Thermofluids I: Thermodynamics ENGN 2610 Lecture Notes PDF

Thermofluids I: Thermodynamics “ENGN 2610” Dr. Ahmed Hassan Department of Design and Sustainable Energy University of Prince Edward Island – Cairo Campus [email protected] OFFICE: B317...

Thermofluids I: Thermodynamics “ENGN 2610” Dr. Ahmed Hassan Department of Design and Sustainable Energy University of Prince Edward Island – Cairo Campus [email protected] OFFICE: B317 1  Thermofluids I: Thermodynamic “ENGN 2610” Lecture 1 Introduction & Basic Concepts  Learning outcomes By the end of the lecture, you should gain the following outcomes: Course outline and important dates. Textbook Chapter 1-1 to 1-7 Main rules to be applied. Introduction to the course illustrating the main contents. Basic thermodynamic concepts. 3  Class Time Group Lecture Lab Tuesday 8:30 – 9:45 [EG15] Thursday 13:25 – 16:00 Thursday 8:30 – 9:45 [EG14] Tuesday 10:00 – 12:35 Sunday 10:00 – 12:35 2 lecture weekly (attendance is mandatory). 1 lab weekly (attendance is mandatory). Problem solving sessions during the lab time (location: B327). Office hours: Tuesday 12:45 pm to 2:30 pm Thursday 12:45 pm to 13:15 pm 3 Quizzes during lab time. 4  Assessment Component Grade Midterm 20% 3 Quizzes 30% Labs 15% Final Exam 35% Total 100% Quizzes schedule Labs submission schedule Quiz 1 Oct. 17th & Oct. 20th 10% Lab 1 Oct. 17th & Oct. 20th 5% Quiz 2 Nov. 14th & Nov. 17th 10% Lab 2 Nov. 7th & Nov. 10th 5% Quiz 3 Nov. 28th & Dec. 1st 10% Lab 3 Nov. 28th & Dec. 1st 5% Lab 1: Measuring pressure using manometers Midterm Oct. 29th 20% Lab 2: Gas Laws Lab 3: Refrigeration cycle 5  Attendance and Punctuality If a student is absent for 25% or more of the class time, tutorials, labs, and/or mandatory office hours, the instructor may: a. Advise the student to drop the course if the absences occur before the drop date for course. b. Give the student a grade of F for the course. c. Give the student an Incomplete grade for the course if the absences are caused by an approved documented illness or emergency. Students would then be given the opportunity to complete the course work as per the academic regulations. 6  What is Thermodynamics? Thermodynamics (Greek) Therme (heat) Dynamis (power) The science of energy The ability to cause changes In its broader sense, thermodynamics includes all aspects of energy and energy transformations, e.g., power generation, refrigeration, relationships among the properties of matter,… etc. 7 Thermodynamics areas 8  Basic contents of the course and learning outcomes Recommended Textbook Cengel and Boles, Thermodynamics: An Engineering Approach (McGraw-Hill) Thermodynamic properties of substances: Pressure, temperature, mass, volume, …. Conservation of energy principle: o One of the most fundamental laws of nature. o It simply states that during an interaction, energy can change from one form to another, but the total amount of energy remains constant. That is, energy cannot be created or destroyed. 1st law of thermodynamics. 9  Basic contents of the course and learning outcomes Recommended Textbook Cengel and Boles, Thermodynamics: An Engineering Approach (McGraw-Hill) 2nd law of thermodynamics: Energy has quality as well as quantity, and actual processes occur in the direction of decreasing quality of energy. Thermodynamic cycles: ❑ Heat Engines. ❑ Refrigeration cycles. 10  Basic content of the course and learning outcomes LO #1 Understand the concept of energy and energy transfer. LO #2 Understand the basic thermodynamic properties of substances. LO #3 Understand the relationship between heat and work in systems. LO #4 Applications of First Law of Thermodynamics. LO #5 Apply the First Law of Thermodynamics to closed systems. LO #6 Apply the First Law of Thermodynamics to open systems. LO #7 Understand the Second Law of Thermodynamics and its applications. LO #8 Understand the classical and statistical definitions of entropy. LO #9 Understand thermodynamic cycles. LO #10 Analyze heat engines and refrigeration cycles. 11  Energy and Energy systems Heat Energy Work 12  Energy and Energy systems Energy Systems Coal Aircraft gas turbine Natural gas Stationary gas turbine Oil Steam power plants Nuclear fission Nuclear power plant Hydro Refrigeration and air conditioning Geothermal Auto and truck engines Solar Locomotives Wind Small engines Biomass Chemical process plants Waste Fuel cells Fusion Compression systems 13  Thermodynamic system System: quantity of matter or a region in space chosen for study. Surroundings: the mass or region outside the system. Boundary: the real or imaginary surface that separates the system from its surroundings. The boundary of a system can be fixed or movable. System System Working fluid Boundary Surroundings 14  Thermodynamic system What may cross the system boundaries? Heat (Q) Mass Energy (m) Work (W) System Working fluid Boundary Surroundings Examples: Closed tank – Piston cylinder device (Internal combustion engines) – Mixer – Heat exchanger – Pump – Turbine – Compressor – Fan. 15  System boundary Real boundary Imaginary boundary Moving boundary CV Fixed boundary Nozzle Piston cylinder device 16  Types of systems 1. Closed system 𝒎 = 𝒄𝒐𝒏𝒔𝒕𝒂𝒏𝒕 A region of space of fixed mass i.e. mass CANNOT cross its boundary. Mass (m) Mass (m) Closed system (m=constant) Closed system Heat (Q) (m=constant) Heat (Q) Work (W) Work (W) Closed tank (V=constant) Piston-cylinder device (Vconstant) 17  Types of systems 2. Isolated system A region of space where NO mass NOR energy can cross the boundary. No interaction with the surroundings. Mass (m) 𝒎 = 𝒄𝒐𝒏𝒔𝒕𝒂𝒏𝒕 Isolated system Heat (Q) 𝑸=𝟎 Work (W) 𝑾=𝟎 18  Types of systems 3. Open system A region of space where both mass and energy can cross the boundary. 𝒎𝒐𝒖𝒕 𝒎𝒊𝒏 Examples: Heat exchangers – Open system Pumps – Turbines – Heat (Q) Compressors – Fans. Work (W) 19  Types of systems Open unsteady system A region of space where both mass and energy can cross the boundary unsteadily. Mass in or out of the system 𝒎𝒊𝒏 𝒐𝒓 𝒎𝒐𝒖𝒕 Open system Examples: Open tanks. Heat (Q) Work (W) 20  Working fluid Continuum: Microscopic System behavior (concerned directly with the structure of matter) Working fluid Macroscopic behavior (concerned with the gross or overall behavior of The continuum idealization allows us to treat properties as point functions and to assume the properties vary continually in space with no jump matter) discontinuities. 21  Property System Property is any macroscopic characteristic of a system (e.g.: mass m, Volume Working fluid V, Temperature T, Pressure P, …). has properties Intensive property Extensive property Independent of the mass Depends on the size or of a system. extent of the system. Pressure. Mass. Temperature. Volume. Density. Properties are either measured or calculated. 22  Property Specific property: is an extensive property per unit mass. Examples: 𝑉 Specific volume: 𝑣 = [𝑚3 /𝑘𝑔] 𝑚 𝐸 Specific total energy: 𝑒 = [𝐽/𝑘𝑔] 𝑚 23  State and equilibrium State: a set of thermodynamic properties at a certain point of time that describes an equilibrium. State 1 State 2 Has a set of fixed properties Has another set of fixed properties 24  State and equilibrium Equilibrium Equilibrium is a state of balance, a system in equilibrium experiences no changes when it is isolated from its surroundings. ❑Thermal equilibrium: if the temperature is the same throughout the entire system. ❑Mechanical equilibrium: if there is no change in pressure at any point of the system with time. ❑Chemical equilibrium: if its chemical composition does not change with time. ❑Phase equilibrium: If a system involves two phases, no net change with the mass of each phase with time. 25  State and equilibrium We don’t need to know all the properties of a state in order to fix the state. The number of properties required to fix the state of a system is called the state postulate. The state of a simple compressible system is completely specified by two independent, intensive properties. Simple compressible No electrical, Independent magnetic, One property can be gravitational, motion, varied while the other or surface tension one is held constant effects 26  Process Process: Any change that a system undergoes from one equilibrium state to another. State 1 Quasi equilibrium process: A transformation from one equilibrium state to another whereby the system remains sufficiently close to an equilibrium state at all times. 27  Cycle A sequence of processes that begins and ends at the same state (there is no net change of state Isothermal Adiabatic Isothermal Adiabatic heating heating compression compression 28  Summary At the end of this lecture, you should be able to answer the following questions: What is thermodynamics and what are its major areas of study? What is a thermodynamic system? What is meant by a boundary? what are the different types of boundaries? Compare between closed, open and isolated systems. What is an unsteady flow system? What is the difference between intensive and extensive property? Give examples. Define thermal, mechanical, chemical, and phase equilibrium. What is meant by quasi equilibrium process? What is a thermodynamic cycle? 29