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
garri49 [273]
3 years ago
14

Air at 2.5 bar, 400 K is extracted from a main jet engine compressor for cabin cooling. The extracted air enters a heat exchange

r where it is cooled at constant pressure to 300 K through heat transfer with the ambient. It then expands adiabatically to 1.0 bar through a turbine and is discharged into the cabin. The turbine has an isentropic efficiency of 80%.
If the mass flow rate of the air is 2.5 kg/s, determine:

(a) the power developed by the turbine, in kw.
(b) the magnitude of the rate of heat transfer from the air to the ambient, in kw
Engineering
2 answers:
Naddika [18.5K]3 years ago
6 0

Answer:

a) 132.89 kW

b) 251.25 kW

Explanation:

a) For the isentropic process:

Power developed by the turbine is given by the relation \dot{W} = \dot{M} c_{p} (T_{2} - T_{3})

Isentropic efficiency, \eta_{t} = 80%

P₂ = 2.5 bar, T₂ = 300 K

P₃ = 1 bar, T_{3s} = ? where T_{3s} is the isentropic temperature at 100% efficiency

The isentropic relation is given by:

\frac{T_{3s} }{T_{2} } = (\frac{P_{3} }{P_{2} }) ^{\frac{\gamma - 1}{\gamma} } \\\frac{T_{3s} }{300 } = (\frac{1 }{2.5 }) ^{\frac{1.4 - 1}{1.4 }

T_{3s} = 230.9 K

To evaluate the temperature at 80% efficiency, we will use the following method:

\eta_{t} = \frac{T_{2} - T_{3} }{T_{2} - T_{3s} } \\0.8= \frac{300 - T_{3} }{300 - 230.9 }

T₃ = 244.72 K

The power developed by the turbine is given by the relation:

\dot{W} = \dot{M} c_{p} (T_{2} - T_{3})\\ \dot{W} = 2.5 * 1.005* (300-244.72)\\ \dot{W} = 138.89 kW

b)

The constant pressure specific heat of air, c_{p} = 1.005 kJ/kg -K

Specific heat ratio for air, \gamma = 1.4

The mass flow rate of air, \dot{m} = 2.5 kg/s

P₁ = 2.5 bar, T₁ = 400 K

P₂ = 2.5 bar, T₂ = 300 K

We going to the steady flow energy equation using this equation:

Q_{1-2} = \dot{m} c_{p} (T_{2} - T_{1} \\Q_{1-2} = 2.5 * 1.005 * (300 - 400)\\Q_{1-2} = -251.25 kW

Hence, the magnitude of the rate of heat transfer from the air to the ambient, in is going to be kw, Q_{1-2} = 251.25 kW

Shkiper50 [21]3 years ago
4 0

Answer:

a) Power developed by the turbine = 132.89 kW

b) magnitude of the rate of heat transfer from the air to the ambient, in kw = 251.25 kW

Explanation:

b) The process is a constant pressure process (Isobaric process)

The constant pressure specific heat of air, c_{p} = 1.005 kJ/kg -K

Specific heat ratio for air, \gamma = 1.4

The mass flow rate of air, \dot{m} = 2.5 kg/s

P₁ = 2.5 bar, T₁ = 400 K

P₂ = 2.5 bar, T₂ = 300 K

Using the steady flow energy equation:

Q_{1-2}  = \dot{m} c_{p} (T_{2} - T_{1} \\Q_{1-2}  = 2.5 * 1.005 * (300 - 400)\\Q_{1-2}  = -251.25 kW

Therefore, the magnitude of the rate of heat transfer from the air to the ambient, in kw, Q_{1-2} = 251.25 kW

a) For the isentropic process:

Power developed by the turbine is given by the relation \dot{W} = \dot{M}  c_{p} (T_{2} - T_{3})

Isentropic efficiency, \eta_{t} = 80%

P₂ = 2.5 bar, T₂ = 300 K

P₃ = 1 bar, T_{3s} = ? where T_{3s} is the isentropic temperature at 100% efficiency

The isentropic relation is given by:

\frac{T_{3s} }{T_{2} } = (\frac{P_{3} }{P_{2} }) ^{\frac{\gamma - 1}{\gamma} } \\\frac{T_{3s} }{300 } = (\frac{1 }{2.5 }) ^{\frac{1.4 - 1}{1.4 }

T_{3s} = 230.9 K

To get the temperature at 80% efficiency, we will use the relation:

\eta_{t} = \frac{T_{2} - T_{3}  }{T_{2} - T_{3s} } \\0.8= \frac{300 - T_{3}  }{300 - 230.9 }

T₃ = 244.72 K

Power developed by the turbine is given by the relation:

\dot{W} = \dot{M}  c_{p} (T_{2} - T_{3})\\ \dot{W} = 2.5 * 1.005* (300-244.72)\\ \dot{W} = 138.89 kW

You might be interested in
Given a force of 72 lbs at a distance of 15 ft, calculate the moment produced.​
Elis [28]

Answer:

1425.78 N.m

Explanation:

Moments of force is calculated as ;

Moments= Force * distance

M= F*d

The S.I unit for moment of force is Newton-meter (N.m)

Given in the question;

Force = 72 lbs

1 pound = 4.45 N

72 lbs = 4.45 * 72=320.4 N

Distance= 15 ft

1ft= 0.3048 m

15 ft = 15*0.3048 = 4.57 m

d= 4.57 m

M= F*d

M=320.4*4.57 =1425.78 N.m

5 0
3 years ago
Write a function call with arguments tensPlace, onesPlace, and userInt. Be sure to pass the first two arguments as pointers. Sam
Trava [24]

Answer:

#include <stdio.h>

void SplitIntoTensOnes(int* tensDigit, int* onesDigit, int DecVal){

  *tensDigit = (DecVal / 10) % 10;

  *onesDigit = DecVal % 10;

  return;

}

int main(void) {

  int tensPlace = 0;

  int onesPlace = 0;

  int userInt = 0;

  userInt = 41;

  SplitIntoTensOnes(&tensPlace, &onesPlace, userInt);

  printf("tensPlace = %d, onesPlace = %d\n", tensPlace, onesPlace);

  return 0;

}

4 0
3 years ago
Name safety hazards that should be included in the design of a school
dem82 [27]

Answer:

Environmental

Explanation:

weather , noise, heat ect

7 0
3 years ago
How should you set up your notes when using the Cornell method?
Semenov [28]

Answer:

With right and left side charts

Explanation:

I was doing research on this exact question, so here is what I have been looking at;

The Cornell method uses a two-column approach. The left column takes up no more than a third of the page and is often referred to as the “cue” or “recall” column. The right column (about two-thirds of the page) is used for taking notes using any of the methods described above or a combination of them. After class or completing the reading, review your notes and write the key ideas and concepts or questions in the left column. You may also include a summary box at the bottom of the page, in which to write a summary of the class or reading in your own words.

5 0
3 years ago
Read 2 more answers
A well-insulated, rigid vessel contains 3 kg of saturated liquid water at 40°C. The vessel also contains an electrical resistor
Olenka [21]

Answer:

The final temperature in the vessel after the resistor has been operating for 30 min is 111.67°C

Explanation:

given information:

mass, m = 3 kg

initial temperature,  T₁ = 40°C

current, I = 10 A

voltage, V = 50 V

time, t = 30 min = 1800 s

Heat for the system because of the resistance is

Q = V I t

where

V = voltage (V)

I = current (A)

t = time (s)

Q = heat transfer to the system (J)

so,

Q = V x I x t

   = 50 x 10 x 1800

   = 900000

   = 9 x 10⁵ J

the heat transfer in the closed system is

Q = ΔU + W

where

U = internal energy

W = work done by the system

thus,

Q = ΔU + W

9 x 10⁵ = ΔU + 0, W = 0 because the tank is a well-insulated and rigid.

ΔU = 9 x 10⁵ J = 900 kJ

then, the energy change in the system is

ΔU = m c ΔT

ΔT = ΔU / m c, c = 4.186 J/g°C

     = 900 / (3 x 4.186)

     = 71.67°C

so,the final temperature (T₂)

ΔT = T₂ - T₁

T₂ = ΔT + T₁

    = 71.67°C + 40°C

    = 111.67°C

5 0
3 years ago
Other questions:
  • A manufacturer makes integrated circuits that each have a resistance layer with a target thickness of 200 units. A circuit won't
    5·1 answer
  • What is the braks mean effictive pressure?
    9·1 answer
  • Provide an argument justifying the following claim: The average (as defined here) of two Java ints i and j is representable as a
    9·1 answer
  • When it comes to making a good impression in a work setting, it does not apply to an initial contact, since both people are meet
    9·1 answer
  • Write a method printShampooInstructions(), with int parameter numCycles, and void return type. If numCycles is less than 1, prin
    15·1 answer
  • a triangle is defined by the three vertices. write the following functions of the triangle class assume that the point class has
    7·1 answer
  • 1.
    11·1 answer
  • To solve the problem, make assumptions for missing data and justify. Given:
    15·1 answer
  • It tells the amount of materials to be purchased.
    14·1 answer
  • Why is communication one of the most important aspects of an engineer's job?
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!