Chemical Engineering @ChemengFiles.Com

Usually a previous course in physics is pre-contextualization of some fundamental concepts such as energy and conservation, labor, movement, heat, temperature etc. It is assumed that they all meet in some measure to address the matter first.

These primitives are expanded, we study all forms of energy that can be related to a system, there are clearly those physical quantities are those thermodynamic properties are not, and different kinds of systems (open, closed, isolated, etc.). It is at this stage which has a first happy encounter with a ration so powerful that it will henceforth be the holy grail of mathematical interpretation of a wealth of practical physical situations: The principle of balance.

+ What is enrolled generated = What + What comes accumulates

If applied to the matter in a system, we speak of the well known law of conservation of mass, which is not considered a law of thermodynamics, but in all cases is mandatory. When applied to energy in a system, we talk about energy conservation, energy balance, or the first principle or first law of thermodynamics. Even if it is treated as a life philosophy can be applied successfully in order to carry with personal finance.

With the first law, we can understand something of enormous importance to the tradition of technology: a heat engine in the form of a steam cycle. It's more than a trivial application, as it was this idea that led to the invention of the steam engine during the industrial revolution, which historically led to lay the foundations of thermodynamics as we know it today.

The study of the heat engine is basically know what happens to water vapor as it passes through a boiler, turbine, pump, a chiller and a valve, along with the meaning of all those terms. Additionally, it is an initiation rite in which the eyes of an engineer or an apprentice (a) chemical (a) first seen the light of an industrial processing and energy interacting with matter.

If properly applied the principle of balance to the physical quantity called entropy that everyone enters you into the land of the second law or second law of thermodynamics. So far avoided using the word entropy, but said the second law and there is no remedy.

I'm not as seasoned as to attempt to answer here the question "What is entropy?. Just mention that this thorny issue is a must for any process of learning the basics and then confess that I do not know what the hell is the entropy. To put a stop to this particular, I will quote what he said the American physicist Arnold Sommerfeld when asked why he had not written a book on thermodynamics:

"Thermodynamics is a funny track. The first time you pass by the matter, do not understand it at all. The second time, you think you understand it except for one or two small points. The third time you are absolutely sure you do not understand it, but by then you're so used to it that you do not care. "

(Cengel, Y., Boles, M. Thermodynamics: An engineering approach, in May 2005 Ed.)

However, I do refer to the second law. It states that the former is not sufficient criterion for deciding which process is possible and what process it is not. Thus, it becomes the expression of restrictions imposed by nature: not everything is possible and what is possible is limited and costs.

While energy is conserved during a transformation after another, not always available so that we can enforce it, eventually there will come a time when, having the same energy as at first, it will have power no longer useful. In that capacity, take advantage of that energy "dead" is not possible. This gradual degradation of the one in power, is actually a loss, a potential that was consumed but it is a price to be paid. The implication is that energy can not be used without a portion is lost and the cost is to renew what was lost.

A very famous result of the second law is that it is impossible the existence of so-called perpetual motion machines, or those which use the same energy over and over and over until eternity, without degradation and without losing availability. This fact is even rooted in popular culture, an example of this is that occasion where the uneasy Lisa Simpson presents his father proud, Homer, a perpetual motion machine. He rebukes saying "Miss, in this house we respect the laws of thermodynamics."

Another interpretation of the second law, particularly useful for chemical engineering, is the fact that the process of transformation is an extreme condition of maximum output, minimum degradation and maximum availability of energy, which is feasible only in theory. It is this limit that is all that is possible. This imaginary process will be as close to perfect something without violating either the first or second laws.

In the case of the heat engine, which has those particular characteristics, it looks like the Carnot cycle in honor of the well known French engineer, who first concluded that a real steam engine could be more daring in their dreams a much lower energy use up to 100%. Any further effort to improve efficiency, would be completely useless.

All this is, roughly, one pass through the basic theoretical framework of classical thermodynamics. Their study and proper understanding is absolutely necessary, without such a firm foundation, not prosper in your applications. As well the saying: "There is nothing more practical than a good theory."