ccb 2024 chapter 1 - introduction may 2013 elearning

7/28/2019 CCB 2024 Chapter 1 - Introduction May 2013 Elearning

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ChemicalEngineeringThermodynamics

CCB 2024Dr. Lukman Ismail (Block 05-03-35) & Dr. Lau Kok Keong


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Nama Mata Pelajaran /

Subject Name

Termodinamik Kejuruteraan Kimia / Chemical Engineering

Thermodynamics

Kod / Code CCB 2024

Status Mata Pelajaran /

Subject Status

Teras / Core

Peringkat / Level Sarjana Muda / Bachelor

Nilai Kredit / Credit Value 4

Prasyarat (jika ada) /

Prerequisite (if any)

Physical Chemistry

Penilaian / AssessmentQuiz / Test / Assignment 40%

Final Exam 60%


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Outcome-Based Education (OBE)


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1. Apply knowledge of mathematics, science and engineering fundamentals and an engineering

specialisation to the solution of complex chemical engineering problems.

2. Identify, formulate, research literature and analyse complex chemical engineering problems

reaching substantiated conclusions using principles of mathematics, natural sciences and

engineering sciences3. Design solutions for complex chemical engineering problems and design systems, components or

processes that meet specified needs with appropriate consideration for public health and safety,

cultural, societal, and environmental considerations.

4. Investigate complex chemical engineering problems using research based knowledge and

research methods including design of experiments, analysis and interpretation of data and

synthesis of information to provide valid conclusions.

5. Use modern engineering and IT tools to evaluate complex chemical engineering activities.

6. Apply reasoning informed by contextual knowledge to assess societal, health, safety, legal and

cultural issues and the consequent responsibilities relevant to professional engineering practice.

7. Understand the impact of professional engineering solutions in societal and environmental

contexts and demonstrate knowledge of and need for sustainable development.

8. Apply ethical principles and commit to professional ethics and responsibilities and norms of

chemical engineering practice

9. Communicate effectively on complex chemical engineering activities with the engineering

community and society.10. Function effectively as an individual, and as a member or leader in diverse teams and in multi-

disciplinary settings.

11. Recognise the need for, and have the preparation and ability to engage in independent and life-

long learning in the broadest context of technological change.

12. Demonstrate knowledge and understanding of engineering and management principles and apply

these to ones own work, as a member and leader in a team, to manage projects and in

multidisciplinary environments.

Chemical Engineering Programme Outcomes (PO)


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At the end of this course, students should be able to:

1. explain and apply the fundamental principles and laws

of thermodynamics.

2. apply the laws of thermodynamics to solve chemical

engineering problems such as fluid properties, phaseequilibria, chemical reaction equilibria and power

cycle.

3. perform different methods of solution to solve ideal/real

gas/liquid in pure component/mixtures.

4. relate the chemical thermodynamics principles with the

application in separation and reaction processes.

Course Learning Outcomes

The above course learn ing outcomes are mapped to the three highl ighted

programme outcomes i.e., PO1& 2


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References:Text book for the 1st part

Thermodynamics: An Engineering Approach(7 th edition)

Yunus A. Cengel & Michael A. Boles

Supplements:

1) Fundamentals of Engineering Thermodynamics

by Moran & Shapiro

2) Fundamentals of Thermodynamics

by Sonntag, Borgnakke & Van Wylen3) Engineering Thermodynamics

by J.B. Jones


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Coursework

Total = 40 %

20% - Dr. Lukman

20% - Dr. Lau

20% - Test 10%

- Quiz 2%

- Video assignment 8%

Final exam (60%): Must obtain 20% minimum

marks, otherwise fail for the course

Attendance : Must exceed 90%, below which the students canbe barred from the final exam.

Attendance of all international students will be recorded and

submitted to the Ministry of Education and will be forwarded to the

Ministry of Home Affairs.


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Course Outlines:

Chapter 1: Basics Concepts of Thermodynamics

Chapter 2: Properties of Pure SubstancesChapter 3: Energy Transfer by Heat, Work and

Mass

Chapter 4: The First Law of ThermodynamicsChapter 5: The Second Law of Thermodynamicsand Entropy


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CHAPTER 1

BASIC

CONCEPTS OF

THERMODYNAMICS


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What is Thermodynamics?

Early description: Convert heat into power

Current Definition:

The study of energy and energy transformations, includingpower generation, refrigeration and relationship among theproperties of matter.

Greek Words

Therme

(Heat)

Dynamis

(Power)


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1.1 What is Energy?

Ability to cause changes

Laws of Thermodynamics:

Zeroth Law = dealing with thermal equilibrium {if two systems arein thermal equilibrium with a third system, they are also in thermalequilibrium with each other}

First Law = deal with conservation of energy

{during an interaction, energy can change from one form toanother but the total amount of energy remains constant. E.g. a rockfalling off a cliff & in the diet industry}


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Second Law = energy has qualityas well as quantity,and actual processes occur in the direction of decreasingthe quality of energy.

heatHot Cold body, spontaneous

heatCold Hot body, requires work

Third Law = entropy of pure crystalline substance atabsolute zero temperature is zero


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Application Areas of Thermodynamics

House-hold utensils appliances:Air-cond, heater, refrigerator

humidifier, pressure cooker, water heater

computer & TV

Engines: Automotive, aircraft, rocket

Plant/ Factory

Refinery, power plants,nuclear power plant Powerplants

The

human

body

Air-condition

ingsystems

Airplanes

Carradiators

Refrigerationsystems


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1.2 Dimensions and Units

DimensionPrimary

Secondary

M - massL - length

T - temperature

t - time

n - mole

A - AmpereEg: Volume V

velocity v

energy E

UnitsSI - International System- Commonly applied

English System - also known as United States Customary

System (USCS)


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1.3 Closed and Open Systems

Thermodynamic system (system) - quantity of matter or a region in

space chosen for study.Surroundings - the mass or region outside the system

Boundary - the real or imaginary surface that separates the system from

its surrounding

- is the contact surface shared by both the system & surroundings

- has zero thickness & can either contain any mass nor occupy

volume in space.

- can be fixed or movable

Boundary

fixed

movable


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Types of system:

(a) isolated - no heat/ mass transfer across boundary

(b) closed(control mass) - only heat transferred(c) open system(control volume) - heat & mass

transferred

(b) (c)


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1.4 Energy

Forms of energy - thermal, mechanical, chemical, kinetic, potential,

electrical, magnetic & nuclearE = total energy i.e sum of all energy in a system

e = total energy = E (kJ/kg)

mass m

Forms of energy that make up the total energy of a system :

Energy form

macroscopic

microscopic

energy of a system as a wholewith respect to some outsidereference frames, e.g. KE, PE

- related to molecular structure of asystem and the degree of molecularactivity- independent of outside referenceframes


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Sum of all microscopic forms of energy = Internal Energy (U)

Macroscopic forms of energy

Therefore, E = U + KE + PE (kJ)

Kinetic energy (KE)

- result of motion relative to some

reference frameKE = mv2/2 (kJ)

where v = velocity of the system

relative to some fixed

reference frame (m/s)

m = mass of an object (kg)

Potential energy (PE)

- due to elevation in a gravitational

field

PE = mgh (kJ)

where g = gravitational acceleration,

9.81 m/s2

h = elevation of center of gravity of

a system relative to somearbitrarily plane (m)


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1.5 Internal Energy

Internal energy - sum of all microscopic forms of energy of asystem

related to - 1) molecular structure2) degree of molecular activity

Latent heat - Internal energy associated to with the phase of asystem

- phase -change process can occur without a change inthe chemical composition of a system

I. EKE

PE

molecular translation

molecular rotation

electron translation

molecular vibration

electron spin

nuclear spin

a.k.asensible energy

depend on thetemperature


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1.6 Properties of a System

Property - any characteristic of a system or any quantity thatdescribe a system

Some familiar properties are P, T, V and m. But can be extended toinclude less familiar ones such as viscosity, thermal conductivity,thermal expansion coefficient and etc

Density (mass per unit volume), (kg/m3) depends on T & P

Specific gravity or relative density (ratio of the density of asubstance to the density of some standard substance at a specifiedtemperature) e.g. for water,

Specific volume, (m3/kg)

V

m

OH

s

2

m

V

T P


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Specific properties - extensive properties per unit mass

E.g. specific volume (v = V/m) and specific total energy (e = E/m)

Properties

Intensive

Extensive

independent of the

size/extent of the system

dependent on the

size/extent of the system

T, P,

age,

colour

m

V

total E


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1.7 State & Equilibrium

State a set of properties that describe the condition of a

system at certain timeAt a given state, all the properties of a system have fixed values.If the value of one property changes, the state will change to adifferent one.

Equilibrium state steady state/ state of balance

& no change in time

Thermal equilibrium T is the same throughout the system

Mechanical equilibrium P is the same throughout the system

Phase equilibrium m of each phase unchanged

Chemical equilibrium chemical composition unchanged


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Thermal equilibrium

(uniform temperature)


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1.8 Processes & Cycle

Process any change that a system undergoes from one

equilibrium state to another

Path Series of states through which a systempasses during a process

need to specify the initial & final states of the process, as well asthe path it follows, and the interactions with the surroundings.


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1.9 Quasi-equilibrium/ Quasi-static

When a process proceeds in such a manner that the system remains

infinitesimally close to equilibrium state at all times.

Sufficiently slow process that allows the system to adjust to itself

internally so that properties in one part of the system do not change

any faster than those at other parts.

Slow compression

(quasi-equilibrium)

very fast compression

(non-quasi equilibrium)


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The prefix iso- is often used to designate a process for which aparticular property remains constant.

Isothermal Process a process when T remains constant

Isobaric P constant

Isochoric/ Isometric specific volume vremains constant

A system is said to have undergone a cycle if it returns to itsinitial state at the end of the process.

For a cycle, the initial & final states are identical

ProcessB

ProcessA

1

2P

V


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1.10 Pressure

P = = Unit = N/m2 or Pa

Gas or liquid Pressure

Solids Stress

Common units

1 bar = 105 Pa

1 atm = 101,325 Pa = 1.01325 bars

1 kgf/ cm2 = 0.9807 bar = 0.96788 atm

English unit Ibf/in2 or psi

Absolute pressure Actual pressure at at given position &

measured relative to absolute vacuumGage pressure Difference between absolute pressure & local

atmospheric pressure

Vacuum pressure Difference between atmospheric pressure &absolute pressure

Area

Force

A

F


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Absolute, gage & vacuum pressures are all +ve quantities &

related to each other by:

Pgage = Pabs - Patm (for pressure above Patm)

Pvac = Patm - Pabs (for pressure below Patm)

In thermo, absolute pressure is always used unless stated.


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Example 1-1

A vacuum gage connected to a chamber reads 5.8 psi at a

location where the atmospheric pressure is 14.5 psi. Determine the

absolute pressure in the chamber.

Using Pvac = Patm - Pabs, So, Pabs = 14.5 - 5.8 = 8.7 psi

Manometer

Small to moderate pressure difference are measured by a manometerand a differential fluid column of height h corresponds to a pressuredifference between the system and the surrounding of themanometer.

P g h kPa ( )


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Other Pressure Measurement Device

Bourdon Tube

Modern pressure sensors:

1) Pressure transducers

2) Piezoelectric material


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Example 1-2

A vacuum gage connected to a tank reads 30 kPa at a location

where the atmospheric pressure is 98 kPa. What is the absolute

pressure in the tank?Solution:

Pabs = Patm - Pgage= 98 kPa - 30 kPa

= 68 kPa

Example 1-3

A pressure gage connected to a valve stern of a truck tire reads 240kPa at a location where the atmospheric pressure is 100 kPa. What isthe absolute pressure in the tire, in kPa and in psia?

Solution:Pabs = Patm - Pgage= 100 kPa + 240 kPa

= 340 kPa


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The pressure in psia is

Pabs = 340 kPa = 49.3 psia

What is the gage pressure of the air in the tire, in psig?Pgage = Pabs - Patm

= 49.3 psia - 14.7 psia

= 34.6 psig

Example 1-4Both a gage and a manometer are attached to a gas tank to measureits pressure. If the pressure gage reads 80 kPa, determine thedistance between the two fluid levels of the manometer if the fluidsis mercury whose density is 13,600 kg/m3.

kPa

psia

3.101

7.14

hP

g

hkPa

kg

m

m

s

N mkPa

N

kg m s

m

80

13600 9 807

10

1

0 6

3 2

3 3

2.

/

/

.


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Temperature Measure of hotness and coldness

Transfer of heat from higher to lower temp. until both bodies attain

the same temp. At that point, heat transfer stops and the two bodieshave reached thermal equilibrium

requirement: equality of temperature

Zeroth Law of Thermodynamics:

Two bodies are in thermal equilibrium when they have reached thesame temperature. If two bodies are in thermal equilibrium with athird body, they are also in thermal equilibrium with each other.

Temperature scales: Celcius (C)

Fahrenheit (F)

Kelvin (K)

Rankine (R)


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Conversion:

T(K) = T(C) + 273.15

T(R) = T(F) + 459.67

T K = (T2C +273.15) - (T1C + 273.15)

= T2C - T1C= TC

T R = TF

T


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Temperature Scale Comparison

ccb 2024 chapter 1 - introduction may 2013 elearning

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