Re: [dwsim-users] DTL entropy is always 0

[Daniel W. <dan...@gm...>]

Hi Urs,

Check your P and T units, they should be in Pa and K.

LKP is slow indeed, the fastest rigorous model is Peng-Robinson.

Regards
Daniel

Em seg., 11 de nov. de 2019 às 09:10, Urs Wagner <or...@gm...> escreveu:

>
> Hello
>
> In my code the entropy is always 0.
> And it is very slow over one minute. Is there a faster variant?
>
> My Source
>
> using DTL.Thermodynamics;
> using System;
> using System.Diagnostics;
> using System.IO;
> using System.Text;
> namespace DTLTest4
> {
>     class Program
>     {
>         static void Main(string[] args)
>         {
>             new Program().Test();
>         }
>         private string FormatDouble(double value)
>         {
>             if (value < 0.0)
>                 return value.ToString("0.0000000E+00");
>             return value.ToString("0.00000000E+00");
>         }
>         public void Test()
>         {
>             var dtlc = new Calculator();
>             dtlc.Initialize();
>             var prpp = dtlc.GetPropPackInstance("Lee-Kesler-Plöcker");
>             var pFrom = 1.0;
>             var pTo = 100.0;
>             var pIteration = 20;
>             var tFrom = 270.0;
>             var tTo = 450.0;
>             var tIteration = 20;
>             var comps = new string[] { "Oxygen", "Nitrogen", "Water" };
>             var fracs = new double[] { 0.065421, 0.747663, 0.186916 };
>             // flash algorithm type
>             // 0 or 2 = NL VLE, 1 = IO VLE, 3 = IO VLLE, 4 = Gibbs VLE, 5
> = Gibbs VLLE, 6 = NL VLLE, 7 = NL SLE, 8 = NL Immisc., 9 = Simple
> LLE
>             int flashalg = 0;
>             Stopwatch sw = new Stopwatch();
>             sw.Start();
>             var dp = Math.Pow(pTo / pFrom, 1.0 / (pIteration - 1));
>             var dt = (tTo - tFrom) / (tIteration - 1);
>             var lines = new StringBuilder();
>             lines.Append("** DTL Thermodynamics Library LKP **" +
> Environment.NewLine);
>             lines.Append("  mol weight" + Environment.NewLine);
>             for (int i = 0; i < pIteration; i++)
>             {
>                 var p = pFrom * Math.Pow(dp, i);
>                 for (var j = 0; j < tIteration; j++)
>                 {
>                     var t = tFrom + j * dt;
>                     var result = dtlc.PTFlash(prpp, flashalg, p, t, comps,
> fracs);
>                     var molFraction1 = double.Parse(result[2,
> 0].ToString());
>                     var molFraction2 = double.Parse(result[3,
> 0].ToString());
>                     var molFraction3 = double.Parse(result[4,
> 0].ToString());
>                     var moleFractions = new[] { molFraction1,
> molFraction2, molFraction3 };
>                     var values = dtlc.CalcProp(prpp, "volume", "Mole",
> "Vapor", comps, t, p, moleFractions);
>                     var specificVolume =
> double.Parse(values[0].ToString());
>                     values = dtlc.CalcProp(prpp, "enthalpy", "Mole",
> "Vapor", comps, t, p, moleFractions);
>                     var enthalpy = double.Parse(values[0].ToString()) /
> 1000.0;
>                     values = dtlc.CalcProp(prpp, "entropy", "Mole",
> "Vapor", comps, t, p, moleFractions);
>                     var entropy = double.Parse(values[0].ToString());
>                     values = dtlc.CalcProp(prpp, "viscosity", "Mole",
> "Vapor", comps, t, p, moleFractions);
>                     var dynamicViscosity =
> double.Parse(values[0].ToString());
>                     lines.Append("  " + FormatDouble(p) + "  " +
> FormatDouble(t) + "  " +
>                                             FormatDouble(specificVolume) +
> "  " +
>                                             FormatDouble(enthalpy) + "  "
> + FormatDouble(entropy) + "  " +
>
> FormatDouble(dynamicViscosity));
>                     if (i == pIteration - 1 && j == tIteration - 1)
>                         lines.Append("  END");
>                     else
>                         lines.Append(Environment.NewLine);
>                 }
>             }
>             File.WriteAllText("gasmatrice", lines.ToString());
>             sw.Stop();
>             Console.WriteLine(sw.ElapsedMilliseconds.ToString());
>             Console.ReadKey();
>         }
>     }
> }
>
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