BASIC CONCEPTAND DEFINITIONS1 2 THERMODYNAMICS CHAPTER 2 Thermodynamic Concets Lecturer Axel GRONIEWSKY, PhD 11 th of February2019 Thermodynamics study of energy and its transformation describes macroscoic roerties of equilibrium systems entirely emirical builton4 Laws Laws of Thermodynamics 0 th Law introducestemeraure, T (Fowler, Guggenheim 1939) 1 st Law introducesenergy, E (Joule, Mayer, Colding1845) 2 nd Law introducesentroy, S (Carnot1824) 3 rd Law determinesthevalueof Entroy(Nerst1907) Lecture BME 31 th January 2018 1 Lecture BME 31 th January 2018 2 BASIC CONCEPT AND DEFINITIONS 1 2 TD: alying the laws of TD to a thermodynamic system Basic concet - black box aroach inside the box not interesting what crosses the box s boundaries interesting Thermodynamic system art of the universe to analyze Surroundings/Environment art of universe, affected by the system System Boundary searates system from surroundings THERMODYNAMIC SYSTEMS 1 2 Tyes of Thermodynamic Systems System rendszerhatár boundary System rendszerhatár boundary rendszerhatár System boundary Isolated System Closed System Oen System mass mass mass energy energy energy Lecture BME 31 th January 2018 3 Lecture BME 31 th January 2018 4 1
THERMODYNAMIC SYSTEMS 1 2 Describing systems requires knowledge whether system is homogeneous or heterogeneous knowledge whether system is in equilibrium state knowledge of the number of comonents macroscoic roerties:, T,, n, m, hysical hase: molecular configuration of matter (solid, liquid, vaor or gas) homogeneous system: system containing only a single hysical hase of a substance heterogeneous system: system containing several hysical hases of a substance PHASES OF MATTER Pure substance - chemically uniform comosition in all its hysical hases elements atoms of single element (O 2, He, Fe ) (well-defined hysical roerties ) comounds -atoms of two or more elements (H 2 O, C 6 H 12 O 6 ) (chemical bond between elements, well-defined hysical roerties ) Mixture Homogeneous Mixtures (air, sea water ) same comosition, no chemical bond comonents are NOT distinguishable Heterogeneous Mixtures (iron owder ) different comosition, no chemical bond comonents are distinguishable Lecture BME 31 th January 2018 5 Lecture BME 31 th January 2018 6 SYSTEM STATES AND THERMODYNAMIC PROPERTIES 1 2 State defined by thermodynamic roerties classification equilibrium state non-equilibrium state (local thermodynamic equilibrium) Thermodynamic roerty deends only on the current state of the system in thermodynamic equilibrium formula relating deendent and indeendent roerties of a system is called a thermodynamic equation of state Classification extensive roerties intensive roerties secific (extensive) roerties SYSTEM STATES AND THERMODYNAMIC PROPERTIES 1 2 Extensive roerties (, m, n, U, H, S ) deend on the mass (size) of the system additive for subsystems Intensive roerties (, T, indeendent of the mass (size) of the system bulk roerty Secific (extensive) roerties ( e=e/m ) extensive roerty divided by mass extensiveroertydividedbymoll (molar secific =/n) in equilibrium, behaves as an intensive roerty within a hase Lecture BME 31 th January 2018 7 Lecture BME 31 th January 2018 8 2
THERMODYNAMIC EQUILIBRIUM An equilibrium imlies a condition of balance between oosing factions Requirements of thermodynamic equilibrium thermal equilibrium: temerature (T) is the same throughout the entire system (hase equilibrium: no hase transformations) mechanical equilibrium: no change in ressure () at any oint of the system with time (elevation as a result of gravitational effects is disregarded) chemical equilibrium: chemical otential is homogeneously distributed within the system (no chemical reactions occur) A systems is in thermodynamic equilibrium if it does not sontaneously change its state after it has been isolated! Lecture BME 31 th January 2018 9 THERMODYNAMIC PROCESSES Thermodynamic rocess: change in state of system Thermodynamic cycle: series of thermodynamic rocesses with the same and states. reversibility: equilibrium (quasistatic) (quasistatic) existence: (arox. by) (arox. by) dissiation: Quasistaticrocess: system remains infinitesimally close to an equilibrium state during rocess (sufficiently slow rocess) Lecture BME 31 th January 2018 10 PRESSURE SCALES Pressure: normal force exerted by a fluid er unit area in gas & liquid. (counterart of ressure in solids is normal stress σ) 1 Pa=1 N/m 2 gage = abs - atm ; vac = atm - abs scalar quantity measured with manometer gage absolute vacuum vac abs atm atm abs abs =0 Lecture BME 31 th January 2018 11 PRESSURE & TEMPERATURE1 2 Temerauter: what dose a liquide in glass thermometer measures? κ isothermalcoefficientof comressibility, 1/Pa β isobariccoefficientof volume exansion, 1/K or 1/ C Thermometers Thermocoules RTDs Thermistors I.C. Sensors Lecture BME 31 th January 2018 12 3
PRESSURE & TEMPERATURE1 2 Temerauter: what dose a liquide in glass thermometer measures? κ isothermalcoefficientof = ( T, ) comressibility, 1/Pa d = d+ dt β isobariccoefficientof volume T exansion, 1/K or 1/ C d 1 d 1 T Thermometers Thermocoules RTDs Thermistors I.C. Sensors = + dt κ= 1 d 1 β= dt T d = β dt κ d ln 2= β T T κ 2 1 2 1 1 Lecture BME 31 th January 2018 13 ZEROTH LAW OF THERMODYNAMICS Zeroth law of thermodynamics if two bodies are in thermal equilibrium with a third body, they are also in thermal equilibrium with each other. (it forms the theoretical basis for temerature measurement technology) Continuum hyothesis large systems made u of many discrete molecules or atoms may be treated as though they were made u of a continuous (i.e., nonmolecular) material. subatomic level: statistical thermodynamics based on the average behavior of large grous of articles macroscoiclevel: classical thermodynamics continuum thermodynamics, based on exerimental observations Lecture BME 31 th January 2018 14 CONSERATION CONCEPTS Balance concet X gain =X tran.into -X leaving +X rod. -X destr. X gain =X tran.net +X rod.net (X somequantity of an arbitrarysystem) Conservation concet conserved quantity can be neither created nor destroyed (X rod. =X destr. =0 X gain =X tran.net ) emirically discovered major entities: mass conservationof mass momentum (linear & angular) conservation of momentum energy(total) conservationof energy 1st lawof TD electrical charge conservation of charge Lecture BME 31 th January 2018 15 CONSERATION OF MASS Conservation of mass massbalance(mb) over timeδt δm system =Σm in -Σm out mass rate balance(mrb) (δm/dt) system =Σ(δm in /dt)-σ(δm out /dt) Lecture BME 31 th January 2018 16 4
THERMODYNAMIC PROBLEMSOLING Readthe roblem statement Sketch the system and its boundary. Identify the unknown(s). Identify the tye of thesystem (closed or oen). Identify the rocess of the states. Write down the basic thermodynamic equations and any useful auxiliary equations. Algebraically solve for the unknown(s). Calculate the value(s) of the unknown(s). Check all algebra, calculations, and units. Thank you for your attention! Lecture BME 31 th January 2018 17 Lecture BME 31 th January 2018 18 5