LE 2 - Transport Processes and Unit Operations Flashcards
is states that the mass entering is equal to the mass leaving plus the mass left in the process
law of conservation of mass
This is a special case of heat transfer, which deals with the evaporation of a volatile solvent such as water from a nonvolatile solute such as salt or any other material in solution.
Evaporation
These ____________________ are common to all types of diverse process industries.
Unit Operations
In process engineering, which often takes place at constant pressure, electrical energy, kinetic energy, potential energy, and work either are not present or can be neglected. Then only the enthalpy of the materials (at constant pressure), the standard chemical reaction energy, and the heat added or removed must be taken into account in the energy balance. This is generally called a?
heat balance
The __________________ of a substance is defined as the amount of heat necessary to increase the temperature by 1 degree.
heat capacity
To solve a material-balance problem it is advisable to proceed by a series of definite steps, as listed below.
- Sketch a simple diagram of the process
- Write the chemical equations involved (if any)
- Select a basis for calculation
- Make a material balance
When chemical reactions occur in the balances (as discussed in Section 1.5D), one should use
kg mol units
At present, the ______________ has been adopted officially for use exclusively in engineering and science
SI system
are almost always represented in terms of mole fractions and not weight fractions
gas mixtures
What are the three main systems of basic units employed at present in engineering and science?
- SI (Système International d’Unités) system
- English System
- CGS System
Methods of Expressing Temperatures and Compositions
- Temperature
- Gas-Law Constant
- Ideal Gas Mixtures
- Vapor Pressure and Boiling Point of Liquids
basic unit of heat
joule
The standard preferred unit of time is the
second (s)
For engineering purposes, ________________________ is sufficiently accurate to use for actual mixtures at total pressures of a few atmospheres or less.
Dalton’s law
energy can appear in many form, and some of the common forms are?
- enthalpy
- electrical energy
- chemical energy
- kinetic energy
- potential energy
- work
- heat inflow
in making material balances, we used the?
law of conservation of mass
Unit operations where momentum transfer occurs?
- fluid flow
- sedimentation
- mixing
In this process a component of a gas or a liquid stream is removed and adsorbed by a solid adsorbent.
Adsorption
is defined as the amount of heat needed to raise 1.0 lb water at 1 degrees Fahrenheit
btu (British thermal unit)
The vapor pressure of a liquid increases markedly with?
temperature
This law, stated simply, says that mass cannot be created or destroyed (excluding, of course, nuclear or atomic reactions). Hence, the total mass (or weight) of all materials entering any process must equal the total mass of all materials leaving plus the mass of any materials accumulating or left in the process.
Law of Conservation of Mass
it represent the sum of the internal energy plus the pressure-volume term
enthalpy (H)
The unit operation ________________ is used to purify or separate alcohol in the beverage industry and hydrocarbons in the petroleum industry.
distillation
This concerns the principles that determine the flow or transportation of any fluid from one point to another.
Fluid Flow
includes distillation, absorption, liquid-liquid extraction, membrane separation, adsorption, and leaching
Mass Transfer
The value of the vapor pressure is _________________________ of the amount of liquid in the container as long as some is present.
independent
basic quantity used in the SI system in the unit of an element is the
kilogram mole (kg mol)
This is concerned with the transfer of momentum in moving media, such as in the unit operations of fluid flow, sedimentation, and mixing.
Momentum Transfer
Temperatures are defined in
kelvin (K)
few of the standard prefixes for multiples of the basic unit are as follows:
- giga (G)
- mega (M)
- kilo (K)
- centi (c)
- milli (m)
- micro (µ)
- nano (n)
We can take these seemingly different chemical, physical, or biological processes and break them down into a series of separate and distinct steps called
Unit Operations
One of the basic laws of physical science is the
law of conservation of mass
Unit operations where mas transfer occurs?
- distillation
- absorption
- liquid-liquid extraction
- membrane separation
- adsorption
- leaching
This concerns the removal of a solute such as a salt from a solution by precipitating the solute from the solution.
Crystallization
basic quantity used in the SI system in the unit of time is the
second (s)
states that the total pressure of a gas mixture is equal to the sum of the individual partial pressures
Dalton’s law for mixtures of ideal gasses
Hence, the following classification of a more fundamental nature is often made into
transfer or transport processes
In this operation volatile liquids, usually water, are removed from solid materials.
Drying
is defined as the amount of heat needed to heat 1.0 g water 1.0 degrees celsius
g calorie (cal)
These involve separation of solids, liquids, or gasses by mechanical means, such as filtration, settling, and size reduction, which are often classified as separate unit operations.
Mechanical-physical separations
Whenever a substance undergoes a change of phase, relatively large amounts of heat changes are involved at a constant temperature. This enthalpy change is called the?
latent heat of fusion
The __________________ is equal to the mole fraction
volume fraction
This unit operation deals with the principles that govern accumulation and transfer of heat and energy from one place to another.
Heat Transfer
basic quantity used in the SI system in the unit of length is the
meter (m)
The __________________ deal mainly with the transfer and change of energy and the transfer and change of materials primarily by physical means but also by physical-chemical means.
unit operations
Such an equation can be used with any system of units provided that the same base or derived units are used throughout the equation. No conversion factors are needed when consistent units are used.
dimensionally homogeneous equation
In this case, a solute in a liquid solution is removed by contacting with another liquid solvent which is relatively immiscible with the solution.
Liquid-liquid extraction
it says that all energy entering a process is equal to that leaving plus that left in the process
law of conservation of energy
3 Fundamental Transport Processes
- Momentum Transfer
- Heat Transfer
- Mass Transfer
Three basic units in SI system
- meter (m)
- kilogram (kg)
- second (s)
A ________________________________ is one in which all the terms have the same units
dimensionally homogeneous equation
The unit operations deal mainly with the transfer and change of energy and the transfer and change of materials primarily by physical means but also by ___________________ means.
physical-chemical
The boiling point of a liquid is defined as the temperature at which the vapor pressure of a liquid equals the _______________
total pressure
the basic mechanism is the same whether the phases are gas, solid, or liquid
Mass Transfer
when heat is given off, the reaction is
exothermic
When a liquid phase vaporizes to a vapor phase under its vapor pressure at constant temperature, an amount of heat called __________________________ must be added
latent heat of vaporization
This process involves the separation of a solute from a fluid by diffusion of this solute from a liquid or gas through a semipermeable membrane barrier to another fluid.
Membrane separation
When a liquid is placed in a sealed container, molecules of liquid will evaporate into the space above the liquid and fill it completely. After a time, equilibrium is reached. This vapor will exert a pressure just like a gas and we call this pressure the ___________________________.
vapor pressure of the liquid
The most generally used numerical method is the parabolic rule often called
Simpson’s rule
This method is well suited for digital computation
Simpson’s rule
basic unit of force
newton
it occurs in the unit operations heat transfer, drying, evaporation, distillation, and others
Heat Transfer
other term for the heat capacities of gases
specific heat
occurs in moving media, such as in the unit operations of fluid flow, sedimentation, and mixing
Momentum Transfer
when heat is absorbed, the reaction is
endothermic
Three basic units in English (FPS) System
- foot (ft)
- pound (lb)
- second (s)
Unit operations where heat transfer occurs?
- heat transfer
- drying
- evaporation
- distillation
basic quantity used in the SI system in the unit of temperature is the
kelvin (K)
This involves treating a finely divided solid with a liquid that dissolves out and removes a solute contained in the solid.
Liquid-solid leaching
The unit operation __________________ occurs in the absorption of oxygen from the air in a fermentation process or in a sewage treatment plant and in the absorption of hydrogen gas in a process for liquid hydrogenation of oil.
absorption
The mechanism of ______________or _________________ occurs in drying, membrane separation, absorption, distillation, and crystallization.
diffusion, mass transfer
basic unit of work
joule
___________________________ is the amount of this limiting reactant actually converted, divided by the amount originally present, times 100.
Percent completion of a reaction
The value of the_____________________ is independent of the amount of liquid in the container as long as some is present.
vapor pressure
Here mass is being transferred from one phase to another distinct phase; the basic mechanism is the same whether the phases are gas, solid, or liquid. This includes distillation, absorption, liquid-liquid extraction, membrane separation, adsorption, and leaching.
Mass Transfer
This area where energy change occur is often called
thermochemistry
unit of pressure is the
pascal (Pa)
12 Classifications of Unit Operations
- Fluid Flow
- Heat Transfer
- Evaporation
- Drying
- Distillation
- Absorption
- Membrane separation
- Liquid-liquid extraction
- Adsorption
- Liquid-solid leaching
- Crystallization
- Mechanical-physical separations
Often the mathematical function f(x) to be integrated is too complex and we are not able to integrate it analytically. In some cases, the function is one that has been obtained from experimental data, and no mathematical equation is available to represent the data so that they can be integrated analytically. In these cases, we can use _____________________
graphical integration
In this process a component is removed from a gas stream by treatment with a liquid.
Adsorption
Power is measured in
joule/s or watts
occurs in drying, distillatics, evaporation, and so on
Heat Transfer
Typical processes that do not undergo chemical reactions are
- drying
- evaporation
- dilution of solutions
- distillation
- extraction
Three basic units in CGS System
- centimeter (cm)
- gram (g)
- second (s)
basic quantity used in the SI system in the unit of mass is the
kilogram (kg)
This is an operation whereby components of a liquid mixture are separated by boiling because of their differences in vapor pressure.
Distillation
is not a standard SI unit but is being used during the transition period
pressure in atmosphere (atm)
In this fundamental process, we are concerned with the transfer of heat from one place to another; it occurs in the unit operations heat transfer, drying, evaporation, distillation, and others.
Heat Transfer
