Thermodynamics Contents-Thermodynamics-Lecture Slides, Slides of Thermodynamics

Download Thermodynamics Contents-Thermodynamics-Lecture Slides and more Slides Thermodynamics in PDF only on Docsity! Thermodynamics Contents 1. Heat 2. Work 3. Systems 4. Units 5. State of a Working Fluid docsity.com Thermodynamics Definition: Applied thermodynamics is the science of the relationship between heat, work, and systems that analyze energy processes docsity.com Heat Other units are 1 cal (calorie)= 4.1868 J 1 Btu (British thermal unit)= 1055.05 J ft.lbf= 1.35582 J kJ= 1000 J MJ= 1E6 J hp.h (horsepower.hour)= 2.6845E6 J kWh= 3.6E6 J MWh= 3.6E9 docsity.com Heat Sensible Heat Heat energy stored in a substance as a result of an increase in its temperature. Latent Heat Latent Heat is defined as the heat which flows to or from a material without a change to temperature. The heat will only change the structure or phase of the material. e.g. melting or boiling of pure materials. docsity.com Work Work is defined as the scalar product of a force, F, and a distance,L. work is done by the system work is done on the system docsity.com Density  Density of a system is the mass of the unit volume of the system.  Note that the density is reciprocal of specific volume i.e.  The density of gases and vapors is dependent on temperature and pressure  Density of most solids and liquids is dependent only on temperature  The SI unit of density is kg/m3 docsity.com Specific Volume The specific volume, v, of a system is the volume occupied by unit mass of the system. The SI unit of specific volume is m3 /kg (cubic meter per kilogram). docsity.com Internal Energy Internal energy of a system, is the energy content of the system due to its thermodynamic properties such as pressure and temperature. The change of internal energy of a system depends only on the initial and final states of the system and not in any way by the path or manner of the change. This concept is used to define the first law of thermodynamics. Specific Internal Energy • Specific internal energy is defined as the internal energy of the system per unit mass docsity.com System Closed System In closed systems, nothing leaves the system boundaries. As an example, consider the fluid in the cylinder of a reciprocating engine during the expansion stroke. The system boundaries are the cylinder walls and the piston crown. Notice that the boundaries move as the piston moves. docsity.com System Open System In open systems there is a mass transfer across the system's boundaries; for instance the steam flow through a steam turbine at any instant may be defined as an open system with fixed boundaries. docsity.com State of Working Fluid  Working fluid is the matter contained within boundaries of a system.  Matter can be in solid, liquid, vapor or gaseous phase.  The working fluid in applied thermodynamic problems is either approximated by a perfect gas or a substance which exists as liquid and vapor.  The state of the working fluid is defined by certain characteristics known as properties. docsity.com State of Working Fluid The thermodynamic properties for a pure substance can be related by the general relationship, f(P,v,T)=0, The thermodynamic laws do not give any information about the nature of this relationship for the substances in the liquid and vapor phases. docsity.com State of Working Fluid The state of any pure working fluid can be defined completely by just knowing two independent properties of the fluid. This makes it possible to plot state changes on 2D diagrams such as: • pressure-volume (P-V) diagram, • temperature-entropy (T-s) diagram, • enthalpy-entropy (h-s) diagram. docsity.com The First Law of Thermodynamics • Conservation of Energy: energy can neither be created nor destroyed •where U1 and U2 are intrinsic energy of the system at initial and final states . Q= The algebraic sum of the heat +Ve or - Ve W= The algebraic sum of the work done +Ve or - Ve docsity.com Thermodynamic Equilibrium (Zeroth Law) Object #1 (Thermometer) When two objects are separately in thermodynamic equilibrium with a third object, they are in equilibrium with each other. Objects in thermodynamic equilibrium have the same temperature. & docsity.com TA = Temperature of Body A TB = Temperature of Body B TC = Temperature of Body C For Thermal Equilibrium TA = TB = TC docsity.com yo" OS docsity.com