Explain Entropy?
Explain Entropy?
(OP)
Can someone quantify entropy for me? I am having a hard time putting the theory of entropy to something real. Can anyone explain this concept to me using a real life example, possibly a heat transfer situation?





RE: Explain Entropy?
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RE: Explain Entropy?
Hello everybody:
This site can help you. http
RE: Explain Entropy?
A common application is in steam power systems.
The conditions (temperature, pressure) of steam entering and exiting a turbine are known.
Look up the entropy for those conditions. The difference in energy is assumed to have been converted to useful work in the turbine.
RE: Explain Entropy?
RE: Explain Entropy?
There are many definitions of entropy as shown in the given links and posts, especially those associated with order and disorder.
The one I like concerns thermo.: An increase in entropy always corresponds to a degradation in energy quality, in that some energy becomes unavailable to do work. Meaning that entropy provides a measure of energy quality.
We could add that ireversible processes in which total energy remains constant, the deterioration of energy quality gives us a measure of the entropy change.
Given two systems with the same energy content, the one with the lower entropy contains the highest quality energy.
Living things and societies represent the organization of matter (entropy decreases) in an universe governed by a tendency toward disorder (entropy increases), come into being by getting high-quality energy from outside and at the expense of greater entropy increases elsewhere in the universe.
They don't escape the second law of thermodynamics: the entropy of the universe can never decrease.
RE: Explain Entropy?
The heat capacity change as the temperature changes = thermodynamic entropy
RE: Explain Entropy?
RE: Explain Entropy?
RE: Explain Entropy?
RE: Explain Entropy?
The best you can do is break even (Bernoulli)
Second law of thermodynamics:
You can't break even (entropy)
RE: Explain Entropy?
Willard3, statistical thermodynamics would rephrase your definition of the second law by stating that one's chances to break even tend → zero.
RE: Explain Entropy?
The best, non-technical definition of entropy is:
There are no free lunches in the Universe!
Milton Beychok
(Visit me at www.air-dispersion.com)
.
RE: Explain Entropy?
Something or someone wound this thing called the universe up in the first place and it is slowly winding down.
rmw
RE: Explain Entropy?
No tiene desperdicio.
saludos.
a.
RE: Explain Entropy?
Consider the case of 2 items coming in contact with each other, but eaach at a different temperature. The 1st law does not define in which direction the heat will flow, but the 2nd law defines that the heat will flow from the hoter body to the colder body.
Another case: a bottle of gas is opened in a closed room. The first law will not predict that the gas will mix with the air in the room, but the 2nd law does predict that process. By the same token, the 2nd law would explain why the N2 and O2 in air will not spontaneously seperate from air and flow all by themselves into 2 seperate containers, although such a process is permitted by teh 1st law.
Likewise, when you burn gas in your car and the exhaust gas leaves the tailpipe and the extra lost heat is emitted tot he radiator, that direction of that process follows the 2nd law- although the 1st law would equally allow the reverse to occur- the exhaust gas return up the tail pipe, the heat to flow from radiator to engine block, and new gasoline to be formed in the cylinders. Basically, the 2nd law prevents things from operating backwards compared to our normal experience.
RE: Explain Entropy?
http://www.spiraxsarco.com/learn/modules/2_15_01.asp
RE: Explain Entropy?
While the first law speaks of energy conservation, the second law (2LOT) teaches us that in the macroscopic world, where friction and other energy-dissipation mechanisms are present, a completely reversible process is an idealization that cannot be realized.
The 2LOT differs from most physical laws in being fundamentally statistical in that it rules out events not because they violate basic laws of mechanics but because they're simply too improbable.
RE: Explain Entropy?
Entropy
go to
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http://www.entropysimple.com/content.htm
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good luck
luis
RE: Explain Entropy?
Good luck,
Latexman
RE: Explain Entropy?
RE: Explain Entropy?
Latexman:
Your professor's "You can't get something for nothing" is the same as my professor's "There are no free lunches in the Universe" ... is it not? (:>)
Milton Beychok
(Visit me at www.air-dispersion.com)
.
RE: Explain Entropy?
Absolutely!
Good luck,
Latexman
RE: Explain Entropy?
I digress...
Why do we care about entropy in the real world is the really important question in my view? To answer this, it may be useful to look at specific examples. Let us say you want to evaluate the performance of a specific piece of equipment, say for example a steam turbine. You feed the machine a certain quantity of high pressure steam and get out the other end some low pressure steam and some power. How do you know how well that machine has done this task? One way is to look at the inlet conditions of the turbine and assume that the process to the outlet condition is reversible. In this case the entropy of the steam going in is equal to the entropy of the steam going out of the device (assume there is no energy losses to the environment due to heat transfer for the turbine casing, ie define the boundaries properly!). You can calculate how much power you could have made under this reversible and unachievable scenario, then compare it to how much power you actually made. This will give you the efficiency of the turbine and tell you how much improvement is possible. This entropy based efficiency of the device (called the isentropic efficiency) is a very useful metric.
Tim
RE: Explain Entropy?
Good luck,
Latexman
RE: Explain Entropy?
As long as the tendency of the energy is to run down (entropy), as for any other closed system, the answer would be: yes.
RE: Explain Entropy?
http://www.multivax.com/last_question.html
-Shaggy
RE: Explain Entropy?
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