SIMULTANEOUS MASS AND ENERGY BALANCES-2
Example: A simplified flow chart for the synthesis of ethyl chloride is
shown below. The reactor is adiabatic and reactor outlet temperature is 50o
C. In the reactor, ethylene reacts with hydrogen chloride in the pr
SIMULTANEOUS MASS AND ENERGY BALANCES
Example: Coke can be converted to CO (a fuel gas) in the reaction:
CO2(g) + C(s) 2CO(g)
A coke that contains 84.00% carbon by mass and 16.00 % noncombustible
ash is fed to a reactor with a stoichiometric amount of CO2
ENERGY BALANCES WITHOUT CHEMICAL REACTION
Reminder: PE and KE will be neglected unless specified otherwise.
TURBINES: Turbines are devices which convert enthalpy of a fluid into
mechanical work. Operation of a turbine is usually adiabatic (qL=0).
Streams 1, 2 and 5 have identical compositions. Only ONE independent
mass balance can be written for the splitter.
Example: Fresh fruit juice is to be concentrated by evaporating
water.(Why?) In ord
Except for a single rule change for counting the number of
independent equations, problems involving reactive processes
are solved in exactly the same way non-reactive processes are
Rule for counting the number of independent ma
In an absorption tower (absorber), a gas is contacted with a liquid such that
one or more components in the gas are transferred into the liquid which is
called solvent. Absorption processes have the following characteristics: The
purpose of the u
THE GENERAL ENERGY BALANCE
Energy exists in different forms such as heat, work, potential
energy, kinetic energy, internal energy, etc. The sum of these
different forms remains constant, i.e., energy is conserved.
Therefore an energy balance around a cont
Example: Humid air at 28C has a dew point of 8C. Using the
psychrometric chart provided, determine the following: relative
humidity, absolute humidity, wet-bulb temperature, dry-bulb
temperature, humid volume, specific enthalpy, and mass of air that
October 26, 2015
Instructions: This is an open book, open notes exam.
Photocopies are not allowed. You are not allowed to
detach papers. Duration is 90 minutes. Whenever you use
data from your book, indicate page and table number.
Psychrometric charts display thermodynamic properties of
humid air (air+water vapor mixtures).
Pure water has a vapor pressure which is a function of
Humid air is
ENERGY BALANCE WITH RECYCLE
Example: 2000.00 kg/hr of wet solids (40.00 % by weight moisture)are
completely dried in a drier where air is blown over the solids. Fresh air
(60o F dry bulb, 45o F wet bulb) is mixed with recycled air (112o F dry
bulb, 104o F
1. There are 5 students in a course. They have achieved
following grades from the course. MT=Midterm, F=Final
MT_1=[60 50 55 65 84]';
MT_2=[50 20 75 75 80]';
F=[60 45 65 75 90]';
Q_1=[80 95 85 85 100]';
Q_2=[80 70 90 90 90]';
Q_3=[90 80 85 85
ENERGY BALANCES WITH CHEMICAL REACTION
Chemical reactions are usually accompanied by strong heat effects: Some
reactions require heat supply in order to take place (endothermic)
whereas some reactions release heat (exothermic) when they take place.
DETERMINATION OF SPECIFIC ENTHALPIES
Pure Substance: h = h(T, P)
Mixture: h = h(T, P, X)
WE USUALLY NEGLECT EFFECT OF PRESSURE!
First: Look it up!
TABLES, CHARTS, DIAGRAMS are available. Internet, books,
Specific enthalpy values are relati
ENERGY BALANCES WTH CHEMICAL REACTION 2
Example: Formaldehyde is produced in a continuous reactor by oxidizing
methane with pure oxygen. Feed streams of 50.00 mol/h of methane and
50.00 mol/h of pure oxygen are fed at 100oC. The exit stream molar flow