W. Vincent Wilding

Brigham Young University - Provo Main Campus, Provo, UT, United States

Are you W. Vincent Wilding?

Claim your profile

Publications (51)40.62 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A first-order temperature-dependent group contribution method was developed to predict Henry’s law constants of hydrocarbons, alcohols, ketones, and formates in which none of the functional groups are attached directly to a benzene ring. Efforts to expand this method to include ester and ether groups were unsuccessful. Second-order groups were developed at a reference condition of 298.15 K and 100 kPa. A second-order temperature-dependent group contribution method was then developed for hydrocarbons, ketones, esters, ethers, and alcohols. These methods were compared to existing literature prediction methods.
    Journal of Chemical & Engineering Data 12/2013; 59(4):1052–1061. · 2.00 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The effectiveness of chemical process designs and the reliability of mixture models are no better than the accuracy of the pure-chemical thermophysical properties used. A systems-analysis approach can be used in evaluating data from all available sources to triangulate on the best values which can be of higher accuracy than the individual values. This approach includes applied constraints on property values from interproperty relationships, expected smooth trends of properties between related chemicals, and the impact of chemical similarities and differences. These constraints are simultaneously included in the evaluation of the raw experimental data to provide recommended values of constant properties and correlations for temperature-dependent properties. This paper will illustrate how this systems approach has been used to provide recommended property values in the DIPPR 801 evaluated database. In particular, a recent re-evaluation of the properties of the 1,n-alkanediol compounds in the DIPPR database, prompted by the availability of more recently measured critical temperatures and pressures of three members of this family, is used as an illustrative case study of this approach, and some of the newly recommended property values and temperature-dependent correlations for this family are provided.
    Journal of Chemical & Engineering Data 11/2013; 59(4):1031–1037. · 2.00 Impact Factor
  • Loren C. Wilson, W. Vincent Wilding, Grant M. Wilson
    [Show abstract] [Hide abstract]
    ABSTRACT: Pressure–volume–temperature (PVT) data on hydrogen fluoride (HF) were measured from (293 to 473) K and from low pressure to near saturation pressure. These data were compared to existing literature data, and a model was developed which accurately represents the association behavior of pure, gaseous hydrogen fluoride. This model includes the assumption of HF dimers and hexamers in equilibrium with monomeric HF. The vapor pressure of hydrogen fluoride was also measured from (293 to 454) K, and these measurements were correlated using the Riedel equation. There is good agreement between these vapor pressures and previous work, while this work extends the measured vapor pressure for HF to within 7 K of the critical temperature.
    Journal of Chemical & Engineering Data 11/2013; 59(4):983–990. · 2.00 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ternary LLE data have been experimentally measured for several systems consisting of biodiesel compounds. Systems measured include mixtures with the methyl esters of lauric, myristic, palmitic, and oleic acids, each with glycerin and water. Data were collected at atmospheric pressure and 60 °C. These ternary systems have been correlated using the NRTL equation. These data and correlation parameters can be used to improve separations efficiency in transesterified biodiesel fuels.
    Journal of Chemical & Engineering Data 03/2013; 58(4):1001–1004. · 2.00 Impact Factor
  • Sonal Patel, W Vincent Wilding, Richard L Rowley
    [Show abstract] [Hide abstract]
    ABSTRACT: Two-phase molecular dynamics simulations employing a Monte Carlo volume sampling method were performed using an ab initio based force field model parameterized to reproduce quantum-mechanical dimer energies for methanol and 1-propanol at temperatures approaching the critical temperature. The intermolecular potential models were used to obtain the binodal vapor-liquid phase dome at temperatures to within about 10 K of the critical temperature. The efficacy of two all-atom, site-site pair potential models, developed solely from the energy landscape obtained from high-level ab initio pair interactions, was tested for the first time. The first model was regressed from the ab initio landscape without point charges using a modified Morse potential to model the complete interactions; the second model included point charges to separate Coulombic and dispersion interactions. Both models produced equivalent phase domes and critical loci. The model results for the critical temperature, density, and pressure, in addition to the sub-critical equilibrium vapor and liquid densities and vapor pressures, are compared to experimental data. The model's critical temperature for methanol is 77 K too high while that for 1-propanol is 80 K too low, but the critical densities are in good agreement. These differences are likely attributable to the lack of multi-body interactions in the true pair potential models used here.
    The Journal of Chemical Physics 12/2011; 135(23):234514. · 3.12 Impact Factor
  • Jiangping Liu, W. Vincent Wilding, Richard L. Rowley
    [Show abstract] [Hide abstract]
    ABSTRACT: A local composition model is developed for mixture dielectric constants based on the nonrandom two-liquid (NRTL) model commonly used for correlating activity coefficients in vapor−liquid equilibrium (VLE) data regression. In this model the NRTL local compositions, which represent an effective local molecular structure, are the counterpart of the Kirkwood factor g, which in dielectric constant theory characterizes local molecular orientations and their effect on the static dielectric constant. The resultant model requires values for the pure-component dielectric constant and binary NRTL model parameters available from VLE data compilations or predicted from the universal functional activity coefficient model (UNIFAC). It is predictive in that no mixture dielectric constant data are used and there are no adjustable parameters. Predictions made on 16 binary and six ternary systems at various compositions and temperatures compare favorably with extant correlations that require experimental values to fit an adjustable parameter in the mixing rule and are significantly improved over values predicted by Oster's equation that also has no adjustable parameters.
    Journal of Chemical & Engineering Data. 03/2011; 56(5).
  • J R Rowley, R L Rowley, W V Wilding
    [Show abstract] [Hide abstract]
    ABSTRACT: A new method of estimating the lower flammability limit (LFL) of general organic compounds is presented. The LFL is predicted at 298 K for gases and the lower temperature limit for solids and liquids from structural contributions and the ideal gas heat of formation of the fuel. The average absolute deviation from more than 500 experimental data points is 10.7%. In a previous study, the widely used modified Burgess-Wheeler law was shown to underestimate the effect of temperature on the lower flammability limit when determined in a large-diameter vessel. An improved version of the modified Burgess-Wheeler law is presented that represents the temperature dependence of LFL data determined in large-diameter vessels more accurately. When the LFL is estimated at increased temperatures using a combination of this model and the proposed structural-contribution method, an average absolute deviation of 3.3% is returned when compared with 65 data points for 17 organic compounds determined in an ASHRAE-style apparatus.
    Journal of hazardous materials 02/2011; 186(1):551-7. · 4.14 Impact Factor
  • Source
    Sonal Patel, W Vincent Wilding, Richard L Rowley
    [Show abstract] [Hide abstract]
    ABSTRACT: Molecular dynamics simulations were performed to determine two-phase configurations of model propane molecules below the critical point and in the near-critical, two-phase region. A postprocessor that uses a Monte Carlo method for determination of volumes attributable to each molecule was used to obtain density histograms of the particles from which the bulk coexisting equilibrium vapor and liquid densities were determined. This method of analyzing coexisting densities in a two-phase simulation is straightforward and can be easily implemented for complex, multisite models. Various degrees of internal flexibility in the propane models have little effect on the coexisting densities at temperatures 40 K or more below the critical point, but internal flexibility (angle bending and bond vibrations) does affect the saturated liquid densities in the near-critical region, changing the critical temperature by approximately 20 K. Shorter cutoffs were also found to affect the phase dome and the location of the critical point.
    The Journal of Chemical Physics 01/2011; 134(2):024101. · 3.12 Impact Factor
  • Jeffrey R. Rowley, Richard L. Rowley, W. Vincent Wilding
    [Show abstract] [Hide abstract]
    ABSTRACT: Published flash point prediction methods are evaluated for accuracy against experimental data from the DIPPR ® 801 database. The most accurate methods require a vapor pressure correlation, which is often not available. Two new methods are presented, one that uses the vapor pressure, and one based on the normal boiling point and enthalpy of vaporization at the normal boiling point. The vapor pressure method shows little improvement over the previous methods unless group contributions are implemented. The boiling point method predicts the flash point within an absolute average deviation of 1.3% when compared with data for more than 1000 compounds. The previous most accurate method that was not based on vapor pressure exhibited an absolute average deviation of 1.84% for the same test set. Copyright © 2010 John Wiley & Sons, Ltd.
    Fire and Materials 11/2010; 35(6):343 - 351. · 1.07 Impact Factor
  • J.R. Rowley, R.L. Rowley, W.V. Wilding
    [Show abstract] [Hide abstract]
    ABSTRACT: The flash point is an important indicator of the flammability of liquids and solids. Many methods of estimating the flash point of pure chemicals have been published, but these methods either rely on accurate thermodynamic data or are limited to hydrocarbons. This work presents a method of estimating the flash point of general organic compounds based entirely on structural contributions. The proposed correlation results in an average absolute deviation of 2.84% from experimental values for more than 1,000 organic compounds. © 2010 American Institute of Chemical Engineers Process Saf Prog, 2010
    Process Safety Progress 09/2010; 29(4):353 - 358. · 0.72 Impact Factor
  • Jeffrey R. Rowley, Richard L. Rowley, W. Vincent Wilding
    [Show abstract] [Hide abstract]
    ABSTRACT: The lower flammability limits of 18 CxHyOzNw liquids were measured as a function of initial temperature in an ASHRAE 12 L style apparatus. Results indicate that the calculated adiabatic flame temperature is not constant, as previously reported but rather decreases with increasing temperature. Consequently, the modified Burgess−Wheeler law does not accurately predict the effect of temperature on the lower flammability limit. Though few direct comparisons are possible, previously reported data agree well with the values measured in this study.
    Journal of Chemical and Engineering Data - J CHEM ENG DATA. 02/2010;
  • [Show abstract] [Hide abstract]
    ABSTRACT: The flash point is an important indicator of the flammability of a chemical. For safety purposes, many data compilations report the lowest value and not the most likely. This practice, combined with improper documentation and poor data storage methods, has resulted in compilations filled with fire-hazard data that are inconsistent with related properties and between members of homologous chemical series. In this study, the flash points reported in the DIPPR® 801 database and more than 1,400 other literature values were critically reviewed based on measurement method, inter-property relations, and trends in chemical series. New measurements for seven compounds illustrate the differences between experimental flash points and data commonly found in fire-hazard compilations. With a critically reviewed set of experimental data, published predictive methods for the flash point were evaluated for accuracy. KeywordsData evaluation-Database-DIPPR-Flash point-Prediction
    International Journal of Thermophysics 01/2010; 31(4):875-887. · 0.57 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Maintaining currency of thermophysical property values in a chemical database with the rapid pace of published new experimental data is particularly difficult for evaluated databases. Evaluated databases that provide recommended values for each of the properties require labor intensive evaluation of not only the newly published property values, but also all related property values stored in the database. One possible solution to this problem is the establishment of a triage system to evaluate the potential influence of new data on recommended property values. Such a priority assignment system for the DIPPR®801 Pure Chemical Database has been developed. Evaluation of the potential impact of new data on the recommended values is done through a correlation for the Influence Factor (IF) that includes weighting factors for the type of property, the experimental methodology, the quality of the data, the quantity of data upon which the current recommendation is based, and the significance of the potential change. Database IFs help prioritize review work on the DIPPR®801 database and thereby contribute to its quality and currency. KeywordsDatabase-DIPPR-Thermophysical properties-Weighting factor
    International Journal of Thermophysics 01/2010; 31(4):860-874. · 0.57 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The dielectric constant (ε) or relative static permittivity of a material represents the capacitance of the material relative to a vacuum and is important in many industrial applications. Nevertheless, accurate experimental values are often unavailable, and current prediction methods lack accuracy and are often unreliable. Reported here is the development and testing of a new QSPR (quantitative structure property relation) correlation of ε for organic chemicals. On the basis of the regression analysis and tests of the correlation in prediction mode, the average absolute percent error is expected to be less than 3 % when applied to hydrocarbons and nonpolar compounds and less than 18 % when applied to polar compounds with ε values ranging from 1.0 to 50.0. The correlation requires values for the dipole moment, solubility parameter, van der Waals area, and refractive index. We show also that density functional calculations of the dipole moment using B3LYP/6-311+G(3df,2p) can be used in the ε correlation, when experimental values are unavailable, with little decrease in accuracy of the predicted values.
    Journal of Chemical and Engineering Data - J CHEM ENG DATA. 09/2009; 55(1).
  • [Show abstract] [Hide abstract]
    ABSTRACT: Intelligent design of chemical-process equipment requires accurate thermophysical property values for pure components and mixtures including solutions. Databases used by practicing engineers should include the best numbers available and estimated uncertainties of these numbers. Many important property values have not been measured and must be estimated. Care should be exercised in selecting the estimation method. Property values that are a function of temperature, pressure, and/or composition can be correlated using appropriate equations. Such equations and the number of adjustable parameters in these equations should be selected with care. Examples of determining uncertainties, estimation techniques used, and correlating equations are given.
    Journal of Thermal Analysis and Calorimetry 01/2008; 92(2):465-470. · 1.98 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: An automated property prediction package has been developed that permits rapid evaluation of group-contribution, corresponding states, empirical, and theoretical property estimation methods. The property prediction package, which is part of the DIPPR® Information And Data Evaluation Manager (DIADEM) software, is used in conjunction with the DIPPR® 801 database to develop and test new prediction methods. The software is freely available to all DIPPR sponsor companies, but is also commercially available. The estimation engine is based on an automated SMILES (Simplified Molecular Input Line Entry Specification) formula parser to provide required molecular structural information, retrieval of required secondary properties from the DIPPR® database, and defined rules for the method. Automatic comparisons of predicted values to experimental data in the DIPPR® database can be made for properties at specified accuracy levels, by chemical family or type, or over the entire database. This allows evaluation of the relative effectiveness of methods for specific chemical families and tailoring of the selected method to specific chemical classes. New methods can readily be added by input using a simple input form. Nearly 200 thermophysical property prediction methods are currently available in DIADEM.
    International Journal of Thermophysics 05/2007; 28(3):824-834. · 0.57 Impact Factor
  • Hua Lei, W. Vincent Wilding, William G. Pitt
    Journal of Chemical and Engineering Data - J CHEM ENG DATA. 01/2007; 52(6):2233-2236.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Most thermophysical-property databases (TPD) provide low-level quality control checks. This manuscript focuses on additional, higher-level data evaluations made possible by the breadth of data stored in the database. For example, thermodynamic equations relate the critical point, vapor-pressure curve, enthalpy of vaporization, liquid density, and liquid and vapor heat capacities to each other. Thermodynamic consistency among these properties can be used to guide selection of the best data sets. Even more broadly, molecular structure-based trends in properties can be identified within the database, and the properties of structurally related compounds can be effectively used to discriminate among available datasets. Automated property predictions can be used in conjunction with the TPD to guide the selection of the most accurate data. These and other high-level consistency tools will be illustrated based on evaluation and quality control work associated with the DIPPR® 801 TPD project for pure chemicals.
    International Journal of Thermophysics 01/2007; 28:805-823. · 0.57 Impact Factor
  • R. J. Hulse, R. L. Rowley, W. V. Wilding
    [Show abstract] [Hide abstract]
    ABSTRACT: Thermal conductivity has been previously obtained from molecular dynamics (MD) simulations using either equilibrium (EMD) simulations (from Green--Kubo equations) or from steady-state nonequilibrium (NEMD) simulations. In the case of NEMD, either boundary-driven steady states are simulated or constrained equations of motion are used to obtain steady-state heat transfer rates. Like their experimental counterparts, these nonequilibrium steady-state methods are time consuming and may have convection problems. Here we report a new transient method developed to provide accurate thermal conductivity predictions from MD simulations. In the proposed MD method, molecules that lie within a specified volume are instantaneously heated. The temperature decay of the system of molecules inside the heated volume is compared to the solution of the transient energy equation, and the thermal diffusivity is regressed. Since the density of the fluid is set in the simulation, only the isochoric heat capacity is needed in order to obtain the thermal conductivity. In this study the isochoric heat capacity is determined from energy fluctuations within the simulated fluid. The method is valid in the liquid, vapor, and critical regions. Simulated values for the thermal conductivity of a Lennard-Jones (LJ) fluid were obtained using this new method over a temperature range of 90 to 900 K and a density range of 1–35 kmol m-3. These values compare favorably with experimental values for argon. The new method has a precision of 10%. Compared to other methods, the algorithm is quick, easy to code, and applicable to small systems, making the simulations very efficient.
    International Journal of Thermophysics 01/2005; 26(1):1-12. · 0.57 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Vapor-phase association greatly affects the pure-component properties of carboxylic acids. This study uses density functional theory (DFT) calculations to quantify the size and distribution of oligomers present in n-aliphatic carboxylic acid vapors and includes recommendations on how this information may be used in modeling the acids. Acids from C2 to C6 were studied using B3LYP/6-31++G(2d,p).New association equations were developed for the acids from C4 to C10 using the family trend obtained from the B3LYP calculations. Dimers were found to be the dominant oligomer in the vapor-phase, with little association of larger oligomers. Association in acids larger than C10 is negligible at modest temperatures and pressures. There is a notable difference in the dimerization enthalpy between acids with an even number of carbon atoms and those with an odd number of carbon atoms.
    Fluid Phase Equilibria 08/2004; 222:239-245. · 2.38 Impact Factor