Resources for our learning

1. ME 200 L1: Introduction to ThermodynamicsEnergy Applications, Systems, Equilibrium Properties, MLTF, Units, States and ProcessesSpring 2014 MWF 1030-1120 AML1 given by Indraneel SircarJ. P. Gore, Reilly University Chair Professorgore@purdue.eduGatewood Wing 3166, 765 494 0061Office Hours: MWF 1130-1230TAs: Robert Kapaku rkapaku@purdue.edu Dong Han han193@purdue.edu

2. Resources for our learning • Fundamentals of Engineering Thermodynamics, Moran, Shapiro, Boettner and Bailey, Seventh Edition. • Read assigned sections before coming to class. • Group class email will be used frequently to communicate. Also use http://www.purdue.edu/mixable • Class participation welcome and essential. • Given the size of the class, smaller groups of ~10 students to be formed soon. Special opportunities offered to individual ME200 Peer Mentor to lead a group. • Other Instructors, T. A. s, Classmates, Organized Learning Groups such as www.purdue.edu/si • Homework: Submission, grading, and return policies will be announced in the class.

3. What is this course? • Thermodynamics is one of the most important global subjects because it drives the fundamentals of energy, environment, and climate. • Please discard whatever you have heard about this course being “extra ordinarily hard,” “a filter,” “impossible to manage,” and give me and yourself a chance to prove all those to be just rumors. • If you do not understand the material, find the reason(s) early and address these. • The reasons may include many, three of which are listed below with answers in parentheses: • I do not speak clearly (Let me know and I will repeat and try my best.). • You do not read assigned sections ahead of class? (Read assigned sections ahead of class.) • You do not do and submit assigned homework “in time,” “at all,” or “independently” (Do assigned homework “in time,” “definitely even if late,” “only with minimal help and confidence that you are learning.”) • You do not have time and/or pre or co-requisites: Chem. 115, 116; Phys. 152; Math 261? (Drop this class unless you feel comfortable with these subjects.)

4. Applications of Thermodynamics

5. Your Performance in the Course • You will find that this is a very interesting course about how many useful devices work: cars, air planes, heaters, power plants, air conditioners, refrigerators etc. • If you don’t do well on early homework, quizzes and exams? • Ensure you understand the material (Ask questions in class, Form a Study Group- use Blackboard and/or Mixable to stay in touch with your study group, See one of the Teaching Assistants or one of the Instructors in their Office Hours) • Ensure you are doing homework on your own (A little help that allows you to complete homework well may not be available in quizzes and exams). • See me early and discuss your situation (in confidence).

6. Learning Outcomes • Understandingof several fundamental concepts in energy analysis. . . Including closed (also called control mass) and open systems (also called control volume), boundary and surroundings, property, state, and processes. • ApplySI and English Engineering units, including units for specific volume, pressure, and temperature.

7. Boundary System Defining Systems • System: whatever we want to study. • Surroundings: everything external to the system. • Boundary: distinguishes system from its surroundings. Surroundings

8. Closed System or Control Mass • A system that always contains the same matter. • No transfer of mass across its boundary can occur. • Isolated system: special type of closed system that does not interact in any way with its surroundings.

9. Open System or Control Volume • A given region of space through which mass flows. • Mass may cross the boundary of a control volume.

10. Macroscopic and Microscopic Views • Systems can be described from the macroscopic and microscopic points of view. • The microscopic approach aims to characterize the behavior of the atomic or molecular particles making up a system. • The macroscopic approach describes system behavior in terms of the gross effects that can be measured by instruments such a pressure gages and thermometers. • Engineering thermodynamics predominately uses the macroscopic approach.

11. Gas Property • A characteristic of a working substance ina system to which a numerical value can be assigned at a given time without knowledge of the previous behavior of the working substance or the system. • Examples include: • Mass: m kg • Volume: V m3 • Energy: J (Joules) • Pressure: N/m2= Pa • Temperature: K, oC, oF, R

12. State: p, V, T, … Gas State • The condition of a working substance in a system as described by its properties. • Example: The state of the Gas in the system shown is described by p, V, T,…. • The state is definedby providing the values of a limited number of independent properties. All other properties are dependent on these.

13. Equilibrium States and Processes • Equilibrium State – no inherent tendency to change. • Mechanical ΣF = 0 • Thermal ΔT = 0 • Phase no evaporation, condensation, freezing, melting, or sublimation • Chemical  no net chemical reaction Process path 3 Process path 2 1 • Process is defined as a transformationfrom one equilibrium state to another equilibrium state. • Process path may or may not consist of interim equilibrium states (ΣF ≈ 0, ΔT ≈ 0, negligible species concentration gradient). Multiple processes can lead to the same end state.

14. Types of Processes • Isothermal ΔT = 0 • Isobaric Δp = 0 • Isochoric ΔV = 0 • Adiabatic  No heat transfer • Other important terms: Steady flow  constant mass flow rate, Steady state  system properties ≠ f(t)

15. State 1: p1, V1, T1, … State 2: p2, V2, T2, … Gas Gas Process • Example: Since V2 > V1, the gas has undergone a process from State 1 to State 2. State 1: Assembled State 2: Disassembled

16. Extensive Depends on mass of system Examples: mass, volume, energy, etc. Intensive Independent of mass Examples: pressure and temperature. Specific Extensive property divided by mass of the system Types of Properties

17. Units • A unit is any specified amount of a quantity by comparison with which any other quantity of the same kind is measured (e.g., meter, kilometers, feet, and miles are all units of length). • Two systems of units: • SI (Système International d’Unités) • English Engineering units.

18. F = ma (Eq. 1.1) SI: 1 N = (1 kg)(1 m/s2) = 1 kg∙m/s2 (Eq. 1.2) English: 1 lbf = (1 lb)(32.1740 ft/s2) = 32.1740 lb∙ft/s2 (Eq. 1.5) Units In these unit systems, mass, length, and time are base units and force has a unit derived from them using,

19. Mass, Specific Volume ( ), Density (r) • Matter is made up of “small,” and “homogeneous,” continuadistributed throughout “space.” Homogeneous refers to our choice of defining averaged properties. • When substances are treated as continua, it is possible to speak of their intensive thermodynamic properties “at a point.” • At any instant the density (r ) at a point is defined as (see text book equations 1.6 and 1.7)

20. Molar Specific Volume ( ), Number of mol (n) • Avogadro’s Number represents the number of molecules in mass containing one “gram mole” or “mole” or “mol.” • Av=6.022x1023 #/gram mole. A “kmol,” will have 103 times more # Molecular/atomic weights M for substances generally of interest in thermodynamics are in Table A-1: C = 12.01 kg/kmol, O2=32.00 kg/kmol, N2=28.01 kg/kmol. Air is a mixture 1 kmol O2 and 3.76 kmol N2 plus small amounts of CO2, Ar, H2O etc. Equivalent Molecular Weight of air is given as 28.97 kg/kmol in Table A-1, p. 890 of text.

21. Pressure (p) • Pressure within gases is force per unit area resulting from molecular collisions with a container wall and amongst molecules within a gas. • Visualize pressure within liquids and solids as a force exerted by neighboring particles and bonds The pressure (p) at the specified point is defined as the limit:

22. Pressure Units, Absolute and Gauge Pressure • SI unit of pressure is the pascal: 1 pascal = 1 N/m2 • Multiples of the pascal are frequently used: • 1 kPa = 103 N/m2,1 bar = 105 N/m2,1 MPa = 106 N/m2 • English units for pressure are: • pounds force per square foot, lbf/ft2 or pounds force per square inch “psi”, lbf/in2 • When system pressure is greater than atmospheric pressure, the term gage pressure is used. p(gage) = p(absolute) – patm(absolute) (Eq. 1.14) • When atmospheric pressure is greater than system pressure, the term vacuumpressure is used. p(vacuum) = patm(absolute) – p(absolute) (Eq. 1.15)

23. Hydrostatic Pressure • The pressure throughout an uninterrupted fluid is constant at a fixed depth. Think about the difference in pressure between points H and I, while we discuss the expressions for hydrostatic pressures.

24. Pressure Measurement • We can make use of the change in pressure with elevation in a fluid to measure pressure. • Examples of devices used to measure pressure are: • manometer • barometer p=patm g

25. Cortesy: Office of Basic Energy Sciences, U. S. Department of Energy

26. Summary • We defined properties such as specific volume and density for small volumes of working substances using limits, integrals and differentials in an intuitive manner. • We defined gravitational forces, pressure, buoyancy and considered a couple of real world problems involving buoyancy for gases and liquids over very wide range of temperature. • We closed with a conversation of atomic, to Nano to Micro to Milli scales. • Conversations about Energy and Temperature follow.