Thermodynamics ME3322 Nader Sadegh George W Woodruff School of Mechanical Engineering Georgia Institute of technology Instructor Information Instructor Nader Sadegh Email nader sadegh me gatech edu Tel 404 894 8172 URL http www me gatech edu nader sadegh Office MARC Building Room 475 Office Hours Tu11 12 Th2 3 or by appointment 1 Grader Information Teaching Practicum Hrishi R Goel Email gtg281v mail gatech edu Office MRDC Lobby Office Hours Th 11 12 Course Description Description Introduction to thermodynamics Thermodynamic properties energy and mass conservation entropy and the second law Second law analysis of thermodynamic systems gas cycles vapor cycles Prerequisite PHYS 2211 General Physics II and MATH 2403 or MATH 2413 or MATH 24X3 or MATH 2602 and ME 2016 Computing Technqiue 2 Textbook Fundamentals of Engineering Thermodynamics Textbook Computer Usage Michael J Moran and Howard N Shapiro Fundamentals of Engineering Thermodynamics 5th Edition John Wiley Sons 2003 Note You might want to save this textbook because it will be used in ME4315 The MATLAB program available on PC s in room MRDC 2105 will be used for performing some of the numerical computations needed for this course 3 Evaluation Quizzes 35 5 semester 20 minutes long Pop Quizzes 1 Midterm 25 Final Examination 35 Computer Assignments 5 10 Important Dates Scheduled Quizzes 1 25 2 13 3 15 4 3 4 19 Midterm Thursday March 1 2007 Final Project Thursday April 26 2007 Final Exam Thursday May 3 2007 4 Academic Honesty All items in the Honor Code under the topic of Academic Misconduct apply to this class In particular the following items are considered to be cheating Submission of an assignment that is copied from another student Copying from another student s paper during an exam Alteration of graded tests submitted for regarding Academic misconduct will be reported to the Vice President for Student Affairs Class Policies If you miss a class you are still responsible for everything done in class No makeup quizzes will be given Cheating will not be tolerated Disruptive actions in the classroom such as talking laughing continual late arrival etc will not be tolerated 5 Course Topics Introduction Energy The 1st Law of Thermodynamics Conservation of Mass Energy Entropy the 2nd Law of Thermodynamics Exergy Analysis Vapor Cycles Gas Cycles Refrigration Cycle Introduction Thermodynamics is the study of how systems interact with their environment through heat mass and work transfer Typical quantities desired How much work is done How much heat is transferred By how much does the energy and other properties change It covers a wide range of applications we choose the system of interest 6 Typical Applications Gas Turbine Engine IC Engines Electric Generator Plant Refrigeration Systems Solar Panels Biomedical Systems Definitions In Thermodynamics we use everyday words in a very precise manner So it is very important to know the thermodynamic definitions of these words Examples heat work entropy etc 7 System Thermodynamic System What we are interested in analyzing The system is separated from its surroundings or environment by the system boundary The surroundings are external to our system of interest complex single gas Closed System Control Mass No mass can cross system boundary Energy may cross system boundary Volume is NOT fixed 8 Open System Control Volume Mass may cross system boundary control surface Volume may may not be fixed Energy may cross system boundary Control Volumes may operate at steady state or change with time empty fill Isolated System Special type of closed system that does not interact with its surroundings gas insulation 9 System Properties State Property Macroscopic characteristic of a system that can be quantified at any instant of time without knowledge of the time history of the system Examples mass volume pressure temperature energy State A minimum set of system properties that completely specifies the condition of a system so that its future behavior can be completely determined Steady State A system is in steady state when none of its properties changes i e constant state Types of Properties System characteristic carries both a numerical value and set of units 3 Types of thermodynamics properties Extensive Intensive Specific Extensive Depend on mass size of system Volume V Intensive Independent of system mass size Pressure P Temperature T Specific Extensive mass Specific Volume v 10 Process Process is a transformation a system undergoes from one state to another Special Types of Processes Isothermal constant temperature process Isobaric constant pressure process Isentropic constant entropy process Adiabatic a process with no heat gain loss Thermodynamic Cycle Cycle Series of processes that return system to initial state Example cool Qout heat compression Win expand Qin Wout T1 T2 T1 T3 T2 T4 T3 P1 P2 P1 P3 P2 P4 P3 V1 V2 V1 V2 V1 V4 V3 11 Equilibrium Mechanics Forces and moments are balanced so that the state linear and angular momentum of the system does not change Thermodynamics All influences on system are balanced thermal mechanical phase chemical The state of a system in thermodynamic equilibrium once isolated remains constant State Transition Thermo state of a system is only defined for systems in equilibrium In thermodynamics we only consider processes that go between equilibrium states Quasi equilibrium A process in which each intermediate state deviates infinitesimally from equilibrium idealization of a real process 12 Measuring properties All physical quantities can be expressed in terms of a set of primary dimensions mass M length L time t Temperature T Force is secondary dimension since F Mxacceleration ML t2 SI M kg L m t s T oK F N English M lbm L ft t s T oR F lbf Note F M acceleration 32 2 Density and Specific Volume Homogeneous object density mass volume In general density is given by dm m lim dV V 0 V m is an intensive property that can vary from point to point The dimensions of are kg m3 SI and lbm ft3 English m dV Total mass Volume 13 Pressure P Uniform Force P Normal Force Area In general P dF lim F dA A 0 A F Units of Pressure Pa 1 N m2 SI lbf ft2 or lbf in2 psi 1 atmosphere 1 01325x105 Pa 14 696 psi A Types of Pressure Types Absolute Gage Vacuum Atmospheric Pabs Pgage Patm 14 Pressure Measurement Manometer Piezoelectric transducer Bourden Table Temperature Measure of thermal energy relative to hotness and coldness Must use absolute temperature scales oR K Temperature Sensors