02/08/2021
Chemical Engineering Thermodynamics
History of thermo: comes from thermo and the other is dynamics || themro means heat and
dynamics means motion || has something to do with the motion of heat or energy || the
focus has something to do with energy or heat || this is the main diff from phychem to
thermo || in phychem we are studying matter that we can feel || phychem is more
generalilzed compared to thermo || because we are discussing gases and liquids and solids
|| thermo is a subset of phychem || we are going to focus ont he energy part here in thermo
|| the relationship of heat to work ||
heat and temp has something to do with the motion of molcules in 1600 || in 1700 they
considered heat has something liek a separate fluid. Heat is like a substance. When you are
hot, they thought that they had fluid in the body that causes heat || In 1840s where the
experiments of James Joule Happened. It has something to do with heat and he observed
heat is not a separate fluid but incorporated with partibles of matter || In 1824 Thay alredy
considered heat as energy ||
Missing info
birth of first and ssecond law in the notion that heat is energy || In micro level 2nd law of
thermo is a bit unwell || in 1857 they believed that gases are molecules in mtion || in 1860
the focus are gases and enerygy related to gases also ||
during those times they do not wnat 2nd law in physics || because they cannot explain in
microscopic view || if they move radomly there could be a lot of numebr of systems for the
individual gas molecules || that is why we cannot provide some infos for the 2nd law || in
1900 we cannot track the movements but we can know the probability ||
The bbirth of thermo was after the development of steam engine which converts heat to
work ||
one of the notion of entropy before was that you cannot allow heat cannot flow from cooler
to hotter point || always from higher to lower. purose: to be able describe completely a
system/it involves all of the propoerties and characteristics of that system/
02/10/2021
These have values changes when the amount of material changes for the Extensive Thermo
Varialbles || Int esinve Thermodynamic Variable is not changing when you cut the material
on half || ratio of 2 extensive property is intensive ||
International System of Units ||
Mass is the amount of substance regardless with gravity which is the same all throughout
||
Measures of Amount or Size || Moalr and Specific Volume are intensive property ||
Temperature is the average kinetic energy of the molecules || Andres Celcius || Daniel
Fahrenheight || William Thomson for Kelvin, and William Rankine for Rankine || basis of
celsius and fahrenheit is absed on water ||
what is the velocit at point B?
02/15/2021
First Law of Thermodynamics || Joules experimetn || relationship of heat and work ||
Internal Energy || the heat absorbed by the individual molecule || Change in internal energy
after adding energy ||
First Law of Thermodynamics ||
Energy Balance for Closed System || there is no transfer of mass only energy || Focus the
sign on the surroundings || In closed system, only internal energy changes when you
supplied energies || it is manifested from the individual moleucles ||
Equilibrium and the Thermodynamic State || the change has somoething to do witht he
driving force and resistance ||
Reversible Process || it is a characteristics of path || reversibility is removing something
infinitesimally || what happened if we return the removed amount, also at equilibrium
because only small amount of mass ||
Closed-System Reversible Process; Enthalpy || enthalpy is simply the total energy of the
molecules plus the energy that are needed to place at a particular position ||
Heat Capacity ||
02/22/2021
LE 1 will be intro to thermo and 1st law of thermo || Volumetric properties of fluid will be
LE 2 ||
Work rate || due to the product of pressure and volume and work from expansion and
contraction || for a certain pipe is parabolic which means that the velocity is linear || which
means it is the average velocity || if in the problem that the reynolds number is not stated,
then assume that it is turbulent || if there is no change in temperature, we can cancel
enthalpy, if no change in velocity, we can cancel the velocity, if the position no change, it is
negligible || if there are no changes or constant on the variables, we can cancel them or
neglect ||
in order to solve many problem we need to measure the amount of enthalpy in the system
if we have a flow calorimeter || the device is created to measure enthalpy || the important
instrument in the flow calorimeter is the heater where we applieda known ammount in the
heater || we are going to do energy balance int he section one and two || follow the formula
|| there will be no accumulation of heat || we tend to control the velocity || level is also the
same || there is no expansion and sub work || it means that the heat is equal to the enthalpy
change int he system || we need to measure the nethalpy if we place a known amount of
heat and we know the amount of entering stram, we can determine the out stream ||
h1 = 376.20 || do interpolation ||
02/24/2021
Do the double interpolation ||
ms(Hs2-Hs1) + ms(Hw2-Hw1) = 0 (hindi na SS)
Volumetric Properties of Pure Fluids || wecan state that thermo state of the system wf we
can describe the p, t, v || we are now finding the state of the systems interms of the
properties pvt || volume changes when pt changes. || v is dependent and pt are
independent ||
Phase Rule ||
PVT Behavior of Pure Substances || @triple point, is always fixed even without giving any
thermodynamic properties/state || PV diagram is special because || Critical Behavior ||
why is it the equation is not applicable if the values of the pressure and temperature is
large? because the pressure and temperature are at constant ||
03/17/2021
HEAT EFFECTS
HEAT EFFECTS IT IS THE CONCEPT OF HEAT IN THE SYSTEM EITHER REMOVED RO
ADDED || LATENT HEAT IS FOR PHASE CHANGE || HEAT OF REACTION || SENDIBLE HEAT
- CHANGE IS TEMPERATURE THAT WE CAN SENSE || INTERNAL ENERGY IS THE
EQUATION FOR THE SENSIBLE HEAT || FOR CLOSED SYSTEM CONSTANT VOLUME
PROCESS, INTERNAL ENERGY IS INDEPENDENT OF VOLUME IF IT IS AN IDEAL GAS AND
INCOMPRESSIBLE FLUID || SENSIBLE HEAT EXPRESSION || WHEN THERE IS INTERNAL
ENERGY, THERE WILL ALWAYS BE ENTHALPY || FOR CONSTANT PRESSURE PROCES,
ENTHALPY IS INDEPENDENT OF PRESSURE IF THE STATE IS IDEAL AND REALS GASES
AT LOW PRESSURE AND HIGH TEMPERATURE ||
TEMPERATURE DEPENDENCE OF THE HEAT CAPACITIES || THE RELATIONSHIP OF THE
CP/R, SO USE THE EQUATION THAT BOXED ||
eVALUATION OF THE SENSIBLE HEAT INTEGAL || MEAN HEAT CAPACITY IS JUST AN
APPROX, IF NOT GIVEN WE NEED TO CALCULATE IN A LONG WAY || REFER TO THE
EQUATION ON THE MID RIGHT SIDE OF THE SCREEN || SIMPLY, DO THE LONG METHOD
|| JSUT MULTIPLY R TO GET THE MEAN HEAT CAPACITY ||
LATENT HEATS OF PURE SUBSTANCES || IT IS MANIFESTED IN THE CHANGE IN PHASES
||
STANDARD HEAT OF REACTION || IF THE DELTA H IS NEGATIVE, IT MEANS THAT THE
HEAT OF THE PRODUCT IS LESS THAN THE HEAT OF THE REACTANT, THE HEAT IS
REMOVED TO THE REATANT, AND THE PROCES IS EXOTHERMIC || IF POSITIVE,
ENDOTHERMIC, THE REACTANTS GAINED HEAT ||
STANDARD HEAT OF FORMATION || THE HEAT OF FORMATION IS AVAILABLE IN
LITERATURE MOSTLY || TO FIND THE HEAT OF REACTION GIVEN THE FORMATION
REACTION, FIND ALL THE HEAT OF FORMATIONS OF THE GIVEN SUBSTANCES
INCLUDING THE REACTION EQUATIONS || THE SUM OF THE HEAT OF FORMATIONS OF
EACH SUBSTANCES IS THE HEAT OF REACTION || USE THE FORMUALA TO GET THE HEAT
OF REACTION USING THE HEAT OF FORMATIONS || (HINDI KO NA SS YUNG SLIDE NA TO)
STANDARD HEAT OF COMBUSTION || TO COMPUTE FOR THE HEAT OF COMBUSTION, WE
CAN USE THE HEAT OF FORMATION STILL ||
03/22/2021
TEMPERATURE DEPENDENCE OF HEAT EFFECTS
CONSTANT PRESSURE SINCE THE REACTION HAPPENED AT ATMOSPHERIC PRESSURE
WHICH IS 1 BAR || IF THERE IS A VESSEL, THERE ARE TOO MANY REACTIONS IN THAT
SYSTEM || SINCE WE ARE USING THE CP/R || THIS IS AT 298.15 K ||
IF THERE IS A ENDOTHERMIC AND EXOTHERMIC REACTION, WE NEED TO ADD THE 2ND
TERM BUT IF THE TEMP IS ROOM TEMP, WE CAN CANCEL THE 2ND TERM ||
WE NEED TO CALCULATE FIRST THE Cpi OF THE INDIVIDUAL SPECIES BUT IT REQUIRES
TOO MUCH WORK SO TO CONDENSE ALL OF THEM, WE JUST NEED TO GET THE DELTA
OF ALL THE FACTORS ||
HEAT EFFECTS OF INDUSTRIAL REACTION || IT IS THE APPLICATION OF EVERYTHING IN
THE HEAT EFFECTS ||
SINCE MAXIMUM, THERE SHOULD BE A COMPLETE REACTION || IF WE ARE ACCOUNTING
THE MAXIMUM TEMPERATURE, IT IS ALWAYS ADIABATIC PROCESS ||
WE ONLY NEED TO GET THE PRODUCT NOT THE REACTANTS || BECAUSE WHEN
FINDING THE MAXIMUM THEMPERATURE, WE ONLY NEED TO CONSIDER THE PRODUCT
OF THE COMBUSTIONS ||
2ND LAW OF THERMODYNAMICS
TO GIVE LIMITATIONS ON THE 1ST LAW ||
STATEMENT OF THE SECOND LAW || CLAUSSIUS DEFINED ENTOPHY, IS SIMPLY THE
QUOTIENT OF THE HEAT AT THE REVERSIBLE PROCESS DIVIDED BY THE
TEMPERATURE || THE SIGNIFICANCE OF ENTROPY IS IS A MEASURE OF DEGREE OF
CHAOSNESS || WHEN WE TRY TO DETERMINE THE STATE OF THE SUYSTEM, DEPENDS
ORDER OR CHAOSNESS OF THE MOLECULE || IT HELPS TO DESCRIBE THE SUSTEM || THE
ENTROPY IS THE GUIDE TO TELL WHETHER A SYSTEM IS ON THE PROCESS OR AT
EQUILIBRIUM ALREADY || IF WE ARE ENG, AND WE HAVE REACTING SUYSTEM. || IT
HELPS US TO DETERMINE IF A CERTAIN PROCESS ALREADY ACHIEVED THE
EQUILIBRIUM ||
CYCLIC PROCESS IS ALWAYS GOING BACK TO THE ORIGINAL STATE ||
03/24/2021
PURPOSE OF HEAT ENGINE IS TO CONVERT HEAT INTO WORK ||
CARNOT'S EQUATION || TO CONVERT ALL HEAT FROM HOT RESRVIOR TO WORK AND
USE THE EQUATION || THE EFFICIENCY IS ONLY A FUNCTION OF THE TEMPERATURE
AND NOT THE TYPE OF SUBSTANCE IN THE ENGINE OR SYSTEM ||
HEAT ENGINES AND HEAT PUMPS || HEAT ENGINES TRNASFORMS HEAT INTO WORK ||
FOR HEAT PUMP IS THE REVERSE OF THE CARNOT CYCLE || TO TRANSFER HEAT FROM
COLD RESERVIOR TO HOT RESERVOIR, WE NEED TO APPLY WORK || EXAMPLES ARE REF
AND AIRCON || QC IS LESS THAN THE WORK YOU DID FOR HEAT PUMPS
CARNOT ENGINE WITH IDEAL GAS STATE WORKING FLUID || THE HEAT FROM THE HOT
AND COLD RESERVOIR CAN ONLY BE GET ON ISOTHERMS || IF TYOU HAVE OPERATION
AND ENGINE IS PRESENT || SO THE ENTROPY IN THE CARNOT CYCLE IS EQUAL
ENTROPY CHANGES IN THE IDEALS-GAS STATE ||
03/29/2021
dS IS ALWAYS POSITIVE || HEAT ENGINE CONVERTS HEAT INTO WORK ||
CALCULATION OF IDEAL WORK ||
LOST WORK || IS THE WORK WASTED RESULTED TO THE IRREVERSABILITY PROESS ||
THE THIRD LAW OF THERMODYNAMICS || GIVE LIMITAITONS ON THE 2ND LAW OF
THERMO || IN THIS LAW, THERE WILL COME A POINT THAT THERE WILL BE NO
ENTROPY AND WILL CEASED TO EXIST AT 0 KELVIN ||
ENTROPY FORM THE MICROSCOPIC VIEWPOINT || WE CANNOT DETERMINE THE
CHAOSNESS OF THE INDIVIDUAL PARTICLE ||
04/05/2021
THE THIRD LAW OF THERMODYNAMICS || AT LOW TEMPERATURE THIS FORMULA IS
FOLLOWED ||
THERMODYNAMIC PROPERTIES OF FLUIDS || ONE OF THE PURPOSE OF THERMO IS FOR
US TO ABE TO DESCRIBE SSTEMS || IN TERMS OF P,V,T AN INTERNAL ENEGY AND
ENTHALPY || BUT WE NEED TO ADD FREE ENERGY ||
FUNDAMENTAL PROPERTY RELATION || HELMHOLTZ IS THE MAX WORK IN THE
SYSTEM || FREE ENERGY HAS SOMETHING TO DO WITH SPONTEINITY IN THE SYSTEM ||
IF THERE IS FREE ENERGY PRESENT IN THE SYSTEM, THE SYSTEM IS STILL NOT IN
EQUILIBRIUM || GIBSS IS THE WORK IN THE REMOVAL OF PV WORK ||
MAXWELL RELATION IS THE RELATIONSHIPS IN PARTIAL DIFFERENTIALS ||
ENTHALPY AND ENTROPY AS A FUNCTION OF T AND P ||