Product Design
Property Estimation
Chapter 3
Article on Phys. Property Estimation
CHEN 4253
Terry A. Ring
University of Utah
Types of Properties
• Thermodynamic Properties
• Transport Proprieties
• Kinetic Properties
Vapor Pressure of Mixture
• VOC – Volatile organic content
• Flash Calc with Process Simulator
• Hand Calc.
– Equation of State
– Activity Coefficient Equation
• Aspen/ProMax
– Pick Thermo Package
• Several are available
– Polar liquids vs non-polar
– Aqueous vs non-aqueous
– High P vs low P
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Input Components
Set up Flash unit with feed streams
Set Feed Stream composition
Run Calc
– Vapor
– Liquid
– Solid
Design Methods
• Physical Properties
– Group Contributions
– Thermo package in Process Simulator
• Process Simulation of Refrigeration cycle
– Condenser
– Vaporizer
– Pump
– Valve to flash liquid to vapor
Refrigerant Design
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Large negative Joule-Thompson Coefficient
Large Enthalpy of Vaporization
High Liquid Heat Capacity
Low Pressure -Tboil below RT
– Vapor Pressure > 1.4 Bar to assure no air leaks
• High Pressure – Compressor/Condensor
– Vapor Pressure < 14 Bar to keep compression ratio
less than 10
Solubility Parameter Prediction
• Solubility Parameter
– Solubility of liquid in liquid
– Solubility of solid in liquid
– Solubility of polymer in liquid
• Group Contributions
– Three parameters
• Dispersive
• Polar
• Hydrogen Bonding
Flory-Huggins solution theory
• The result obtained by Flory[1] and
Huggins[2] is
• The right-hand side is a function of the number of moles n1 and
volume fraction φ1 of solvent (component 1 or a), the number of
moles n2 and volume fraction φ2 of polymer (component 2 or b),
with the introduction of a parameter chi, χ, to take account of the
energy of interdispersing polymer and solvent molecules.
• Molar volume of polymer segment
• δ are Hildebrand solubility parameters, δ=√((ΔHvap-RT)/Vmolar)
• δ=√(δd 2 + δp 2 + δh2), linkage to Hansen Solubility parameters
Hansen Solubility Parameter
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Hansen Solubility Parameters were developed by Charles Hansen as a way of predicting if one
material will dissolve in another and form a solution [1]. They are based on the idea that like
dissolves like where one molecule is defined as being 'like' another if it bonds to itself in a similar
way.
Specifically, each molecule is given three Hansen parameters, each generally measured in :
The energy from dispersion bonds between molecules
The energy from polar bonds between molecules
The energy from hydrogen bonds between molecules
These three parameters can be treated as co-ordinates for a point in three dimensions also known
as the Hansen space. The nearer two molecules are in this three dimensional space, the more
likely they are to dissolve into each other. To determine if the parameters of two molecules
(usually a solvent and a polymer) are within range a value called interaction radius (R0) is given to
the substance being dissolved. This value determines the radius of the sphere in Hansen space
and it's center is the three Hansen parameters. To calculate the distance (Ra) between Hansen
parameters in Hansen space the following formula is used:
Combining this with the interaction radius gives the relative energy difference (RED) of the
system:
RED < 1 the molecules are alike and will dissolve
RED = 1 the system will partially dissolve
RED > 1 the system will not dissolve
See Articles Solvents_Data.pdf
Group Contribution Methods
• Group (bond) Contribution
Methods
– ni=number of groups of type
i in polymer repeat unit or
molecule
– N= number of group types
– Ai=group contribution to
property p{n}
– Mwi= Molecular weight of
group I, sometimes another
group contribution property
– d=exponent for property


  Ai ni 

p{n}   Ni 1
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  Mwi ni 
 i 1

N
d
Group Contribution Methods
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Polymer Glass Transition Temp.
Polymer Molar Volume
Polymer Density
Polymer Water Absorption
– P. 66 of your book
Liquid Surface Tension/Wetting
Group Contribution Method
• Contact Angle – Young’s Equation
• cos Θ = (γSV- γSL)/ γLV
• Wetting when Θ => 0
• Predicting Liquid surface tension
• γLV=[ρLMw-1 Σ(NiPi)]4
• Pi=Parachor Value of group
– Surface tension in [dyne/cm]
– Density [gm/cm^3]
– Mw [gm/mole]
• Liquid Mixtures surface tension based upon mole
fraction, Xi
• γLV= Σ γLV_iXi
Parachor Values
CH2=CH O CH3
Groups
C
3
H to C
6
O to ether
1
Double Bond
1
Pi
4.8
17.1
20
23.2
γLV=[ρLMw-1 Σ(NiPi)]4
Tables from Ring, Fundamentals of Ceramic Powder
Processing, Academci Press 1999.
Select Surfactants for Dispersion
• Lower Surface tension of a liquid
– Detergency
• Hydrophilic-lipophilic Balance-HLB
– HLB = 7+ ΣHi – ΣLi
• Stabilized Suspension
– HLBsurfactant= HLBparticle
Tables from Ring, Fundamentals of Ceramic Powder Processing, Academic Press 1999.
Group Contributions - HLB
TiO2
Tables from Ring, Fundamentals of Ceramic Powder Processing, Academic Press 1999.
Drago E and C
• Used to predict the Heat of mixing, ΔHAB
– Acid (A) – Base (B) Interactions
– Good for non-polar solvents
 H AB  EA EB  CACB
– E = Electrostatic Contributions
– C = Covalent Contributions
Acids
Bases
Can be predicted from Infrared or NMR peak shifts due to mixing
See Wettability By John C. Berg
Wetting - Good Method
• Work of Adhesion between to materials,
WaAB= -(γSV-γSL) – γLV Energy to replace solid-vapor
and liquid-vapor interfaces with liquid-vapor interface.
– Predicted by
Liquid
Wetting –Fowkes (Drago) Method
• Work of Adhesion
– N = moles of interaction functional groups per
unit area
– f = factor to convert enthalpy to work
Transport Properties
• Molecular Dynamics Calculations
– Intermolecular Forces
• Lennard-Jones Potentials between Atoms
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Location of Atoms in Molecule
Molecules Free to move
Monte Carlo Methods
Statistical Analysis
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Molecular Structure Determined From Otimization
Drug Molecule Binding
DAB=<x>2/t
Gives Upper and Lower Bounds of Property
Drug/Enzyme Target Development
Bio Concentration
• BioConcentration factor=BCF
• log BCF = 0.76 log Kow-0.23
– Kow =octanol/water partition factor
– Kow =Xo_w/Xw_o=(γ∞o_wMwo)/(γ ∞ w_oMww)
• Easily get this from a liquid-liquid Flash calc.
• Toxicity
– LC50=lethal concentration when 50% are dead
– log LC50= -0.87 log Kow - 0.11
p. 73 of your book
Kinetic Parameter Prediction
• Flash Point
– Tf =0.683 Tboil-119K
• Explosive Potential depends upon the
flash point
• Tboil from flash calc.
p. 73 of your book
Many Desired Properties of a
Product
• 1) Determine list of desired properties
• 2) Use desired properties to determine
– Figure of Merit
• Grouping of Important Qualities for a product
and/or its use.
– Minimized Deviations from Ideal Property
Values
• Minimize Σ (Ai-Adesired)2 for various properties, Ai,
for product formulations. [p. 49]
• Often minimization is carried out with upper and
lower bounds on specific properties or in
comparison with competitor’s product
Minimization Problem
• x,y,z are property axes
• Minimize Σ (Ai-Adesired)2
• With constraints of
– |A1-A1,desired| < 0.05 A1,desired
– |A2-A2,desired| < 0.1 A2,desired
Overview
• Property Estimation
– Use Thermo-package in Process Simulator
– Use Hansen solubility parameters
– Use Group Contribution Methods
– Use statistical mechanics