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Introduction and Basic Concepts of Chemical Engineering Thermodynamics

THERMODYNAMICS 1

Department of Chemical Engineering, Semarang State University

Dhoni Hartanto S.T., M.T., M.Sc.

Course title : Thermodynamics 1

Time slot : Monday, 11.00 – 13.00 am

Classroom/credit : E2-307/ 2 sks

Instructor : Dhoni Hartanto, S.T., M.T., M.Sc.

Office : GC-MS Laboratory, E-2 building, Faculty of engineering, UNNES

Telephone : +62821-4154-8851

E-mail : dhoni.hartanto@gmail.com

Office hours : Monday-Friday 07.00 am– 04.00 pm

Course books : Smith, J. M., Van Ness, H.C., Abbott, M. M. 2011. Introduction toChemical Engineering Thermodynamics, 6th ed., McGraw-HillCo., Singapore.

References books :

1. Poling, B. E., Prausnitz, J. M., O’Connell. 2001. The properties of gases and liquids fifth edition, McGraw-Hill, New York, USA.

2. Sandler, S. I. 1999, Chemical Chemical, Biochemical, and Engineering Thermodynamics, 5th ed., Joh Wiley and Sons, Inc., USA

3. Praustnitz, J. M., Lichtenthaler, R. N., and de Azevedo, E. G. 1999. Molecular Thermodynamics of Fluid-Phase Equilibria, 3rd ed., Prentice Hall PTR. USA.

Course Details

Course book : Smith, 2011

Course Details (cont.)

Ref. Book : Poling, 2001

Ref. Book : Sandler, 1999

Ref. Book : Praustnitz, 1999

Topics

1. Thermodynamics : Definition

2. Thermodynamics : Example

3. Dimensions and Units

4. Measures of Amount or Size

5. Force

6. Temperature

7. Pressure

8. Work

9. Energy

10. Heat

Definition

Thermodynamics: The science of energy

The name thermodynamics stems from the Greek words therme (heat)

and dynamis (power)

Thermodynamics is the study of energy conversion between heat andmechanical work, and subsequently the macroscopic variables such astemperature, volume, and pressure.

THERMO : HEAT and TEMPERATUREDYNAMICS : MOTION

Example

The production of chemicals, polymers, pharmaceuticals and otherbiological materials, and oil and gas processing, all involve chemical orbiochemical reaction that produce a mixture of reaction product.

(e.g : production of tert-butanol)

1. These must be separated from the mixture and purified to result in product of societal, commercial, or medicinal value.

2. These is the area where thermodynamics plays a central role in process eng.

3. Separation processes, e.g. distillation are designed based on information from thermodynamics such as vapor-liquid equilibrium data.

Example (cont.)

Vapor-Liquid

Equilibrium

(VLE) data

Example (cont.)

Extractive

Distillation Column

Pump

Evaporator

Steam in

Condense out

Feed

Preheater

Concentrated

Buffer Solution

Distillation method based on the addition

of an entrainer (extractive distillation)

(Hartanto et al, 2013)

Buffering-effect of TRIS on the VLE of the tert-butanol (1) +

water (2) system. x1' was calculated from buffer-free base :

(■), 0.05; (▲), 0.10; (●), 0.20; (___), calculated from the

NRTL model; (-∙∙-), smoothed results for the TRIS-free system

(Hartanto et al, 2013)

Dimensions and Units

- Dimension is recognize through our sensory perceptions and not

definable without the definition of arbitrary scales of measure,

divided into specific units of size.

The units have been set by international

agreement, and are

codified as the International System of Units (SI).

Dimensions and Units (cont.)

Any physical quantity can be characterized by dimensions.

The magnitudes assigned to the dimensions are called units.

Some basic dimensions such as mass m, length L, time t, and temperature T are selected as primary or fundamental dimensions, while others such as velocity V, energy E, and volume V are expressed in terms of the primary dimensions and are called secondary dimensions, or derived dimensions.

Metric SI system: A simple and logical system based on a decimal relationship between the various units.

English system: It has no apparent systematic numerical base, and various units in this system are related to each other rather arbitrarily.

Dimensions and Units in HYSYS v3.2

Dimensions and Units (cont.)

American Engineering Units (Field)

SI units

Dimensional Homogeneity

Dimensions and Units (cont.)

Unity Conversion RatiosAll nonprimary units (secondary units) can be formed by combinations of primary units. Force units, for example, can be expressed as

They can also be expressed more conveniently

as unity conversion ratios as

Unity conversion ratios are identically equal to 1 and are

unitless, and thus such ratios (or their inverses) can be

inserted conveniently into any calculation to properly

convert units.

Measurements of Amount and Size

•Three measures of amount or size are in common use:Mass, m ; Number of moles, n ; Total volume, Vt

• Mass, m divided by the molar mass M (molecular weight) to yield number of moles;

,M

mn Mnm

Total volume, divided by the mass or number of moles of the system to yield specific or molar volume.

• Specific volume:

• Molar Volume:

mVV t m

VV

t

or

nVV t n

VV

t

or

Measurements of Amount and Size (cont.)

Properties in HYSYS

Force

SI unit Metric engineeringsystem units

Newton (N) Kilogram force (kgf)

F = ma

mag

Fc

1

21

c

2

c

s f kg m kg .80665 9 g

ms 9.80665 x kg 1 x g

1 kgf 1

* Note : The kilogram force is equivalent to 9.80665 N

Temperature All temperature scales are based on some easily reproducible states such as the

freezing and boiling points of water: the ice point and the steam point. Ice point: A mixture of ice and water that is in equilibrium with air saturated with

vapor at 1 atm pressure (0°C or 32°F). Steam point: A mixture of liquid water and water vapor (with no air) in equilibrium

at 1 atm pressure (100°C or 212°F). Celsius scale: in SI unit system Fahrenheit scale: in English unit system Thermodynamic temperature scale: A temperature scale that is independent of the

properties of any substance. Kelvin scale (SI) Rankine scale (E) A temperature scale nearly identical to the Kelvin scale is the ideal-gas temperature

scale. The temperatures on this scale are measured using a constant-volume gas thermometer.

Temperature (cont.)

Pressure

Pressure: A normal force exerted by a fluid per unit area

ghA

gAh

A

mg

A

FP

A

mg

A

FP

Pressure (cont.)

Absolute pressure: The actual pressure at a given position. It is measured relative to absolute vacuum (i.e., absolute zero pressure).

Gage pressure: The difference between the absolute pressure and the local atmospheric pressure. Most pressure-measuring devices are calibrated to read zero in the atmosphere, and so they indicate gage pressure.

Vacuum pressures: Pressures below atmospheric pressure

Work

Work, W is performed whenever a force acts through a distance

t

t

V

V

t

t

t

PdVW

PdVdW

A

VPAddW

FdldW

2

1

Energy

1. Kinetic EnergyWhen a body of mass m dacted upon by a force F is displaced a distance dl during a

differential interval of time dt .

Acceleration a = du / dt, where u is the velocity of the body

Velocity u = dl / dt, the expression work becomes

dlmadW

dudt

dlmdl

dt

dumdW

2

22

1

2

2

2

1

2

2

2

1

2

1

222

22

muE

mumumuW

uumduumW

dumudW

k

u

u

Thank you