MET 211 Module 2 introduction_to_thermodynamics
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1) Thermodynamics is the science of energy and deals with energy transfer and its effects on substances. Some common types of energy transfer include heat to mechanical, mechanical to electrical, and electrical to mechanical. 2) The basic laws of thermodynamics include the zeroth law regarding temperature scales and equilibrium, the first law regarding energy conservation, and the second law regarding energy quality and processes. 3) Important thermodynamic concepts include systems, properties of systems, state, processes, cycles, and the different types of processes like isothermal, isobaric, and isochoric processes.
MET 211 Module 2 introduction_to_thermodynamics
- 1. Module 2 INTRODUCTION TO THERMODYNAMICS By: Dr. Taib Iskandar bin Mohamad 1
- 2. Definition • Thermodynamic is a science of energy. It deals with energy transfer and its effect on properties of substance • Energy trnasfer – Heat mechanical (petrol engine) – Mechanical electrical (generator) – Electrical mechanical (motor) – Heat electrical (power plant) 2
- 3. Basic laws of Thermodynamics • Zeroth Law – temperature scale and equilibrium • First Law – Energy Conservation • Second Law – Energy quality and process 3
- 4. Scope of Thermodynamics • Conversion between heat and mechanical work • General procedure – Problem definition – Data collection – Data analysis – Solution and implementation decision 4
- 5. Defining view point • Macroscopic (classical thermodynamics) – Total view- not to molecular level – Properties are taken as average – Simple mathematical formulae • Microscopic (statistical thermodynamics) – Molecular level – Requires advanced statistical and mathematical model from large number of variables 5
- 6. Important definitions • Working substance – substance that carry energy to complete process (work or heat) • Pure substance – homogeneous substance whose chemical composition remain constant • System – portion of universe or certain quantity of matter under study • Boundary and surroundings – define system 6
- 7. Types of system • Closed system – No mass transfer across boundary • Open system – Mass and energy cross boundary • Adiabatic system – No heat cross boundary • Isolated system – No energy and mass cross system 7
- 8. Control volume and surface 8
- 9. PROPERTIES OF A SYSTEM • Property: Any characteristic of a system. • Some familiar properties are pressure P, temperature T, volume V, and mass m. • Properties are considered to be either intensive or extensive. • Intensive properties: Those that are independent of the mass of a system, such as temperature, pressure, and density. • Extensive properties: Those whose values depend on the size— or extent—of the system. • Specific properties: Extensive Criterion to differentiate intensive properties per unit mass. and extensive properties. 9 9
- 10. State • The number of properties required to fix the state of a system is given by the state postulate: – The state of a simple compressible system is completely specified by two independent, intensive properties. • Simple compressible system: If a system involves no electrical, magnetic, The state of nitrogen is fixed gravitational, motion, and by two surface tension effects. independent, intensive properties. 10 10
- 11. PROCESS Process: Any change that a system undergoes from one equilibrium state to another. Path: The series of states through which a system passes during a process. To describe a process completely, one should specify the initial and final states, as well as the path it follows, and the interactions with the surroundings. 11 11
- 12. Process diagrams plotted by employing thermodynamic properties as coordinates are very useful in visualizing the processes. Some common properties that are used as coordinates are temperature T, pressure P, and volume V (or specific volume v). The prefix iso- is often used to designate a process for which a particular property remains constant. Isothermal process: A process during which the temperature T remains constant. Isobaric process: A process during which the pressure P remains constant. Isochoric (or isometric) process: A process during which the specific volume v remains constant. Cycle: A process during which the initial The P-V diagram of a compression and final states are identical. process. 12
- 13. QUASISTATIC OR QUASI-EQUILIBRIUM PROCESS: When a process proceeds in such a manner that the system remains infinitesimally close to an equilibrium state at all times. 13
- 14. Cycles and cyclic process • A system undergoes a succession of processes that at the end of the final state equals the initial states 14