...Thermodynamics is a branch of physics concerned with heat and temperature and their relation to energy and work. It defines macroscopic variables, such as internal energy, entropy, and pressure, that partly describe a body of matter or radiation. It states that the behavior of those variables is subject to general constraints, that are common to all materials, not the peculiar properties of particular materials. These general constraints are expressed in the four laws of thermodynamics. Thermodynamics describes the bulk behavior of the body, not the microscopic behaviors of the very large numbers of its microscopic constituents, such as molecules. Its laws are explained by statistical mechanics, in terms of the microscopic constituents. Thermodynamics applies to a wide variety of topics in science and engineering, especially Physical chemistry, Chemical engineering, thermal power generation and steam and combustion turbines. Historically, thermodynamics developed out of a desire to increase the efficiency and power output of early steam engines, particularly through the work of the French physicist Nicolas Léonard Sadi Carnot who believed that the efficiency of heat engines was the key that could help France win the Napoleonic Wars. The Irish-born British physicist Lord Kelvin was the first to formulate a concise definition of thermodynamics in 1854: Initially, thermodynamics, as applied to heat engines, was concerned with the thermal properties of their 'working materials'...
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...Moran, M.J. “Engineering Thermodynamics” Mechanical Engineering Handbook Ed. Frank Kreith Boca Raton: CRC Press LLC, 1999 c 1999 by CRC Press LLC Engineering Thermodynamics Michael J. Moran Department of Mechanical Engineering The Ohio State University 2.1 Fundamentals....................................................................2-2 Basic Concepts and Definitions • The First Law of Thermodynamics, Energy • The Second Law of Thermodynamics, Entropy • Entropy and Entropy Generation 2.2 Control Volume Applications.........................................2-14 Conservation of Mass • Control Volume Energy Balance • Control Volume Entropy Balance • Control Volumes at Steady State 2.3 Property Relations and Data ..........................................2-22 Basic Relations for Pure Substances • P-v-T Relations • Evaluating ∆h, ∆u, and ∆s • Fundamental Thermodynamic Functions • Thermodynamic Data Retrieval • Ideal Gas Model • Generalized Charts for Enthalpy, Entropy, and Fugacity • Multicomponent Systems 2.4 2.5 2.6 2.7 Combustion ....................................................................2-58 Reaction Equations • Property Data for Reactive Systems • Reaction Equilibrium Exergy Analysis..............................................................2-69 Defining Exergy • Control Volume Exergy Rate Balance • Exergetic Efficiency • Exergy Costing Vapor and Gas Power Cycles ........................................2-78 Rankine and...
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...Unit Two Homework Solutions, September 9, 2010 1 A frictionless piston-cylinder device initially contains 200 L of saturated liquid refrigerant-134a. The piston is free to move, and its mass is such that it maintains a pressure of 900 kPa on the refrigerant. The refrigerant is now heated until its temperature rises to 70oC. Calculate the work done during this process. The freely-moving piston can be interpreted as giving a constant pressure process such that P1 = P2 = P = 900 kPa. For a constant pressure process, the concept that the work is the area under the path is particularly simple. That area is a rectangle whose area is P (V2 – V1). We know that P is 900 kPa, and the initial volume is 200 L = 0.2 m3, but we have to find the final volume. Because this is a constant pressure process, the final pressure equals the initial pressure of 900 kPa (0.9 MPa) and we are given that the final state has a temperature of 70oC. From the superheat tables for refrigerant-134a in Table A-13 on page 930, we find that the specific volume at this temperature and pressure is 0.027413 m3/kg. In order to find the volume (V in m3 as opposed to the specific volume, v, from the property tables in m3/kg), we have to know the mass. We can find the mass from the initial volume and the value of the specific volume at the initial state of saturated liquid at 900 kPa. At this pressure, we use the saturation table, A-12, on page 928, to find the specific volume of the saturated liquid, vf =...
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...MECH3401 Thermofluids 3 – Assignment 2 i) The balanced stoichiometric equation for the reaction of a 10/90 mixture of Octane and nitro methane is; (9CH_3 NO_2+C_8 H_18 )+19.25(O_2+3.76N_2 ) □(→┴ ) 17CO_2+〖76.88N〗_2+〖22.5H〗_2 O With 20% excess air this equation becomes; (9CH_3 NO_2+C_8 H_18 )+23.1(O_2+3.76N_2 ) □(→┴ ) 17CO_2+〖91.356N〗_2+〖22.5H〗_2 O+3.85O_2 Stoichiometric combustion of octane in air; C_8 H_18+12.5(O_2+3.76N_2 ) □(→┴ ) 8CO_2+〖47N〗_2+〖9H〗_2 O ii) For combustion of octane in 20% excess air C_8 H_18+15(O_2+3.76N_2 ) □(→┴ ) 8CO_2+56.4N_2+〖9H〗_2 O+10O_2 Molar mass of octane= 114 kg/kmol Converting calorific value of octane to kJ/mol; 43.7 MJ/kg×1000kJ/MJ×114/1000 kg/mol=4981.8 kJ/mol Molar mass of nitro methane= 61 kg/kmol Converting calorific value to kJ/mol; 11.3 MJ/kg×1000kJ/MJ×61/1000 kg/mol=689.3 kJ/mol Determining the molar consumption of octane to produce 100kW power. Assuming ideal efficiency. 100kJ/s×1/4981.8 mol/kJ=0.02007 mol/s For 0.2007 mol/s of octane, we would require 0.301 mol/s of air (20%excess) As volumetric efficiency of the engine remains the same, we assume that the air flow rate is the same in each case. Thus we will use 0.301mol/s of air for the dragster fuel mix. Using the ratio of reactants from the balanced equation, we require 0.013mol/s of (9CH3NO2 + C8H18). The power output with the dragster fuel would therefore be;...
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...Introduction Thermodynamics is the area of science that includes the relationship between heat and other kinds of energy. Thermodynamics was discovered and studied beginning in the 1800s. At that time, it was linked to and gained importance because of the use of steam engines. Historically, thermodynamics developed out of a desire to increase the efficiency of early steam engines, particularly through the work of French physicist Nicolas Leonard Sadi Carnot . Who believed that the efficiency of heat engines was the key that could help France win the Napoleonic Wars.[1] Scottish physicist Lord Kelvin was the first to formulate a concise definition of thermodynamics in 1854. Thermodynamics is built on the study of energy transfers that can be strictly resolved into two distinct components, heat and work, specified by macroscopic variables.[17] Though thermodynamics originated in the study of cyclic non-equilibrium processes such as the working of heat engines, study of the subject gradually revealed that the notion of heat is inextricably tied to the notion of thermodynamic equilibrium.[18]Thermodynamics is well understood and validated for systems in thermodynamic equilibrium, but as the systems of interest become further and further from thermodynamic equilibrium, their thermodynamical study becomes more and more difficult. Systems in thermodynamic equilibrium have very well experimentally reproducible behaviour, and as interest moves further towards non-equilibrium systems...
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...Introduction and Concepts January 23rd 2013 Thermodynamics: Is the science that deals with work, heat and other form of energy (Kinetic Energy, Potential Energy, Enteral Energy) also their transformation and their relationships with properties. Definitions • System (closed system): A region isolated from the rest of the matter that under study. Nothing crosses boundaries. • Surrounding: Everything external and not in the system. • Control System (open system): A region where mass may cross the boundary of a control volume. Examples: Turbines – Niggles – Compressors – Heat Exchange – Pumps – Pipe Flows. • Properties: Are the Microscopic Characteristics of a System / of a Control Volume. Examples: Temperature - Pressure – Density – Volume – Internal Energy – Enthalpy and Entropy. • Extensive Properties: A Property if its value for an overall system is the sum of its values for the parts into which system is divided. Examples: Mass - Volume. • Intensive Properties: Properties are not additive and in the sense of previously considered. Example: Pressure. • Processes: A change of state of a system or control volume. • Cycle: A process whose initial and final states are identical. • Thermodynamic equilibrium: For thermodynamic equilibrium the following must be satisfied → o Mechanical equilibrium: A condition of balanced Forces. o Thermal equilibrium: No Change in Temperature. o Chemical equilibrium: No chemical reaction. o Electrical equilibrium:...
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...Thermodynamics is a branch of physics that applies to heat and temperature’s relation to work and energy. There are four well-known laws of thermodynamics. The zeroth law stated that if two systems are within thermal equilibrium with a third systems, then those two systems are also within equilibrium with each other. The first law states that an increase in energy of a closed system equals the difference of heat supplied by the system and work completed by the reaction. The second law states that heat cannot spontaneously flow from cool to warm. The gradient must flow from warmer to cooler regions. The third law states that when a system approaches absolute zero, the entropy also approaches a minimum value. The entropy defines the unavailable energy of the system and signifies the disorder within the unit. The laws of thermodynamics help explain that energy exists within a closed system. There is only so much energy within that system. There are ways to “tap into” the less available energy, but that using that energy leads to disorder. The laws clearly explain that there is only a specified amount of energy in a system and once this energy is used, there is no more. This means that there has to be some amount of energy conservation in order to guarantee that there remains available energy within the system. There are also various types of energy. Even though energy is converted from one form to another, the same amount of energy is present, independent of the type. Fossil...
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...Thermodynamics: Chapter 6 * ability to do work * * energy used to take a mass and object with mass to move is called work * energy used ti cause the temp of an object to rise is called heat * energy from a battery * change chemical energy into heat or work * radiant energy comes form the sun and is earths primary energy source * thermal energy is energy associated with random motion of atoms and molecules * chemical energy is the energy stored within the bonds of chemical substances * nuclear energy is energy stored within collection nuetrons and protons * PE= ENERGY OF A OF POSITION * KE- ENERGY of of motion * energy released when bonds forms – bond energy (0-400 kj) * energy absorbed when bond breaks _bond energy (-i400 to -100) * when atoms in right distance 0 0, decrease in pe * completely p\apart and no affinity between the two * most important potential electrostatic energy in molecules is electros- associated with kollumbs law * si unit of energy is joule (J) 1 J- 1 kgm2/s2 * 1 cal in nutrition = 1 kcal in nutrition * 1 cal= 4.184 J * 1 cal = amount energy required to raise 1 g of water 1 C * ---- A food calorie is actually a kcal * the surroundings includes the universe * he system includes the molecules we want to study (here the hydrogen and oxygen molecules) * energy can enter or leave system as heat or as work done on a piston * Thermodynamics is the study of heat...
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...HW4 Thermodynamics Answer Key | Procedure Answer the following questions as your teacher discusses the Introduction to Thermodynamics presentation. List three examples of a thermodynamic system. a. Nuclear power b. Electronic heat sink c. Rocket launch Define thermal energy. * Kinetic energy in transit from one object to another due to temperature difference Define temperature. * The average kinetic energy of particles in an object * Define absolute zero. All kinetic energy is removed - 0K Define thermal equilibrium. Touching objects within a system reach the same temperature Define the 1st Law of Thermodynamics. Thermal energy can change form and location, but it cannot be created or destroyed. List two ways thermal energy can be increased in a system. d. Adding thermal energy e. Performing work on the system Define the 2nd Law of Thermodynamics. Thermal energy flows from hot to cold. Define entropy. The measure of how evenly distributed heat is within a system Define convection. The transfer of thermal energy by movement of fluid (liquid or gas) List two examples of convection. f. Weather g. Boiler systems Define conduction. The transfer of thermal energy within an object or between objects from molecule to molecule List two examples of conduction. h. Metal spoon i. Heat through a wall * Conduction Equations: Define...
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...Laws of Thermodynamics Joshua Gibbs Grantham University First Law of Thermodynamics: The first law states that Energy can neither be created nor destroyed. Energy just changes its form from one to another. The total energy present in the universe remains constant. Examples of the first law of thermodynamics can be: Electrical Bulbs convert electrical energy to light energy; Mechanical systems in cars convert the heat energy released from petrol into kinetic energy. Second Law of Thermodynamics This law states that energy of all forms moves from higher concentration of energy to lesser concentration energy. When energy moves from high concentration to lesser concentration then some energy is dispersed or spreads out. Entropy is a measure of how much energy is spread out in a particular process. Examples are: When we exercise not all of our energy is converted into muscles in fact more energy disperses away in sweat. The Second Law of Thermodynamics implies that high-quality energy can never be used over again. Once a barrel of Oil is burned its high energy is lost forever. We cannot use the same barrel of oil to burn again. The diesel engine of a generator converts fuel energy into mechanical and thermal energy. During this process of conversion of energy some of the energy is lost or leaked out as heat from the wires of generator or dissipated as heat from the machine. The total amount of energy has not changed but it is now so dispersed that it can never be re-used...
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...8/22/2012 Chapter 1 Fundamental Concepts Shensheng Tang, Ph.D. Department of Engineering Technology Missouri Western State University St. Joseph, MO 64507 Email: stang@missouriwestern.edu 1.1 Introduction • Thermodynamics: – the study of energy, heat, work, the properties of media employed, and the processes involved. – the study of the conversion of one form of energy to another. Solar S l energy → electricity l i i Use of solar energy for the heating of water Dr. Tang @ MWSU 1 1 8/22/2012 1.2 Properties of a System • System: – A grouping of matter taken in any convenient or arbitrary manner. – For a design of diesel engine, it is possible to consider the entire engine as a system or a portion of the engine as a system. Property: – A property is an observable characteristic that is determined by the state of a system and, in turn, aids in determining the state of a system. – The condition of a system, described by its position, energy, and so on, is called the state of the system. The system’s properties determine its state. A given state of a system is reproduced when all its properties are the same. • – – Extensive E t i property: the properties that depend on th size and total mass of a t th ti th t d d the i dt t l f system. Intensive property: independent of the size of a system. Examples: pressure, temperature. Specific properties: they are given per unit mass or per defined mass in the system. Dr. Tang @ MWSU 2 ...
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...Assignment # 2 Petroleum Engineering Thermodynamic 1. PCB/PDB 1043 A piston–cylinder device initially contains 0.07 m3 of nitrogen gas at 130 kPa and 120°C. The nitrogen is now expanded to a pressure of 100 kPa polytropically with a polytropic exponent whose value is equal to the specific heat ratio (called isentropic expansion). Determine the final temperature and the boundary work done during this process. 2. A frictionless piston–cylinder device contains 2 kg of nitrogen at 100 kPa and 300 K. Nitrogen is now compressed slowly according to the relation PV1.4 =constant until it reaches a final temperature of 360 K. Calculate the work input during this process. 3. Complete the table below on the basis of the conservation of energy principle for a closed system. Qm kJ 350 350 130 260 -500 -50 Wout kJ E1 kJ 1020 550 600 1400 1000 900 E2 kJ 860 M kg 3 5 2 7 3 -200 150 e2-e1 kJ/kg 4. A well-insulated rigid tank contains 2 kg of a saturated liquid-vapor mixture of water at 150 kPa. Initially, three-quarters of the mass is in the liquid phase. An electric resistor placed in the tank is connected to a 110-V source, and a current of 8 A flows through the resistor when the switch is turned on. Determine how long it will take to vaporize all the liquid in the tank. Also, show the process on a T-V diagram with respect to saturation lines. 5. An 80-L vessel contains 4 kg of refrigerant -134a at a pressure of 160 kPa. With the help of Pressure Table for saturated refrigerant-134a...
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...Interesting Facts About Laws of Thermodynamics • Zeroth law: Although the concept of thermodynamic equilibrium is fundamental to thermodynamics, the need to state it explicitly as a law was not widely perceived until Fowler and Planck stated it in the 1930s, long after the first, second, and third law were already widely understood and recognized. Hence it was numbered the zeroth law. The importance of the zeroth law as a foundation to the earlier laws is that it defines temperature in a non-circular logistics without reference to entropy, its conjugate variable. • First law is nothing but a connotation of Energy Conservation • Second Law of Thermodynamics has been formulated differently by many scientists like Kelvin, Planck, Clausius and Caratheodory. But this law is the outcome of a very basic fact that Entropy of a spontaneous system always increases. Entropy is also defined qualitatively as Disorder of state. This is a common experienced fact that if let on its own, the disorder of a system always increases and work has to be done to bring it back in order. • According to the second law the entropy of any isolated system, such as the entire universe, never decreases. If the entropy of the universe has a maximum upper bound then when this bound is reached the universe has no thermodynamic free energy to sustain motion or life, that is, the heat death is reached. • The famous theory of evolution violates our Second Law of thermodynamics. Second law states that...
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...Sierra Sisson Mrs. Webb PWC Period 7 December 2nd, 2013 1. What is the impact of entropy on a steam engine? A steam engine could not function without entropy. Entropy is what is quantified when the substances in a system reach thermal equilibrium, and thermal equilibrium is another thing that the engine would not be able to function without either. Once the coal is heated up by the fire/source of heat in the engine so that it reaches thermal equilibrium with the heat source, the resulting energy is then converted into work, which is what the steam engine needs to function. 2. Why does heat energy only flow from hot areas or materials to colder areas? This is because of thermodynamics; substances want to be at thermal equilibrium. Obviously, this means that they are both at the same temperature and will not change any more. If a hot substance and a cold substance are beside each other, the hotter substance will transfer its heat to the colder substance so that they become equal to each other in temperature. 3. What does the author mean by thermal equilibrium? They have given the definition of thermal equilibrium to be what is achieved when the substances in a system have reached the same exact temperature and do not change any further. They also get a bit more specific in saying that it also means that “the system is not only in thermal, but also in mechanical, chemical as well as radioactive equilibrium.” 4. What happens when a thermometer reaches a person’s body...
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...Reginald Sanford AIU Online SCIE210 - 1403B – 08 IP3 August 9, 2014 . The first law of thermodynamics would consist of energy not being able to be formed or demolished. Energy is all around and it is made up of everything no matter if it’s the smallest particle or biggest. Being that energy can reorganize itself, it will always change from one form to another. The second law of thermodynamics would consist of the entropy; if it is not in a thermal balance then it will almost always increase. You can say that in the second law would state that if a room is not cleaned it will perpetually become more messy and unsystematic with time. The third law of thermodynamics would be that when a entropy reaches a constant value as it approaches zero. Fossil Fuel pros and cons, the pros of using fossil fuel is that we are able to develop new technology to harness energy from this natural source. Fossil fuel is cheap and there are no other things needed to gather energy from this fuel, it is considered being a reliable source of energy. Think about load-based needs, fossil fuel is more preferred then other sources of energy that are consider being unreliable. The cons of using fossil fuel are that it contributes to the worsening of global warming. Fossil fuel is not an environment-friendly source of energy even dough it is consider a natural source. It is the main contributors in global warming due to it releasing high amounts of carbon. Nuclear energy unlike fossil fuel does not...
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