I don't know what thermodynamics would say about your question, but I predict you are feeling pretty bad about now.
Well, no actually.
Since how people think and feel is tied into the stock market, how would you know the Etp model is valid?
The Etp Model Has Been Empirically Confirmed
- Thread starter Futilitist
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Well, no actually.
Since how people think and feel is tied into the stock market, how would you know the Etp model is valid?
Ha ha. What's with the short page?
Really?
---Futilitist
Really?
---Futilitist
That neither matches your own previous claims about entropy nor how entropy actually works. You're flailing. Your own claims require that I should be able to set up a hydroelectric dam, never use it, and the "entropy" generated around it by other processes will make it less and less efficient over time, even though the parts of my dam remain brand-new and its maintenance costs never change. Either way, thermodynamics is a precise science. You should be able to calculate from readily available information on the internet what the original efficiency of the Hoover Dam was and current efficiency is due to the "entropy" generated (the western drought notwithstanding) during its lifespan. The Hoover Dam had its turbines replaced a while back, which would eliminate any wear-and-tear issues, but by your previous logic should still result in a less efficient power production than it was previously capable of.
You mean you can't answer the question. Something I've asked before and more than once. A simple idea to invalidate the Etp model would be to wonder what it would be like if one country 'Beerland' controlled 90% of the worlds oil and I can effect the price of oil on a whim. How would you graph that, my emotions?
Are you using thermodynamics/entropy akin to dark energy? Should I myself look into graphing the Big Rip correlation with oil prices and apocalypse? Are you meaning that oil wells are sunbject to diffusion and that meaning the oil supply dwindles even when not pumped? And just how old is the oil we are pumping?
That is correct Russ. You all lost the argument and your grotesque arrogance was the cause. You need to go away now.
The Second Law of Thermodynamics is one of the greatest achievements in the history of science. And you constructed a careful lie about it to misinform and mislead the readers of this science forum. I think this forum has rules about knowingly and intentionally presenting false information. If you persist in your squirming and trolling, I will start a thread in site feedback and get you banned.
I wonder what they would think about what you did on Physics Forums?
Shame on you, Russ.
Go for it. Get me banned too!
Yeah, I'm in for the feedback thread. The mods aren't paying attention to this thread, so that would spotlight it for their scrutiny. He can't possibly be so lacking in self awareness that he couldn't predict how that would go for him, is he?
Damn Russ.
You are still making false claims about entropy.
https://orionmagazine.org/article/calamity-on-the-colorado/
Calamity on the Colorado
ASKED IN 1995 what the Bureau of Reclamation plans to do when sediment threatens to fill Lake Powell, the 186-mile-long reservoir on the Colorado River, former reclamation commissioner Floyd Dominy replied, “We will let people in the future worry about it.” Lake Powell and Glen Canyon Dam are less than 50 years old, yet already we can see that those who will bear their true costs will not be some generation in a distant future, but our children and grandchildren, and even ourselves.
Glen Canyon was the second of two high dams on the Colorado. In 1936 Franklin D. Roosevelt dedicated the earlier of the pair, Hoover Dam, the first of nearly 50,000 large dams built worldwide, 90 percent of them since 1950. To justify this frenzy of construction, proponents and funders routinely exaggerated benefits and longevity while underestimating and ignoring costs. The most obvious cost of Glen Canyon Dam is the chasm that it drowned, western explorer John Wesley Powell’s “ensemble of wonderful features — carved walls, royal arches, glens, alcove gulches, mounds, and monuments.” These the Bureau of Reclamation sacrificed to fuel the juggernaut of development in Arizona, California, and Nevada. But there are other costs.
The dam not only drowned Glen Canyon, it radically changed the Colorado River downstream in Grand Canyon. Before the dam, the river was so muddy that the pioneer explorers joked (as they did about many free-running Western rivers) that it was “too thick to drink and too thin to plow.” The Colorado delivers enough sediment to Lake Powell to fill 1,400 ship cargo containers each day. The dam traps it all, leaving the water below clear as air and starving plant and animal species in Grand Canyon of the sediment they need for habitat and spawning.
Spring snowmelt once swelled the unimpeded river to 100,000 cubic feet per second (cfs) or more, equal to the summertime flow of Niagara Falls. In midwinter the flow dropped to only a few thousand cfs. To meet the demand for power in the Southwest, dam operators smoothed out the seasonal variations while they drastically increased the hourly ones, the released water surging through Grand Canyon like mini-tsunamis, washing away what sediment there is.
We justify dams for the hydropower, flood protection, irrigation water, and recreation that they provide. Yet over time, accumulating silt reduces and then eliminates each benefit. As long as the laws of physics hold, large reservoirs must fill with mud. After Lake Powell fills, the Colorado River will meander across a mud flat and plunge down the face of Glen Canyon Dam in a waterfall that will undercut and eventually collapse the dam. In time, the river will remove the dam debris and lake sediments as though they never existed. Dams imprison rivers, but eventually they annihilate their jailers and escape. Like the truth, a river will out.
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You clearly don't understand even the concept of entropy. Or you are pretending.
Either way, you are losing the debate.
I'm good for now. It's fun watching you desperately scramble to invent more lies to cover your lies.
---Futilitist
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Yet another copy-past of new irrelevance does not constitute a response to my request. So what you are really saying is "No, Russ, I have no idea how to calculate a hydro plant's (or any other basic thermodynamic system) efficiency loss over time due to entropy." Right? How about another way: surely, manufacturers must publish such information and since you are so fond of googling, find me a spec sheet for a machine - any machine - that indicates it's loss of efficiency over time, due to entropy.
I figured as much. Despite all your trolling blather, you do actually know the score.
Yet another false claim does not constitute a response to my post.
My post certainly does constitute a direct response to your request. Citing an authoritative source for my claim is the way I can establish that you are lying constantly.
This is the way that straw men are constructed.
Yes I was right. This is a straw man and a total red herring.
But since you brought it up, why don't you explain how to "calculate a hydro plant's (or any other basic thermodynamic system) efficiency loss over time due to entropy"? That way we can all see if you really know anything at all. I want to see the math.
Stop it!
You are trying to set up the same false claim about the second law of thermodynamics that got you into trouble before.
You are jumping the shark by switching to machines.
Machines are not relevant because the world oil production system is not a machine! Machines are idealized thermodynamic systems. They are closed systems. The oil production system is an open system. It can be modeled using the Entropy Rate Balance Equation for Control Volumes, as is accomplished in the Etp model.The idealized closed system you keep bringing up so deceptively is what is called adiabatic. Adiabatic means it occurs without transfer of heat or matter between a system and its surroundings; energy is transferred only as work. Closed systems are what is called reversible. Theoretically their entropy production rate is zero (ΔS = 0), but this does not actually happen in nature.
With the exception of idealized adiabatic and isentropic systems, all other systems in the universe are open systems. Open systems are what is called irreversible. That means that their entropy production rate is greater than zero (ΔS > 0).
These are the most basic concepts in thermodynamics, Russ!
You can't just lie about them!Reread carefully what INFO-MAN and Chestermiller had to say about the subject:
INFO-MAN said:
I agree that most people have a very hard time grasping entropy and the second law of thermodynamics. But I am not sure I understand why your article keeps referring to reversible processes and adiabatic idealizations. In natural systems, the entropy production rate of every process is always positive (ΔS > 0) or zero (ΔS = 0). But only idealized adiabatic (perfectly insulated) and isentropic (frictionless, non-viscous, pressure-volume work only) processes actually have an entropy production rate of zero. Heat is produced, but not entropy. In nature, this ideal can only be an approximation, because it requires an infinite amount of time and no dissipation.
Chestermiller said:
This is an example of one of those instances I was referring to in which the constraints on the equations is not spelled out clearly enough, and, as a result, confusion can ensue. The situation you are referring to here with the inequality (ΔS > 0) and equality (ΔS = 0) applies to the combination of the system and the surroundings, and not just to a closed system. Without this qualification, the student might get the idea that for a closed system, ΔS≥0 always, which is, of course, not the case.
Even though reversible processes are an idealization, there is still a need for beginners to understand them...
INFO-MAN said:
You hardly mention irreversible processes. An irreversible process degrades the performance of a thermodynamic system, and results in entropy production. Thus, irreversible processes have an entropy production rate greater than zero (ΔS > 0), and that is really what the second law is all about (beyond the second law analysis of machines or devices). Every naturally occurring process, whether adiabatic or not, is irreversible (ΔS > 0), since friction and viscosity are always present.
Chestermiller said:
I'm sorry that impression came through to you because that was not my intention. I feel that it is very important for students to understand the distinction between real irreversible processes paths and ideal reversible process paths. Irreversible process paths are what really happens. But reversible process paths are what we need to use to get the change in entropy for a real irreversible process path.
INFO-MAN said:
Here is my favorite example of an irreversible thermodynamic process, the Entropy Rate Balance Equation for Control Volumes:
$$\frac{dS_{CV}}{dt} =\sum_j\frac{\dot{Q}_{j}}{T_{j}} +\sum_i\dot{m}_{i}s_{i} -\sum_e\dot{m}_{e}s_{e}$$
Chestermiller said:
This equation applies to the more general case of an open system for which mass is entering and exiting, and I was trying to keep things simple by restricting the discussion to closed systems. Also, entropy generation can be learned by the struggling students at a later stage.
INFO-MAN said:
And here are are a couple of other important things you did not mention about entropy:
1) Entropy is a measure of molecular disorder in a system. According to Kelvin, a pure substance at absolute zero temperature is in perfect order, and its entropy is zero. This is the less commonly known Third Law of Thermodynamics.
2) "A system will select the path or assemblage of paths out of available paths that minimizes the potential or maximizes the entropy at the fastest rate given the constraints." This is known as the Law of Maximum Entropy Production. "The Law of Maximum Entropy Production thus has deep implications for evolutionary theory, culture theory, macroeconomics, human globalization, and more generally the time-dependent development of the Earth as a ecological planetary system as a whole."
Chestermiller said:As I said above, I was trying to limit the scope exclusively to what the beginning students needed to understand in order to do their homework.
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Looks like you need to do your homework, Russ!
INFO-MAN and Chestermiller are talking about the thermodynamic analysis of open vs closed systems. They even mention the Entropy Rate Balance Equation for Control Volumes. That is the second law statement that is validly used to construct the Etp model!
Both INFO-MAN and Chestermiller agree with me about the nature of entropy. They both seem to understand thermodynamics pretty well. Are you claiming they are both wrong?
You bet I do.
Hey Russ, remember, you have the right to remain silent.
---Futilitist
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Really? Did you read pages 50 and 51?Beer w/Straw said:
Once again:
Here is a good explanation of thermodynamics of open systems, plus the valid methodology used to the create the Etp model:
http://chemwiki.ucdavis.edu/Physical_Chemistry/Thermodynamics/A_System_And_Its_Surroundings
A System and Its Surroundings
In thermodynamics, it is imperative to define a system and its surroundings because that concept becomes the basis for many types of descriptions and calculations.
Introduction
A primary goal of the study of thermochemistry is to determine the quantity of heat exchanged between a system and its surroundings. The system is the part of the universe being studied, while the surroundings are the rest of the universe that interacts with the system. A system and its surroundings can be as large as the rain forests in South America or as small as the contents of a beaker in a chemistry laboratory. The type of system one is dealing with can have very important implications in chemistry because the type of system dictates certain conditions and laws of thermodynamics associated with that system.
Open System
An open system is a system that freely exchanges energy and matter with its surroundings. For instance, when you are boiling soup in an open saucepan on a stove, energy and matter are being transferred to the surroundings through steam. The saucepan is an open system because it allows for the transfer of matter (for example adding spices in the saucepan) and for the transfer of energy (for example heating the saucepan and allowing steam to leave the saucepan).
Let us examine how matter and energy are exchanged in an open system. Matter can be exchanged rather easily: by adding matter (i.e spices) or removing matter (i.e tasting what is being cooked). Energy exchange is a little bit more complicated than matter exchange. There are a couple of ways energy can be exchanged: through heat and through work (a more in-depth discussion of heat and work has been included below). Energy induced through heat can be demonstrated by bringing the system close to an object that dissipates heat (i.e. Bunsen burner, stove, etc.). By doing so, one is able to change the temperature of the system and therefore, induce energy through heat. Another way to increase the energy is through work. An example of inducing work is by taking a stirrer and then mixing the coffee in the cup with the stirrer. By mixing coffee, work is done as the coffee is being moved against a force.
Note: the blue diagram depicting the transfer of energy and matter is showing how energy and matter can enter the system AND leave the system. Do not be fooled by the one way arrows.
https://en.wikipedia.org/wiki/Thermodynamic_system
Open system
In an open system, matter may flow in and out of some segments of the system boundaries. There may be other segments of the system boundaries that pass heat or work but not matter. Respective account is kept of the transfers of energy across those and any other several boundary segments.
The region of space enclosed by open system boundaries is usually called a control volume.
Here is a description of the boundary conditions used in the Etp model and the derivation of equation#7 from the Entropy Rate Balance Equation for Control Volumes:
"Crude oil is used primarily as an energy source; its other uses have only minor commercial value. To be an energy source it must therefore be capable of delivering sufficient energy to support its own production process (extraction, processing and distribution); otherwise it would become an energy sink, as opposed to a source. The Total Production Energy ($$E_{TP}$$) must therefore be equal to, or less than EG, its specific exergy. To determine values for $$E_{TP}$$ the total crude oil production system is analyzed by defining it as three nested Control Volumes within the environment. The three Control Volumes (where a control volume differs from a closed system because it allows energy and mass to pass through it's boundaries) are the reservoir, the well head, and the Petroleum Production System (PPS). The PPS is where the energy that comes from the well head is converted into the work required to extract the oil. The PPS is an area which is distributed within, and throughout the environment. It is where the goods and services needed for the production process originate. This boundary make-up allows other energy, and mass transfers to be considered as exchanges, such as natural gas used in refining, electricity used in well pumping, or water used for reservoir injection."
~BW Hill
Values for $$E_{TP}$$ are derived from the solution of the Second Law statement, the Entropy Rate Balance Equation for Control Volumes:
$$\frac{dS_{CV}}{dt}
=\sum_j\frac{\dot{Q}_{j}}{T_{j}}
+\sum_i\dot{m}_{i}s_{i}
-\sum_e\dot{m}_{e}s_{e}
+\dot{\sigma}_{cv}$$
"Where $$\frac{dS_{CV}}{dt}$$ represents the time rate of change of entropy within the control volume. The terms $$\dot{m}_{i}s_{i}$$ and $$\dot{m}_{e}s_{e}$$ account, respectively, for rates of entropy transfer into and out of the control volume accompanying mass flow. The term $$\dot{Q}_{j}$$ represents the time rate of heat transfer at the location on the boundary where the instantaneous temperature is $$T_{j}$$. The ratio $$\frac{\dot{Q}_j}{T_j}$$ accounts for the accompanying rate of entropy transfer. The term $$\dot{\sigma}_{cv}$$ denotes the time rate of entropy production due to irreversibilities within the control volume."
~(Taken from Fundamentals of Engineering Thermodynamics by Moran and Shapiro)
Because there is only one temperature boundary (at the exit point of the reservoir) and no crude oil enters the reservoir from the environment, the equation reduces to:
$$\frac{dS_{CV}}{dt}=\frac{\dot{Q}_{j}}{T_{j}}-\dot{m}_{e}s_{e}+\dot{\sigma}_{cv}$$
giving: $$\frac{BTU}{sec*°R}$$
For this application, crude oil and water can be treated as incompressible substances. Their specific entropies are only affected by a temperature change.
For specific heats: $$c_{v}=c_{p}=c$$, and $$s_{2}-s_{1}=c*\ln{\frac{T_{2}}{T_{1}}}$$ The reservoir temperature is constant, therefore the entropy of the reservoir must decrease at the same rate that the entropy is transferred from the reservoir by mass flow. Thus, the heat leaving the reservoir is negative in sign and the equation becomes:
$$\frac{\dot{Q}_{j}}{T_{j}}=\dot{\sigma}_{cv}$$
giving: $$\frac{BTU}{sec*°R}$$
The rate of entropy production in the petroleum production system is equal to the rate of heat extracted from the reservoir divided by the reservoir temperature.
The rate of irreversibility production in the petroleum production system therefore becomes:
$$\dot{I_{cv}}=T_{O}*\dot\sigma_{cv}$$
giving: $$\frac{BTU}{sec}$$
Where $$T_{O}$$ equals the standard reference temperature of the environment, 537 °R (77° F).
Therefore:
$$E_{TP}=\int_{t1}^{t2}\dot{I_{cv}}dt$$
giving: $$BTU$$
Because the mass removed from the reservoir is limited to crude oil and water, the increase in $$E_{TP}$$ per billion barrels (Gb) of crude extracted as $$ds=c\frac{dT}{T}$$ is:
(Equation#7)
$$\frac{E_{TP/lb}}{Gb}
=\begin{bmatrix}\frac{(m_{c}*c_{c}
+m_{w}*c_{w})(T_{R}-T_{O})}{m_{c}} \end{bmatrix}/Gb$$
giving: BTU/lb/Gb
$$m_{c}$$ = mass of crude, lbs.
$$c_{c}$$ = specific heat of crude, BTU/lb °R
$$m_{w}$$ = mass of water, lbs.
$$c_{w}$$ = specific heat of water, BTU/lb °R
$$T_{R}$$ = reserve temperature, °R
$$T_{O}$$ = standard reference temperature of the environment, 537 °R
$$s_{i}$$ = specific entropy into the control volume
$$s_{e}$$ = specific entropy exiting the control volume
BTU/gal/Gb for 35.7° API crude = BTU/lb/Gb * 7.0479 lb/gal
Evaluation of $$E_{TP}$$ from Equation# 7 requires the determination of three variables: mass of the crude ($$m_{c}$$) mass of the water ($$m_{w}$$), and the temperature of the reservoir ($$T_{R}$$). These must be determined at time (t).
1) The mass of crude at time (t) is derived from the cumulative production function,
2) the mass of water is derived from the average % surface water cut (fw) of the reservoir,
3) temperature of the reserve is derived from the well depth. This assumes an earth temperature gradient of 1°F increase per 70 feet of depth.
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So that pretty much answers your stupid and repetitive question again.
---Futilitist
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exchemist
Valued Senior Member
Not entirely. It isn't my speciality but I think the idea is that if you account for all the mass and energy flows (with their bulk properties) across the boundaries to a defined section of a system, then even though it is not closed, you can define thermodynamic quantities for it. But of course this Etp Model does not define any of the boundaries properly, or explain how all the flows and properties traversing these boundaries are accounted for. Shouting repeatedly about "nested control volumes", as Fute likes to do, without explaining how each is defined, doesn't do it, obviously.
Hmm...up till now, you have represented yourself as an expert.
Basically. Here are the things you need to know:
1) The mass of crude at time (t) is derived from the cumulative production function,
2) the mass of water is derived from the average % surface water cut (fw) of the reservoir,
3) temperature of the reserve is derived from the well depth. This assumes an earth temperature gradient of 1°F increase per 70 feet of depth.
That is false. The boundary conditions you ask for now are fully described in the very post you are responding to, the one you just read, that fully describes the boundary conditions you are asking for again.
Not for you apparently. Like I said, they have been well defined many times on this very thread. Mostly directed at you, I believe.
Please re-re-re-re-read my last post directly above describing, in engineer terms, just how the three nested control volumes are laid out. When you understand what you are looking at, please describe, in you own words, exactly why you think the boundary conditions used in the Etp model are supposedly not valid. Thank you. Or good bye for a while, as happened last time I put this question in front of you.
---Futilitist
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You're talking about the whole world, remember?
Yep. Because I actually care about the whole world.
What do you care about?
---Futilitist
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Oy. You can't turn this around, Futilitist, because what you are claiming quite simply does not exist. There is no math to describe something that doesn't happen, so there is nothing for me to demonstrate (except, perhaps, that the Hoover Dam's efficiency today is actually higher than when it was built, not lower - from nameplate specs).But since you brought it up, why don't you explain how to "calculate a hydro plant's (or any other basic thermodynamic system) efficiency loss over time due to entropy"? That way we can all see if you really know anything at all. I want to see the math.
Then get, whatever your work is, published.
Um... If I believed in the collapse of civilization?
That is correct:
Control mass = closed system
Control volume = open system
For a control mass, you need to pay attention to energy inputs and outputs and for a control volume, mass inputs and outputs too.
Fute doesn't actually know any of that, which is why he tries to distract with a flood instead of just providing the simple answer.
Don't rewrite the question.
I care about the whole world. That is what makes me curious about how it actually works.
What do you care about?
Science has it's place, but there are many important things that can never be understood by the human mind.
1) Disagree Strongly
2) Disagree Mostly
3) Disagree Somewhat
4) Agree Somewhat
5) Agree Mostly
6) Agree Strongly
---Futilitist
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