Open Systems

[MarkE]

The cop with this system is 1. This i have been through with Mark-energy is conserved-->are you going to argue with that?.

Energy is conserved but you are not accounting for it correctly.

[profitis]

Mark E says to tinman: 'Energy is conserved but you are not accounting for it correctly.'

I say to mark E: he's on track

[MarkE]

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Well here in Australia it is the most commonly used messure of force. There are times when the term force is used,but force is pressure-so either is ok.

The difference between pressure and force is so basic that I hope you mean you do something other than substitute pressure directly for force.

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You think that faster moving particals create more heat,where as i think more heat causes the particles to move faster. What happens to the particles in the air when the air is warmed by the sun-->the particles move faster. Now there was no compressing of the particles there,and yet they sped up.

LE's point is that faster moving particles have more internal energy.  That is simple kinetics.  The industrial world operates on the fact that gasses can exchange internal energy with the outside world by either thermal or mechanical means.

[MarkE]

Quote from: MarkE on February 04, 2015, 09:01:52 PM


           What would you like to equate the force to?

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    Yes, you are very badly lost on very fundamental issues.

We shall see soon enough.

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    Wow Mark,you have just invented an OU device. We now have more stored force than we started with. How did you do that when it was clearly stated that it was a frictionless device.

The good news is that you intend to experiment.  The bad news is that at least for the time being you remain at odds with the very basics of thermodynamics for which there are thousands of good tutorials available to you for free on the www.

No, this is again where you are just lost.  Please avail yourself to any of the many thousands of reputable online references because you stopped paying attention to any of the correct explanations offered by others and myself here a long time ago.

You have to understand that i dont see all post when im working 17 hours a day,they are easly missed when trying to keep up during work hours. I am interested as to how you managed to achieve a higher pressure after all the energy was returned on the return stroke of the piston.

I appreciate that you work very hard.

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    You have made a series of incorrect statements that are refuted left and right by that "200 year old" physics that you disdain.  Experiment after experiment refutes your assertions.

You mean you think i have made a series of incorrect statements based on your belief that the ideal gas laws can be applied to my system.

No, with all due respect:  We are talking about very basic, extraordinarily well proven principles.  While anyone can be mistaken, and any principle has a finite possibility of being wrong under some circumstance: the chances here are so close to nil that I make no distinction for the extremely good cause that there is no evidence of any kind that disputes these fundamentals which have been proven billions of times by every hot gas engine and heat pump built over the past 200 years.

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    My definition is one who engages in personal attack rather than debate the merits of their arguments.Yes it is!" and "No it isn't!" are declarations, not arguments.

Like telling some one who has a different belief than yourself that there full of shit?-Maybe that was just your way of telling me no.

The distinction that I draw is decrying ideas that cannot stand rather than the person.  If you feel personally offended by anything I have said then I apologize for that.

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    For the umpteenth time, if the piston does work on the outside world, then it transfers energy to the outside world.

Respectfully !no!-no energy is lost to the outside world,as the unit as a whole is all enclosed in an insulated room.

Here we are back at the crux of the situation.  Is it fair to say that you believe that because at a given internal energy a particular quantity of gas has a P*V product that P or V can be changed to new values without usng or adding energy so long as the P*V product remains fixed?  If so that is called an adiabatic condition.  It is an extremely useful, but hypothetical condition.  If you understand that work is the integral of F*ds, or less rigorously:  force times distance, then you should understand that if we have gas in a cylinder, and if we change the volume of the cylinder, then we apply force along the axis of the cylinder and therefore either put work into the cylinder by compressing it, or take work out by allowing the cylinder to expand.  LE has used the bicycle pump example and I have used the aerosol can example.  I don't think that there is any debate that where P₁V₁ = P₂V₂ the internal energy is the same.  The debate is whether it is possible to change state from P₁V₁ without exchanging external energy.

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    It exerts that force in the direction of motion.  It performs work.  That work comes from the internal energy of the gas.

No,that work comes from the force/pressure that already exist and is already accounted for within the system.

See above.

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    Going the opposite way:  External force must be applied to the piston in order to force the gas into a smaller volume.

Not part of the process in my system,as the gas is already compressed.

Again, see above.

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    That work increases the internal energy of the gas.  It increases nRT and consequently the PV product just as surely as the piston pushing out against a load transfers internal energy from the gas to the external load

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No,the gas and all the energy it contains remains within the internal system. You just dont see the opperation of the system as a whole because you believe that your ideal gas law applies to all the action within my system.

See above.

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    The industrial world is based on these simple facts that you reject.You suffer from a fundamental misconception and have defied all patient efforts to disabuse you of that false notion.

Once again,you assume that the ideal gas laws can be applied to my system-they cannot while the system is in opperation.

Your first problem is that if you want to claim an exception to general principles then you either need to make an argument for why that exception should exist, or demonstrate that it appears to exist.

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    The total force is the product of the surface area of the vessel and the pressure.

Indeed-on this we agree.Please remember you agree with this,as it will come into play soon enough.

That's not a problem for me.

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    Force is not energy.    Since for a given internal energy and vessel volume we will have a corresponding pressure that is independent of the surface area of the vessel, for a given internal energy we can design vessels that minimize or maximize force on a given internal surface by our choice of the vessel shape.

No ,force is not energy,but gives rise to energy.
The vessel of choice in this system will be a cylinder type vessel.

Energy is the integral of F*ds.  We must have force and some portion of it must be applied through the direction of motion.

Mark.

You think i show you disrespec,but that is what i have seen from you toward myself. The button was pushed when you said i was full of shit just because i have different beliefs to you. From then on you were given as good as you gave,and there are many examples of that in this thread. You telling me i need to go do some study,and me telling you you need to stop living in the past-you telling me i dont understand or know what im doing,and me telling you that you dont understand my system,and that your ideal gas laws cannot be applied to my system while it is in operation. It can go on and on,and at the moment im guessing the one thing we gan agree on is that neither of us has respec for the other. I am not sure what you feel that your position here on this forum is,but im thinking that you see your self as some sort of teacher,and we are your student's. Well im sorry,but im not here to live by the ways of old-->im here to find the holes in the physics that you love so much. Im here to find the errors in those said laws,and to find where they dont apply-->and i believe my system is one such case.

I hope you appreciate that we did not arrive at our current understanding of the physical world by proclamation.  Our understanding is based on countless experiments devised and executed by very bright people.  While there is always more to learn, and there is always the finite possibility that we will find an exception to basic principles, the odds against any kind of experiment that repeats conditions that have been tested millions of times finding something new are really, really, small.

So lets start working on this together,insted of seeing who can insult the other the most. First up,some question's.
1-As i understand,there has to be one constant for us to be able to use the ideal gas laws on my system. Either P,V,T or n--Is this correct?

No, not really.  In order for the ideal gas law to be a good approximation the effects of things like Van Der Waal forces have to be small. nRT is going to give the internal energy of the gas.  Under any static conditions and volumes like you are talking about PV will be so close to nRT that we do not distinguish the two.

2- If the pressure rises within the storage tank/vessel,then the heat will rise as well?

A higher P*V product means more internal energy, IE higher nRT, than a lower P*V product.  R is a constant.  So if n is constant, then P*V changes with T and vice-versa.

3-If the volume increases,but n is constant,then the pressure and heat will drop?

The internal energy is nRT.  The disagreement that you have with basic thermodynamics is the idea that you can change P or V without exhanging work that would change nRT and therefore the product of P*V.  You are free to try and find a way to enlarge V and still keep Elvis in the building.

And 4-if i give you the parameters,are you able to convert the energy stored within the storage vessel into joules of energy using the ideal gas laws?.

It's a simple calculator plug to take n and T and multiply by R.  If n is unknown, but P and V are known, it is also a simple calculator plug to get the energy.

[LibreEnergia]

You think that faster moving particals create more heat,where as i think more heat causes the particles to move faster. What happens to the particles in the air when the air is warmed by the sun-->the particles move faster. Now there was no compressing of the particles there,and yet they sped up.

This is incorrect.

Heat is the sum of the kinetic energies of all the particles in the system.  A system being heated doesn't "care" how the particles in it were accelerated, only that they were. If they are going faster they have more heat. 

The increased movement might have been caused by absorbing radiation or physical collisions with another particle. In the case of IR absorption some is re-emitted, but a portion is absorbed and causes the particle to move faster.

In the case of a piston advancing into a cylinder the piston is hitting particles faster than when it is at rest, and that momentum is transferred to the particle. After the piston stops the gas now has more internal energy or heat. It is as simple as that.