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
One half of 17’ 9 3/16”
Mademuasel [1]
555.66 is the answer I think
6 0
2 years ago
The heat rate is essentially the reciprocal of the thermal efficiency. a)- True b)- False
jeyben [28]

Answer:

a). TRUE

Explanation:

Thermal efficiency of a system is the defined as the ratio of the net work done to the total heat input to the system. It is a dimensionless quantity.

Mathematically, thermal efficiency is

        η =  net work done / heat input

While heat rate is  the reciprocal of efficiency. It is defined as the ratio of heat supplied to the system to the useful work done.

Mathematically, heat rate is

       Heat rate = heat input / net work done

Thus from above we can see that heat rate is the reciprocal of thermal efficiency.

Thus, Heat rate is reciprocal of thermal efficiency.

4 0
3 years ago
A lower coefficient of thermal conductivity along with a higher coefficient of thermal expansion and higher electrical resistanc
HACTEHA [7]

Answer:

stainless steel

Explanation:

Conductivity refers to the degree to which a specified material conducts electricity. It is the ratio of the current density in the material and the electric field.

The thermal conductivity of a material measures its ability to conduct heat.

In materials of low thermal conductivity, heat transfer occurs at a lower rate as compared to materials of high thermal conductivity.

Thermal expansion of the material refers to its tendency to change its shape, area, and volume as a result of change in temperature.

The electrical resistance of a material refers to the measure of its opposition to the flow of electric current.

<u>Stainless steel</u> has a lower coefficient of thermal conductivity along with a higher coefficient of thermal expansion and higher electrical resistance.

5 0
3 years ago
Air from a workspace enters the air conditioner unit at 30°C dry bulb and 25°C wet bulb temperatures. The air leaves the air con
PSYCHO15rus [73]

Answer:

See explaination

Explanation:

The volume flow rate Q Q QQ of a fluid is defined to be the volume of fluid that is passing through a given cross sectional area per unit time.

Kindly check attachment for the step by step solution of the given problem.

4 0
3 years ago
A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at 2308C by rejectin
lord [1]

Answer:

hello your question is incomplete attached below is the missing part and also attached is the solution

answer: a) 0.4801

              b) 5.398 kw

              c) 2.14

              d) 12.72

Explanation:

The quality of the refrigerant at the evaporator inlet

h4 = hf4 + x4(hfx4)

Refrigeration load

Ql = m(h1-h4)

COP of the refrigerator

Ql / m(h2-h1) - Qm

Theoretical maximum refrigeration load

( Ql )max = COPr.rev * [m(h2-h1) - Qin]

5 0
3 years ago
Other questions:
  • The underground storage of a gas station has leaked gasoline into the ground. Among the constituents of gasoline are benzene, wi
    12·2 answers
  • A 30 mm thick AISI 1020 steel plate is sandwiched between two 10 mm thick 2024-T3 aluminum plates and compressed with a bolt and
    9·1 answer
  • A converging-diverging nozzle has an area ratio of 5.9. (1) Determine the (P0/Pt) values corresponding to the 1st, 2nd, and 3rd
    5·1 answer
  • You want to plate a steel part having a surface area of 160 with a 0.002--thick layer of lead. The atomic mass of lead is 207.19
    15·1 answer
  • Which permission do you need to shoot on the owner’s property?
    8·1 answer
  • Affect the amount and rate the alcohol reaches the<br> bloodstream.
    10·1 answer
  • The 240-ft structure is used to provide various support services to launch vehicles prior to liftoff. In a test, a 12-ton weight
    14·1 answer
  • Hey any one ride dirtbikes here
    5·2 answers
  • 7–2 Cooling of a Hot Block by Forced Air at High
    6·1 answer
  • A clean machine is a _______________ machine.
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!