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Revisiting The First Law of Energy Conservation The 2005 International Mechanical Engineering Congress and Exhibition November 5-11, 2005 Walt Disney World Dolphin Hotel, Orlando, Florida, USA Prof. M. Kostic Mechanical Engineering NORTHERN ILLINOIS UNIVERSITY © M. Kostic <www.kostic.niu.edu> 041115 World Energy and Future: Importance of Energy Conservation and Renewable and Alternative Energy Resources 1.37 kW/m2 ·12% 165 W/m2 2000 kcal/day100 Watt World over 6 billion 2,200 Watt/c 275 Wel /c © M. Kostic <www.kostic.niu.edu> 041115 USA about 0.3 billion 12,000 Watt/c 1500 Wel /c The two things are certain (1) the world population and their living-standard expectations will substantially increase (over 6 billion people now, in 50 years 10-11 billion - energy may double) (2) fossil fuels’ economical reserves, particularly oil and natural gas, will substantially decrease (oil may run out in 30-50 years) © M. Kostic <www.kostic.niu.edu> 041115 Some Headlines…: It took World 125 years to consume the first trillion barrels of oil – the next trillion will be consumed in 30 years. The World consumes two barrels of oil for every barrel discovered. Only “Human Power” can deliver MORE energy with LOWER emission © M. Kostic <www.kostic.niu.edu> 041115 Population & Energy: Unrestricted Exponential Growth About one million years ago our own species, homo sapiens, first appeared, strived most of the history and boomed with agricultural and industrial revolution. We are over 6 billion now. Standard of living and energy use have been growing almost exponentially due to abundance of resources. The growth will be naturally restricted with overpopulation and resource depletion as we know it. © M. Kostic <www.kostic.niu.edu> 041115 Time in history Population in millions Most of BC history 10 due to hardship AD 1 300 1750 760 1800 1,000 1950 2,500 2000 6,000 The energy “difficulties” … (1) will be more challenging than what we anticipate now (2) NO traditional solutions (3) New knowledge, new technology, and new living habits and expectations will be needed © M. Kostic <www.kostic.niu.edu> 041115 So, what are we going to do? Do we need CASH for ALCOHOL research? © M. Kostic <www.kostic.niu.edu> 041115 Earth Energy Balance: All energy to Earth surface is 99.98 % solar, 0.02% geothermal, and 0.002% tidal-gravitational. About 13 TW world energy consumption rate now (0.007% of solar striking Earth) is about 7 times smaller than global photosynthesis (all life), the latter is only 0.05% of total solar, and global atmospheric water and wind are about 1% of solar. Source: Basic Research Needs To Assure A Secure Energy Future, ORNL Report, 2003 © M. Kostic <www.kostic.niu.edu> 041115 © M. Kostic <www.kostic.niu.edu> 041115 Energy: Physics Manuscript by M. Kostic for Dekker's ENCYCLOPEDIA OF ENERGY ENGINEERING AND TECHNOLOGY Outline I. Energy: From Work to Heat to General Concept II. Energy Forms and Classifications: Energy Transfer versus Energy Property III. The First Law of Energy Conservation: Work-Heat-Energy Principle IV. The Second Law of Energy Degradation: Entropy and Exergy V. Concluding Remarks © M. Kostic <www.kostic.niu.edu> 041115 Energy: Property vs. Transfer © M. Kostic <www.kostic.niu.edu> 041115 Energy: Property vs. Transfer (2) ETransfer QnetIN WnetOUT QnetIN WnetIN TdS d ( Ax) dA Vdq E d (VP) o H d (VM ) ... PdV COMPR. STRETCHING. SHEARING CHARGING POLARIZATION MAGNETIZATION ETC . E Sys E K E Pg E Pdeff . EUth EUch E Nucl E El E Magn ... Etc. Thermal EMechanical Internal ( total) © M. Kostic <www.kostic.niu.edu> 041115 Energy: Different types of energy (a) potential gravitational and electromagnetic radiation; m (a) (b) organized energy as work transfer; (b) (c) disorganized thermal energy as heat transfer. (c) © M. Kostic <www.kostic.niu.edu> 041115 Energy: Structure, Forces, and Energies TABLE 1: Material system structure and related forces and energies Particles Forces Energies Atom nucleus Strong and weak inter-nucleus Nuclear Electron shell electromagnetic Electrical, magnetic, electromagnetic Molecules Inter-atomic, within molecule chemical Molecules Random collision and inertial, Potential inter-molecular Sensible thermal Molecules Potential inter-molecular Latent thermal Molecules Potential inter-molecular Mechanical elastic System mass Inertial and gravitational Mechanical kinetic and gravitational potential © M. Kostic <www.kostic.niu.edu> 041115 Energy: Physics © M. Kostic <www.kostic.niu.edu> 041115 Energy: Physics © M. Kostic <www.kostic.niu.edu> 041115 Energy: Physics Is this “flow” or “elastic” energy? © M. Kostic <www.kostic.niu.edu> 041115 Energy: Forms of Heat Transfer © M. Kostic <www.kostic.niu.edu> 041115 Energy Interactions: © M. Kostic <www.kostic.niu.edu> Coupled, Adiabatic, and Caloric 041115 Energy & Entropy: Control Volume © M. Kostic <www.kostic.niu.edu> 041115 Entropy: Reversible and Unrestricted Expansions © M. Kostic <www.kostic.niu.edu> 041115 Entropy (2) If heat or work at higher potential (temperature or pressure) than necessary, is transferred to a system, the energy at excess potential will dissipate spontaneously to a lower potential (if left alone) before new equilibrium state is reached, with entropy generation, i.e. increase of entropy displacement over a lower potential. A system will ‘accept’ energy at minimum necessary (infinitesimally higher) or higher potential. Furthermore, the higher potential energy will dissipate and entropy increase will be the same as with minimum necessary potential, like in reversible heating process, i.e.: dS Q T or S Q T S ref However, the source entropy will decrease to a smaller extent over higher potential, thus resulting in overall entropy generation for the two interacting systems, © M. Kostic <www.kostic.niu.edu> 041115 The Second Law: (A) Kelvin-Plank statement (B) Clausius statement © M. Kostic <www.kostic.niu.edu> 041115 Heat Engine: Ideal Carnot Cycle © M. Kostic <www.kostic.niu.edu> 041115 ENERGY Property and Transfer/Exchange "... Energy is the ‘‘building block’’ and fundamental property of matter and space and, thus, the fundamental property of existence. Energy exchanges or transfers are associated with all processes (or changes) and, thus, are indivisible from time." © M. Kostic <www.kostic.niu.edu> 041115 Focus and Goal: Focuses on philosophical and practical aspects of energy and entropy, with emphasis on reversibility and irreversibility, and Goal to better understand the concept and application of Energy Conservation (The 1st Law), and Energy Degradation (The 2nd Law) © M. Kostic <www.kostic.niu.edu> 041115 Objective: … to emphasize known, but not so well-recognized issues about energy and entropy, irreversibility and reversibility, as well as to put certain physical and philosophical concepts in perspective, and initiate discussion and arguments about the paper theme. © M. Kostic <www.kostic.niu.edu> 041115