Aspen Physical Property System - Physical Property Models

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The reference enthalpy is calculated at T ref as: Where: Hi *,ig Hi *,v - Hi *,ig = Ideal gas enthalpy 236 2 Thermodynamic Property Models = Vapor enthalpy departure from equation of state �vapHi *,l = Heat of vaporization from General model T ref = Reference temperature, specified by user. Defaults to 298.15 K See General Pure Component Heat of Vaporization for parameter requirement and additional details. Enthalpies Based on Different Reference States Two property methods, WILS-LR and WILS-GLR, are available to calculate enthalpies based on different reference states. The WILS-LR property method is based on saturated liquid reference state for all components. The WILS-GLR property method allows both ideal gas and saturated liquid reference states for different components. These property methods use an enthalpy method that optimizes the accuracy tradeoff between liquid heat capacity, heat of vaporization, and vapor heat capacity at actual process conditions. This highly recommended method eliminates many of the problems associated with accurate thermal properties for both phases, especially the liquid phase. The liquid enthalpy of mixture is calculated by the following equation (see the table labeled Liquid Enthalpy Methods): Where: Hm ig Hi *,ig = Enthalpy of ideal gas mixture = = Ideal gas enthalpy of pure component i (Hm l -Hm ig ) = Enthalpy departure of mixture For supercritical components, declared as Henry's components, the enthalpy departure is calculated as follows:
For subcritical components: Hm l -Hm ig Hm E,l HA *,l -HA *,ig 2 Thermodynamic Property Models 237 = = = Enthalpy departure of pure component A H *,ig and H *,l can be calculated based on either saturated liquid or ideal gas as reference state as described in the sections that follow. For the WILS-LR property method, H *,ig and H *,l are calculated based on the saturated liquid reference state for all components. For the WILS-GLR property method, H *,ig and H *,l can be calculated based on the saturated liquid reference state for some components and the ideal gas reference state for other components. You can set the value of a pure component parameter called RSTATE to specify the reference state for each component. RSTATE = 1 denotes ideal gas reference state. RSTATE = 2 denotes saturated liquid reference state. If it is not set, the following default rules apply based on the normal boiling point of the component, i, TB(i): � If TB(i) 298.15 K, saturated liquid reference state is used. Saturated Liquid as Reference State The saturated liquid enthalpy at temperature T is calculated as follows: Where: Hi ref,l Cp,i *,l = Reference enthalpy for liquid state at Ti ref,l = Liquid heat capacity of component i The saturated liquid Gibbs free energy is calculated as follows: Where: Gi ref,l = Reference Gibbs free energy for liquid state at Ti ref,l �i *,l = Liquid fugacity coefficient of component i p = System pressure p ref = Reference pressure (=101325 N/m 2 ) For the WILS-LR property method, Hi ref,l and Gi ref,l default to zero (0). The reference temperature Ti ref,l defaults to 273.15K. For the WILS-GLR property method, the reference temperature Ti ref,l defaults to 298.15K and Hi ref,l defaults to:
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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
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ti' = �ij 2 Thermodynamic Propert
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Wagner Interaction Parameter The Wa
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References G.M. Wilson, J. Am. Chem
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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 and 230: The expression for the liquid mole
Page 231 and 232: � Entropy: � Heat capacity: �
Page 233 and 234: Parameter Name † /Element CPIXPn/
Page 235 and 236: Option Codes for Electrolyte NRTL E
Page 237: Parameter Name Applicable Component
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 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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References R.C. Reid, J.M. Prausnit
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The mixture surface tension is then
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Parameter Name/Element 3 Transport
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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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