Part1_ThermoArab3

7/27/2019 Part1_ThermoArab3

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1..........................................................................................................................1............................................................................81............................................................91......................................................................................10

2. ...............................................................................2..CCE AD LA.....................................................................112..E................................................................................................112..AE EIEEILIBI........................................112..DIEI AD I..................................................................122..DEI...................................................................142..EE.............................................................................................152..EEAEEH LA.......................................162..EEAE CALE..........................................162.........................................................................................192.................................................................................................192........................................................................20

3. ...............................................................................3...................................................................................................233..KIEIC AD EIAL EEGIE........................................233..IEAL EEG...........................................................................243..K AD E..........................................................................253........................................................................263............................................................................273...............................................................................303..HEA................................................................................................303..:........................................................................................313.............................................................................32

4. ..............................4...........................................................................................................364....................................................................................................364.................................................................42


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4.............................................................................424............................................................................444..................................................................464...........................................................48

5. ..................................5.............................................................................................................535..........................................................................535..................................................................................535..............................................................545...............................................555..

.........................................................59

5........................................................................................595.......................................................................................615.........................................................................................655....................................................................655.............................................................................68

6. ............................6...........................................................................................................756..CE F IEEIBILI......................................................756...............................................................................................766........................................................................................786.................................................................806.............................................................816.....................................................................................................816.............................................................................................................826..............................................................................................836...................................................................846...........................................................................86

7................................................................................................7..CLAI IEALI..................................................................897..E......................................................................................917...................................................................92


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7................................................................................................967..AL ( EAC)DIFFEEIAL......................................................987.....................................................................997.................................................................1007......................................................................................1047............................................................................106

8. ................................................................................8............................................................................................................1138..AI K AD IEEIBILI:.................................1138..AAILABILIEEG:...........................................................................1148...........................................................................1168...................................................................................117

9..............................................................................................................................................................................................................................: .............................................)(.............


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.

.

Thermodynamics 1 Basic concepts

Pure substance Ideal gases First law and

Second law of thermodynamics. EntropyExergy or Availability.

Thermodynamics 2 .

Power cycles Refrigeration cycles. .

Chemical thermodynamics Chemical equilibrium

Maxwell thermodynamic relations .

. .

.

. )

( .

) ( .

.

.

:


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. ) (

)Power point presentation( .

.

.

.

E-Learning

.

.

Entropy.

Clausius inequality . .

. .

Caratheodory . .

. . Statistical

thermodynamics. .

) ( .

.

.


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.

. .

. .

. .

. irreversible ) ( .

. . .

Principle of entropy increase :dSirrev > 0. .

. .

:dSirrev/dt > 0 . . WdW .

state property dW. )d d( .

. :dtW&. W&

:vF =W&

. dt . dtW& . ) W dtW&(

W. . QdQ dtQ&.

.

. .


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1.

1.. ) (Thermodynamics .

.

:Heat) ( Kinetic and Potential Energies (

Internal Energy Evaporation andcondensation Electric Energy)(.

Chemical Energy . .

Fuel combustion EnginesRefrigerators

Enthalpy) ( TurbinesPumpsCompressors BoilersCondensersCooling towers

Steam Power Plants Nuclear Power Plants. .

.

Environmental Impact New and Renewable Energy

Sources Energy Conservation . 1-1.

) ( : .

) .( .

) (Heat Transfer . Fluid Mechanics Theory of Machines

) (. .

) (. .


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: InternalCombustion Engines Power Plants Refrigeration and Air

Conditioning Hydraulic Machines .

1.. .

Macroscopic a continuum of mater Internal structure. ) (

.

1-1

Microscopic molecules . Global Properties )

( . ) Statistical

Thermodynamics( .

.


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.

1.. . )2(

)3(. )4(

. )5()6( )78( .

.


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2.

2.. . ) (

Concepts. Laws .

Pressure Temperature .

Equation of state. )Simulation or

Modeling) . ) ()

(. .

.

2..System .

Surroundings or Neighborhood Boundaries. .

. ) ( .

. . Closed System Control mass.

Open System Control volume. Isolated System .

2.. State .

.


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State Properties .

Internal state ) ( External state )

(. Extensive properties )

..(Intensive properties ) ...(

x. xx/2 .

.

. Specific Properties . Specific Volume

) ( . Electric charge density

. System in equilibrium.

Spontaneously .

) Mechanical

equilibrium( Thermal equilibrium(. Chemical equilibrium . ) (

.

2.. Dimension. Units

.

. . Basic Dimension .

. )S.I. Systme International(

. :length mass time electric current intensity temperature

quantity of matter luminous intensity)2-1(.

kilo Mole.


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12 kg C. Avogadro's number NA )(

Molecular weight .2-1

SI Base Units

QuantityUnit

Name

Unit

Symbol

Length meter m

Mass kilogram kg

Time second s

Electric current ampere A Si Supplementary Units

Thermodynamic temperature Kelvin K Quantity Name Symbol

Amount of matter mole mol Plane angle Radian Rad

Luminous intensity candela cd Solid angle steradian Sr

:1 mol of O2= 0.032 kg of O2

1 kmol of N2= 28. kg of N2

1 kmol of H2= 2. kg of H2

Number of moles nMass m :m= n. Derived Units)2-2(.

Coherence . Force F Newton N

ma:F = m. a

1 N = 1 kg. 1 m/ s2

) Pound forcelbf( :F = m. a / gc

gc .gc .

2-2

SI Unit

Quantity Name Symbol

Area square meter m

Volume cubic meter m

Speed, velocity meter per second m/s

Acceleration meter par second squared m/s

Density kilogram per cubic meter kg/m

Specific volume cubic meter per kilogram m /kg

Current density Ampere per square meter A/m


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Examples of Si Derived Units with Special Names

Quantity Name Symbol

Expression in

Terms of Other

Units

Expression in

Terms of Si

Base Units

Force Newton N m. kg/sPressure Pascal Pa N/m kg/(m.s )

Frequency Hertz Hz 1/s 1/s

Energy, work, heat Joule J N.m m . kg/s

Power Watt W J/s m . kg/s

Quantity of

electricity

Coulomb C A.s s. A

Electric potential Volt V W/A m . kg/(s .A)

Capacitance Farad F C/V s .

A2/(m

2.kg)

Electric resistance Ohm

V/A m .

kg/(s3.A2)

Conductance Siemens S A/V s .A /(m .kg)

Magnetic flux Weber Wb V.s m . kg/(s .A)

Magnetic flux density Tesla T Wb/m kg/(s . A)

Inductance Henry H Wb/A m .kg/(s .

A2)

Luminous flux lumen Im cd.sr

Illuminance lux lx cd.sr/m

2.. Density .

. V . m Density:= limV(m/V)

. V :

) .( .

Finite. 20C 25.

Mass Density Molal Density ) ( ) Molecular Weight :( = /

vSpecific Volume :v= 1 / Molal Specific Volume v:v = 1/

Specific Weight w :w= g / gc


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2.. Temperature T

. ) ( .

) .( ....

. .

) .(

) ( .

) ...( .

Thermal Equilibrium. .

:If A is in equilibrium with C; B is in equilibrium with C A is in equilibrium with B

Zeroth Law . .

. Thermometer

Thermometric Property.

2..

Conventional .

: Thermometric property

.

. .


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.t = a x + b

1948)2-3.( Ice point

(t 0100(tf)32212 tf= 32 + (9/5) *tc

.

:T = a x

2.

Defining fixed pointsTriple point of hydrogen

Normal boiling point of n

Triple point of oxygen

Normal boiling point of o

Triple point of water

Normal boiling point of w

Normal freezing point of t

Normal freezing point of

Normal freezing point of s

Normal freezing point of

17

.

. x :

a , fixed points

Celsiu 1Steam p. )Fahrenheit Scale

:tc= (5/9) *(tf 32)

)2.(

T x .

2.

2-3

T(K)13.81

on 27.102

54.361

xygen 90.188

273.16

ater 373.15

in 505.078

inc 692.73

ilver 1235.08

old 1337.58

2..1

t

b.

s Scale1 oint

2..2

.

2.

t(C)-259.34

-246.048

-218.789

-182.952

0.01

100.00

231.928

419.58

961.93

1064.43


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water triple point : ) .(

Kelvin scale TK :273.16 Rankinscale TR :491.69. 0.01

32.02 )2-4( :TK= tc+ 273.15TR= tf+ 459.67TK= (5/9) TR

Absolute temperature.

2-4

Fixed point Celsius Fahrenheit Kelvin Rankine

Absolute zero -273.15 -549.67 0.00 0.00

Ice point 0.00 32.00 273.15 491.67Triple point of water 0.0100 32.02 273.16 491.69

Steam point 100.00 212.00 373.15 671.67

2..3

2. . . R t:

R = a + b t + c t2

. a, b, c

2..4

)2.( Tc Th V :

V = S(Th Tc). Seebeck coefficient S

2..5

. Stefan Boltzmann

I T :I = a T4 Optical pyrometer

) Electric Filament(. ) ( .

) (

.


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. . . .

2.. Process

. . .

.

. Quasi Static

Process. Isochoric or Isometric orConstant Volume Isobaric or Constant Pressure

)Isothermal or Constant Temperature( )Adiabatic( .Cycle .

2.. Conservation of Mass

)

Relativistic phenomena.( ms Mass FlowRatem&:outins mmdtdm && =inm& outm& .

. dA v. dt

)2.( dAvdt. dt: vdt dA

: = areacross dAm v&

2. V . V :Am v=&


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5"

Hg30

si

A B

Steady State 1 2 :1v1A1= 2v2A2

2.. Solved Examples 2: BASIC CONCEPTSExample 2. 1 A mass of 10 slugs is to be accelerated to 180 in/s2. Find the force necessary

in poundal, lbf, N, Dyne and kgf.

Answer:

From Newton's Second Law we get F: F = ma

/ g

c

Where gc is a constant that depends on the units used (see the table below). The

elementary units relations needed are:

1 ft = 12 in, 1 in = 0.0254 m, 1 m = 100 cm

1 slug = 32.174 lbm, 1 lbm = 0.4535 kg, 1 kg = 1000 g.

mass

unit

accel.

unit

force

unit gc m a F

lbm ft/s Poundal 1.0 321.74 15.00 4826.10

lbm ft/s lbf 32.174 321.74 15.00 150.00

slug ft/s lbf 1.0 10.00 15.00 150.00

kg m/s N 1.0 145.91 4.572 667.10

g cm/s Dyne 1.0 145910 457.2 66.71 10

kg m/s kgf 9.81 145.91 4.572 68.03

Note that: 1 lbf = 32.174 poundal = 0.4535 kgf.

1 kgf = 9.81 N, 1 N = 105Dyne.

Example 2. 2

A mass of 50 lbm is placed at an altitude where the acceleration of gravity is30 ft/s2. Find its weight in 1bf, N.

Answer:

Applying Newton's second law: F =ma

/ g

c

Weight w= 50 lbm * 30 ft/s2/ 32.174 = 46.62 lbf

NB: The weight of 50 lbm is not always 50 lbf!

To get the weight in N use: F = m a

Weight w= (50*0.4535 kg) * (30*0.3048 m/s2) = 207.34 N

Example 2. 3 If the atmospheric pressure is 1 atm, what arethe gage and absolute pressures of gases A and B in bar if

manometer reading was 5" mercury and that of the pressuregauge is 30 psi?

Answer:

PB gage=g h= 13600*9.81* (5*0.0254 m)* 10-5

= 0.169 bar

PB abs= PB gage+ 1 atm= 0.169 +1.013 = 1.182 bar

The Bourdon gage reading indicates the difference between the gas pressure to which it is

connected and the gas pressure in which the gage is placed, i.e.:PA gage= PB gage+ 30 psi = 0.169+30/14.504=2.237 bar

PA abs= PB abs+ 30 psi = 1.182+30/14.504 = 3.25 bar

Or = PA gage+ 1 atm = 2.237 + 1.013 = 3.25 bar


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Example 2. 4 It is required to construct a liquid-in-glass thermometer of Celsiustemperatures in the range -25C to 100C. The following table gives the specific volume

(in cm3/g) of three different fluids at different temperatures as indicated by an ideal gas

thermometer. Which of the three fluids is more suitable?

Answer:

For the liquid-in-glass thermometer we can assume that the reading t*

follows the relation:t*= a x + b

Wherexis the specific volume of the fluid, the constants a, bare determined such that

the reading is exact at 0C and 100C, then:

t*= 100* (x-x0) / (x100-x0)

Wherex0andx100are specific volumes at 0C and 100C respectively, Applying this

relation we get t*for all three fluids as indicated in the table:

water isopropyl alcohol Mercury

tC x t* x t

* x t

*

-25 - - 1.2167 -18.8 0.073220 -25.0

0 1.0002 0.0 1.2475 0.0 0.073556 0.0

25 1.0029 6.2 1.2800 19.8 0.073890 24.9

50 1.0121 27.5 1.3170 42.4 0.074225 49.9

75 1.0259 59.4 1.3604 68.8 0.074561 74.9

100 1.0135 100.0 1.4116 100.0 0.074898 100.0

Water is clearly the worst of the three liquids; besides yielding very poor accuracy, it

freezes at 0C. Isopropyl alcohol, although better than water, is also unacceptable because

its specific volume dependence on temperature is not quite linear in this range. Mercury is

best, because its specific volume varies linearly with temperature between 0 and 100oC.

Example 2. 5

Air enters a 5 cm diameter heating tube at a velocity of 1 m/s and a density of1.2 kg/m3. Because of heating air leaves the tube at a density of 0.8 kg/m

3, what is the

mass flow rate of air and the exit velocity?

Answer:

Assuming that this is a steady flow process,

=1v1A1= 1.2 *1.0* *(0.05)2/4 =2.036*10-3kg/s

v2= /2A2= (2.036*10

-3)/(0.8**(0.05)2/4) = 1.5 m/s

Example 2. 6 A thermometer is being designed such as to use a thermometric propertycalledp, which is assumed to have the following relation with the absolute temperature T:

T= a ln(p/p0) + b, wherep0is a known property value at a reference condition (assumep0= 2) and both aand bare adjustable parameters. The thermometer has been calibrated by

subjecting it to two temperatures belonging to the international set of standard fixed points:

point 1 is the freezinc point of tin (231.928oC), point 2 is the freezing point of zinc

(419.527oC). Thermometer readings were respectivelyp1= 3,p2= 5. Find appropriate

values for parameters aand b.

Answer:

Applying the logarithmic relation at both fixed points: Ti= a ln(pi/p0) + b, where i= 1 or

2, we get two equations in the unknowns aand b. Note that Tis the absolute temperature,

which is equal to the Celsius temperature plus 273.15. Hence:

231.928 + 273.15 = a ln(3/2) + b (1)

419.527 + 273.15 = a ln(5/2) + b (2)


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By solving above equations we get a= 367.247; b= 356.172.

Example 2. 7 A barometer is used in an airplane to measure its altitude. At ground level,barometer reading is 758 mm Hg. At a certain height, the same barometer reads 510 mm

Hg. What is the airplane height, assuming average air density is 1.1 kg/m3?

Answer:Barometer reading indicates a pressure difference of:

Pbarometer = (758 - 510)/1000 * 13 600 * 9.81 = 33 872 PaAtmospheric pressure difference between the unknown heightHand ground:

Patmospheric =H* 1.1 * 9.81 = Pbarometer = 33 872 PaHence H = 3 066.2 m.

Example 2. 8 In a refrigerator, pressures at evaporator inlet (which lies within the freezingcompartment) as well as at compressor outlet (which is also at inlet of the serpentine lying

behind the refrigerator) were measured giving respectively 120 mm Hg vacuum and 25 psi.

What is the pressure difference in kPa?

Answer:Since evaporator pressure is vacuum, i.e. negative compared to atmospheric pressure,

then pressure difference is:

P= 25 / 14.504 * 105+ (120/1000 * 13 600 *9.81) Pa= 172 370 + 16 010 Pa = 188.38 kPa.


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3.

3.. Energy . .

. .

) ( .

. reference level (Datum) .

. ) ( )

( .

3.. Kinetic Energy Potential Energy

Newton. Conservative Force Field .

. ) .(

Earth Gravitational Field. mdz d (PE) :

d (PE)= m g dz

1 2 : ( )122

112zzmgmgdzPEPEPE ===

z1 z :PE = m g z

.

(KE) m a:=2

1dxmaKEdx

. v Referencesystem of coordinates. .

. :


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KE = m (dv/dt) dx = m vdv= m v2

Rotational Kinetic Energy KEr:KEr= I2I Moment of Inertia Angular Velocity.

3.. Internal Energy

. .

. . . N m. :M=Nm. i

vi. . :NN iavg = 1 vv

. . :

vi* = vi vavg. :

( ) ( ) ( ) ( ) ++=+==N

avg

N

avg*i

N *i

N

avg*i

N

i mmmmmKE 1

2

11

2

1

2

1

22222 vvvvvvv

.

:( ) ( ) ( ) bodyavgavgN

avg KEMmNm ===22

1

2222 vvv.

:( ) ( ) 011

=== avgavgN

avgi

N *

i N vvvvv.

KEmolecules . . .

.

.

. .

. . .

. .

.

) (


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.

. .

.( . W&Power

Fsys

msysW vF =&

=== msys dtdtWW vF&

nposi

)( :( )= rnvm

25

) (

. .

.

) .

Scalar Product

:

msys dxF (

ion vector r

)3..(nr |r| sin . vm

3.

.

3.. Work .

.

vm.

xm)

nr


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( ) == TW sys rnF&

(F =sys

T. :

=== TdtTdtWW &

Space Distribution .

Earth Gra

Elect .

z

z(.

.

3..

0>

W

. .

. )3.:(

26

:

TorqueT :)r

vitational Force

El ic Field Magnetic Field

m

:=2

112 mgdzW

:

) ( Fext D:Fext= k xk) stifness(

Fsys= Fext = kx.

0>

W0

Part1_ThermoArab3

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