tailieunhanh - Lecture Companion site to accompany thermodynamics: An engineering approach (7/e): Chapter 3 - Yunus Çengel, Michael A. Boles

Chapter 3 - Properties of pure substances. The objectives of Chapter 3 are to: Introduce the concept of a pure substance, discuss the physics of phase-change processes. Illustrate the P-v, T-v, and P-T property diagrams and P-v-T surfaces of pure substances, demonstrate the procedures for determining thermodynamic properties of pure substances from tables of property data, describe the hypothetical substance “ideal gas” and the ideal-gas equation of state,. | Chapter 3 Properties of Pure Substances Study Guide in PowerPoint to accompany Thermodynamics: An Engineering Approach, 7th edition by Yunus A. Çengel and Michael A. Boles We now turn our attention to the concept of pure substances and the presentation of their data. Simple System A simple system is one in which the effects of motion, viscosity, fluid shear, capillarity, anisotropic stress, and external force fields are absent. Homogeneous Substance A substance that has uniform thermodynamic properties throughout is said to be homogeneous. Pure Substance A pure substance has a homogeneous and invariable chemical composition and may exist in more than one phase. Examples: 1. Water (solid, liquid, and vapor phases) 2. Mixture of liquid water and water vapor 3. Carbon dioxide, CO2 4. Nitrogen, N2 5. Mixtures of gases, such as air, as long as there is no change of phase. State Postulate Again, the state postulate for a simple, pure substance states that the . | Chapter 3 Properties of Pure Substances Study Guide in PowerPoint to accompany Thermodynamics: An Engineering Approach, 7th edition by Yunus A. Çengel and Michael A. Boles We now turn our attention to the concept of pure substances and the presentation of their data. Simple System A simple system is one in which the effects of motion, viscosity, fluid shear, capillarity, anisotropic stress, and external force fields are absent. Homogeneous Substance A substance that has uniform thermodynamic properties throughout is said to be homogeneous. Pure Substance A pure substance has a homogeneous and invariable chemical composition and may exist in more than one phase. Examples: 1. Water (solid, liquid, and vapor phases) 2. Mixture of liquid water and water vapor 3. Carbon dioxide, CO2 4. Nitrogen, N2 5. Mixtures of gases, such as air, as long as there is no change of phase. State Postulate Again, the state postulate for a simple, pure substance states that the equilibrium state can be determined by specifying any two independent intensive properties. The P-V-T Surface for a Real Substance P-V-T Surface for a Substance that contracts upon freezing For more information and animations illustrating this topic visit the Animation Library developed by Professor S. Bhattacharjee, San Diego State University, at this link. P-V-T Surface for a Substance that expands upon freezing Real substances that readily change phase from solid to liquid to gas such as water, refrigerant-134a, and ammonia cannot be treated as ideal gases in general. The pressure, volume, temperature relation, or equation of state for these substances is generally very complicated, and the thermodynamic properties are given in table form. The properties of these substances may be illustrated by the functional relation F(P,v,T)=0, called an equation of state. The above two figures illustrate the function for a substance that .