Technology & Engineering
Thermodynamic System
A thermodynamic system is a region of space that is under study, and it can be a single object or a group of objects. It is defined by a boundary that separates it from its surroundings. The system can exchange energy and matter with its surroundings, and it is often used to analyze and understand the behavior of various engineering and technological processes.
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11 Key excerpts on "Thermodynamic System"
eBook - PDF- Gerard Olivier, Vincent Lemort, Georges de Pelsemaeker(Authors)
- 2023(Publication Date)
- Wiley(Publisher)
1 1 Fundamentals 1.1 Introduction This textbook deals with the study of different vehicle thermal systems and components from an energy engineering point of view. It is therefore necessary to recall the fundamentals of heat trans- fer as well as thermodynamics and some elements of fluid mechanics for a good understanding of the content of the next Chapters 2, 3, and 4. This is the objective of the present chapter, the content of which has been largely summarized from major reference textbooks, especially those of Incropera and DeWitt (2002), Çengel and Boles (2006), Braun and Mitchell (2012), and Klein and Nellis (2016). 1.2 Fundamental Definitions in Thermodynamics Thermodynamics is the branch of physics that studies conversions between heat and work in one or the other direction. Thermodynamics is particularly useful for the analysis of components and systems presented in this book. Thermodynamics makes use of some important notions to which the reader should become familiar. 1.2.1 System, Surroundings, and Universe In thermodynamics, a system is defined as a delimited region of space or a quantity of matter that is investigated. The concept of “investigation” may still be a little bit fuzzy and will progressively develop. Let’s say that investigating a system means quantifying its energy performance and the relation between this performance and operating conditions. The system is delimited by a boundary (Figure 1.1). A boundary has neither mass nor thickness. The surroundings of the system are the region of space or the quantity of matter that is outside the system. Hence, the boundary is the sur- face that separates the system from its surroundings. The system and its surroundings constitute the universe. Among the systems, one can distinguish the closed systems and the open systems. A closed system does not exchange any mass with its surroundings.
eBook - PDFEntropy Generation Minimization
The Method of Thermodynamic Optimization of Finite-Size Systems and Finite-Time Processes
- Adrian Bejan(Author)
- 2013(Publication Date)
- CRC Press(Publisher)
1 THERMODYNAMIC CONCEPTS AND LAWS The subject of engineering thermodynamics revolves around two pivotal state-ments, the first and the second laws of thermodynamics. Both laws are old, relative to our lifetime experience, the first law being the product of a vehement debate started approximately 200 years ago. Because the objective of all introductory thermodynamics courses is to explain the meaning and usefulness of the two laws and their related concepts (Moran, 1989), in the present treatment it is assumed that the laws are known and accepted. However, in order to provide a common language and ground for the issues to be debated in this book, the basic concepts introduced in engineering through thermodynamics are reviewed in this chapter. The review is limited to the thermodynamics of a pure substance. 1.1 DEFINITIONS A key concept in thermodynamic analysis, often abused, is the concept of system. A Thermodynamic System is the region or collection of matter in space that is selected for analysis. The concept of system requires the recognition of an envi-ronment, which is the space, or system, external to the system of interest. Separating the two systems is the system boundary (frontier), which, in general, is a real or imaginary surface delineating the contour of the system of interest. The system boundary may or may not possess special features that, as a matter of consequence, lead to a hierarchic ordering of Thermodynamic Systems for the purpose of analysis. For example, a boundary that is impermeable to mass flow defines a closed system. Naturally, in a closed system the matter (mass inventory) is conserved. On the other hand, a boundary that is permeable (has openings, ports) for mass transfer defines an open system. The flow of mass through the system boundary is only one of the three transfer effects (interactions) commonly encountered in engineering applications. The other two effects are heat transfer and work transfer.
- John Reisel(Author)
- 2021(Publication Date)
- Cengage Learning EMEA(Publisher)
This doesn’t mean that every engineer will be performing thermodynamic analyses every day of his or her career, but some engineers do frequently design and analyze devices and processes by relying on the principles of ther- modynamics. Others will only occasionally need to invoke thermodynamic principles in their careers. Still others rarely use thermodynamics directly, but thermodynamics still informs their work and may influence their work in ways that are not immediately apparent. As such, it is important for all engineers to be fluent in the basics of thermodynamics. Before we can explore the principles of thermodynamics, we must first define and de- scribe a number of basic concepts upon which our subsequent presentations will be based. This is the focus of the next section. 1.1 BASIC CONCEPTS: SYSTEMS, PROCESSES, AND PROPERTIES 1.1.1 The Thermodynamic System At the basis of all thermodynamic analysis is a construct known as the Thermodynamic System. A Thermodynamic System is the volume of space that contains the object(s) that are the focus of the thermodynamic analysis. The system is defined by the person performing the analysis and should be made as simple as possible. Unnecessary complexity should be avoided because it will either result in an incorrect analysis or will lead to significant amounts of additional work on the part of the person performing the analysis. As shown in Figure 1.6, a Thermodynamic System is delineated by a system boundary; everything inside the system boundary (which we will represent with a dashed line) is the sys- tem, and everything outside the boundary is considered the surroundings. Figure 1.7 shows several possible systems that could all be considered the system for analyzing a particular problem. The quantity to be determined is the amount of heat needed to heat liquid water in a kettle on a stove. In Figure 1.7a, the system is proposed to be only the water in the kettle.
eBook - ePub- Michael J. Moran, Howard N. Shapiro, Daisie D. Boettner, Margaret B. Bailey(Authors)
- 2018(Publication Date)
- Wiley(Publisher)
CHAPTER 1 Readings
Medical professionals rely on measurements of pressure and temperature, introduced in Secs. 1.6 and 1.7 .Engineering Context
Although aspects of thermodynamics have been studied since ancient times, the formal study of thermodynamics began in the early nineteenth century through consideration of the capacity of hot objects to produce work. Today the scope is much larger. Thermodynamics now provides essential concepts and methods for addressing critical twenty-first-century issues, such as using fossil fuels more effectively, fostering renewable energy technologies, and developing more fuel-efficient means of transportation. Also critical are the related issues of greenhouse gas emissions and air and water pollution.Thermodynamics is both a branch of science and an engineering specialty. The scientist is normally interested in gaining a fundamental understanding of the physical and chemical behavior of fixed quantities of matter at rest and uses the principles of thermodynamics to relate the properties of matter. Engineers are generally interested in studying systems and how they interact with their surroundings. To facilitate this, thermodynamics has been extended to the study of systems through which matter flows, including bioengineering and biomedical systems.The objective
- S. Bobby Rauf(Author)
- 2021(Publication Date)
- River Publishers(Publisher)
However, in this chapter we will focus on categorization of Thermodynamic Systems based on their interaction with the surroundings or environment. From Thermodynamic System and environment interface perspective, Thermodynamic Systems can be categorized as follows: 91 92 Thermodynamics Made Simple for Energy Engineers I. Open Thermodynamic Systems II. Closed Thermodynamic Systems III. Isolated Thermodynamic Systems Open Thermodynamic Systems Open Thermodynamic Systems are systems in which, in addition to the exchange of heat energy with the surroundings, mass or matter are free to cross the system boundary. Also, in open Thermodynamic Systems, work is performed on or by the system. The type of open Thermodynamic Systems where entering mass fow rate is the same as the exiting mass fow rate is referred to as a Steady Flow Open System . Examples of Steady Flow Open Systems include pumps, compressors, turbines and heat exchangers. Closed Thermodynamic Systems Closed Thermodynamic Systems are systems in which no mass crosses the system boundary. Energy, however, can cross through the system boundary in form of heat or work. Examples of closed Thermodynamic Systems include: sealed pneumatic pistons and refrigerant in a refrigeration system. Isolated Thermodynamic Systems Isolated Thermodynamic Systems are systems in which no work is performed by or on the system; no heat is added or extracted from the system and no matter fows in or out of the system. Imagine a rigid sealed steel cylinder containing liquid nitrogen. This steel cylinder is heavily insulated and is placed inside another sealed steel container such that cylinder’s walls do not come in contact with the outside steel container. If vacuum is now created between the outer container and the inner gas cylinder, you would have a Thermodynamic System that is “isolated” for most practical purposes.
eBook - PDF- R. Prasad(Author)
- 2016(Publication Date)
- Cambridge University Press(Publisher)
The zeroth law, that defines the state of thermal equilibrium, was considered to be more fundamental than the already formulated three laws and was, therefore, assigned number zero in the hierarchy of thermodynamic laws. Like all other branches of science, thermodynamics also has its own terminology. Some of the terms frequently used in thermodynamics are defined here. 3.1 System, Boundary and Surroundings Since it is not possible to observe whole of the universe at a time it is generally a part of the universe that is studied. The portion or part of the universe (which is under observation) enclosed by a boundary is called the system. The boundary of the system divides the universe into two parts, the system and the surroundings or the environment. In other words, system and surroundings make the universe. The system may be anything: a solid, liquid, gas, or plasma, or a mixture of all these. It might be a distribution of charges or magnetic poles or radiations, i.e., photons in vacuum, etc. A system is called closed when the total mass contained in the system does not change. It means that in a closed CHAPTER 3 94 Classical and Quantum Thermal Physics system neither additional mass may enter through the boundary nor any mass from the system can leave through the boundary. However, energy may leave or enter a closed system. A system is said to be an isolated system if neither mass nor energy may leave or enter the system through its boundary. When a system may exchange matter (mass) and energy with its surroundings, the system is called an open system. The fact is that most of the systems in nature are open systems. However, for the easy of analysis, one may approximate a system as closed or isolated under suitable boundary conditions. The boundary separating the system from the environment may be a real boundary, like the walls of a container that holds a liquid or a gas as the system.
eBook - PDF- Donald Olander(Author)
- 2007(Publication Date)
- CRC Press(Publisher)
• The isolated system : Thermodynamics reserves a special name for a boundary that is both adiabatic and rigid, and is not penetrated by rotating shafts, electrical wires or other devices that could transmit non-pV forms of work. A system protected by such a boundary is called isolated . It would appear that a system that cannot be influenced by its surroundings is of little practical interest. This is indeed so. However, the isolated system occupies a hallowed niche in thermodynamic theory because it provides one of the simplest ways of elucidating some of its more esoteric features, such as equilibrium, spontaneity of change and entropy. • Mass transmission : The mass-transmitting capabilities of a system bound-ary possess limits analogous to those of heat and work transmissibility. Concepts and Definitions 15 The boundaries of the closed system are impervious to all matter; the material inside a closed system retains its elemental identity during passage of heat and/or work across its boundaries. However, the system’s molecular composition may change by chemical reaction. In an open system, matter flows across inlets and outlets in the boundary (Figure 1.9). At steady state, the quantity of matter in an open system is constant. In contrast to a closed system, gradients of thermodynamic properties are permitted in open systems (e.g., the pressure decrease through a turbine). 1.5 THERMODYNAMIC PROCESSES A thermodynamic process is the act of changing the state of a system. The state of the system is defined by a few properties such as temperature, pressure, etc. The process may occur spontaneously, such as the reaction of H 2 and O 2 to form H 2 O, or it may be induced as a result of the interchange of heat and work with the surroundings. We are always interested in the initial and final states of a process, and often in the path followed between these two states. However, thermodynamics is blind to the rate of the process.
- Anthony R. Philpotts, Jay J. Ague(Authors)
- 2022(Publication Date)
- Cambridge University Press(Publisher)
In this and the following two chapters, the focus is on the more important fundamental concepts. Physical chemistry and petrologic thermodynamic texts will provide the reader with more extensive coverage (e.g., Zemansky 1943; Wood & Fraser 1977; Powell 1978; Castellan 1983; Atkins & de Paula 2014). 8.1 BASIC THERMODYNAMIC CONCEPTS AND DEFINITIONS The general applicability of thermodynamics stems from the fundamental nature of the principles on which it is based, namely simple observations on the behavior of energy. For example, although energy can be converted from one form to another (kinetic to potential, chemical to thermal, etc.), it can never be destroyed. Furthermore, experience tells us that heat naturally flows from hot to cold bodies, but never the reverse. The first observation, which concerns the conservation of energy, is embodied in the first law of ther- modynamics, whereas the second one, which deals with the natural direction of processes, leads to the second law of thermodynamics. When discussing the energy of processes, the part of space under consideration is called the system (Fig. 8.1). The boundary of the system separates it from the surround- ings. The boundary could be real, such as the walls of a magma chamber, or invented, such as an imaginary bound- ary surrounding a cubic meter of magma at the center of the chamber. The system is chosen to suit the particular problem. Systems are isolated if they do not interact with their surroundings, closed if they exchange only energy, and open if they exchange both energy and material. Truly isolated systems are hypothetical, but their concept is important for derivations of certain theoretical relations. Many geological systems can be considered closed, such as a small rapidly cooling dike that is losing heat to its surroundings. An open- system example would be a metamorphic rock volume that is both heated by a nearby magma and intruded by dikes from the magma.
- Daniel Walgraef, J Martinez-mardones, Carlos Hernan Worner(Authors)
- 2000(Publication Date)
- World Scientific(Publisher)
PHYSICO-CHEMICAL THERMODYNAMICS OF MATERIAL SYSTEMS: A REVIEW OP BASIC CONCEPTS AND RESULTS ARMANDO FERNANDEZ GUILLERMET Consejo National de Investigaciones Cientificas y Ttcnicas Centra Atomico Bariloche-Instituto Balseiro 8400 San Carlos de Bariloche-Argentina. E-mail: [email protected] 1 Introduction 1.1 General Considerations Thermodynamics developed from the study of heat-engines and the relations between heat and work. However, after some time, it was recognized that the study of the effects of the thermal and mechanical interactions between the system and the surroundings provides valuable information on the equilibrium properties of the material systems, and on the reactions or transformations which occur. Today, thermodynamics might be considered as a discipline which deals with (i) a wide class of macroscopic properties of material sys-tems, (ii) the way in which these properties are influenced by the thermal, mechanical and chemical interactions with other systems, and (iii) the reac-tions or transformations involved. One of the key variables in the thermodynamic approach is temperature, and, in a certain sense, thermodynamics may be defined as the science dealing with the forms in which the properties of matter are modified by the changes in temperature. In particular, for material systems, it is interesting to determine the effects of temperature upon the equilibrium properties of a given structure, and to explore the possibility of inducing changes of structure by suitable temperature variations. The question of identifying the most stable structure for given external conditions is usually known as the Phase Stability Problem, which is often considered as a central problem in the study of material systems. Classical thermodynamics developed without referring to any particular model of the structure of matter.
eBook - PDFThermo and Fluid Dynamics
Recent Advances
- Dritan Hoxha(Author)
- 2019(Publication Date)
- Arcler Press(Publisher)
Here I will make a parenthesis. People often confuse heat and thermal energy or worse, they consider them as the same thing. Heat and thermal energy, earlier, used to be considered as synonyms. But they differ as follows: Heat is the thermal energy transferred across a boundary of one region of matter to another. As a process variable, heat is a characteristic of a process, not a property of the system. Thermal energy is the internal energy present in a system by virtue of its temperature. The average kinetic energy (translational) possessed by free particles in a system of free particles under thermodynamic equilibrium. One of the most important objectives when dealing with thermodynamics is to measure the amount of thermal energy involved in a certain situation. However, this is a very complicated process because the systems we consider when considering a thermodynamic related situation have a very large number of particles which interact with each other in many ways. Thus, we must have any facility when dealing with these situations in order to make them easier to study. Hence, if these systems are more or less balanced a situation known as equilibrium then it is possible to describe it through a small number of measurements or as otherwise known, “system parameters” [1]. Such a situation exists only in theory and it may occur only when the system is idealized as well as all quantities involved in this system such as the mass, pressure, and volume, or any other equivalent set of numbers. These numbers describe a very large number of variables ranging from 10 26 to 10 30 nominal independent variables. A General View on Thermodynamics 3 Below a map showing several branches of Physics is shown. It will help the reader to understand the place and importance of Thermodynamics as one of key Physics branches. 1.2. ETYMOLOGY OF THERMODYNAMICS It has not been so easy to determine the name of this branch of Physics, although it is relatively a new one.
eBook - PDF- Bernard Desmet(Author)
- 2022(Publication Date)
- Wiley-ISTE(Publisher)
1 Energy Conversion: Thermodynamic Basics Georges DESCOMBES 1 and Bernard DESMET 2 1 CNAM, Paris, France 2 INSA – HdF, Université Polytechnique Hauts-de-France, Valenciennes, France 1.1. Introduction We are interested here in the conversion of heat into mechanical work via machines using a fluid medium in a continuous flow, or functioning in a cyclic manner. This first chapter succinctly presents the main concepts of thermodynamic used in this context. For a more in-depth study, the reader may consult the specialized works of Borgnakke and Sonntag (2013), Feidt (2014), Foussard et al. (2021) and Çengel et al. (2019). Classical sign conventions will be used: the quantities of heat and work exchanged between a system and its exterior will be positive while they are received by the system. Work, quantities of heat and extensive state quantities – quantities of which the value is proportional to the quantity of matter of the system – will be denoted in uppercase when they refer to the whole system and in lowercase when they are expressed per unit mass. Therefore, W, Q, U, etc. refer to work exchange, heat, internal energy, etc. for the considered system, and w, q, u, etc. are the corresponding specific quantities. Thermodynamics of Heat Engines, coordinated by Bernard DESMET. © ISTE Ltd 2022. 2 Thermodynamics of Heat Engines 1.2. Principles of thermodynamics 1.2.1. Notion of a Thermodynamic System In the strict sense of the term, a Thermodynamic System or even a closed system does not exchange matter with its exterior. Its boundary is impermeable to the exchange of matter. In technical thermodynamics, we are interested more often in the equipment (heat exchangers, turbines, compressors, etc.) through which one or more fluids flow. Generally, we look for characteristics (pressure, temperature, mass flow rate, etc.) in the fixed sections located on either side of the component being studied and defined as the inlet and output of this component.
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