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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 : [email protected]
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.)
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
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.
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