What is thermodynamics? This is a branch of physics that studies the properties of macroscopic systems. At the same time, methods of converting energy and methods of its transmission also fall under study. Thermodynamics is a branch of physics that studies the processes occurring in systems and their states. Today we’ll talk about what else falls into the list of things she is studying.
Definition
In the picture below you can see an example of a thermogram obtained by studying a jug of hot water.
Thermodynamics is a science that relies on generalized facts obtained experimentally. The processes occurring in thermodynamic systems are described using macroscopic quantities. Their list includes parameters such as concentration, pressure, temperature and the like. It is clear that they are not applicable to individual molecules, but are reduced to a description of the system in its general form (in contrast to those quantities that are used in electrodynamics, for example).
Thermodynamics is a branch of physics that also has its own laws. They, like the rest, are of a general nature. The specific details of the structure of one or another substance chosen by us will not have a significant effect on the nature of the laws. That is why they say that this branch of physics is one of the most applicable (or, rather, successfully applied) in science and technology.
Application
Examples can be listed for a very long time. For example, many solutions based on thermodynamic laws can be found in the field of thermal engineering or electric power. What can we say about the description and understanding of chemical reactions, phase transitions, transport phenomena. In a way, thermodynamics “collaborates” with quantum dynamics. The scope of their contact is a description of the phenomenon of black holes.
The laws
The picture above demonstrates the essence of one of the thermodynamic processes - convection. The warm layers of the substance rise up, the cold - fall down.
An alternative name for laws, which, incidentally, is used more often than an example, is the beginning of thermodynamics. To date, there are three of them (plus one “zero”, or “common”). But before talking about what each of the laws implies, let us try to answer the question of what the beginnings of thermodynamics are.
They represent a set of certain postulates that underlie the understanding of the processes occurring in macrosystems. The provisions of the principles of thermodynamics were established empirically as a series of experiments and scientific studies were carried out. Thus, there is certain evidence that allows us to take the postulates into service without any doubt about their accuracy.
Some people wonder why thermodynamics needs these very laws. Well, we can say that the need to use them is due to the fact that in this section of physics the macroscopic parameters are described in a general way, without any hint of considering their microscopic nature or features of the same plan. This is not a sphere of thermodynamics, but of statistical physics, to be more specific. Another important thing is the fact that the beginnings of thermodynamics are independent of each other. That is, one of the second cannot be deduced.
Application
The use of thermodynamics, as mentioned earlier, goes in many directions. By the way, one of its principles is taken, by the way, which is otherwise interpreted in the form of the law of conservation of energy. Thermodynamic solutions and postulates are successfully implemented in industries such as the energy industry, biomedicine, chemistry. Here in biological energy, the law of conservation of energy and the law of probability and direction of the thermodynamic process are widely used. Along with this, there are used the three most common concepts on which the whole work and its description are based. This is a thermodynamic system, process and phase of the process.
The processes
Processes in thermodynamics have varying degrees of complexity. There are seven of them. In general, a process in this case should be understood as nothing more than a change in the macroscopic state to which the system was brought earlier. It should be understood that the difference between the conditional initial state and the final result can be negligible.
If the difference is infinitesimal, then the process that has occurred can be called elementary. If we discuss the processes, we will have to resort to the mention of additional terms. One of them is the “working fluid”. A working fluid is a system in which one or several thermal processes occur.
Conventionally, processes are divided into nonequilibrium and equilibrium. In the case of the latter, all the states through which the thermodynamic system has to go are, respectively, nonequilibrium. Often the change of state is in such cases at a rapid pace. But the equilibrium processes are close to quasistatic. In them, changes are an order of magnitude slower.
Thermal processes occurring in thermodynamic systems can be both reversible and irreversible. In order to understand the essence, we will divide in our view the sequence of actions at certain intervals. If we can do the same process in the opposite direction with the same “intermediate stations”, then it can be called reversible. Otherwise, this will not work.