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Introduction toTransport Phenomena

ChE 131 Transport Processes

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Outline

¤ Welcome to the class

 – What is transport phenomena?

 – Why is it important for chemical engineers?

 – How are we going to learn it in this class?

 –Basic concepts and definitions

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 What is Transport Phenomena?

¤ Application of conservation equations

¤ Analysis of how physical systems approach equilibrium

¤ A core chemical engineering science

¤ Traditionally comprised of 

MomentumTransfer

Heat Transfer Mass Transfer

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 What is Transport Phenomena?

¤ Application of conservation equations

 – Mass, energy, chemical species, momentum (linear and

angular), charge, etc.

 – Whether the system is

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Transport Phenomena in ChE

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Transport Phenomena in Other Fields

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Class Policies

¤ University rule on attendance: max of 6 absences

 –>6 and the instructor has the prerogative to drop you from theclass

¤ Exams – Mondays (Mar 9, Apr 20, May 18, May 25)

 – Submit answer sheets one meeting BEFORE the exam

 –  Automatic 10-point deduction for late answer sheets

 – One-week grievance period ONLY

 –NO make-up exam

¤ Design Project – To be done in teams of 3 (all members in the same section)

 – Details TBA (after LE1)

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Basic Concepts and Definitions

¤ Functional notation:

¤ Steady-state:

¤ Uniform:

¤ Flux = flow rate / area

 – Volume:   velocity

 –

Momentum: 

stress – Energy:

 – Mass:

(,,,)   ,, = 0   ,,

=     ,,=     ,,

= 0

1 

 =

 

1 

  = 1

  =

 

1 

 =

   ∙

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Basic Concepts and Definitions

¤ Total flow rate

 – If flux is constant: flux x area

 – If flux is varying with area:

¤ Average flow rate:

¤ Total volume property or rate

 – If property or rate is uniform or constant:

 – If property or rate is varying with volume:

 

 

  ×

 

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Basic Concepts and Definitions

¤ Ex. Energy generation rate per unit volume as a resultof an electric current passing through a rectangular

plate of cross sectional area A and thickness L is given

by

 –What is the unit of S0 in SI system?

 – Calculate the total energy generation rate in the plate

 = sin

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Basic Concepts and Definitions

¤ Ex. A fluid is flowing in the z-direction between twoparallel plates of length L and width W, separated by a

distance 2B. The steady-state velocity profile given as

 – Calculate the average velocity.

 – Express the velocity profile in terms of the average velocity

 – Calculate the volumetric flow rate.

 =   Δ 2 1 −  

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Basic Concepts and Definitions

¤ Ex. A fluid is flowing in the z-direction between twoparallel plates of length L and width W, separated by a

distance 2B.

 – Show that if the coordinate system was chosen as shown

below, the velocity profile will be

 –Show that the average velocity and volumetric flow rate arethe same in both coordinate systems.

 =   Δ2 2

   −