We plot of the Ponchon-Savarit diagram (i.e.,
H
v
(y)
and
h
l
(x)
) for a methanol-water mixture at a total pressure, P=760 mmHg.
​
In addition, the tie lines or isotherms are shown in green.
​
The data obtained in our simulation agrees very well with those given in Henley and Seader’s classic textbook [1], which are
given below and shown by red dots in the diagram.
​
Finally, we depict the vapor-liquid equilibrium data in a separate diagram.
​
​Reference:​
[1] E. J. Henley and J. D. Seader, Equilibrium-Stage Separation Operations in Chemical Engineering, New York: Wiley, 1981.
​
Expressions for pure component vapor and liquid enthalpies were adapted from Aspen-HYSYS. Enthalpies are above
0°C
and are given in
Btu/lb-mol
.

Plot of the data provided in Henley and Seader' s textbook (i.e., enthalpies expressed in Btu/lbmol)
In[]:=
P1=Show[ListPlot[{{0,20720},{0.05,20520},{0.1,20340},{0.15,20160},{0.2,20000},​​{0.3,19640},{0.4,19310},{0.5,18970},{0.6,18650},{0.7,18310},​​{0.8,17980},{0.9,17680},{1.0,17390}},PlotStyle{Red,PointSize[0.022]},FrameTrue,FrameLabel{Style["methanol mole fraction",14],Style["enthalpy Btu / lb-mol ",14]},GridLinesAutomatic,ImageSize{550,420},PlotStyleThick,AspectRatio1],ListPlot[{{0,3240},{0.05,3070},{0.1,2950},{0.15,2850},{0.2,2760},​​{0.3,2620},{0.4,2540},{0.5,2470},{0.6,2410},{0.7,2370},​​{0.8,2330},{0.9,2290},{1.0,2250}},PlotStyle{Red,PointSize[0.022]},FrameTrue,FrameLabel{Style["methanol mole fraction",14],Style["enthalpy Btu / lb-mol ",14]},GridLinesAutomatic,ImageSize{550,420},PlotStyleThick,AspectRatio1],PlotRange{{0,1},{1500,22000}}]
Out[]=
Total pressure is set equal to 760 mmHg
In[]:=
P=760
Out[]=
760
Antoine Constants and equation for methanol and water.
In[]:=
Aa1=8.08097;Ba1=1582.271;Ca1=239.726;​​Aa2=8.07131;Ba2=1730.63;Ca2=233.426;​​​​Psat1=10^(Aa1-Ba1/(T+Ca1));​​Psat2=10^(Aa2-Ba2/(T+Ca2));
Binary interaction parameters for the Van Laar activity coefficient model
In[]:=
A12=0.76429;A21=0.62569;​​​​Gam1[xa_]:=Exp[A12(A21(1-xa)/(A12xa+A21(1-xa)))^2];Gam2[xa_]:=Exp[A21(A12xa/(A21(1-xa)+A12xa))^2];
Computing VLE data for the binary system: methanol and Water
In[]:=
i=0;​​​​While[i<1001,{xa=i0.001,​​sol=FindRoot[Psat1xaGam1[xa]+Psat2(1-xa)Gam2[xa]P,{T,77,78}];xe[i]=xa,ye[i]=Psat1xaGam1[xa]/P/.sol,​​Te[i]=T/.sol,i++}];​​Tbl1=Table[{xe[i],Te[i]},{i,0,1000}];Tbl2=Table[{ye[i],Te[i]},{i,0,1000}];​​Tbl3=Table[{xe[i],ye[i]},{i,0,1000}];​​​​Tx=Interpolation[Tbl1,InterpolationOrder1];Ty=Interpolation[Tbl2,InterpolationOrder1];xy=Interpolation[Tbl3,InterpolationOrder1];
vapor-phase and liquid-phase enthalpies of the mixture (expressed in Btu/lbmol)
In[]:=
A=(0.0+105.80T-0.181115100T^2+3.1263370010^-004T^3-3.6393090010^-013T^4)/.T(273.15);​​hl1=0.0+105.80T-0.181115100T^2+3.1263370010^-004T^3-3.6393090010^-013T^4-A;​​​​B=(0.0+76.2820400T+2.5651420010^-002T^2-1.1279380010^-004T^3+1.3259630010^-007T^4)/.T(273.15);​​hl2=0.0+76.2820400T+2.5651420010^-002T^2-1.1279380010^-004T^3+1.3259630010^-007T^4-B;​​​​Hv1=50918.3600+93.976T-0.374347200T^2+7.9373420010^-004T^3-6.269264010^-007T^4-A;​​Hv2=47304.1700+107.579100T-0.220258100T^2+3.6616110010^-004T^3-3.2280850010^-007T^4-B;​​​​Hvhysys[y_]:=0.94782×0.45359237(yHv1+(1-y)Hv2)/.T(Ty[y]+273.15);​​hlhysys[x_]:=0.94782×0.45359237(xhl1+(1-x)hl2)/.T(Tx[x]+273.15);
Plot of the Ponchon-Savarit diagram at P=760 mmHg.
Tie-lines are given in Green.
Dew line and bubble line are in Yellow and Blue.
In[]:=
P2=Show[Plot[{hlhysys[x],Hvhysys[x]},{x,0,1},FrameTrue,FrameLabel{Style["methanol mole fraction",14],Style["enthalpy Btu / lb-mol ",14]},GridLinesAutomatic,ImageSize{550,420},PlotStyleThick,PlotRange{{0,1},All},AspectRatio1],Graphics[{Thick,Green,Table[Line[{{i,hlhysys[i]},{xy[i],Hvhysys[xy[i]]}}],{i,0,1,.05}],Black,Table[Style[Text[Row[{ToString[NumberForm[Tx[i],{4,2}]]," °C"}],{(i+xy[i])/2+0.001,(hlhysys[i]+Hvhysys[xy[i]])/2},Automatic,{10000,(hlhysys[i]-Hvhysys[xy[i]])/(i-xy[i])+10}],10],{i,0.05,0.95,0.05}]}]]
Out[]=
Comparison of our data with their counterparts (the red dots) reported in Henley and Seader’s textbook (Ref. 1).
In[]:=
Show[P1,Show[Plot[{hlhysys[x],Hvhysys[x]},{x,0,1},FrameTrue,FrameLabel{Style["methanol mole fraction",14],Style["enthalpy Btu / lb-mol ",14]},GridLinesAutomatic,ImageSize{550,420},PlotStyleThick,PlotRange{{0,1},All},AspectRatio1]],AxesOrigin{0,1500}]
Out[]=
Plot of the VLE diagram at P=760 mmHg. Check of our VLE data against the values given in Ref. 1 (red dots)

CITE THIS NOTEBOOK

Ponchon-Savarit Diagram for the Methanol-Water Binary Mixture at Atmospheric Pressure​
by Housam Binous and Ahmed Bellagi
Wolfram Community, STAFF PICKS, January 12, 2024
​https://community.wolfram.com/groups/-/m/t/3101318