static double RegionOutputBackward(double p, double X, IF97Parameters inkey)
{
// Note that this routine returns only temperature (IF97_T). All other values should be
// calculated from this temperature and the known pressure using forward equations.
// Setup Backward Regions for output
// Make sure input and output keys are valid for Backward formulas
if ((inkey != IF97Parameters.h) && (inkey != IF97Parameters.s))
throw new ArgumentException("Backward Formulas take variable inputs of Enthalpy or Entropy only.");
// Get Saturation Parameters
IF97REGIONS region = RegionDetermination_pX(p, X, inkey);
switch (region)
{
case IF97REGIONS.REGION_1:
if (inkey == IF97Parameters.h)
return B1H.T_pX(p, X);
else
return B1S.T_pX(p, X);
case IF97REGIONS.REGION_2:
if (inkey == IF97Parameters.h)
{
if (p <= 4.0)
return B2aH.T_pX(p, X);
else if (X >= BackwardsRegion.H2b2c_p(p))
return B2bH.T_pX(p, X);
else
return B2cH.T_pX(p, X);
}
else
{
if (p <= 4.0)
return B2aS.T_pX(p, X);
else if (X >= Constants.S2bc)
return B2bS.T_pX(p, X);
else
return B2cS.T_pX(p, X);
};
case IF97REGIONS.REGION_3:
if (inkey == IF97Parameters.h)
{
if (X <= BackwardsRegion.H3ab_p(p))
return B3aH.T_pX(p, X);
else
return B3bH.T_pX(p, X);
}
else
{
if (X <= Constants.Scrit)
return B3aS.T_pX(p, X);
else
return B3bS.T_pX(p, X);
};
case IF97REGIONS.REGION_4: return Tsat97(p);
default: throw new ArgumentOutOfRangeException("Unable to match region");
}
} // Region Output backward
static IF97BACKREGIONS RegionDetermination_HS(double h, double s)
{
// Check Overall Boundaries
if ((s < Constants.Smin) || (s > Constants.Smax))
throw new ArgumentOutOfRangeException("Entropy out of range");
if ((h > Hmax(s)) || (h < Hmin(s)))
throw new ArgumentOutOfRangeException("Enthalpy out of range");
// ============================================================================
// Start at the low entropy curves and work our way up.
// =================================== Region 1 Check =========================
if (s <= Constants.SfT23)
{
if (h < BackwardsRegion.Hsat_s(s)) // If below Saturated Liquid Curve
return IF97BACKREGIONS.BACK_4; // REGION 4
else if (s < Constants.S13min) // If below H13 Curve
return IF97BACKREGIONS.BACK_1; // REGION 1
else
{ // IF within H13 Curve (S13min < s < SfT23)
if (h < b13.h_s(s)) // below curve
return IF97BACKREGIONS.BACK_1; // REGION 1
else // above curve
return IF97BACKREGIONS.BACK_3A; // REGION 3
} //
}
else if (s <= Constants.Scrit)
{ //========== Region 3a Check (S < Scrit) ==============
if (h < BackwardsRegion.Hsat_s(s)) // If below Saturated Liquid Curve
return IF97BACKREGIONS.BACK_4; // REGION 4
else // If above curve
return IF97BACKREGIONS.BACK_3A; // REGION 3(a)
}
else if (s <= Constants.S23min)
{ //========== Region 3b Check ==============
if (h < BackwardsRegion.Hsat_s(s)) // If below Saturated Liquid Curve
return IF97BACKREGIONS.BACK_4; // REGION 4
else // If above curve
return IF97BACKREGIONS.BACK_3B; // REGION 3(a)
}
else if (s <= Constants.S23max)
{ //========== Region 3b/2c Check Along B23 Curve ======
if (h < BackwardsRegion.Hsat_s(s)) // if below Saturated Vapor Curve
return IF97BACKREGIONS.BACK_4; // REGION 4
else if (h < Constants.H23min) // if below bounding box
return IF97BACKREGIONS.BACK_3B; // REGION 3(b)
else if (h > Constants.H23max) // if above bounding box
return IF97BACKREGIONS.BACK_2C; // REGION 2(c)
else
{ // Need to check TB23 Curve
double TB23 = b23hs.t_hs(h, s); // Calc TB23(h,s)
double PB23 = Region23_T(TB23); // Calc Corresponding PB23
double P = R2c.p_hs(h, s); // Calc P(h,s) using Region 2c
if (P > PB23) // Above B23 Curve
return IF97BACKREGIONS.BACK_3B; // REGION 3(b)
else // Below B23 Curve
return IF97BACKREGIONS.BACK_2C; // REGION 2(c)
}
}
else if (s <= Constants.S2bc)
{ //========== Region 3b Check ==============
if (h < BackwardsRegion.Hsat_s(s)) // If below Saturated Liquid Curve
return IF97BACKREGIONS.BACK_4; // REGION 4
else // If above curve
return IF97BACKREGIONS.BACK_2C; // REGION 2(c)
}
else if (s < Constants.Sgtrip)
{ //========== Region 2a/2b (s > S2bc) above Sat. Curve ==
if (h < BackwardsRegion.Hsat_s(s)) // If below Saturated Vapor Curve
return IF97BACKREGIONS.BACK_4; // REGION_4
else
{ // If above Curve then
if (h > BackwardsRegion.H2ab_s(s)) // if h > h2ab(s) Curve (P=4 MPa)
return IF97BACKREGIONS.BACK_2B; // REGION 2(b)
else // if h < h2ab(s) Curve (P=4 MPa)
return IF97BACKREGIONS.BACK_2A; // REGION 2(a)
}
}
else
return IF97BACKREGIONS.BACK_2A; //========== Region 2a fall thru ========================
}// Region Determination HS
