Product DesignProperty Estimation

Chapter 3Article on Phys. Property Estimation

CHEN 4253Terry 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

• 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

• 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 + δh

2), linkage to Hansen Solubility parameters

Hansen Solubility Parameter• 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

d

N

iii

N

iii

nMw

nAnp

1

1}{

Group Contribution Methods

• Polymer Glass Transition Temp.

• Polymer Molar Volume

• Polymer Density

• Polymer Water Absorption– P. 66 of your book

Liquid Surface Tension/WettingGroup 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

Tables from Ring, Fundamentals of Ceramic Powder Processing, Academci Press 1999.

CH2=CH O CH3 Groups Pi

C 3 4.8H to C 6 17.1O to ether 1 20Double Bond 1 23.2

γLV=[ρLMw-1 Σ(NiPi)]4

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

Tables from Ring, Fundamentals of Ceramic Powder Processing, Academic Press 1999.

TiO2

Drago E and C

• Used to predict the Heat of mixing, ΔHAB

– Acid (A) – Base (B) Interactions– Good for non-polar solvents

– E = Electrostatic Contributions– C = Covalent Contributions

BABAAB CCEEH

Acids

Bases

Can be predicted from Infrared or NMR peak shifts due to mixingSee Wettability  By John C. Berg

Wetting - Good Method

• Work of Adhesion between to materials, Wa

AB= -(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

– Location of Atoms in Molecule– Molecules Free to move– Monte Carlo Methods– Statistical Analysis

• 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 - 0.11p. 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