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 Re: [Freesteam-users] Calculate Density as a function of Pressure and Enthalpy From: John Pye - 2008-10-11 08:12:58 ```Hi Javier Those derivatives are not currently implemented in freesteam. It should be possible to determine them, at least for some of the regions, using the 'supplementary equations' of IAPWS-IF97, but I haven't currently implemented that. If you'd like to help out with the implementation of that stuff, let me know and I can try to give you some assistance. Cheers JP Javier Bonilla wrote: > Hi again. > > Can I get this information? > > - ddhp - The partial derivative of density with respect enthalpy > keeping pressure constant. > - ddph - The partial derivative of density with respect pressure > keeping enthalpy constant. > > Thank you very much in advance. > > Cheers, Javi. > > Javier Bonilla wrote: >> Hi John. >> >> Thank you very much, it's just what I was looking for!. >> >> Regards, Javi. >> >> John Pye wrote: >>> Hi Javier >>> >>> I have uploaded a new example file to Subversion, you can view it here: >>> >>> http://freesteam.svn.sourceforge.net/viewvc/freesteam/freesteam/trunk/example/dens_ph.cpp?revision=456&view=markup >>> >>> FWIW, as I recall, there are some small errors with the (p,h) solver in >>> the vicinity of the critical point. Depending on your application you >>> might need to be wary of that. >>> >>> I'd be very interested to hear about your application of freesteam -- >>> are you doing some DSG calculation, perhaps? I'm involved in solar >>> energy too, at ANU in Canberra, Australia. Good luck! >>> >>> Cheers >>> JP >>> >>> Javier Bonilla wrote: >>> >>>> Hi! >>>> >>>> I only want to know if it is possible to calculate density in function >>>> of pressure and specific enthalpy using the last version of freesteam 0.8.1. >>>> >>>> Thanks in advance, Javi. >>>> >>>> >>>> >>> >>> >> >> -- >> ---------------------------------------- >> - Javier Bonilla Cruz - >> - CIEMAT - Plataforma Solar de Almería - >> - Automática e Informática Industrial - >> - - >> - Crta. de Senés, s/n - >> - 04200 TABERNAS - >> - ALMERÍA - >> - - >> - Tlf: +34 950 387803 - >> - Fax: +34 950 365015 - >> - Web: http://www.psa.es - >> - - >> - E-mail: javier.bonilla@... - >> ---------------------------------------- >> > > -- > ---------------------------------------- > - Javier Bonilla Cruz - > - CIEMAT - Plataforma Solar de Almería - > - Automática e Informática Industrial - > - - > - Crta. de Senés, s/n - > - 04200 TABERNAS - > - ALMERÍA - > - - > - Tlf: +34 950 387803 - > - Fax: +34 950 365015 - > - Web: http://www.psa.es - > - - > - E-mail: javier.bonilla@... - > ---------------------------------------- > > ------------------------------------------------------------------------ > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's challenge > Build the coolest Linux based applications with Moblin SDK & win great prizes > Grand prize is a trip for two to an Open Source event anywhere in the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > ------------------------------------------------------------------------ > > _______________________________________________ > Freesteam-users mailing list > Freesteam-users@... > https://lists.sourceforge.net/lists/listinfo/freesteam-users > ```
 Re: [Freesteam-users] Calculate Density as a function of Pressure and Enthalpy From: Javier Bonilla - 2008-10-10 12:28:26 Attachments: Message as HTML ```Hi again. Can I get this information? - ddhp - The partial derivative of density with respect enthalpy keeping pressure constant. - ddph - The partial derivative of density with respect pressure keeping enthalpy constant. Thank you very much in advance. Cheers, Javi. Javier Bonilla wrote: > Hi John. > > Thank you very much, it's just what I was looking for!. > > Regards, Javi. > > John Pye wrote: >> Hi Javier >> >> I have uploaded a new example file to Subversion, you can view it here: >> >> http://freesteam.svn.sourceforge.net/viewvc/freesteam/freesteam/trunk/example/dens_ph.cpp?revision=456&view=markup >> >> FWIW, as I recall, there are some small errors with the (p,h) solver in >> the vicinity of the critical point. Depending on your application you >> might need to be wary of that. >> >> I'd be very interested to hear about your application of freesteam -- >> are you doing some DSG calculation, perhaps? I'm involved in solar >> energy too, at ANU in Canberra, Australia. Good luck! >> >> Cheers >> JP >> >> Javier Bonilla wrote: >> >>> Hi! >>> >>> I only want to know if it is possible to calculate density in function >>> of pressure and specific enthalpy using the last version of freesteam 0.8.1. >>> >>> Thanks in advance, Javi. >>> >>> >>> >> >> > > -- > ---------------------------------------- > - Javier Bonilla Cruz - > - CIEMAT - Plataforma Solar de Almería - > - Automática e Informática Industrial - > - - > - Crta. de Senés, s/n - > - 04200 TABERNAS - > - ALMERÍA - > - - > - Tlf: +34 950 387803 - > - Fax: +34 950 365015 - > - Web: http://www.psa.es - > - - > - E-mail: javier.bonilla@... - > ---------------------------------------- > -- ---------------------------------------- - Javier Bonilla Cruz - - CIEMAT - Plataforma Solar de Almería - - Automática e Informática Industrial - - - - Crta. de Senés, s/n - - 04200 TABERNAS - - ALMERÍA - - - - Tlf: +34 950 387803 - - Fax: +34 950 365015 - - Web: http://www.psa.es - - - - E-mail: javier.bonilla@... - ---------------------------------------- ```
 Re: [Freesteam-users] Calculate Density as a function of Pressure and Enthalpy From: Javier Bonilla - 2008-10-10 07:29:19 Attachments: Message as HTML ```Hi John. Thank you very much, it's just what I was looking for!. Regards, Javi. John Pye wrote: > Hi Javier > > I have uploaded a new example file to Subversion, you can view it here: > > http://freesteam.svn.sourceforge.net/viewvc/freesteam/freesteam/trunk/example/dens_ph.cpp?revision=456&view=markup > > FWIW, as I recall, there are some small errors with the (p,h) solver in > the vicinity of the critical point. Depending on your application you > might need to be wary of that. > > I'd be very interested to hear about your application of freesteam -- > are you doing some DSG calculation, perhaps? I'm involved in solar > energy too, at ANU in Canberra, Australia. Good luck! > > Cheers > JP > > Javier Bonilla wrote: > >> Hi! >> >> I only want to know if it is possible to calculate density in function >> of pressure and specific enthalpy using the last version of freesteam 0.8.1. >> >> Thanks in advance, Javi. >> >> >> > > -- ---------------------------------------- - Javier Bonilla Cruz - - CIEMAT - Plataforma Solar de Almería - - Automática e Informática Industrial - - - - Crta. de Senés, s/n - - 04200 TABERNAS - - ALMERÍA - - - - Tlf: +34 950 387803 - - Fax: +34 950 365015 - - Web: http://www.psa.es - - - - E-mail: javier.bonilla@... - ---------------------------------------- ```
 Re: [Freesteam-users] Calculate Density as a function of Pressure and Enthalpy From: John Pye - 2008-10-10 03:52:37 ```Hi Javier I have uploaded a new example file to Subversion, you can view it here: http://freesteam.svn.sourceforge.net/viewvc/freesteam/freesteam/trunk/example/dens_ph.cpp?revision=456&view=markup FWIW, as I recall, there are some small errors with the (p,h) solver in the vicinity of the critical point. Depending on your application you might need to be wary of that. I'd be very interested to hear about your application of freesteam -- are you doing some DSG calculation, perhaps? I'm involved in solar energy too, at ANU in Canberra, Australia. Good luck! Cheers JP Javier Bonilla wrote: > Hi! > > I only want to know if it is possible to calculate density in function > of pressure and specific enthalpy using the last version of freesteam 0.8.1. > > Thanks in advance, Javi. > > ```
 Re: [Freesteam-users] Calculate Density as a function of Pressure and Enthalpy From: John Pye - 2008-10-09 13:36:15 ```Hi Javier Yes, this is possible. I'll send you an example of how to do this tomorrow. Cheers JP Javier Bonilla wrote: > Hi! > > I only want to know if it is possible to calculate density in function > of pressure and specific enthalpy using the last version of freesteam 0.8.1. > > Thanks in advance, Javi. > > ```
 [Freesteam-users] Calculate Density as a function of Pressure and Enthalpy From: Javier Bonilla - 2008-10-09 12:43:19 ```Hi! I only want to know if it is possible to calculate density in function of pressure and specific enthalpy using the last version of freesteam 0.8.1. Thanks in advance, Javi. -- ---------------------------------------- - Javier Bonilla Cruz - - CIEMAT - Plataforma Solar de Almería - - Automática e Informática Industrial - - - - Crta. de Senés, s/n - - 04200 TABERNAS - - ALMERÍA - - - - Tlf: +34 950 387803 - - Fax: +34 950 365015 - - Web: http://www.psa.es - - - - E-mail: javier.bonilla@... - ---------------------------------------- ```
 Re: [Freesteam-users] Code for Water/Steam properties From: John Pye - 2008-10-09 04:26:47 ```Hi KP KP wrote: > Hi JP, > > I was actually aware of the freesteam project before I wrote my code. > The code I wrote was a minor part of a different application and the > powers that be did not appreciate the "licensing" situation with > freesteam. Also, I'm not a big fan of the template laden approach ... > but every code has its niche. But with regards to freesteam, I'll > check it out and take a look. > The template-laden code in freesteam is exactly the sort of thing that it would be good to clean up a bit. I think that it should be pretty easy to clear out the templates for the core evaluation routines, and just leave the template layer in place for the Solver2 code, perhaps. That way, people could use the core routines (IAPWS-95 and IAPWS-IF97) directly, and just use the Solver2 code if they particular environment doesn't provide something equivalent. freesteam could be divided into two libraries that way - the core library and a solver library. > Also, I was wondering ... are you aware of any IAPWS95 implementations > that use TTSE approach (Tabular Taylor Series Expansion)? It's my > understanding that it's much faster and is probably easier to write > solver routines around. > I've heard mention of this but haven't tried an implementation as yet; it sounds quite interesting. I found this paper: http://cat.inist.fr/?aModele=afficheN&cpsidt=2653137 For the moment, with FPROPS, I've been trying to get a 'first-pass' accurate and complete implementation of Helmholtz-based property evaluation, with the intention of adding optimisations later on. Also, I note that the code for REFPROP (from NIST) seems to include some code that caches powers of delta and tau, to improve speed; whether that turns out to be a comparable efficiency improvement I don't know. FWIW in freesteam, there is a some optimisation, which is that a 'steam state' is returned from the Solver or Solver2 routines (single- or two-variable iteration), which means that once the state has been determined, subsequent property evaluations, eg h(T,s), p(T,s), rho(T,s) don't require any further iteration. Cheers JP > --KP > > On Oct 8, 6:57 pm, John Pye wrote: > >> Hi KP >> >> Thanks for that. Before you implement IAPWS-IF97 you might want to look >> at freesteam, which implements quite a lot of it and includes a CppUnit >> test suite, as well as IAPWS-95 for validation, and has hooks for Python >> as well as ASCEND. It's all in C++ and includes some use of templates >> for dealing with units of measurement and some algorithms. Perhaps >> rather than starting a new project, you might like to collaborate on >> improving the freesteam code a little further? >> >> freesteamhttp://freesteam.sourceforge.net/http://freesteam.svn.sourceforge.net/viewvc/freesteam/freesteam/trunk/ >> >> One aspect of freesteam that works rather well is the 'Solver2' >> interface which gives a robust calculation of properties in terms of >> (p,h), (p,s), (u,v), (T,s) and various other combinations. This was >> rather difficult to implement in the case of IAPWS-IF97 because of the >> way that the correlation is given in terms of different independent >> variables in different regions. >> >> You might also want to look at FPROPS, which I mentioned previously, >> which is currently confined to just Helmholtz energy functions, such as >> as IAPWS-95, written in pure C:http://ascendcode.cheme.cmu.edu/viewvc.cgi/code/branches/extfn/models... >> >> Cheers >> JP >> >> KP wrote: >> >>> Hi all: >>> >>> I know some of you are working on thermodynamic property prediction. >>> I've just uploaded some c and python source that implements the >>> IAPWS95 and IAPWS84 standards for water/steam. I hope people will find >>> this useful and avoid duplicate efforts. >>> >>> The project is hosted athttp://code.google.com/p/proph2o/ >>> >>> Thanks, >>> KP >>> > --~--~---------~--~----~------------~-------~--~----~ > You received this message because you are subscribed to the Google Groups "Open source Process Simulator" group. > To post to this group, send email to opsim@... > To unsubscribe from this group, send email to opsim+unsubscribe@... > For more options, visit this group at http://groups.google.com/group/opsim?hl=en > -~----------~----~----~----~------~----~------~--~--- > > ```
 Re: [Freesteam-users] isoentropic process From: Maxim A. Belov - 2008-10-07 12:48:44 ```Hi Thank you very much for your solution! John Pye пишет: > Hi Maxim > > Did you try using the 'Solver2' interface? It seems to work OK when I > try it: > > john@...:~/freesteam/example\$ g++ -L/usr/lib -lfreesteam > -I/usr/include isentropic.cpp && ./a.out > >From 14 bar, 250 C ---> 6 bar > T1 = 523.15 K = 250 °C > p1 = 1.4e+06 Pa > T2 = 431.982 K = 158.832 °C > p2 = 600000 Pa > >From 10 bar, 191 C ---> 4 bar > T1 = 464.15 K = 191 °C > p1 = 1e+06 Pa > T2 = 416.763 K = 143.613 °C > p2 = 400000 Pa > > See attached source code. > > Cheers > JP > > Maxim A. Belov wrote: > >> Greetings >> I tried to use freesteam library to calculcate isoentropic >> steam decompression from pressure p0 to pressure p1 with initial >> temperature t1. >> >> I use SteamCalculator to get entropy s for state p0,t0 >> then i have to calculate parameters of second state >> I use Solver to get required state, but >> it fails for some parameters >> >> for example, for t0=250 C, p0 = 14 bar, p1 = 6 bar such approach works >> but for t0=191 C, p0 = 10 bar, p1 = 3 bar Solver fails. >> >> I tried to solve the equation for the 2nd case without solver object - I >> need to find temperature for a state with pressure p1 and entropy s (in >> decribed case it's 6,648 kJ/kgK). I saw that there is a phase transition >> from steam to water. But in this case i need steam in region 4. so I >> make use of the following >> >> >> try { >> >> S1.set_PT(p0,t0) >> s = S1.specentropy() >> >> // solver succeeded >> } catch { >> // solver failed >> >> > varying steam quality> >> } >> >> >> and it works. >> >> >> Finally, my question >> >> Is there a way to simulate isoentropic decompression for any parameters >> by using only Solver? >> >> >> >> ------------------------------------------------------------------------- >> This SF.Net email is sponsored by the Moblin Your Move Developer's challenge >> Build the coolest Linux based applications with Moblin SDK & win great prizes >> Grand prize is a trip for two to an Open Source event anywhere in the world >> http://moblin-contest.org/redirect.php?banner_id=100&url=/ >> _______________________________________________ >> Freesteam-users mailing list >> Freesteam-users@... >> https://lists.sourceforge.net/lists/listinfo/freesteam-users >> >> > > ```
 Re: [Freesteam-users] isoentropic process From: John Pye - 2008-10-07 00:07:39 Attachments: isentropic.cpp ```Hi Maxim Did you try using the 'Solver2' interface? It seems to work OK when I try it: john@...:~/freesteam/example\$ g++ -L/usr/lib -lfreesteam -I/usr/include isentropic.cpp && ./a.out >From 14 bar, 250 C ---> 6 bar T1 = 523.15 K = 250 °C p1 = 1.4e+06 Pa T2 = 431.982 K = 158.832 °C p2 = 600000 Pa >From 10 bar, 191 C ---> 4 bar T1 = 464.15 K = 191 °C p1 = 1e+06 Pa T2 = 416.763 K = 143.613 °C p2 = 400000 Pa See attached source code. Cheers JP Maxim A. Belov wrote: > Greetings > I tried to use freesteam library to calculcate isoentropic > steam decompression from pressure p0 to pressure p1 with initial > temperature t1. > > I use SteamCalculator to get entropy s for state p0,t0 > then i have to calculate parameters of second state > I use Solver to get required state, but > it fails for some parameters > > for example, for t0=250 C, p0 = 14 bar, p1 = 6 bar such approach works > but for t0=191 C, p0 = 10 bar, p1 = 3 bar Solver fails. > > I tried to solve the equation for the 2nd case without solver object - I > need to find temperature for a state with pressure p1 and entropy s (in > decribed case it's 6,648 kJ/kgK). I saw that there is a phase transition > from steam to water. But in this case i need steam in region 4. so I > make use of the following > > > try { > > S1.set_PT(p0,t0) > s = S1.specentropy() > > // solver succeeded > } catch { > // solver failed > > varying steam quality> > } > > > and it works. > > > Finally, my question > > Is there a way to simulate isoentropic decompression for any parameters > by using only Solver? > > > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's challenge > Build the coolest Linux based applications with Moblin SDK & win great prizes > Grand prize is a trip for two to an Open Source event anywhere in the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > _______________________________________________ > Freesteam-users mailing list > Freesteam-users@... > https://lists.sourceforge.net/lists/listinfo/freesteam-users > ```
 [Freesteam-users] isoentropic process From: Maxim A. Belov - 2008-10-05 09:25:38 ```Greetings I tried to use freesteam library to calculcate isoentropic steam decompression from pressure p0 to pressure p1 with initial temperature t1. I use SteamCalculator to get entropy s for state p0,t0 then i have to calculate parameters of second state I use Solver to get required state, but it fails for some parameters for example, for t0=250 C, p0 = 14 bar, p1 = 6 bar such approach works but for t0=191 C, p0 = 10 bar, p1 = 3 bar Solver fails. I tried to solve the equation for the 2nd case without solver object - I need to find temperature for a state with pressure p1 and entropy s (in decribed case it's 6,648 kJ/kgK). I saw that there is a phase transition from steam to water. But in this case i need steam in region 4. so I make use of the following try { S1.set_PT(p0,t0) s = S1.specentropy() // solver succeeded } catch { // solver failed } and it works. Finally, my question Is there a way to simulate isoentropic decompression for any parameters by using only Solver? ```

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