工程热力学：01绪论 及 第一章 基本概念（1）.ppt

1、Jilin University Thermal Engineering Department,1,Introduction,Engineering Thermodynamics,主讲教师：金英爱 教授 汽车工程学院热能工程系 吉林大学,Jilin University Thermal Engineering Department,2,References,工程热力学第四版 华自强 张忠进 高青 高等教育出版社，2009 Thermodynamics -An Engineering Approach Sixth Edition, Yunus A. Cengel, Michael A. Bole

2、s Mc Graw Hill (Publishing House of Electronics Industry), 2009,Jilin University Thermal Engineering Department,3,Introduction,Thermodynamics is a basic science that deals with energy and has long been an essential part of engineering curricula all over the world. To cover the basic principles of th

3、ermodynamics. To present a wealth of real-world engineering applications to give students a feel for engineering practice.,Objectives,Jilin University Thermal Engineering Department,4,Some application areas of thermodynamics,Introduction,Jilin University Thermal Engineering Department,5,Some applica

4、tion areas of thermodynamics,Introduction,Jilin University Thermal Engineering Department,6,Power station,Boiler Turbine Condenser Pump Question: Does thermal energy can all change into mechanical energy?,Introduction,Jilin University Thermal Engineering Department,7,Internal combustion engine,Intak

5、e Compression Combustion Expansion Exhaust,Introduction,Jilin University Thermal Engineering Department,8,Gas turbine engine,Compressor Combustion Chamber Gas turbine,Introduction,Jilin University Thermal Engineering Department,9,Modern jet engine,Introduction,Jilin University Thermal Engineering De

6、partment,10,Refrigeration Cycles,Question: Does thermal energy can transfer from low temperature to high temperature? How can it be done?,Compressor Condenser Expansion valve Evaporator,Introduction,Jilin University Thermal Engineering Department,11,What its All About,Thermodynamics is a science and

7、, more importantly, an engineering tool used to describe processes that involve changes in temperature, transformation of energy, and the relationships between heat and work.,Introduction,Jilin University Thermal Engineering Department,12,The laws of thermodynamics. The properties of mass. How to im

8、prove the efficiency of energy converting cycle.,What its All About,Introduction,Jilin University Thermal Engineering Department,13,省级精品课程： 工程热力学,校园网 吉林大学 教学在线 吉林大学课程中心 课程资源 精品课程 工程热力学,Jilin University Thermal Engineering department,14,Chapter One Basic Concepts,Engineering Thermodynamics,Jilin Univ

9、ersity Thermal Engineering department,15,System, surroundings, and boundary., 1-1 Thermodynamic System,Closed system (Control mass ) Open system (Control volume ),Jilin University Thermal Engineering department,16,Mass cannot cross the boundaries of a closed system, but energy can., 1-1 Thermodynami

10、c System,Jilin University Thermal Engineering department,17,A control volume may involve fixed, moving, real, and imaginary boundaries., 1-1 Thermodynamic System,Jilin University Thermal Engineering department,18,Adiabatic system Isolated system High temperature thermal energy reservoir (Called Sour

11、ce) Low temperature thermal energy reservoir (Called Sink), 1-1 Thermodynamic System,Jilin University Thermal Engineering department,19,The thermodynamic state of a system is defined by specifying values of a set of measurable properties sufficient to determine all other properties., 1-2 The Concept

12、 of “State”,Property For a given state, all have their own state parameters. 2. The property is independent of the path used to arrive at the system.,Jilin University Thermal Engineering department,20, 1-2 The Concept of “State”,Extensive properties are those whose values depends on the size or exte

13、nt of the system. Intensive properties are those that are independent on the mass of a system.,Jilin University Thermal Engineering department,21,For fluid systems, typical properties are pressure, specific volume and temperature., 1-2 The Concept of “State”, m3/kg ,Density , kg/ m3 ,1. Specific vol

14、ume v,Jilin University Thermal Engineering department,22, 1-2 The Concept of “State”,2. Pressure p Pa,Absolute pressure Gage pressure Vacuum pressure,1 Pa =1 N/ m2,The absolute pressure is the actual pressure.,Burden tube gage,Jilin University Thermal Engineering department,23,Absolute, gage, and va

15、cuum pressures., 1-2 The Concept of “State”,2. Pressure p Pa,Jilin University Thermal Engineering department,24,3. Temperature T Temperature is a measure of “hotness” or “coldness”. The zeroth law of thermodynamics states that if two bodies are in thermal equilibrium with a third body, they are also

16、 in thermal equilibrium with each other., 1-2 The Concept of “State”,Jilin University Thermal Engineering department,25,3. Temperature T Comparison of temperature scales: Celsius scale Kelvin scale Fahrenheit scale Rankine scale, 1-2 The Concept of “State”,T（K）= 273.15 + t ( ),Jilin University Therm

17、al Engineering department,26,Equilibrium state The word equilibrium implies a state of balance. In an equilibrium state there are no unbalanced potentials (or driving force) within the system. A system in equilibrium experiences no changes when it is isolated from its surroundings., 1-3 Equilibrium

18、State,Jilin University Thermal Engineering department,27, 1-3 Equilibrium State,A system in thermodynamic equilibrium satisfies: mechanical equilibrium (no unbalanced forces) thermal equilibrium (no temperature differences) chemical equilibrium,Jilin University Thermal Engineering department,28,Stat

19、e Postulate The thermodynamics state of a simple compressible system is completely specified by two independent , intensive properties., 1-3 Equilibrium State,Jilin University Thermal Engineering department,29,A process between states 1 and 2 and the process path., 1-3 Equilibrium State,Jilin Univer

20、sity Thermal Engineering department,30,The P-V diagram of a compression process., 1-3 Equilibrium State,Jilin University Thermal Engineering department,31, 1-4 Gas Equation of State,This implies: (1) very little molecular interaction (p 0),and (2) molecules are point masses, i.e., zero volume.,Gas e

21、quation of state,For 1kg,For 1mol,The ideal gas equation of state,Jilin University Thermal Engineering department,32,The universal gas constant,M = Molecular weight, kg/kmol, 1-4 Gas Equation of State,Jilin University Thermal Engineering department,33, 1-4 Gas Equation of State,Example Mass of Air i

22、n a Room Determine the mass of the air in a room whose dimensions are 4m5m6m at 100kPa and 25. Solution The mass of air in a room is to be determined. Analysis Air at specified conditions can be treated as an ideal gas. The gas constant of air is Rg=287J/(kgK) and the absolute temperature is T=25+273=298K. The volume of the room is V=4m5m6m=120m3 The mass of air in the room is determined from the ideal gas relation to be,