Aspen Physical Property System - Physical Property Models

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Reference C. Tsonopoulos, Fluid Phase Equilibria, 186 (2001), 185-206. Other Thermodynamic Property Models The Aspen Physical Property System has some built-in additional thermodynamic property models that do not fit in any other category. This section describes these models: � Cavett Liquid Enthalpy Departure � Barin Equations for Gibbs Energy, Enthalpy, Entropy and Heat Capacity � Electrolyte NRTL Enthalpy � Electrolyte NRTL Gibbs Energy � Liquid Enthalpy from Liquid Heat Capacity Correlation � Enthalpies Based on Different Reference States � Helgeson Equations of State � Quadratic Mixing Rule Cavett The general form for the Cavett model is: Parameter Name/Element 228 2 Thermodynamic Property Models Symbol Default MDS Lower Limit Upper Limit Units TC T ci — — 5.0 2000.0 TEMPERATURE PC p ci — — 10 5 DHLCVT ZC X 0.1 0.5 — 10 8 PRESSURE Barin Equations for Gibbs Energy, Enthalpy, Entropy, and Heat Capacity The following equations are used when parameters from the Aspen Physical Property System inorganic databank are retrieved. � Gibbs energy: � Enthalpy: (2) (1)
� Entropy: � Heat capacity: � refers to an arbitrary phase which can be solid, liquid, or ideal gas. For each phase, multiple sets of parameters from 1 to n are present to cover multiple temperature ranges. The value of the parameter n depends on the phase. (See tables that follow.) When the temperature is outside all these temperature ranges, linear extrapolation of properties versus T is performed using the slope at the end of the nearest temperature bound. The four properties Cp, H, S, and G are interrelated as a result of the thermodynamic relationships: There are analytical relationships between the expressions describing the properties Cp, H, S, and G (equations 1 to 4). The parameters an,i to hn,i can occur in more than one equation. The Aspen Physical Property System has other models which can be used to calculate temperature-dependent properties which the BARIN equations can calculate. The Aspen Physical Property System uses the parameters in THRSWT to determine which model is used. See Pure Component Temperature-Dependent Properties for details. If this parameter is 200 to 211 Then the BARIN equations are used to calculate THRSWT/3 Liquid vapor pressure THRSWT/5 Solid heat capacity THRSWT/6 Liquid heat capacity THRSWT/7 Ideal gas heat capacity The liquid vapor pressure is computed from Gibbs energy as follows: ln p = (G L - G V )/RT + ln p ref where p is the vapor pressure, and p ref is the reference pressure 101325 Pa. Thus, parameters for both liquid and vapor are necessary to calculate vapor pressure. Solid Phase The parameters in range n are valid for temperature: Tn,l s < T < Tn,h s 2 Thermodynamic Property Models 229 (4) (3)
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Aspen Physical Property System Phys
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Contents Contents..................
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General Pure Component Solid Molar
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1 Introduction This manual describe
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Pure Component Temperature- Depende
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the Properties Parameters Pure-Comp
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2 Thermodynamic Property Models Thi
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Property Model Model Name Phase(s)P
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Property Model Model Name 2 Thermod
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Where: Parameter Name/Element 2 The
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critical temperature, the critical
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Where the ideal-gas contribution
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, where � For polar, associating
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Parameter Name/ Element 2 Thermodyn
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The denominator of equation 8 is gi
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V. V. De Leeuw and S. Watanasiri, "
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References M. Benedict, G. B. Webb,
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References L. Haar, J.S. Gallagher,
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Parameter Name/Element NTHDDH 0 †
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Gibbs free energy departure: The fo
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For a block copolymer, there is onl
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Copolymer PC-SAFT Dispersion Term T
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The association-site number of the
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Then I2(�) and I3(�) are comput
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A databank called PC-SAFT contains
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Parameter Name/Element PRKBV/1 k ij
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Predictive SRK (PSRK) This model us
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ka,ij kb,ij = = For best results, b
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J. Schwartzentruber and H. Renon, "
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Redlich-Kwong-Soave-MHV2 This equat
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‡ RKUC0, RKUC1, and RKUC2 are tre
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Parameter Name/ Element SRKLIJ/3 l
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Parameter Name/ Element Symbol Defa
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Association Equilibria Every associ
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and respectively. For the reactions
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R. W. Long, J. H. Hildebrand, and W
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Where the L, M, and N are parameter
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Alpha function Model name First Opt
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mi = Computed by equation 6 Equatio
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Parameter Name/Element 2 Thermodyna
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standard RKS alpha function, except
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These mixing rules are discussed se
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Where both Ai* and Am are calculate
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Like Huron and Vidal, the limiting
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Model Type Wilson Local composition
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Therefore, the simplified Pitzer eq
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Parameter Name/Element Symbol Defau
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Where: �i 2 Thermodynamic Propert
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The electrolyte NRTL model uses the
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Parameter Symbol No. of Name Elemen
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with Where: xi = Mole fraction of c
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It should be understood that equati
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The reference Gibbs energy is deter
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Where: j and k can be any species (
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The pure component dielectric const
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2 Thermodynamic Property Models 109
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�I *PDH = Pitzer-Debye-Hückel te
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Where: �i Vi = Activity coefficie
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Recommended cij Values for Differen
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Parameter Name/ Element 2 Thermodyn
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NRTL-SAC Reference States The NRTL-
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For an anionic component, we have M
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For a molecular segment, the activi
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Specifically, The long range intera
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where and are activity coefficients
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and Y+, are used to reflect the wid
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Parameter Name/ Element Symbol Defa
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Reference C.-C. Chen and Y. Song, "
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Parameter Name GMPTPS, GMPTP1, GMPT
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zi = Charge of ion i Subscripts c,
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For option code = 0 (default), the
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and for n-m electrolytes: 2 Thermod
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= 0.00979 Perform the necessary con
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Pitzer, K.S., J.R. Peterson, and L.
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A4,ij = gij / T + hij A5,ij = mij /
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Symmetric and Unsymmetric Electroly
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Parameter Symbol No. of Name Elemen
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Reference state for ionic component
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with 2 Thermodynamic Property Model
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G for these pairs is calculated the
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with 2 Thermodynamic Property Model
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Activity Coefficient Basis for Henr
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Where is the liquid Gibbs free ener
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Ionic components 2 Thermodynamic Pr
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the pure fused salts. Applying Eq.
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�k is the activity coefficient of
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References U. Weidlich and J. Gmehl
Page 179 and 180: ti' = �ij 2 Thermodynamic Propert
Page 181 and 182: Wagner Interaction Parameter The Wa
Page 183 and 184: References G.M. Wilson, J. Am. Chem
Page 185 and 186: Extended Antoine Equation Parameter
Page 187 and 188: IK-CAPE Vapor Pressure Equation The
Page 189 and 190: Harlacher and Braun, "A Four-Parame
Page 191 and 192: Parameter Name/Element 2 Thermodyna
Page 193 and 194: General Pure Component Heat of Vapo
Page 195 and 196: IK-CAPE Heat of Vaporization Equati
Page 197 and 198: Where: xp = Mole fraction of pseudo
Page 199 and 200: Parameter Name/Element VLBROC/1 V i
Page 201 and 202: Where: Vm l,t = Liquid volume per n
Page 203 and 204: Debye-Hückel Volume The Debye-Hüc
Page 205 and 206: DIPPR DIPPR equation 105 is the def
Page 207 and 208: Rackett The Rackett equation is: Wh
Page 209 and 210: Rackett/Campbell-Thodos Mixture Liq
Page 211 and 212: Zm RA Zi *,RA Vcm 2 Thermodynamic P
Page 213 and 214: General Pure Component Solid Molar
Page 215 and 216: Liquid Volume Quadratic Mixing Rule
Page 217 and 218: If THRSWT/6 is This equation is use
Page 219 and 220: Parameter Symbol Default MDS Lower
Page 221 and 222: General Pure Component Ideal Gas He
Page 223 and 224: (Other DIPPR equations may sometime
Page 225 and 226: General Pure Component Solid Heat C
Page 227 and 228: Parameter Name/Element 2 Thermodyna
Page 229: The expression for the liquid mole
Page 233 and 234: Parameter Name † /Element CPIXPn/
Page 235 and 236: Option Codes for Electrolyte NRTL E
Page 237 and 238: Parameter Name Applicable Component
Page 239 and 240: For subcritical components: Hm l -H
Page 241 and 242: The vapor enthalpy is calculated fr
Page 243 and 244: Where: 2 Thermodynamic Property Mod
Page 245 and 246: Correlation algorithms for ionic sp
Page 247 and 248: Model Model name Phase(s) Pure Mixt
Page 249 and 250: Model Type Aspen Liquid Mixture Vis
Page 251 and 252: (Other DIPPR equations may sometime
Page 253 and 254: Parameter Symbol Default MDS Lower
Page 255 and 256: �i = Viscosity of component i (N-
Page 257 and 258: Parameter Name/Element 3 Transport
Page 259 and 260: Where: The Stockmayer or Lennard-Jo
Page 261 and 262: Where: Vcij = �ij = 0 (in almost
Page 263 and 264: Where: Vcij = �ij = 0 (in almost
Page 265 and 266: Jones-Dole Electrolyte Correction T
Page 267 and 268: Letsou-Stiel The Letsou-Stiel model
Page 269 and 270: Where: The parameter is the mole fr
Page 271 and 272: Reference C.H. Twu, "Internally Con
Page 273 and 274: Vcij 3 Transport Property Models 27
Page 275 and 276: You must provide parameters for the
Page 277 and 278: Linear extrapolation of � *,l ver
Page 279 and 280: If TRNSWT/4 is This equation is use
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Parameter Name/Element 3 Transport
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Parameter Symbol Default MDS Lower
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References R.C. Reid, J.M. Prausnit
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The mixture surface tension is then
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Where: �solv = Dielectric constan
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4 Nonconventional Solid Property Mo
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wij = Mass fraction of the jth cons
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The oxygen and organic sulfur conte
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The complete oxidation of carbon is
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The equation for �i dm is good fo
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5 Property Model Option Codes The f
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Model Name Option Code 5 Property M
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Model Name Option Code 5 Property M
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Soave-Redlich-Kwong Option Codes Th
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Model Name Option Code HLRELNRT and
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Model Name Option Code GLRELNRT, GL
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Index A activity coefficient models
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ideal gas/DIPPR heat capacity model
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S Sato-Riedel/DIPPR thermal conduct
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Aspen Physical Property System - Physical Property Models

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