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
Lynna [10]
3 years ago
6

Air at 300 K and 100 kPa steadily flows into a hair dryer having electrical work input of 1500 W. Because of the size of the air

intake, the inlet velocity of the air is negligible. The air temperature and velocity at the hair dryer exit are 80°C and 21 m/s, respectively. The flow process is both constant pressure and adiabatic. Assume air has constant specific heats evaluated at 300 K. Determine the air mass flow rate into the hair dryer, in kg/s.
Engineering
2 answers:
dezoksy [38]3 years ago
8 0

Answer:

0.0280Kg/s

Explanation:

Given:

W = 1500

V2 = 300

V1 = 0

Q = 0 ( adiabatic)

T1 = 300

T2 = 20 m/s = converting to degrees we have 353°c

Let's use the energy equation

Q - W = m_• *( Cp(dT) + 0.5*(V2^2 - V1^2) Q = 0

[/tex] m_• = W / (Cp(dT) + 0.5*V2^2) [/tex]

= 1500 / (1005(353 - 300) + 0.5*21^2)

= 1500 W / 53485.5 =0.0280 kg/s

maks197457 [2]3 years ago
8 0

Answer:

The rate of air mass flow is given as \dot{m}=0.02804 kg/s^2

Explanation:

The steady state energy equation is given as

\dot{Q}-\dot{W}=\dot{m}\left[(h_2-h_1)+\left(\dfrac{V_1^2-V_2^2}{2}\right)+g(z_1-z_2)\right]

Here,

Q' is heat interaction per unit time with the hair dryer

W' is work interaction per unit time with the system

m' is mass flow rate into the hair dryer

Since the process is adiabatic so the value of Q' is 0 .

The elevations at inlet and outlet are same(z_1=z_2) so z_1-z_2=0

So the equation becomes

0-\dot{W}=\dot{m}\left[(h_1-h_2)+\left(\dfrac{V_1^2-V_2^2}{2}\right)+g(0)\right]\\\dot{W}=-\dot{m}\left[(h_1-h_2)+\left(\dfrac{V_1^2-V_2^2}{2}\right)\right]\\\dot{W}=\dot{m}\left[(h_2-h_1)+\left(\dfrac{V_2^2-V_1^2}{2}\right)\right]\\\dot{W}=\dot{m}\left[C_p(T_2-T_1)+\left(\dfrac{V_2^2-V_1^2}{2}\right)\right]

Now the value of power is given as 1500 W so the value of W' is 1500 W

m' is to be calculated

T_2 is the temperature at the exit given as 80 C or 80+273=363K

T_1 is given as 300 K

V_1 is given as negligible so it is 0

V_2 is given as 21 m/s

C_p is given as 1.005 kJ/kgK

So the equation becomes

\dot{W}=\dot{m}\left[C_p(T_2-T_1)+\left(\dfrac{V_2^2-V_1^2}{2}\right)\right]\\1.5 kW=\dot{m}\left[1.005 kJ/kgK(363-300 )K+\left(\dfrac{21^2-0^2}{2}*(1/1000)\right)\right]\\1.5=\dot{m}(53.48)\\\dot{m}=\dfrac{1.5}{53.48}\\\dot{m}=0.02804 kg/s^2

So the rate of air mass flow is given as \dot{m}=0.02804 kg/s^2

You might be interested in
Question 64 (1 point)
Xelga [282]

Answer: c fine sand aggregate, portland cement,fine sand

Explanation:

7 0
3 years ago
Which of the following is NOT true concerning the color of minerals? A. Some minerals have a consistent color, but many have a r
mixer [17]

Answer:

Option D

A mineral’s color reflects the wavelengths of light that are absorbed by the mineral.

Explanation:

Color is one of the physical properties of minerals. Many minerals have a wide range of colors but there are some minerals with one consistent color and such minerals are referred as monochromatic minerals for example azurite. Normally, the streak color tends to be less variable than the color of the whole mineral and impurities or minor chemical components in a mineral react and often control the display color of resultant mineral. Option D is incorrect since mineral's color don't reflect wavelengths of light absorbed by such minerals.

5 0
3 years ago
Sarah needs to create an architectural drawing for a museum building with an inclined surface. Which presentation view will be t
prohojiy [21]

Answer: auxiliary

Explanation: got it right

7 0
2 years ago
A transmission line with an imperfect dielectric is connected to an ideal time-invariant voltage generator. The other end of the
kari74 [83]

Answer and Explanation:

O decreases linearly with the distance from the generator

4 0
3 years ago
Seawater containing 3.50 wt% salt passes through a series of 11 evaporators. Roughly equal quantities of water are vaporized in
statuscvo [17]

Answer: the mass flow rate of concentrated brine out of the process is 46,666.669 kg/hr

Explanation:

F, W and B are the fresh feed, brine and total water obtained

w = 2 x 10^4 L/h

we know that

F = W + B

we substitute

F = 2 x 10^4 + B

F = 20000 + B .................EQUA 1

solute

0.035F = 0.05B

B = 0.035F/0.05

B = 0.7F

now we substitute value of B in equation 1

F = 20000 + 0.7F

0.3F = 20000

F = 20000/0.3

F = 66666.67 kg/hr

B = 0.7F

B = 0.7 * F

B = 0.7 * 66666.67

B = 46,666.669 kg/hr

the mass flow rate of concentrated brine out of the process is 46,666.669 kg/hr

8 0
3 years ago
Other questions:
  • Water flows down a rectangular channel that is 1.2 m wide and 1 m deep. The flow rate is 0.95 m/s. Estimate the Froude number of
    15·1 answer
  • An empty metal can is heated to 908C and sealed. It is then placed in a room to cool to 208C. What is the pressure inside the ca
    11·1 answer
  • a valueable preserved biological specimen is weighed by suspeding it from a spring scale. it weighs 0.45 N when it is suspendedi
    11·1 answer
  • In Visual Basic/Visual Studio, characteristics of controls, such as the Name of the control, or the Text displayed on the contro
    10·1 answer
  • A steel rectangular tube has outside dimensions of 150 mm x 50 mm and a wall thickness of 4 mm. State the inside dimensions, the
    5·1 answer
  • Using phasors, the value of 37 sin 50t + 30 cos(50t – 45°) is _________ cos(50t+(_____°)). Please report your answer so the magn
    5·1 answer
  • List two possible reasons the engine oil could have a strong gasoline smell
    15·1 answer
  • What differentiates the master builder approach prior to the Renaissance from later approaches? Projects do not depend on indivi
    14·1 answer
  • For laminar flow of air over a flat plate that has a uniform surface temperature, the curve that most closely describes the vari
    15·1 answer
  • Conclude from the scenario below which type of documentation Holly should use, and explain why this would be the best choice
    15·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!