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  1. delittle

    Isentropic Flash Calculations

    RVAmeche, in this forum you can find several references to Prode Properties since the library includes several equilibrium (HEM) and non-equilibrium (HNE) models, there is an Excel page with VBA code for API HEM (posted by PaoloPemi) but (as far as I know) the procedures included in the library...
  2. delittle

    0.5 ppm max impurity specifications for a distillation Product; Validity of design procedures

    maybe Separation Process Principles (Henley, Seader...) and / or similar textbooks can help
  3. delittle

    Calculation of JT Effect for Gas Temperature Change

    the value dT/dP is not constant over a range of pressures, a better solution is to calculate H1(tin,Pin) and then t(H2,P2) where H2 = H1 for that you need a table with the properties (H) of Silane, suppliers as AirLiquide can provide these tables. As alternative you may run a software, for...
  4. delittle

    Joule-Thomson Inversion Point

    Morten, no problems about different opinions about applications of SRK vs PR equations of state, these EOS are available in almost all simulators and one can test both, by the way many papers suggest SRK over PR for natural gas mixtures. At some conditions positive dT/dP may occour but for such...
  5. delittle

    Joule-Thomson Inversion Point

    can't you model the valve with a flash operation such as H-P and a proper EOS such as Soave Redlich Kwong ? Joule-Thomson calculated at initial t, p provides dT/dP at initial conditions, it is NOT constant over that pressure range, better to integrate enthalpy or another property to estimate the...
  6. delittle

    liquid water carryover in natural gas

    ISO 18453 has the advantage to give a "certified" accuracy within the allowable range of application (both usual and extended) which is good. As noted by zdas04 a chart may result difficult to read and real accuracy in some cases may be questionable.
  7. delittle

    Latent Heat in HYSYS for multicomponent mixture

    Mike, the original post did ask a method for calculating the latent heat of a mixture >I am trying to get a value for latent heat of a mixture. and Hv = SUM(Wi*Hvi) where Wi is the incipient vapor fraction is a correct answer in my opinion the method proposed by Morten >Set the pressure to...
  8. delittle

    Latent Heat in HYSYS for multicomponent mixture

    Mike, the method described by apetri Hv = SUM(Wi*Hvi) where Wi is the incipient vapor fraction (see above posts) should returns the same values as that described by Morten, they both return "istantaneous" values (as mentioned by apetri), You seem to be inferring your conclusion from the...
  9. delittle

    thermophysical properties in Mathcad

    which version of Mathcad ? I have read that there is a link with Prode Properties, see http://communities.ptc.com/community/mathcad/chemical_engineering/blog/2012/12/16/mathcad-links-with-prode-physical-properties Prode has many features and it should be able to do all what you need.
  10. delittle

    PSV discharging temperature (valve outlet)

    Paolo, to answer your question, I do not know of any point in API std. discussing this topic, perhaps you may contact the API Subcommittee on Pressure-Relieving Systems http://mycommittees.api.org/standards/cre/scprs/default.aspx I have read they have been discussing that model (numerical...
  11. delittle

    Gas pipeline packing/unpacking calculations

    thanks BigInch and zdas4, I did suppose something as nonlinear distribution of pressures (and related densities) along the pipe segment but I was unable to explain the origin of the 2/3 rule of thumb.
  12. delittle

    Gas pipeline packing/unpacking calculations

    BigInch I see that you suggest Pavg=P1+(2/3)*(P2-P1) instead of Pavg=P1+(1/2)*(P2-P1) or Pavg = (P1+P2)/2 I am just curious about the reason
  13. delittle

    water H2o density and bulk modulus at 194 C 180 Bar abs

    my copy of IAPWS 1995 steam tables give 883.176 kg/m3 and 13263.97 (Bar) in agreement with values calculated by paolopemi

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