A hair dryer is basically a duct of constant diameter in which a few layers of electric resistors are placed. A small fan pulls the air in and forces it through the resistors where it is heated. If the density of air at the inlet is 1.20 kg/m^3 and 0.95kg/m^3 at the exit, determine the percent increase in the velocity of the air as it flows through the dryer.

Answers

Answer 1

Answer:

% increase = 26.32%

Explanation:

From conservation of mass, we can say that;

Mass flow rate at inlet = mass flow rate at exit.

Thus;

m'1 = m'2

Formula for mass flow rate is;

m' = ρV'

Where V' is volumetric flow rate = Av

Thus;

m' = ρAv

Where;

ρ is density

A is area

v is velocity

Therefore from m'1 = m'2, we can say that;

ρ1•A1•v1 = ρ2•A2•v2

Since the duct has a constant diameter, then A1 = A2

Thus, we now have;

ρ1•v1 = ρ2•v2

Making v2 the subject, we have;

v2 = ρ1•v1/ρ2

Now, since we want to find the percent increase in the velocity of the air as it flows through the dryer,we would use;

% increase = ((v2 - v1)/v1) × 100%

We have v2 = ρ1•v1/ρ2

Thus;

% increase = ((ρ1•v1/ρ2) - v1)/v1) × 100%

Factorizing v1 out, we have;

% increase = ((ρ1/ρ2) - 1)/1) × 100%

We are given;

ρ1 = 1.2 kg/m³

ρ2 = 0.95 kg/m³

Thus;

% increase = ((1.2/0.95) - 1)/1) × 100%

% increase = 26.32%


Related Questions

Air enters a control volume operating at steady state at 1.2 bar, 300K, and leaves at 12 bar, 440K, witha volumetric flow rate of 1.3 m3/min. The work input to the control volume is 240 kJ per kg of air flowing. Neglecting kinetic and potential energy effects, determine the heat transfer rate, in kW.

Answers

Answer:

Heat transfer = 2.617 Kw

Explanation:

Given:

T1 = 300 k

T2 = 440 k

h1 = 300.19 KJ/kg

h2 = 441.61 KJ/kg

Density = 1.225 kg/m²

Find:

Mass flow rate = 1.225 x [1.3/60]

Mass flow rate = 0.02654 kg/s

mh1 + mw = mh2 + Q

0.02654(300.19 + 240) = 0.02654(441.61) + Q

Q = 2.617 Kw

Heat transfer = 2.617 Kw

the pressure rise, across a pump can be expressed as where D is the impeller diameter, p, is the fluid density, w is the rotational speed, adn q is the flowrate. determine a suitable set of dimensionless parameters

Answers

Answer:

hello your question is incomplete below is the complete question

The pressure rise Δp across a pump can be expressed as Δp = f(D, p, w, Q) where D is the impeller diameter, p is the fluid density, w is the rotational speed, and Q is the flowrate. determine a suitable set of dimensionless parameters

answer : Δp / D^2pw^2 = Ф (Q / D^3w )

Explanation:

k ( number of variables ) = 5

r ( number of reference dimensions ) = 3

applying the pi theorem

hence the number of pi terms = k - r = 5 - 3 = 2

1. Consider a solid cube of dimensions 1ft x 1ft x 1ft (=0.305m x 0.305m x 0.305m). Its top surface is 10
ft (=3.05 m) below the surface of the water. The density of water is pf=1000 kg/m3.
Consider two cases:
a) The cube is made of cork (pB=160.2 kg/m3)
b) The cube is made of steel (pB=7849 kg/m3)
In what direction does the body tend to move?​

Answers

Answer:

  a) up

  b) down

Explanation:

When the cube is less dense than water, it will tend to float (move upward). When it is more dense, it will sink (move downward).

a) 160.2 kg/m^3 < 1000 kg/m^3. The cube will move up.

__

b) 7849 kg/m^3 > 1000 kg/m^3. The cube will move down.


A 550 kJ of heat quantity needed to increase water temperature from 32°C to 80°C. Calculate the mass
of the water when the specific heat capacity of water is 4200 J/kg °C.​

Answers

Answer:

  2.728 kg

Explanation:

The units help you keep the calculation straight.

  [tex]\dfrac{550\text{ kJ}}{(80^\circ\text{C}-32^\circ\text{C})(4.200\text{ kJ/kg\,$^\circ$C})}=\dfrac{550}{48\cdot4.2}\text{ kg}\approx\boxed{2.728\text{ kg}}[/tex]

Consider a single crystal of some hypothetical metal that has the FCC crystal structure and is oriented such that a tensile stress is applied along a [112] direction. If slip occurs on a (111) plane and in a [011] direction, and the crystal yields at a stress of 5.12 MPa, compute the critical resolved shear stress.

Answers

Answer:

imma leabe

Explanation:

leabe leave*

Consider the flow of mercury (a liquid metal) in a tube. How will the hydrodynamic and thermal entry lengths compare if the flow is laminar

Answers

Answer:

Explanation:

Considering the flow of mercury in a tube:

When it comes to laminar flow of mercury, the thermal entry length is quite smaller than the hydrodynamic entry length.

Also, the hydrodynamic and thermal entry lengths which is given as DLhRe05.0= for the case of laminar flow. It should be noted however, that Pr << 1 for liquid metals, and thus making the thermal entry length is smaller than the hydrodynamic entry length in laminar flow, like I'd stated in the previous paragraph

Sharon has just invented a new tractor that will plow and plant a new hybrid of corn at the same time. Which type of engineer is she?

Answers

Answer:

Agricultural engineer

1) What conditions must be satisfied to assure that a refutable hypothesis will be obtained just by examining the structure of the FOC? (Assume that SOCs are satisfied as well).

Answers

Answer:

The derivative of a function must be equal to zero ( 0 )  if this condition is not met then a hypothesis is refuted

Explanation:

The conditions that must be satisfied to assure that a refutable hypothesis will be obtained by examining the structure of the FOC  is

The derivative of a function must be equal to zero ( 0 )  if this condition is not met then a hypothesis is refuted

i.e. dy/dx w.r.t.x = 0   for FOC  to be refutable

Find the perpendicular distance from the point P(9,11,−8) ft to a plane defined by three points A(1,9,−4) ft, B(−4,−8,6) ft, and C(−1,−2,2) ft

Distance = ______ ft

Answers

Answer:

  0 ft

Explanation:

The equation of the plane can be found from the cross product AC×BC. That vector is ...

  N = (2, 11, -6) × (-3, -6, 4) = (8, 10, 21)

Then the equation of the plane is ...

  8x +10y +21z = 14 . . . . . 14 = N·A

Point P satisfies this equation, so is on the plane. The distance is 0 feet.

  8(9) +10(11) -8(21) = 72 +110 -168 = 14

Design a circuit that outputs a 1 when the bit pattern (101) has been applied to input, and 0 otherwise.

Answers

Answer:

  see the attachment

Explanation:

The circuit shown uses Nand and Nor gates to produce the desired logic. The input bits are numbered 0 to 2, right to left.

The logic is ...

  out = ((b2·b0)' + b1)'

  out = b2·b1'·b0

Liquid water at 300 kPa and 20°C is heated in a chamber by mixing it with superheated steam at 300 kPa and 300°C. Cold water enters the chamber at a rate of 2.6 kg/s. If the mixture leaves the mixing chamber at 60°C.

Required:
Determine the mass flow rate of the superheated steam required.

Answers

Answer:

0.154kg/s

Explanation:

From this question we have the following information:

P1 = 300kpa

T1 = 20⁰c

M1 = 2.6kg/s

For superheated system

P2 = 300kpa

T2 = 300⁰c

M2 = ??

T2 = 60⁰c

From saturated water table

h1 = 83.91kj/kg

h3 = 251.18kj/kg

From superheated water,

h2 = 3069.6kj/kg

The equation of energy balance

m1h1 + m2h2 = m3h3

When we input all the corresponding values:

We get

m2 = -434.902/-2818.42

m2 = 0.15430

m2 = 0.154kg/s

This is the mass flow rate of the superheated steam

Please check attachment for more detailed explanation.

thank you!

This question involves the concepts of energy balance and mass flow rate.

The mass flow rate of the superheated steam required is "0.15 kg/s".

Applying the energy balance in this situation, we get:

[tex]m_1h_1+m_2h_2=m_3h_3[/tex]

where,

m₁ = mass flow rate of liquid water at 300 KPa and 200°C = 2.6 kg/s

m₂ = mass flow rate of superheated at 300 KPa and 300°C = ?

h₁ = enthalpy of liquid water at 300 KPa and 200°C = 83.91 KJ/kg (from saturated steam table)

h₂ = enthalpy of superheated at 300 KPa and 300°C = 3069.6 KJ/kg (from superheated steam table)

h₃ = enthalpy of exiting fluid at 60°C = 251.18 KJ/kg (from saturated steam table)

m₃ = mass flow rate of exiting fluid = 2.6 kg/s + m₂

Therefore,

[tex](2.6\ kg/s)(83.91\ KJ/kg)+(m_2)(3069.6\ KJ/kg)=(2.6\ kg/s+m_2)(251.18\ KJ/kg)\\m_2(3069.6\ KJ/kg-251.18\ KJ/kg)=(2.6\ kg/s)(251.18\ KJ/kg-83.91\ KJ/kg)\\\\m_2=\frac{434.902\ KW}{2818.42\ KJ/kg}[/tex]

m₂ = 0.15 kg/s

Learn more about energy balance here:

https://brainly.com/question/9839609?referrer=searchResults

Match the use of the magnetic field to its respective description.​

Answers

oooExplanation:

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What test should be performed on abrasive wheels

Answers

Answer:

before wheel is put on it should be looked at for damage and a sound or ring test should be done to check for cracks, to test the wheel it should be tapped with a non metallic instrument (I looked it up)

The  test that should be performed on abrasive wheels is the ring test.

What is the purpose of the ring test on the  abrasive wheels?

The ring test can be regarded as one of the mechanical test that is used to know whether the wheel is cracked or damaged.

To carry out this test , the wheel will be arranged to be in the 45 degrees each side and it is then aligned to be at a specific diameter, this can be done by the expert in this field to know the state of that wheel.

Learn more about  ring test  on:

https://brainly.com/question/4621112

#SPJ9

Quadrilateral ABCD is a rectangle.
If m ZADB = 7k + 60 and mZCDB = -5k + 40, find mZCBD.

Answers

Hope this helps...........

List in order first three steps to square a board

Answers

Answer:

STEP1 Cut to Rough Length

STEP2 Cut to Rough Width

STEP 3 Face-Jointing

HOPE THAT HELPSSS!!!

Available for ceiling and wall installation, can be covered with a finish covering material, plastered, or mounted directly to the ceiling or wall. TERE SESELT BP
A. hydronic heating systems
B. evaporative systems
C. electric radiant heating
D. panels unit cooling systems

Answers

Answer:

Hydronic heating system

Explanation:

From the available options, Hydronic heating systems can be covered with a finishing covering material, plastered or can be mounted directly to the celing or wall.

This system heats water and then moves it through pipes that are sealed pipes to radiators all around a house.

This sealed system is useful for heating towel rails, floor slabs, and also swimming pools, whenever it is useful

Hydronic Heating water is heated through the use of super energy

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