1、Chapter One Basic Concepts,Engineering Thermodynamics,Jilin University Thermal energy engineering department,2019/1/1,1,Jilin University Thermal energy engineering department,System, surroundings, and boundary., 1-1 Thermodynamic System,Closed system (Control mass )Control volume,2019/1/1,2,Jilin Un
2、iversity Thermal energy engineering department,Mass cannot cross the boundaries of a closed system, but energy can., 1-1 Thermodynamic System,2019/1/1,3,Jilin University Thermal energy engineering department,A control volume may involve fixed, moving, real, and imaginary boundaries., 1-1 Thermodynam
3、ic System,2019/1/1,4,Jilin University Thermal energy engineering department,The thermodynamic state of a system is defined by specifying values of a set of measurable properties sufficient to determine all other properties. For fluid systems, typical properties are pressure, volume and temperature.,
4、 1-2 The Concept of “State”,2019/1/1,5,Jilin University Thermal energy engineering department,A process between states 1 and 2 and the process path., 1-2 The Concept of “State”,2019/1/1,6,Jilin University Thermal energy engineering department,Absolute, gage, and vacuum pressures., 1-2 The Concept of
5、 “State”,2019/1/1,7,Jilin University Thermal energy engineering department,Comparison of temperature scales. Celsius scale Kelvin scale Fahrenheit scale Rankine scale, 1-2 The Concept of “State”,2019/1/1,8,Jilin University Thermal energy engineering department,Celsius Scale Triple point of water at
6、P = 1 atmT = 0 oC Steam point of water at P = 1 atmT = 100 oC1 oC = 1 K,Kelvin Scale Triple point of water at P = 1 atmT = 273.15 K Steam point of water at P = 1 atmT = 373.15 K, 1-2 The Concept of “State”,Temperature scales,2019/1/1,9,Jilin University Thermal energy engineering department, 1-3 Equi
7、librium State,A system in thermodynamic equilibrium satisfies: mechanical equilibrium (no unbalanced forces) thermal equilibrium (no temperature differences) chemical equilibrium,2019/1/1,10,Jilin University Thermal energy engineering department,State PostulateThe thermodynamics state of a simple co
8、mpressible system is completely specified by two independent , intensive properties., 1-3 Equilibrium State,2019/1/1,11,Jilin University Thermal energy engineering department,The P-V diagram of a compression process., 1-3 Equilibrium State,2019/1/1,12,Jilin University Thermal energy engineering depa
9、rtment, 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 equation of state,For 1kg,For 1mol,The ideal gas equation of state,2019/1/1,13,Jilin University Thermal energy engineering department,The universal g
10、as constant,M = Molecular weight, kg/kmol, 1-4 Gas Equation of State,2019/1/1,14,Jilin University Thermal energy engineering department,A gas does a differential amount of work W as it forces the piston to move by a differential amount ds., 1-5 Quasi-static Process and reversible process,2019/1/1,15
11、,Jilin University Thermal energy engineering department,Only “infinitesimal” unbalanced forces exist, so that the process can be viewed as taking place in a series of “quasi-equilibrium” states. (The term quasi can be taken to mean “as if”.),For this to be true the process must be slow in relation t
12、o the time needed for the system to come to equilibrium internally., 1-5 Quasi-static Process and reversible process,2019/1/1,16,Jilin University Thermal energy engineering department,A reversible process for a system is defined as a process that, once having taken place, can be reversed, and in so
13、doing leaves no change in either the system or surroundings.,In other words the system and surroundings are returned to their original condition before the process took place.,In reality, there are no truly reversible processes; however, for analysis purposes, one uses reversible to make the analysi
14、s simpler, and to determine maximum theoretical efficiencies., 1-5 Quasi-static Process and reversible process,2019/1/1,17,Jilin University Thermal energy engineering department, 1-6 The work of reversible process,Interactions,2019/1/1,18,Jilin University Thermal energy engineering department,Deform
15、ation of the system boundary,2019/1/1,19, 1-6 The work of reversible process,Jilin University Thermal energy engineering department,Evaluating the work .Integral for a quasi-static process.,2019/1/1,20, 1-6 The work of reversible process,Jilin University Thermal energy engineering department, 1-7 Heat,A resistor heating water,Evaluating the heat .Integral for a quasi-static process.,2019/1/1,21,Jilin University Thermal energy engineering department, 1-8 Cyclic Processes,2019/1/1,22,Jilin University Thermal energy engineering department,
