Basic Concepts of Thermodynamics Reading 2-1 2-8 Problems 2-44, 2-48, 2-78, 2-100 Thermal Sciences The thermal sciences involve the storage, transfer and conversion of energy. We will study the basic laws and principles that govern the three disciplines of thermal sciences, namely, thermodynamics, heat transfer and uid mechanics. Thermodynamics Conservation of mass Conservation of energy Second law of thermodynamics Properties Heat Transfer Conduction Convection Radiation Conjugate yn am ics He at mo d a Tr ns Thermal Systems Engineering Th er fer Fluids Mechanics Fluid Mechanics Fluid statics Conservation of momentum Mechanical energy equation Modeling 1 Thermodynamic Systems Isolated Boundary Surroundings W ork He at System Surroundings - everything that interacts with the system System Boundary (real or imaginary fixed or deformable) System - may be as simple as a melting ice cube - or as complex as a nuclear power plant SYSTEM: any speci ed collection of matter under study. thermodynamic systems are classi ed as either open or closed Closed System: composed of a control (or xed) mass where heat and work can cross the boundary but no mass crosses the boundary. Open System: composed of a control volume (or region in space) where heat, work, and mass can cross the boundary or the control surface WORK &amp; HEAT TRANSFER: work and heat transfer are NOT properties they are the forms that energy takes to cross the system boundary 2 <a href="/keyword/thermodynamic-properties/" >thermodynamic properties</a> of Systems Basic De nitions Thermodynamic Property: Any observable or measurable characteristic of a system. Any mathematical combination of the measurable characteristics of a system Intensive Properties Pressure Temperature P T Extensive Properties N/m2 or P a K Volume Mass V m3 m kg Other Properties (Intensive and Extensive) V /m = v = 1/v = m/V E/m = e U/m = u H/m = h = u + P v S/m = s Cp, Cv R = Cp Cv m3 /kg kg/m3 J/kg J/kg J/kg J/kg K J/kg K J/kg K Speci c VolumeA Density Total EnergyB Internal EnergyB EnthalpyB EntropyB Speci c Heat Ideal Gas Constant Notes: A The term speci c denotes that the property is independent of mass. There are two exceptions: 1) speci c gravity (or relative density) is given where: s = / H2 O and H2 O is 1000 kg/m3 . 2) speci c weight is weight per unit volume (i.e. W/V = mg/V = g = ) B The given internal energy, enthalpy and entropy are speci c properties. The term speci c is dropped. 3 Pressure P ressure = F orce Area ; N m2 Pa in uids, this is pressure (normal component of force per unit area) in solids, this is stress 1 kP a = 103 P a 1 bar = 105 P a : : 1 M P a = 106 P a 1 atm = 101, 325 P a Pressure gauge pressure Patm vacuum pressure absolute vacuum pressure ABSOLUTE ATMOSPHERIC PRESSURE absolute pressure Manometer a device that measures pressure using a column of liquid 4 the uid pressure at any point, 1 in a manometer is given as P1 = Patm + gh Bourdon Tube a device that measures pressure using mechanical deformation Pressure Transducers devices that use piezoelectrics to measure pressure Barometer device that measures atmospheric pressure 5 Temperature temperature is a pointer for the direction of energy transfer as heat TA &gt; TB TA Q TB TA &lt; TB TA Q TB It follows that temperature is a property two systems have in common when they are in thermal equilibrium with each other Thermal Equilibrium: TA = TB and Q=0 0th Law of Thermodynamics: if system C is in thermal equilibrium with system A, and also with system B, then TA = TB = TC two bodies are in thermal equilibrium if they have the same temperature, even if they are not in contact with one another State and Equilibrium the state of a system is its condition as described by a set of relevant energy related properties. thermodynamic equilibrium refers to a condition of equilibrium with...