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Flash column fixed, Energy balance added #49

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Flash column fixed, Energy balance added #49

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2 changes: 1 addition & 1 deletion Simulator/Examples/Flash.mo
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Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,7 @@ package Flash
Placement(visible = true, transformation(origin = {56, -16}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
Simulator.Examples.Flash.ms S3(Nc = Nc, C = C) annotation(
Placement(visible = true, transformation(origin = {54, 28}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
Simulator.Examples.Flash.fls B1(Nc = Nc, C = C) annotation(
Simulator.Examples.Flash.fls B1(BTdef = true, C = C,Nc = Nc, Tdef = 368) annotation(
Placement(visible = true, transformation(origin = {-14, 2}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
equation
//=====================================================================
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25 changes: 18 additions & 7 deletions Simulator/UnitOperations/Flash.mo
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@ model Flash "Model of a flash column to separate vapor and liquid phases from a
//Model Variables
Real T(unit = "K", start = Tg, min = 0) "Flash column temperature";
Real P(unit = "Pa", start = Pg, min = 0) "Flash column pressure";
Real Hin(unit = "kJ/kmol") "Inlet Enthalpy";
Real Pbubl(unit = "Pa", min = 0, start = Pmin) "Bubble point pressure";
Real Pdew(unit = "Pa", min = 0, start = Pmax) "Dew point pressure";
Real F_p[3](each unit = "mol/s", each min = 0,start = {Fg,Fliqg,Fvapg})"Feed stream mole flow";
Expand All @@ -33,6 +34,7 @@ model Flash "Model of a flash column to separate vapor and liquid phases from a
Real S_p[3](each unit = "kJ/[kmol.K]") "Molar entropy in phase";
Real xliq(unit = "-", min = 0, max = 1, start = xliqg)"Liquid phase mole fraction";
Real xvap(unit = "-", min = 0, max = 1, start = xvapg) "Vapor phase mole fraction";
Real Q(unit = "W") "Heat Added / Removed";
//===============================================================================
//Instantiation of Connectors
Simulator.Files.Interfaces.matConn In(Nc = Nc) annotation(
Expand All @@ -58,6 +60,7 @@ equation
In.P = P;
end if;
In.F = F_p[1];
In.H = Hin;
In.x_pc[1, :] = x_pc[1, :];
Out2.T = T;
Out2.P = P;
Expand All @@ -69,29 +72,34 @@ equation
Out1.x_pc[1, :] = x_pc[3, :];
//=================================================================================
//Mole Balance
F_p[1] = F_p[2] + F_p[3];
x_pc[1, :] .* F_p[1] = x_pc[2, :] .* F_p[2] + x_pc[3, :] .* F_p[3];
// F_p[1] = F_p[2] + F_p[3];
for i in 1:Nc loop
x_pc[1, i] .* F_p[1] = x_pc[2, i] .* F_p[2] + x_pc[3, i] .* F_p[3];
end for;
//==================================================================================
//Bubble point calculation
Pbubl = sum(gmabubl_c[:] .* x_pc[1, :] .* exp(C[:].VP[2] + C[:].VP[3] / T + C[:].VP[4] * log(T) + C[:].VP[5] .* T .^ C[:].VP[6]) ./ philiqbubl_c[:]);
//==================================================================================
//Dew point calculation
Pdew = 1 / sum(x_pc[1, :] ./ (gmadew_c[:] .* exp(C[:].VP[2] + C[:].VP[3] / T + C[:].VP[4] * log(T) + C[:].VP[5] .* T .^ C[:].VP[6])) .* phivapdew_c[:]);
if P >= Pbubl then
x_pc[3, :] = zeros(Nc);
F_p[3] = 0;
x_pc[2, :] = x_pc[1, :];
F_p[2] = F_p[1];
F_p[3] = 1e-10;
elseif P >= Pdew then
//===================================================================================
//VLE region
for i in 1:Nc loop
x_pc[2, i] = x_pc[1, i] ./ (1 + xvap * (K_c[i] - 1));
x_pc[3, i] = K_c[i] * x_pc[2, i] ;
end for;
sum(x_pc[3, :]) = 1;
sum(x_pc[2, :]) = 1;
else
//==================================================================================
//above dew point region
x_pc[2, :] = zeros(Nc);
F_p[2] = 0;
x_pc[3, :] = x_pc[1, :];
F_p[3] = F_p[1];
F_p[2] = 1e-10;
end if;
//===================================================================================
//Energy Balance / Specific Heat and Enthalpy calculation from Thermodynamic Functions
Expand All @@ -118,6 +126,9 @@ equation
S_p[1] = xliq * S_p[2] + xvap * S_p[3];
S_pc[1, :] = x_pc[1, :] * S_p[1];
//=======================================================================================
//Energy Balance
F_p[1] * Hin + Q - F_p[2] * sum(H_pc[2, :] .* x_pc[2, :]) - F_p[3] * sum(H_pc[3, :] .* x_pc[3, :]) = 0;
//=======================================================================================
//phase molar fractions
xliq = F_p[2] / F_p[1];
xvap = F_p[3] / F_p[1];
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