digplanet beta 1: Athena
Share digplanet:

Agriculture

Applied sciences

Arts

Belief

Business

Chronology

Culture

Education

Environment

Geography

Health

History

Humanities

Language

Law

Life

Mathematics

Nature

People

Politics

Science

Society

Technology

In thermodynamics, a departure function is defined for any thermodynamic property as the difference between the property as computed for an ideal gas and the property of the species as it exists in the real world, for a specified temperature T and pressure P. Common departure functions include those for enthalpy, entropy, and internal energy.

Departure functions are used to calculate real fluid extensive properties (i.e. properties which are computed as a difference between two states). A departure function gives the difference between the real state, at a finite volume or non-zero pressure and temperature, and the ideal state, usually at zero pressure or infinite volume and temperature.

For example, to evaluate enthalpy change between two points h(v1,T1) and h(v2,T2) we first compute the enthalpy departure function between the v1 and infinite volume at T=T1, then add to that the ideal gas enthalpy change due to the temperature change from T1 to T2, then subtract the departure function value between v2 and infinite volume.

Departure functions are computed by integrating a function which depends on an equation of state and its derivative.

General Expressions[edit]

General Expressions for the Enthalpy H, the Entropy S and the Gibbs Energy G are given by[1]

Departure functions for Peng-Robinson equation of state[edit]

The Peng-Robinson equation of state relates the three interdependent state properties pressure P, temperature T, and molar volume Vm. From the state properties (P, Vm, T), one may compute the departure function for enthalpy per mole (denoted h) and entropy per mole (s)[2]:

Where is defined in the Peng-Robinson equation of state, Tr is the reduced temperature, Pr is the reduced pressure, Z is the compressibility factor, and

Typically, one knows two of the three state properties (P, Vm, T), and must compute the third directly from the equation of state under consideration. To calculate the third state property, it is necessary to know three constants for the species at hand: the critical temperature Tc, critical pressure Pc, and the acentric factor ω. But once these constants are known, it is possible to evaluate all of the above expressions and hence determine the enthalpy and entropy departures.

References[edit]

  • ^ Poling, Prausnitz, O'Connell: The Properties of Gases and Liquids, 5th Ed., McGraw-Hill, 2001. p. 6.5.
  • ^ Kyle, B.G.: Chemical and Process Thermodynamics, 3rd Ed., Prentice Hall PTR, 1999. p. 118-123.

Correlated terms[edit]


Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Departure_function — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.
91012 videos foundNext > 

How to Use Departure Functions : Physics & Chemistry Education

Subscribe Now: http://www.youtube.com/subscription_center?add_user=ehoweducation Watch More: http://www.youtube.com/ehoweducation The departure ...

Departure functions

Difference between real and ideal gas properties.

Departure Function: van der Waals Fluid

Discusses the enthalpy departure function for van der Waals fluid. Made by faculty at the University of Colorado Boulder, Department of Chemical and Biological ...

Entropy and Enthalpy departure from EOS

Enthalpy Departure Function for Throttle Feed

Use the exit conditions from a throttle to determine the enthalpy departure function for the inlet fluid. Made by faculty at the University of Colorado Boulder, ...

Departure Entropy (Review)

Calculates the departure entropy for a real gas. Made by faculty at the University of Colorado Boulder, Department of Chemical and Biological Engineering.

Enthalpy and Entropy Departure Functions (Interactive Simulation)

Describes how to use an interactive simulation that uses the Peng-Robinson equation of state and heat capacities to calculate enthalpy and entropy of real ...

Departure function in Adrena by Charles Caudrelier (Groupama 4)

Planning the start of a race is essential in inshore racing. Charles Caudrelier, skipper in charge of the performance inboard VOR70 Groupama during the Volvo ...

Departure Internal Energy from EOS

Continental 2017 prototype AR-Head Up Display showing Lane Departure Warning function

July 2014 video of Continental's prototype 2017 Augmented Reality Head-Up Display showing the Lane Departure Warning function as the driver sees it. Posted ...

91012 videos foundNext > 

We're sorry, but there's no news about "Departure function" right now.

Loading

Oops, we seem to be having trouble contacting Twitter

Support Wikipedia

A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia. Please add your support for Wikipedia!

Searchlight Group

Digplanet also receives support from Searchlight Group. Visit Searchlight