1 / 16

Constitutive Relations

Constitutive Relations. What are constitutive relations?. Relate conserved extensive quantities to intensive variables Help define physico-chemical quantities (e.g. enthalpies, densities, viscosities ,…) Define transfer rates (mass, energy, …) Other relations to “constitute” the model.

upton
Download Presentation

Constitutive Relations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Constitutive Relations

  2. What are constitutive relations? • Relate conserved extensive quantities to intensive variables • Help define physico-chemical quantities (e.g. enthalpies, densities, viscosities ,…) • Define transfer rates (mass, energy, …) • Other relations to “constitute” the model

  3. How do constitutive relations arise ? • Related to the terms in the conservation equations for mass, energy and momentum • Convective flow terms (process streams) • Molecular flow streams (fluxes) • Internal processes • Defining intensive variables in terms of extensive quantities and other physico-chemical properties • Constraints on the system (control relations)

  4. Balance volumes, flows and system processes

  5. Classes of Relations

  6. 1. Transfer Relations • General form • Particular forms • mass transfer • heat transfer

  7. 2. Reaction rates • Reaction rate • General reaction expression

  8. 3. Thermodynamic relations • Property relations (density, viscosity, …) • Equilibrium relations • Raoult’s law • Relative volatility, K-value • Activity coefficient

  9. Thermodynamic properties • Enthalpy • linear • nonlinear

  10. Thermodynamic properties • Equations of state • ideal gas • cubic EoS • SRK • Peng Robinson • NRTL

  11. 4. Balance volume relations • Relations between phases VG VL

  12. 5. Equipment and Control • Sensors

  13. 6. Control Elements • Transmitters (4-20mA, 20-100kPa)

  14. Controllers • Traditional (P, PI, PID)

  15. Actuators on valves

  16. Valves • Static valves • Control valves • characteristics

More Related