Chemical Engineering Thermodynamics (ChE 7120) Lecture – 1 Introduction to the course and basics principles Know Your Instructor: Prof. B. Bharti PhD: 2009-2012 Postdoc: 2012-2016 Assistant Prof.: 2016- 2022 Associate Prof.: 2022-present Postdoc: 2014 BS: 2004-2007 MS: 2007-2009 Bharti Research Group: 2016-present Environmental chemical science Bio-nano interactions 10 5 10 3 10 1 Field driven effects Intensity I(q) / a.u. 9.6 8.3 6.5 4.5 3.0 10 -1 10 -3 10 -5 pH DS = 7 nm 0.1 1 q / nm Lee, BB et al. ACS Appl. Mater. Interf., 2018 Lee, BB et al. ACS Sustainable Chem Eng. 2021 Al Harraq, BB et al. ACS Env. Au 2022, 2023 Meissner, BB et al. Soft Matter, 2019 Lee, BB et al. Langmuir 2021 Lignin NPs for oil herding and microplastics Binding of proteins on nanoparticles -1 4 Lee, BB et al. Nat. Commun. 2019 Al Harraq, BB et al. Science Advances 2020 Al Harraq, BB et al. Commun. Chem. 2022 Active transport and self-propulsion of colloids • 6 Graduate students • 2 Undergraduate students • Up to 3 graduate students may join in Fall-2023 Group members: 2023 3 Syllabus and policies Textbook • Prausnitz, Lichtenthaler and Gomes de Azevedo, Molecular Thermodynamics of fluid-phase equilibria, 3rd edition, Prentice Hall 1999. Supplementary reading • Stanley I. Sandler, “Chemical, Biochemical, and Engineering Thermodynamics” 4th ed., John Wiley & Sons, 2006 • Milo D. Koretsky, “Engineering and Chemical Thermodynamics” 2nd edition, Wiley, 2013 • T. L. Hill, An Introduction to Statistical Thermodynamics (1986) Dover Publications • J. N. Israelachvili, Intermolecular and Surface Forces, 2nd edition (1998) Academic Press. • D. A. McQuarrie, J. D. Simon, J. Choi, Physical Chemistry: A Molecular Approach (1997) Univ. Science Books. Grade calculations: A weighted average numerical grade will be calculated as follows: • Mid-term exams = 30% • Final exam = 30% • Term paper and presentation = 40% (20% each) Numerical ≥98 Score Letter Grade A+ 97.993 A 92.990 A- 89.987 B+ 86.983 B 82.980 B- 79.977 C+ 76.973 C 72.970 C- 69.967 D+ 66.963 D 62.9- <60 60 4 DF Course contents Part 1: Classical thermodynamics Laws of thermodynamics Vapor-liquid and multiphase equilibria Thermodynamics of mixtures Reaction equilibria Part 2: Molecular and statistical thermodynamics Kinetic theory of molecules Introduction to statistical thermodynamics Intermolecular interactions Lattice models of mixtures and polymers Part 3: Selected topics Surface and interfacial thermodynamics Thermodynamics of biological molecules 5 What is Thermodynamics? Thermodynamics From Greek, ‘therme’= Heat From Greek, ‘dynamis’ = strength, power • Original definition from 1700s: The study of how to convert heat into ‘useful work’ • Thermodynamics is play a crucial role in every industry and process. • It is also applicable to atoms and molecules as well as to the planets and stars. Petroleum Electronics Food Biomedicine 6 Thermodynamics and kinetics Thermodynamics • Given initial and final states, calculate change of properties between them • Pressure, temperature, density, energy, etc. • Given initial state, what is the final equilibrium state? • No idea of time (how long it will take to get from initial to final state) Kinetics / transport (fluid mechanics, heat and mass transfer, reaction kinetics) • Time is important • Flow rates; how fast heat is transferred; how long will it take to separate two components from a mixture; time to react a significant amount of A + B into C • Depend on different variables (temperature, pressure, concentration, type of equipment, how close we are to equilibrium, etc.) • How fast we can reach equilibrium 7 Basic Thermodynamic Definitions Driving Force Transferred Quantity "Allowing" boundary "Preventing" boundary ÑT Q (heat) Diathermal Adiabatic -Ñ P V (volume) Movable Rigid ÑC M (mass) or Ni (moles) Permeable Impermeable Ñe q (charge) Unshielded Shielded Intensive variables Extensive variables V Conversion: =V Extensive/extensive = intensive N i Types of equilibria: Stable, Metastable, Indifferent, Kinetically stable, Quasi-equilibrium Homogenous vs. heterogeneous systems: Phases, phase boundaries and phase equilibria 8 Heat, Work, Mass and Energy Internal Energy U: Stored in the system because of molecular motion and interactions Volume work d W = - P d V V2 W = -ò P dV V1 Heat Q For a closed system: DU = Q + W dU = dQ + dW Simplest expressions of the first law: although energy assumes many forms, and freely converts between them, the total quantity of energy is constant. Shaft work W s = ± t w Kinetic energy Ek = Potential energy 1 M v2 2 Ep = M g D z 9 Mass and Energy Balances – Open System J1A 1 M(t) J2 A 2 Full mass balance: J3 A 3 W dM = å M k (mass) or dt k Q dN = å N k (moles) dt k Full energy balance: ü d ì v2 v2 ˆ íU + M ( + g Dz )ý = å M k (U + + g Dz ) k + Q + W s - P V + å M k ( P Vˆ ) k dt î 2 2 k þ k 10 Energy Balances – Enthalpy Define Enthalpy: H º U + P V then: 2 ü d ì v2 v íU + M ( + g Dz ) ý = å M k (Uˆ + + g Dz ) k + å M k ( P Vˆ ) k + Q + W s - P V dtî 2 2 k þ k ü d ì v2 v2 ˆ íU + M ( + g Dz ) ý = å M k ( H + + g Dz ) k + Q + W dtî 2 2 þ k Uniform system, no shaft work, low to medium stream velocities molar basis dU = å N k H k + Q + P V dt k dU =H d N + d Q - P dV Differential expression - not as well defined mathematically, but extremely useful 11 Example of Enthalpy Use – Throttling Process (Joule-Thomson expansion) P1, T1 P2, T = ? Valve or porous plug Insulated pipe Open, steady state system: 2 v å M k ( Hˆ + 2 + g Dz ) k + Q + W s = 0 k Constant Hˆ 1 (T1 , P1 ) = Hˆ 2 (T2 , P2 ) Negligible none none H 1 (T1 , P1 ) = H 2 (T2 , P2 ) Constant enthalpy (isenthalpic) process 12 Example and exercise What happens when methane at 20 MPa and 340 K is throttled to 0.5 MPa ? What if throttling is done from 10 MPa and 340 K to 0.1 MPa ? 13 State variables and equations of state Any of the intensive variables of a system at equilibrium is state variable Examples: T, P, U, H, S, density r, polarisability, etc. The state of the system is described with a single point in a multidimensional space T H P U V S Allows constructing multiparametric diagrams and tables (e.g. steam tables). In order to calculate such relations for a given substance, we need the equations of state. Generic example - ideal gas PV = R T 14 Thermodynamic Properties of Matter Relation between the internal energy of a given substance and temperature (d U )V = (d Q )V Constant volume: Constant-volume heat capacity Constant-pressure heat capacity For ideal gas: CV = 1 N (d U + P dV )P = (d H )P Constant Pressure: PV = R T dU =d Q - P dV = N CV ( d T )V CP = æ ¶U ö æ ¶U ö çç ÷÷ = çç ÷÷ ¶ T ¶ T è øV è øV = N C P (d T ) P 1 N æ¶ H ö æ¶ H ö çç ÷÷ = çç ÷÷ ¶ T ¶ T è øP è øP U = U (T ) only; CV* (T ) = dU dT C P* (T ) = d H dU dT = +R = CV* (T ) + R dT dT dT H = U (T ) + P V = U (T ) + R T = H (T ) 15 Process calculations with ideal gas (1) N CV d T = d Q - P d V or (2) N (CP - R ) dT = d Q - P d V (3) - PdV = dW = - N R T d V V Isochoric (Constant-V) process: d V = 0, (1) d Q = d U = N CV d T Q = D U = N ò CV d T è Isobaric (Constant-P) process, N R dT = P d V (2) d Q = d H = N CP d T Q = D H = N ò CP d T è Isothermal (Constant-T) process, (1) dV - dQ = dW = - R T V è - Q = DW = - R T ln V2 P = R T ln 2 V1 P1 Adiabatic (Q = 0) process N CV d T = - N R T dV V è also dT R dV = T CV V T2 æ P2 ö = çç ÷÷ T1 è P1 ø R CP è and ln T2 V R = ln 2 T1 CV V1 P2 æ V1 ö =ç ÷ P1 çè V2 ÷ø è T2 æ V1 ö =ç ÷ T1 çè V2 ÷ø CP CV 16 R CV Summary: Lecture 1 • First law dU = dQ + dW • Enthalpy H º U + PV • Mass and energy balances • Heat capacities • Process calculations 2 v å M k ( Hˆ + 2 + g Dz ) k + Q + W s = 0 k æ¶ H ö æ¶ H ö çç ÷÷ = çç ÷÷ C P (T ) = CV (T ) + R ¶ T ¶ T è øP è øP V P - Q = DW = - R T ln 2 = R T ln 2 V1 P1 CP = 1 N 17