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Thermodynamic R&E

Thermodynamic R&E. Rational Thermodynamics. Identify the canonical variables of the model. In practice either or These are homogeneous functions which can be added to yield a total contribution:. Rational Thermodynamics.

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Thermodynamic R&E

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  1. Thermodynamic R&E

  2. Rational Thermodynamics • Identify the canonical variables of the model. In practice either or • These are homogeneous functions which can be added to yield a total contribution:

  3. Rational Thermodynamics • The standard state contribution can be split into new (sub)contributions:

  4. Rational Thermodynamics • Proposition: Only 3 algebraic operators are needed for a thermodynamic setup! 1) The chain operator for doing things like: 2) The patch operator for defining sub-graphs:

  5. Rational Thermodynamics • Operator precedence: patch (*) > chain (+) • An equation of state VLE model can now be written: • Where the standard state is defined as:

  6. + * * * Rational Thermodynamics • An equivalent calculation graph is:

  7. Rational Thermodynamics • The object is stored in an “onion-structure”:

  8. Rational Thermodynamics n = [‘Nitrogen’,’O2’,’ARGON’] A = Surface.new(n) * ( Helmholtz.new(n) * ( StandardState.new(n) * ( MuT_cp.new(n,:poly3,’ig’,:reid77) * ( MuT_hs.new(n,:h0,’ig’,:reid87) + MuT_hs.new(n,:s0,’ig’,:dippr96) ) ) + EquationOfState.new(n) * ( ModTVN_ideal.new(n,:idealgas,’ig’) ) + EquationOfState.new(n) * ( ModTVN.new(n,:srk,’fl’,:reid77).tell(:m_gd,[‘fl’,’a’,’mfac’],:reid87) ) ) )

  9. Rational Thermodynamics • Helmholtz is explicit in (T,V,N). For practical use the output needs to be transformed into (H,P,N), (S,P,N), (T,V,N), etc: • Legendre: extensive <=> intensive variable. • Massieu: function <=> extensive variable. • A new object is required to take care of the transformations.

  10. Rational Thermodynamics More Ruby code => air=f(H,V/T,N) air = Surface.new(n,:legendre,’p’) * Surface.new(n,:massieu,’s’) * Surface.new(n,:legendre,’-t’) * A

  11. Rational Thermodynamics • Use of operators => thermodynamic frameworks can be described by small, manageable, expressions. • The algebra is not tied to any particular implementation => easy to export, exchange and update model info. • Export formats are Matlab, LaTeX, XML, etc.

  12. H P T H Flowsheet calculations • Example: Propane-butane splitter with multiple coordinate specifications.

  13. Flowsheet calculations • Proposition: Networks of thermodynamic nodes can be described in terms of U(S,V,N) and f(H,V/T,N). • The functions A(T,V,N), H(S,p,N), S(H,p,N) are obtained by Legendre and Massieu transformations. • Constraints in the extensive coordinates = Euler integration.

  14. Flowsheet calculations • Flash block: • Transformation block: • Mixer block:

  15. Flowsheet calculations • Thermodynamic surface transformations => canonical (and aesthetically pleasing) equation system.

  16. Truths and myths I • Thermodynamics will play an increasingly important role in e.g. model predictive control and fluid dynamics. • Monolithic thermodynamic software has no future (ASPEN, FACT, etc.) • The future lies in distributed & modular software communicating through open protocols (e.g. XML).

  17. Truths and myths II • There will be increased focus on complex systems like acetic acid + HC, urea, formaldehyde, electrolytes, etc. • Statistical mechanics models will replace old work-horses like SRK, PR, etc. • The newer models will be incredibly complex compared to the old ones.

  18. Truths and myths III • Physicists master field theory (e.g. Maxwell’s equations). • Mechanical engineers master turbulence theory (e.g. combustion). • Chemical engineers master multi-component phase theory (e.g. VLLE) => if we don’t succeed in this respect we will be extinct in <10 years.

  19. Challenges for the classroom • Physical chemistry. • Statistical mechanics. • Multi-component phase theory. • Numerical mathematics. • Programming. • Measurements.

  20. Challenges for the future • Phase modeling (reliable & flexible model, predictable cost, fast delivery). • Distributed & modular programming (no waste of time writing & maintaining proprietary program interfaces). • Thermodynamics made easy (high level modeling based on physical insight without numerical fuss).

  21. Things I have not mentioned • TABBE = den Termodynamiske ArBeidsBokEn. • Matlab exercises for SIK2005, SIK2010, SIK2015, SIK2025, SIK3035. • Sublattice NRTL:

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