5 replies to this topic

[Alpe]

I need to calculate vapor and liquid flows plus thermo physical properties (density, heating value, viscosity , thermal conductivity) for both vapor and liquid in different zones (zone analysis) of heat exchangers,

 

I know I can simulate heat exchangers in Excel with Prode Properties solving flash operations but how can I calculate vapor and liquid flows ?

Prode gives phase fractions (vapor, liquid, solid) not the flows,

can you provide a working example ? (with VBA or Excel macros)

 

Thanks !

[PaoloPemi]

there was a Excel page showing how to calculate properties in different zones I attach a copy, you can examine the VBA code for details,

 

Prode Properties can export flows or you can calculate from (molar) phase fractions and molar weights of different fractions, see this VBA example

 

PF = StrLf(Stream)
If (PF > 0.000001) Then ' Liquid present ?
            mw = StrLMw(Stream)
            Cells(rpt + I, 6) = W * PF * mw / mwm ' Liquid Flow

 

and so on...

 

you can calculate mixture properties (density, viscosity, thermal conductivity etc.) in different ways,

Prode Properties exposes methods StrGD, StrLD etc. (there are about 300 methods...)

in this Excel VBA example the procedure calculates vapor properties as

 

            Cells(rpt + I, 14) = StrGMw(Stream)
            Cells(rpt + I, 15) = StrGCp(Stream)
            Cells(rpt + I, 16) = StrZv(Stream)
            Cells(rpt + I, 17) = StrGD(Stream)
            Cells(rpt + I, 18) = StrGV(Stream)
            Cells(rpt + I, 19) = StrGC(Stream)

 

of course different variants are possible (many methods available),

 

you can solve many different Flash Operations with Prode Properties, in this case (heat exchanger simulation) the procedure solves a operation with specified P and H but different alternatives are possible

 

 htcprops.xls   176.5KB   50 downloads

[Alpe]

thanks,

about alternatives, does StrLf(Stream) offer some advantages over StrPF(Stream,1)  ?

[PaoloPemi]

StrLf(Stream) returns the total liquid fraction (with two liquid phases you obtain the total)

StrPf(Stream,Ph) returns the molar fraction of phase Ph which can be vapor, liquid or solid / hydrate ,

it depends from application...

[mgerian]

thanks Paolo for the Excel VBA example

[chemdoc]

thanks !