double getSatDensityAtTemp(double tempK, LiqGasProperties props)
{
double tau = 1 - tempK;
double tau35 = Math.Pow(tau, 0.35);
double tau2 = tau * tau;
double tau3 = tau * tau2;
double tau65 = Math.Pow(tau, 0.65);
double dens = props.densCrit * (1 + (props.k1 * tau35 + props.k3 * tau2 + props.k4 * tau3) / (1 + props.k2 * tau65));
return(dens);
}
// API 11.2.4 Section 5.1.1.3
// Temperature compensation CTL
public double GetCTLLiqGas(double tempF, double api60)
{
// Step T24/3
// Check Density and Temperature range
COMMODITY_GROUP grp = COMMODITY_GROUP.LPG_NGL;
checkRange(api60, "API", grp);
checkRange(tempF, "degF", grp); // Group must be specified
// Step T24/2
// Convert temp to Kelvin and roundup
tempF = RoundUp(tempF, -1);
double Tx = Conversions.DegFtoDegK(tempF);
// Convert to relative density and roundup
double relDens60 = Conversions.APItoSG(api60);
relDens60 = RoundUp(relDens60, -4);
// Step T24/4
// Chose reference fluid subscripts (1,2)
LiqGasProperties f1 = null;
LiqGasProperties f2 = null;
LiqGasProperties prev = null;
foreach (var lgProp in lgProps)
{
if (prev != null)
{
if (lgProp.Value.relDens60 >= relDens60)
{
f2 = lgProp.Value;
f1 = prev;
break;
}
}
prev = lgProp.Value;
}
if (f2 == null || f1 == null)
{
throw (new ArgumentException(String.Format("Relative density {0} is out of the range of API 11.2.4 Table 1", api60)));
}
// Step T24/5
// Compute interpolation variable
double delta = (relDens60 - f1.relDens60) / (f2.relDens60 - f1.relDens60);
// Step T24/6
// Compute interpolated critical temperature
double Tc = f1.tempCritK + delta * (f2.tempCritK - f1.tempCritK);
// Step T24/7
// Compute reduced temperature ratio
double Trx = Tx / Tc;
if (Trx > 1)
{
throw (new ArgumentException(String.Format("Temperature {0} will result in supercritical conditions which are not supported by this computation", tempF)));
}
// Step 24/8
// Compute reduced temperature at 60F
double t60K = Conversions.DegFtoDegK(60);
double Tr60 = t60K / Tc;
// Step 24/9
// Compute scaling factor
double h2 = (f1.comprFactCrit * f1.densCrit) / (f2.comprFactCrit * f2.densCrit);
// Step 24/10
// Compute saturation density of both fluids at 60F
double dens60_1 = getSatDensityAtTemp(Tr60, f1);
double dens60_2 = getSatDensityAtTemp(Tr60, f2);
// Step 24/11
// Calculate interpolating factor
Func <double, double, double> ratio = (dens1, dens2) => dens1 / (1 + delta * (dens1 / (h2 * dens2) - 1));
double X = ratio(dens60_1, dens60_2);
// Step 24/12
// Opbtain saturation density of both fluids at Trx
double densX_1 = getSatDensityAtTemp(Trx, f1);
double densX_2 = getSatDensityAtTemp(Trx, f2);
// Step 24/13
// Obtain CTL
double CTL = ratio(densX_1, densX_2) / X;
return(CTL);
}
public static Dictionary <LIQ_GAS_FLUID, LiqGasProperties> GetLiqGasProperties()
{
Dictionary <LIQ_GAS_FLUID, LiqGasProperties> props = new Dictionary <LIQ_GAS_FLUID, LiqGasProperties>();
// EE(68/32)
LiqGasProperties props1 = new LiqGasProperties()
{
Fluid = LIQ_GAS_FLUID.EE_68_32,
relDens60 = 0.325022,
tempCritK = 298.11,
comprFactCrit = 0.27998,
densCrit = 6.250,
k1 = 2.54616855327,
k2 = -0.058244177754,
k3 = 0.803398090807,
k4 = -0.745720314137
};
props.Add(props1.Fluid, props1);
// Ethane
LiqGasProperties props2 = new LiqGasProperties()
{
Fluid = LIQ_GAS_FLUID.ETHANE,
relDens60 = 0.355994,
tempCritK = 305.33,
comprFactCrit = 0.28220,
densCrit = 6.870,
k1 = 1.89113042610,
k2 = -0.370305782347,
k3 = -0.544867288720,
k4 = 0.337876634952
};
props.Add(props2.Fluid, props2);
// EP(65/35)
LiqGasProperties props3 = new LiqGasProperties()
{
Fluid = LIQ_GAS_FLUID.EP_65_35,
relDens60 = 0.429277,
tempCritK = 333.67,
comprFactCrit = 0.28060,
densCrit = 5.615,
k1 = 2.20970078464,
k2 = -0.294253708172,
k3 = -0.405754420098,
k4 = 0.319443433421
};
props.Add(props3.Fluid, props3);
// EP(35/65)
LiqGasProperties props4 = new LiqGasProperties()
{
Fluid = LIQ_GAS_FLUID.EP_35_65,
relDens60 = 0.470381,
tempCritK = 352.46,
comprFactCrit = 0.27930,
densCrit = 5.110,
k1 = 2.25341981320,
k2 = -0.266542138024,
k3 = -0.372756711655,
k4 = 0.384734185665
};
props.Add(props4.Fluid, props4);
// Propane
LiqGasProperties props5 = new LiqGasProperties()
{
Fluid = LIQ_GAS_FLUID.PROPANE,
relDens60 = 0.507025,
tempCritK = 369.78,
comprFactCrit = 0.27626,
densCrit = 5.000,
k1 = 1.96568366933,
k2 = -0.327662435541,
k3 = -0.417979702538,
k4 = 0.303271602831
};
props.Add(props5.Fluid, props5);
// i-Butane
LiqGasProperties props6 = new LiqGasProperties()
{
Fluid = LIQ_GAS_FLUID.iBUTANE,
relDens60 = 0.562827,
tempCritK = 407.85,
comprFactCrit = 0.28326,
densCrit = 3.860,
k1 = 2.04748034410,
k2 = -0.289734363425,
k3 = -0.330345036434,
k4 = 0.291757103132
};
props.Add(props6.Fluid, props6);
// n-Butane
LiqGasProperties props7 = new LiqGasProperties()
{
Fluid = LIQ_GAS_FLUID.nBUTANE,
relDens60 = 0.584127,
tempCritK = 425.16,
comprFactCrit = 0.27536,
densCrit = 3.920,
k1 = 2.03734743118,
k2 = -0.299059145695,
k3 = -0.418883095671,
k4 = 0.380367738748
};
props.Add(props7.Fluid, props7);
// i-Pentane
LiqGasProperties props8 = new LiqGasProperties()
{
Fluid = LIQ_GAS_FLUID.iPENTANE,
relDens60 = 0.624285,
tempCritK = 460.44,
comprFactCrit = 0.27026,
densCrit = 3.247,
k1 = 2.06541640707,
k2 = -0.238366208840,
k3 = -0.161440492247,
k4 = 0.258681568613
};
props.Add(props8.Fluid, props8);
// n-Pentane
LiqGasProperties props9 = new LiqGasProperties()
{
Fluid = LIQ_GAS_FLUID.nPENTANE,
relDens60 = 0.631054,
tempCritK = 469.65,
comprFactCrit = 0.27235,
densCrit = 3.200,
k1 = 2.11263474494,
k2 = -0.261269413560,
k3 = -0.291923445075,
k4 = 0.308344290017
};
props.Add(props9.Fluid, props9);
// i-Hexane
LiqGasProperties props10 = new LiqGasProperties()
{
Fluid = LIQ_GAS_FLUID.iHEXANE,
relDens60 = 0.657167,
tempCritK = 498.05,
comprFactCrit = 0.26706,
densCrit = 2.727,
k1 = 2.02382197871,
k2 = -0.423550090067,
k3 = -1.152810982570,
k4 = 0.950139001678
};
props.Add(props10.Fluid, props10);
// n-Hexane
LiqGasProperties props11 = new LiqGasProperties()
{
Fluid = LIQ_GAS_FLUID.nHEXANE,
relDens60 = 0.664064,
tempCritK = 507.35,
comprFactCrit = 0.26762,
densCrit = 2.704,
k1 = 2.17134547773,
k2 = -0.232997313405,
k3 = -0.267019794036,
k4 = 0.378629524102
};
props.Add(props11.Fluid, props11);
// n-Heptane
LiqGasProperties props12 = new LiqGasProperties()
{
Fluid = LIQ_GAS_FLUID.nHEPTANE,
relDens60 = 0.688039,
tempCritK = 540.15,
comprFactCrit = 0.26312,
densCrit = 2.315,
k1 = 2.19773533433,
k2 = -0.275056764147,
k3 = -0.447144095029,
k4 = 0.493770995799
};
props.Add(props12.Fluid, props12);
return(props);
}
