General Considerations
General Considerations
Unlike conductive and convective heat transfer, radiation heat transfer can occur
in the absence of matter
Emission is due to the propagation of photons or quanta. It can also be viewed as
the propagation of
View Factor Integral
The View Factor (also Configuration or Shape Factor)
The view factor,
is a geometrical quantity corresponding
to the fraction of the radiation leaving surface i that is intercepted by
surface j.
Qi j Ai J i Fij where J i Ei i Gi
E,
G
Entrance Conditions
Must distinguish between entrance and fully developed regions.
Hydrodynamic Effects: Assume laminar flow with uniform velocity profile at
inlet of a circular tube.
Velocity boundary layer develops on surface of tube and thickens wit
Introduction
How to determine convection heat transfer coefficients for flows over different
surfaces and shapes
Here we assume forced convection (pump, fan, etc.) with no phase change
We learned that heat/mass transfer coefficients can be correlated via
Types
Heat Exchanger Types
Heat exchangers are ubiquitous to energy conversion and utilization. They involve
heat exchange between two fluids separated by a solid and encompass a wide
range of flow configurations.
Concentric-Tube Heat Exchangers
Parallel
General Considerations
General Considerations
Mass transfer refers to mass in transit due to a species concentration gradient
in a mixture.
Must have a mixture of two or more species for mass transfer to occur.
The species concentration gradient is the
Two-film Theory
Two-film Theory
Simultaneous transport/mass transfer in two adjacent phases. This leads to the
formation of two film resistances, and brings us to the so-called two-film theory
In the case of equilibrium at the phase
boundary, from thermo
Chapter-1
Course Description
This course covers the principles of heat and mass transfer. The contents include
conductive and convective heat transfer; radiation heat transfer; process heat
exchangers; diffusion mass transfer; Two-film theory; Gas scrubbe
Introduction to Convection
When cold air blows over a hot surface, it sweeps away hot air entangled with the
hot surface and constantly replaces it with cold air. The amount of heat and mass
transfer is dictated by the motion of the air over the surface.
Fouriers Law
A rate equation that allows determination of the conduction heat flux
from knowledge of the temperature distribution in a medium
Its most general (vector) form for multidimensional conduction is:
q k T
Implications:
Heat transfer is in the
General Considerations
Free convection refers to fluid motion induced by buoyancy forces.
Buoyancy forces may arise in a fluid for which there are density gradients
and a body force that is proportional to density.
In heat transfer, density gradients a
A Shell and Tube HX with single shell and single tube passes is used to cool the oil
of a large marine engine. Lake water on the shell side enters at 2kg/s and 15oC, the oil
enters the tubes at 1kg/s and 140oC. The oil flows trough 100 tubes, each 500mm l
Complex Shell-and-Tube and Cross-Flow Heat Exchangers:
the appropriate form of DTlm is obtained by applying correction factor F to the
Value of DTlm that would be calculated under the assumption of parallel flow (e.g. double-pipe):
F = f ( P, R )
P is
Exercise 1
A simple sorting algorithm (without using the built in sort functions).
The VI should have a numeric control array on the front panel which the user can fill (by hand) with a
random sequence of numbers.
When the program is run, it should sort t
CHEN 351 Process Instrumentation and Measurement
Assignment III
Problem 1:
Indexing elements into an array using while loops.
Watch the 2 minute tutorial to learn more about indexing tunnels in structures in labview:
https:/www.youtube.com/watch?v=hnutkQv
CHEN 351 Process Instrumentation and Measurement
Assignment I
Instructions:
Make sure to submit a separate VI for each problem.
The VI should be named with your AUBnet name (e.g. nk64) followed by the problem number (i.e.
nk64_assignment1_problem1).
CHEN 351 Process Instrumentation and Measurement
Assignment IV
Problem 1:
An XY graph requires 2 arrays of values, one array representing the values of the x-axis of the plot, and
the second representing the y-axis. Note that both arrays should be t
CHEN351 - Process Instrumentation and Measurements
Lab F inal Exam
Problem 1:
Create a VI with 2 array (numeric) controls on the front panel. The first will store the X coordinates and the 2", Y.
The data the user will insert will represent the coordinate
CHEN 351 Process Instrumentation and Measurement
Assignment II
Instructions:
Make sure to submit a separate VI for each problem.
The VI should be named with your AUBnet name (e.g. nk64) followed by the problem number (i.e.
nk64_assignment1_problem1).
Mass Balance
General problem solving strategy
Mass balance problem solving approach
Batch versus Continuous versus Semi-batch
Steady state versus Transient
Types of Mass Balance Problems
A mixing problem (two streams in, one stream out)
A condenser (one s
Special form of the Energy balance Equation
In chemical process units such as reactors, distillation columns, evaporators and heat exchangers shaft work
and kinetic and potential energy terms tend to be negligible compared with heat flows and internal ene
Balances on Reactive Processes
Incomplete Combustion of Methane
Methane is burned with air in a continuous steady state combustion reactor to yield a mixture of carbon
monoxide, carbon dioxide and water. The reactions taking place are:
CH4
O2
CH4 2O2
CO
2
MATERIAL BALANCES FOR
REACTING SYSTEMS
Chapters 9 and 10 (7th Edition)
Chapter 5 (8th Edition)
Mass Balance for Reacting Units
Stoichiometry
Limiting reactant
Fractional Excess and conversion
Extent of Reaction
Multiple Reactions: Yield and Selectivity
Ba
BASIC CONCEPTS AND DEFINITIONS
Contents
Units and Dimensions
Conversion Factors
Dimensional Homogeneity
Significant Figures and Errors
Mole
Solutions, mole fractions and mass fractions
Measures of Concentration
Density and Specific Gravity
Temperature
Pre
Material Balances for Multi-Unit Systems
Process Flow Diagram (Sheet) vs Block Diagram
Sequential Multi-Unit Systems
Mixers and Splitters
Recycle Streams
Bypass Streams
Purge Streams
1
Multiple Units
Schematic of an activated sludge process.
Multipl
Gases, Vapours, Liquids and Solids
Unit 3: Contents
Ideal Gas Equation of State
Deviations from Ideal Gas Law:
Compressibility Factor
Equations of State
Vapour Liquid Equilibria
Vapour Pressure
Gibbs Phase Rule
Raoults Law
Henrys Law
Vapour Liquid Eq
Enthalpy Change
Suppose, for example, that we wish to calculate the change in
enthalpy for a process in which solid phenol at 25C and 1 atm is
converted to phenol vapor at 300 C and 3 atm. If we had a table of
enthalpies for phenol, we could simply subtra
Derivation of the equation (variation with depth)
To obtain a relation for the variation of pressure with depth, consider a
rectangular fluid element of height z, length x, and unit depth (into the
page) in equilibrium, as shown in the figure below. Assum