Introduction_to_Metallurgical_Thermodynamics_Presentation.pptx

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1. Introduct I on to Metallurg I cal Thermodynam I cs MSE 2003 Metallurgical Thermodynamics Prof. Dr. Cevat Sarıoğlu Ress . Ass . Dr. Burcu Nilgün Çetiner ( Teaching assistant )

2. Course Objectives Understand the fundamental principles of thermodynamics. Apply these principles to metallurgical processes. Explore real-world applications in materials science and engineering. Build a foundation for more advanced topics in metallurgical thermodynamics.

3. What is Thermodynamics? Thermodynamics is the study of energy, heat, and work, and how they relate to matter. Fundamental to understanding processes in metallurgy, from refining to alloy creation.

4. Key Concepts of Thermodynamics 1st Law of Thermodynamics: Energy cannot be created or destroyed, only transferred or changed in form. 2nd Law of Thermodynamics: Entropy of an isolated system always increases over time. 3rd Law of Thermodynamics: As temperature approaches absolute zero, the entropy of a system approaches a constant minimum.

5. Applications in Metallurgy Predicting the stability of phases in metals. Understanding alloy formation and phase diagrams. Calculating heat requirements for melting and refining.

6. Systems and Phases in Thermodynamics System: The part of the universe being studied (e.g., a crucible of molten metal). Phases: Different states of matter in the system (solid, liquid, gas).

7. Energy in Metallurgical Processes Key Types of Energy: Internal Energy Enthalpy Gibbs Free Energy Understanding these energies helps in designing efficient processes, such as reducing energy consumption in smelting.

8. Introduction to Gibbs Free Energy Gibbs Free Energy (G) determines the spontaneity of a process. Relevance to Metallurgy: Predicting whether a metallurgical reaction will proceed on its own (e.g., metal reduction or oxidation). Equation: G = H - TS (where G = Gibbs Free Energy, H = Enthalpy, T = Temperature, S = Entropy)

9. Why Study Thermodynamics in Metallurgy? Critical for designing processes like refining, smelting, alloying. Helps engineers optimize energy use and material properties. Examples: Reducing energy consumption in steel production, understanding temperature effects on alloys.

10. Overview of Course Topics Thermodynamic Laws in Detail Thermodynamic Properties of Materials Reactions in Metallurgical Systems (e.g., oxidation, reduction) Practical Applications in Industrial Metallurgy

11. Expectations and Assessments Class Expectations: Active participation in discussions and exercises. Regular quizzes and maybe 2 midterms to reinforce concepts. Final exam involving thermodynamic analysis of a metallurgical process. Assessment: Quizzes ( 30 %) Midterms (30%) Final Exam ( 4 0%)

12. Course Material

13. Some concepts of Thermodynamics The word "thermodynamics" is derived from the Greek words for "heat" and "power." It defines heat as the process of energy transfer across a temperature gradient and focuses on the conservation of energy, its conversion into different forms, and work. Thermodynamics distinguishes between a system (the part of the universe being studied) and its surroundings (the external environment).

14. Some concepts of Thermodynamics The interaction between the system and its surroundings is facilitated by a boundary, which may allow exchanges of energy, work, or matter.There are three types of systems based on interactions with surroundings: Isolated systems: No exchange of energy or matter occurs, and the system remains unaffected by the surroundings. Closed systems: Energy can be exchanged with the surroundings, but matter cannot. Open systems: Both energy and matter can be exchanged with the surroundings. Boundaries of systems can be classified based on their permeability to energy and matter: Adiabatic: No thermal energy can pass. Diathermal: Thermal energy can pass. Permeable: Matter can pass . Impermeable : Matter cannot pass. Semipermeable: Some components can pass, while others cannot.Temperature , a macroscopic property, plays a significant role in thermodynamics but is not involved in the mechanical description of matter. The conversion of mechanical energy into thermal energy, and vice versa, was a key discovery in the development of classical thermodynamics. The focus of applied thermodynamics is to understand how the surroundings influence a system's equilibrium state by transferring energy or matter.

15. Some concepts of Thermodynamics T hermodynamic state, which refers to the condition of a system defined by its measurable variables such as energy, temperature, and pressure. The microscopic state of a system could, in principle, be described if one knew the exact details of every particle's motion and position, but this is impractical for large systems with more than 10 24 coordinates . Instead, classical thermodynamics focuses on the macroscopic state, which is determined by a small set of measurable variables. The thermodynamic state of a system is considered to be in equilibrium when all thermodynamic variables are fixed. Notably, for simple systems with fixed composition, only two variables, called independent thermodynamic variables (such as temperature and pressure), are needed to define the system's state. Once these two are fixed, all other thermodynamic variables become dependent and are determined by these independent variables. This principle is known as the Duhem postulate.

16. Some concepts of Thermodynamics In some cases, additional independent variables may be required, such as when electric or magnetic fields are involved. Thermodynamic variables are considered intrinsic to the state of the system and do not depend on the system's history or the path taken to reach that state. These are referred to as functions of state and can be expressed mathematically as exact differentials. Conversely, properties that do depend on the history of the system are called extrinsic properties and may change over time but can be manipulated for optimal material characteristics .

17. Some concepts of Thermodynamics An example provided in the text discusses the relationship between volume, pressure, and temperature for 1 mole of a gas, emphasizing that fixing any two of these variables determines the third when the system is in equilibrium.

18. Some concepts of Thermodynamics

19. Some concepts of Thermodynamics

20. Some concepts of Thermodynamics Boyle’s Law (@ cte T) Charles’ Law (@ cte P) In 1802, Joseph-Luis Gay-Lussac (1778–1850) observed that the thermal coefficient of what were called permanent gases was a constant. Previously, we noted that the coefficient of thermal expansion, α, is defined as the fractional increase of the volume of the gas, with the change in temperature at constant pressure; that is

21. Some concepts of Thermodynamics

22. Some concepts of Thermodynamics

23. Some concepts of Thermodynamics

24. Some concepts of Thermodynamics Thermodynamic state variables are either extensive or intensive. Extensive variables have values which depend on the size of the system, whereas values of intensive variables are independent of the size of the system. Volume is an extensive variable , and temperature and pressure are intensive variables. The values of extensive variables, expressed per unit volume or unit mass of the system, have the characteristics of intensive variables; for example, the volume per unit mass (specific volume) and the volume per mole (molar volume) are variables whose values are independent of the size of the system. For a system of n moles of an ideal gas, the equation of state is

25. Some concepts of Thermodynamics

26. Some concepts of Thermodynamics

27. Some concepts of Thermodynamics Sometimes, thermodynamics is summarized by stating its laws, which can be treated either as experimentally determined facts of nature or as axioms from which other thermodynamic relationships can be derived. We have seen that the so-called Zeroth Law introduces us to the important intensive thermodynamic variable temperature, T, which is a measure of the thermal intensity of a material and allows the determination of thermal equilibrium. The other three laws are summarized in the following subsections and will be the subject of study throughout the text

28. Some concepts of Thermodynamics The First Law not only states that the energy of the universe is conserved but it also posits that the various forms of energy (e.g., thermal, electrical, magnetic, and mechanical ) can be converted into other forms of energy. When first delineated, it was the fact that thermal energy (heat) could be converted to mechanical work that was of special interest (heat engines). This law also defines an important extensive thermodynamic state function called the internal energy, U, of the system under investigation.

29. Some concepts of Thermodynamics Although the Second Law is the one that often gets the most attention in popular discussions of science, it is often incorrectly understood! Care must be taken in applying the law by delineating the system and the surroundings. This law allows us to make important predictions of the direction in which a system will evolve with time during spontaneous processes, if other important caveats are taken into account . The Second Law introduces another important extensive thermodynamic state function called entropy, S. A short version of the Second Law is that the entropy of the universe never decreases.

30. Some concepts of Thermodynamics In its boldest form, the Third Law states that when a system which is in complete internal equilibrium approaches the absolute zero in temperature, all of the aspects of its entropy approach zero. Sometimes, the Third Law is stated as follows: a system can never be taken to the absolute zero in temperature. This is also called the unattainability principle.

31. Some concepts of Thermodynamics

32. Questions?