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Conductive phenomena are ubiquitous in nature and in technical and social systems. We have already seen and discussed examples of uniform models of conduction in fluids and electricity (Chapter 1), in mechanics (Chapter 3), heat (Chapter 4), and chemical processes (Chapter 6). Finally, the foundation was laid for the treatment of conduction in continuous models (Chapter 11).
Traditional courses treat thermodynamics in a form unlike anything else known in physics. In particular, we are told that it is a theory of the equilibrium of heat and not of how and how fast things happen in real life. This combines with the conceptualization of heat as energy (or a form of energy) and thermal processes as the result of the motion of little particles. The result is a theory that...
In this chapter, I will go more deeply into some phenomena having to do with phase change and mixtures of gases such as moist air. These will lead to important applications in engineering and the natural sciences. First, there will be a description of phase change that makes use of concepts developed in the previous chapters. Then I turn to mixtures of two phase fluids such as moist air which will...
In this chapter, hydraulic and electric phenomena will be introduced and described with concepts known from the physics of dynamical systems and processes. We start with fluids in systems of tanks, pipes and pumps, and extend the description to electrical processes by making use of analogical reasoning. Dynamical models will be constructed that share the same underlying structure even though the phenomena...
In Chapter 4 we learned that loss of power of thermal engines is related to entropy production (Section 4.4.3). This observation suggests that we should avoid–or at least minimize–entropy production if we want to optimize thermal engines. In this chapter I would like to show by example that the idea of minimizing entropy production rates is a powerful principle of thermal design and appears to be...
Thermodynamics is the science of heat and hotness, of how bodies and other physical systems respond to heat, and of how heat can be used to drive other processes. In this chapter, I will introduce the fundamental quantities and concepts of thermodynamics and create dynamical models of some interesting phenomena. I shall justify the generic laws of thermal physics which we are going to use throughout...
In this first chapter of Part III, I am going to develop an approach to the thermodynamics of spatially uniform fluid systems and processes which has been inspired by continuum thermodynamics. It demonstrates the application of the laws of balance as the starting point of a description of nature. In contrast to the method used in Part II, it does not assume the form of the relationship between currents...
So far we have not made use of an important aspect of physical phenomena. Whenever something happens in the physical world, processes are accompanied by an additional quantity– energy. We will see that energy plays a unique role, unlike the roles of quantities which are often mistaken for it such as electricity, motion, or heat.
In this final chapter, solar radiation and aspects of its nature that are important in solar energy engineering will be discussed. The results concerning radiative transfer of entropy and energy, and spectral distributions of radiation derived in Chapter 12 will be made use of.
In this chapter I will present theories of the thermodynamics of some spatially uniform materials that are more complex than the one treated in Chapter 4. There we worked with a material that responds to entropy by changing its temperature only (Section 4.5). The approach taken and the basic ideas assumed to be valid are the same as those developed in the previous chapter; only the form of the constitutive...
So far we have used laws of balance and expressions for processes, i.e., for flows, source rates and production rates, in their integral forms; in other words we have written and applied the appropriate equations for an entire body. Now we will justify and derive the proper equations of balance of mass, entropy, and momentum, for continuous bodies. This will prepare the ground for theories of thermodynamics...
Processes that have to do with the nature and behavior of substances are called chemical processes. They deal with the quantity of chemical species, their strength or intensity relative to each other, and their power to cause other phenomena. Chemical processes are essentially of two types: Transport and reaction. Substances can wander from place to place, or they can change–in fact, they get produced...
Convective transport of heat leads to many interesting natural phenomena and to important technical applications. Theoretically, the subject is very demanding. For this reason we have so far dealt with convection only briefly. In Chapter 7, we used a simple expression to calculate heat transfer at a solid-fluid interface. Knowing the heat transfer coefficient, we can establish a relation which serves...
In Chapter 7, we dealt with entropy transfer in closed systems. Closed systems do not exchange matter with the environment. In other words, they are non-flow systems. Flow systems, on the other hand, allow matter to cross the boundary of a control volume. These are called open systems.
Rotation and translational motion can be treated analogously to the theories of fluids and electricity presented in Chapter 1. This becomes particularly clear in single dimensional applications (motion along a straight line, rotation about a fixed axis; for the latter see Section 2.5). Momentum and spin (angular momentum) are stored in moving and rotating bodies, and they are exchanged with other...
In this chapter, we shall take a closer look at the transport of entropy. Simple aspects will be introduced that go beyond what we already studied in Chapter 4 (Section 4.6). This extends the treatment of thermal processes into the realm of phenomena which are missing from the theory of the thermodynamics of ideal fluids (Chapter 5). Many texts on thermodynamics and on heat transfer sharply distinguish...
In this final chapter of Part III, thermal radiation will be studied from various perspectives that go beyond the uniform systems view taken in Chapter 7. The treatment offered here will not be a complete continuum model; rather, we will take a closer look at some aspects that make radiation unique among the heat transfer modes. Certain forms of distributions of radiation need careful consideration...
Based on courses for students of science, engineering, and systems science at the Zurich University of Applied Sciences at Winterthur, this text approaches the fundamentals of thermodynamics from the point of view of continuum physics. By describing physical processes in terms of the flow and balance of physical quantities, the author achieves a unified approach to hydraulics, electricity, mechanics...
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