2 answers
  • This test should be performed on all cord sets, receptacles that aren't part of a building or structure's permanent wiring, and
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!