8/12/2019 01 Chapter 01 (Compiled)
1/34
CHAPTER 1
Mohd Asmadi Bin Mohammed Yussuf
Faculty of Chemical Engineering
Universiti Teknologi Malaysia, 81310 UTM
Johor, Johor Bahru, Malaysia
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Introduction to Chemical
Engineering Thermodynamics
N02 2-6, 11.00 1.00P.M Feb 10, 2013 (Mon)
8/12/2019 01 Chapter 01 (Compiled)
2/34
Week Topic Topic Outcomes
1 Introduction to Chemical
Engineering Thermodynamics
Overview of thermodynamic
application in chemical
industry
Application of thermodynamic
properties and equations inchemical process
It is expected that students are
able to:
Describe the importance of
chemical engineering
thermodynamics in chemical
engineering profession.
Apply the thermodynamicsproperties in the chemical process
simulators.
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Topic Outcomes
8/12/2019 01 Chapter 01 (Compiled)
3/34
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Scope of Lecture
Overview of thermodynamic appl icat ion
in chem ical indus try
Appl icat ion of thermodynam ic propert ies
and equat ions in chem ical process
8/12/2019 01 Chapter 01 (Compiled)
4/34
Thermodynamic Applications
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
8/12/2019 01 Chapter 01 (Compiled)
5/34
Definition
The study of the effects of work, heat and energy on thesystem).
Only concerned with large scale observations.
Ref: NASA . Available from: http://www.grc.nasa.gov/WWW/k-12/airplane/thermo.html. (Accessed 8 Feb, 2013).
0thLaw:
Thermodynamic
equilibrium, temperature
1st Law:
Work, heat, energy
2ndLaw:
Entropy
3rdLaw:
As the T of a substance
approaches absolute zero
itsentropy approaches zero
8/12/2019 01 Chapter 01 (Compiled)
6/34
Applications of Thermodynamics
Types of process applications of thermodynamics, namely:
Ref: Edmister W C (1945) Applications of Thermodynamics to the Process Industries. Journal of Chemical Education. pp13 - 19
Combustion
Heat balances
Power
Phase equilibrium
Chemical reaction equilibrium
8/12/2019 01 Chapter 01 (Compiled)
7/34
Chemical Engineer & Thermodynamics
Why is thermodynamics useful to chemical engineers?
Heat transfer
Mass transfer
Separation process
Chemical reactions
Ref: Girard-Lauriault P-L . Chemical Engineering Thermodynamics
CHEE220. (Accessed 8 Feb, 2013); Selis . KMU 220 -
Chemical Engineering Thermodynamics (Accessed 8 Feb, 2013)
Calculation of heat and work requirements for physical and
chemical processes.
Transfer of chemical
species between phases
Determination of
equilibrium conditions
Physical processes
(e.g. distillation)
8/12/2019 01 Chapter 01 (Compiled)
8/34
Chem. Engineer & Thermo. (Cont.)
Thermodynamics permits
to determine how far
processes will proceed.
Chemical kinetics
helps evaluate how
fast.
The 2 concepts are at the base of many of the
considerations of Chemical Engineers.
Ref: Girard-Lauriault P-L . Chemical Engineering Thermodynamics
CHEE220. (Accessed 8 Feb, 2013); Selis . KMU 220 -
Chemical Engineering Thermodynamics (Accessed 8 Feb, 2013)
Deals with driving force
Does not deal with RATEs of
physical or chemical phenomena.
8/12/2019 01 Chapter 01 (Compiled)
9/34
Examples
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
8/12/2019 01 Chapter 01 (Compiled)
10/34Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Manufacture of Ethylene Glycol
Desired reactionH2C CH2 1/2O2
CatalystH2C CH2
O
+
H = 24.7 kcal/gmole
Need to be heated to 250 C before enter the reactor
To design the preheater
MUST KNOW HOW MUCH HEAT IS TRANSFERRED
CATALYTIC OXIDATION REACTIONMost effective when carried out at T 250 C
8/12/2019 01 Chapter 01 (Compiled)
11/34
T
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Undesired Reaction
H2C CH2 3O2+ 2CO2 + 2H2O
H = 320 kcal/gmole
Combustion reaction
Tend to raise the temperature
Heat is removed from reactor
T does not rise much above 250 C
To design the reactor
REQUIRES KNOWLEDGE OF THE RATE OF HEAT TRANSFER
8/12/2019 01 Chapter 01 (Compiled)
12/34Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Hydrolysis Reaction
H2C CH2
O + H2O HOCH2CH2OH
Recovered by distillation,vaporization & condensation
Heat evolved because of
Phase change
Dissolution process
Hydration reaction between the
dissolved ethylene oxide and H2O
8/12/2019 01 Chapter 01 (Compiled)
13/34
CSTRs with Heat Exchanger
Ref: Fogler H S (1999). Chapter 8: Elements of Chemical Reaction Engineering, 3rd Ed. Prentice Hall. Pp 426 477; CSTR:
Continuous stirred-tank reactor.
Continuous-flowreactors
outoutinin EFEFWQdt
Ed
0HFHFWQ i
n
1i
ii0
n
1i
i0s
At steady state,
CSTR with heat exchange
n
1i
i0piiRpR
o
RX
A0
a T-TCTTC)( THXF
TTUA ~
RPRRX
i0pii
A0
a
EBTTC)( TH
TTCF
TTUA
X
~
8/12/2019 01 Chapter 01 (Compiled)
14/34
Determination of X & T
5. Energy Balance (Calculate XEB)
6. Calculate XMB
Elementary irreversible liquid phase reaction A B
Non-adiabatic
RX
0PAA0aEB
H
)T( TC) /FTUA( TX
~
A0
A0
0MB F
VC
V
;.k1
.k
X
E/RTAek
7. Plot X vs. T
X
T
XEB
XMB
Ref: Fogler H S (1999). Chapter 8: Elements of Chemical Reaction Engineering, 3rdEd. Prentice Hall. Pp 426 477; X: Conversion,
T: Temperature; EB: Energy balance; MB: Mole balance.
Algorithm
1. Design equation
2. Rate law
3. Stoichiometry
4. Combining
8/12/2019 01 Chapter 01 (Compiled)
15/34
Properties & Equations
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
8/12/2019 01 Chapter 01 (Compiled)
16/34Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Thermodynamic Properties
The thermodynamic properties required for the manyfluids handled in the process industries include:
Densities
Vapor pressures
Critical state
Fugacities
Entropies
Enthalpies
Free energies
Some of these propertiesexperimentally determined Others are computedfrom basicexperimental data
thermodynamicequations.
8/12/2019 01 Chapter 01 (Compiled)
17/34Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Some Basic Relations in Thermodynamics
First law:
Second law:
Phase equilibrium relations:
Chemical reaction equilibrium:
genEflowEWQEt
genSflowST
QSt
iii fff
GRTlnK
iv
0
i
i
f
f
K
8/12/2019 01 Chapter 01 (Compiled)
18/34Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Dimensions & Units
Dimension SI Unit English Unit
Time second, s
Distance meter, m
foot, ft
(1 ft = 0.3048 m)
(1 m = 3.28084 ft)
Mass kilogram, kg
pound mass, Ibm
(1 Ibm= 0.4536 kg)
(1 kg = 2.2046 Ibm
Temperature Kelvin, k Rankine, R
T(R) = 1.8T(K)
Amount of substance gram mole, g molepound mole, Ib mol
(1 Ib mol = 453.59 g mol)
Note: Appendix A : Table A.1, Conversion factors
f f S
8/12/2019 01 Chapter 01 (Compiled)
19/34Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Prefixes for SI Units
Multiple Prefix Symbol Multiple Prefix Symbol
1015 femto f 102 hecto h
1012 pico p 102 kilo k
109 nano n 106 mega M
106 micro 109 giga G
103
milli m 1012
tera T
102 centi c 1015 peta P
Note: Appendix A : Table A.1, Conversion factors
M f A & Si
8/12/2019 01 Chapter 01 (Compiled)
20/34Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Measures of Amount & Size
3 basic measures
Mass, m(kg)
Number f moles, n(mol)
Total volume, Vt(m3)v
4 derivatives Specific volume,
Molar volume,
Specific density,
Molar density,
/kgmm
VV 3
t
/molmn
VV 3
t
3t
kg/mV
1
V
m
3t
mol/m
V
1
V
n
F (N t 2 d L )
8/12/2019 01 Chapter 01 (Compiled)
21/34Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Force(Newton 2ndLaw)
SI units:
English units:
maF
mag1Fc
Force(N = kg ms-2), defined as that force
which accelerates 1 kg mass 1.0 ms
-2
Mass(kg)
Acceleration(ms-2), 1 ms-2= 3.20808 (ft)(s)-2
The acceleration of gravity a = g = 9.81ms-2
Force (Ibf), 1 Ibf represents the force that
accelerates 1 Ibm at a = 32.1740 (ft)(s-2)
Mass(Ibm)
Acceleration(ft)(s)-232.1740 (Ibm)(ft)(Ibf)-1(s)-2
T t
8/12/2019 01 Chapter 01 (Compiled)
22/34
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Temperature
Temperature scale
The Celsius Scale : 0C & 100C correspond to the ice point (freezing
point) & the steam point (boiling point) of pure water
at standard atmospheric pressure.
The Fahrenheit scale : T (F) = 1.8T (C) + 32 or T (C) = [T (F)32]5/9
The Kelvin scale
(absolute T)
: T (K) = T (C) + 273.15
The Rankine scale : T (R) = 1.8 T (K)
T (R) = T (F) + 459.67
R l ti hi A T S l
8/12/2019 01 Chapter 01 (Compiled)
23/34
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Relationship Among T Scales
Celsius FahrenheitKelvin RankineSteam point
Ice point
Absolute zero
P
8/12/2019 01 Chapter 01 (Compiled)
24/34
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Pressure
Defined as the normal force exerted by a fluid on a
surface per unit area of the surface.
SI units : N/m2= Pascal (Pa)
English units : (lbf)/(in)2= pound force per square inch (psi).
1 psi = 6894.8 Pa
1 atm = 101325 Pa
1 atm = 14.7 psi
M t M th d
8/12/2019 01 Chapter 01 (Compiled)
25/34
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Measurement MethodDead-Weight Gauge Manometer
To pressuresource
h
Weight
PanPiston
Cylinder
Oil
To pressure
source
A
mg
A
FP
gh
A
gAh
A
mg
A
FP
m-the mass of the piston, pan and weights;
g- the local acceleration of gravity;
A- the cross-sectional area of the piston.
h- the relative height of the fluid;
- the fluid density;
g- the local acceleration of gravity.
P (C t )
8/12/2019 01 Chapter 01 (Compiled)
26/34
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Pressure (Cont.)
Gauge Pressure vs. Absolute Pressure
Different SI units for Pressure
Readings from most pressure gauges and the manometers correspondto gauge pressures which are the difference between the pressure of
interest and the pressure of the surrounding atmosphere.
P (absolute) = P (gauge) + P (barometric)
1 kPa = 103Pa
1 MPa = 106Pa
1 torr = 1 mm Hg = 133.32 Pa
1 atm = 101325 Pa
= 101.325 kPa = 0.101325 MPa
= 760 mm Hg = 760 torr
= 14.7 psi
1 bar = 105Pa = 0.986923 atm
W k
8/12/2019 01 Chapter 01 (Compiled)
27/34
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Work
Push-Pull Work
dlFdW
SI units : Joule (J), 1 J = 1 N m = 1 Pa. m3
English units : (Ibf)(ft), 1 (Ibf)(ft) = (4.4482 N)(0.3048) =1.3558 J
2
1
l
lFdlW
Work done by the force Fover the distance of (l2l1)
Sign of the work:
+ve when the displacement d l is in the same direction as the
applied force.
-ve when they are in opposite directions.
W k (C t )
8/12/2019 01 Chapter 01 (Compiled)
28/34
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Work (Cont.)
PV Work
tt
pdVA
VdPAdlFdW
2
1
V
V
tPdVW
Sign of the work:
+ve for compression
-ve for expansion.
C l l ti f PV W k
8/12/2019 01 Chapter 01 (Compiled)
29/34
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Calculation of PV Work
Graphical method
2
1
V
V
tPdVWRelationshipbetweenP and V
AreaW
E
8/12/2019 01 Chapter 01 (Compiled)
30/34
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Energy
Energy is something that a body can store, and
which it can receive or give away as workor heat.
Thus, energy, workand heatare closely related.
Work and heat are energy in transit, and are
never regarded as residing in a body.
Energy, work and heat have the same units:
Joule (SI)or lb ft (English)
8/12/2019 01 Chapter 01 (Compiled)
31/34
P t ti l E (E )
8/12/2019 01 Chapter 01 (Compiled)
32/34
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Potential Energy (EP)
Consider a body of mass m, acted upon by a force F =
mg, is raised from position z = z1to z = z2.
The total work done by theF is
p
z
z
z
z
E
mgzmgzmgzdlmgFdlW
12
2
1
2
1
SI system : EPmgz Units of Joule or N.m or kgm2s-2English system : Epmgz/gc Units of (Ibf)(ft),
where gc= 32.1740 (Ibm)(ft)(Ibf)-1(s)-2
Energ Conser ation
8/12/2019 01 Chapter 01 (Compiled)
33/34
Chemical Reaction Engineeri ng Group, Universiti Teknologi Malaysia
Energy ConservationConsider a body of mass m, falls freely from position z
= z1to z = z2, where the body gains in velocity u1u2.
2121
2
1
2
2
22
mgzmgzzzmgFlWmumu
EK
In this process, the body gains in kinetic energy is
the work done by the force of gravity, i.e.,
While in this process, the change in the bodys
potential energy is EP= (mgz) = (mgz2mgz1)
Thus, EK+ E
P= (mgz
1mg
2) + (mgz
2mgz
1)
Therefore, for purely mechanical processes without
friction, the energy conserves, i.e.,
0 KK EE 22
2
1
2
1
22mgz
mumgz
muor
Heat
8/12/2019 01 Chapter 01 (Compiled)
34/34
HeatHeat (Q) always transfers from a high temp. body to a lower temp. one.
The rate of heat transfer ( ) is proportional to the temp. difference T
Like work, heat exists only as energy in transitfrom one body to another
or between a system and its surroundings.
When energy in the form of heat is added to a system, this part of
energy is stored NOT as heat, but as kinetic and potential energy of
atoms/molecules in the system.
Q
Units of heat
SI system : Joule (J)Calorie (Cal), 1 Cal = 4.184 J
British system : (Ibf)(ft), 1 (Ibf)(ft) = 1.3558 J
British thermal Unit (Btu), 1 (Btu) = 1055.04 J