Could Both Carnot and Tom be Correct?

[Fool]

Could Both Carnot and Tom be Correct?

I've always suspected the following, but just figured it out. Heat is being rejected in a nonmagical but different way than through the cold plate.

The question is why are both Carnot and Tom correct? The answer is buffer pressure. The derivations I've provided in the past, are valid for both an engine running in a vacuum or with a buffer pressure. Tom is working exclusively with a buffer pressure. Although the efficiency equations are not affected. the heat gets rejected in different ways depending on having a buffer pressure or not.

The fact that an isothermal power stroke is 100% efficient, heat in equals work output, only applies to zero buffer pressure, and a single stroke. Many derivations, using calculus, assumes integration to zero pressure. And or zero Kelvin. Running an atmosphere or buffer pressure, the zero in calculus now becomes the buffer pressure. Easily recalculated, should someone care to do so. Adds a simple subtraction of buffer pressure.

Buffer pressure 15 psi. Plus of minus 5 psi. 15/5 = 0.3 or 30%.

A nonzero buffer means the power stroke is no longer 100%. Example, say 30%. 70% of the heat coming in goes out as work through the piston into the cold sink known as the atmospheric pressure. This energy is lost directly to the outside air. It is gone. It doesn't get rejected as heat through the cold plate. In fact the cold plate gets colder during this stroke if insulated. The gas, by definition, isothermal, stays hot.

The regenerator and displacer change the gas temperature to cold Tc, while saving that energy difference and using zero work (constant volume).

It gets worse for the return stroke. The work lost during the power stroke, is returned by atmospheric pressure. The gas adiabatically heats from the retuned work. It heats less than the work from the power stroke, because the gas is colder than for the expansion power stroke. The cold plate might be slightly colder than the atmosphere. The air rushing back into the piston cylinder could also be slightly colder. They are subjected to hysteresis. That cold air is pulled into and through Tom's insulation, further cooling the cold side of the engine and reducing the work needed and returned.

​The displacer and regenerator return the energy back to the gas, becoming hot Th.

​In other words, for a 80% Carnot rule engine, the buffer pressure eats 70% of the rejected heat as atmospheric work. Leaving 10% or less to come out of the returning piston and cold plate.

10W Qh, 2W power output max, 7W heat removed by working the atmosphere directly. 1W removed by the cold plate, which is fanned by the piston pushing air in and out through the insulation.

​Now just imagine how those figures would decrease if the engine could only absorb 1/10 or 1/100 that amount of power?

​It may very well reject more heat with insulation than not, for atmospheric LTD engines, running unloaded, only.

​If anything, Tom's experiment verified Carnot. It still needs measurement of work output to confirm that theory. Thanks Tom.

[VincentG]

I don't care to find it, but there was a conversation where you explicitly said buffer pressure was irrelevant.

I've always agreed with Tom that the cold plate can get colder, I just don't think it's really happening with an LTD model without great changes to volume ratios.

[Fool]

My memory of that conversation is that buffer pressure doesn't affect the calculations for efficiency. It very obviously affects the running of the engine. It primary effect is reduction of flywheel mass.

This is an overlooked effect. Reducing the effective work per power stroke, lessens the heat the cold plate must reject. I almost realized it in the let's beat up Carnot thread, but didn't because that thread was dealing primarily with adiabatic expansion.

This is a tentative theory to help describe what Tom is seeing within the laws of classical thermodynamics. Working some real numbers and tests are necessary. I just wanted to get it out for review.

[matt brown]

I've always agreed with Tom that the cold plate can get colder, I just don't think it's really happening with an LTD model without great changes to volume ratios.

As a long time alpha fanboy, I'm still getting up to speed with this gamma stuff. Here's a tidbit that I'll be adding to my gamma anomaly thread...

Ian-Hall gas flow.png (26.45 KiB) Viewed 3936 times

This follows my A-B-C cycle post where cycle A is 300-450k, but here I've unbundled the gas flow more accurately. Anyone who looks at this and doesn't get it fairly quickly is either a newbie or needs a new hobby.

Fool - take a close look at these PVT values, you owe me a beer LOL. I started a similar graphic with 300-900k cycle, but reverted to this 300-450k as a "buoy check" and everything fell into place.

I've never seen anything like this before, but anyone could have done this years ago. Jeez, this answers lots of questions without any need for thermo bashing...

Vincent - enjoy !!!

[Tom Booth]

Oh boy, another thread about Tom. And next "fool" will be complaining again how Tom is monopolizing the forum.

Are you two working as a tag team?

Keep dredging up old threads of mine or starting new ones so you have grounds to complain how I'm monopolizing the forum?

Don't you people have anything else to talk about?

​If anything, Tom's experiment verified Carnot. ... Thanks Tom.

LOL... What a joke.

[VincentG]

Lol at 2x zero point. Looks like things would get pretty chilly by that last frame Matt.

[matt brown]

This graphic is sweet and I couldn't resist that 2x tag. Yeah, reminds me of the old Jethro Tull tune "Skating Away (on the thin ice of a new day)"...

[Fool]

Matt, I'm still going over it. I'm interested how much work is done inside compared with outside. PV gas, verses, PV atmosphere.

Could we please get some ideal PV diagrams for these vodo cycles?

Tom, this isn't a thread about you. It is a thread about your experiments and subsequent temperature anomaly, and Carnot.

[Tom Booth]

...
Tom, this isn't a thread about you. It is a thread about your experiments...

Oh my, big difference.

Moron.

So a thread is started about my experiments and the results of my experiments, but you think I should be excluded from having any input or I'm "monopolizing" the forum.

How about you "Tom Booth" paparazzi find something else to obsess over.

[Fool]

I thought it would complement your experiment.

[matt brown]

Matt, I'm still going over it. I'm interested how much work is done inside compared with outside. PV gas, verses, PV atmosphere.

I kept the pressure inline my A-B-C cycles in gamma anomaly post comparing Ian-Hall gamma vs Essex where I used 1 bar at Vmin 300k as a constant. I mainly used this to follow typical model values, but it also was inline Hall video. Don't get bogged down by buffer pressure and consider this sequence in vacuum or with pressure raised thruout sequence (I can't recall that common line about pressure a thing apart).

Regarding work, the challenge is variable PVTm values. I'm attempting to resolve heat and work similar Schmidt analysis via a difference table for DP vs PP, but this is all nit picking vs the 800 lb gorilla in this graphic.

Could we please get some ideal PV diagrams for these voodoo cycles?

AFAIK all gamma and beta PV are "fake" due to PVTm variables. No worries, I have more tricks up my sleeve.

Tom, this isn't a thread about you.

But I predict this Bozo will

(1) be 'late to the party' with endless BS
(2) claim 'proof of concept' with endless BS
(3) 'crash and burn' with endless BS

[Tom Booth]

Tom, this isn't a thread about you.

But I predict this Bozo will

(1) be 'late to the party' with endless BS
(2) claim 'proof of concept' with endless BS
(3) 'crash and burn' with endless BS

This entire thread is full of meaningless drivel as far as I can see:

Tom is working exclusively with a buffer pressure

What in hell are you even talking about?

I'm working with open atmosphere engines. For "buffer pressure" you need a sealed engine with a buffer space not open to atmosphere.

Loony nonsense followed by ohhh ohhh! Tom proved Carnot!!!

Asinine bullshit.

[Fool]

I'm working with open atmosphere engines. For "buffer pressure" you need a sealed engine with a buffer space not open to atmosphere.

Perhaps one day you'll learn to be consistent with your own definitions.

viewtopic.php?p=16567&hilit=Senft+buffer#p16567

He introduces a modification of the old PV (pressure / volume) diagram. Again, something I've never seen before. He includes the "buffer" or atmospheric pressure (designated by the horizontal line Pb = buffer pressure) and makes a distinction between "effective work" which translates into useful shaft work, or mechanical work output of the engine and "forced work" which is really negative work that has to be subtracted from the effective work to get the net work output of the engine.

And Senft's. But please continue with late posts, and entertaining errors.

Perhaps Dr. Senft considers Earth's atmosphere to be a closed pressured sealed engine.


.

[Fool]

Matt, how much heat goes in verses how much work comes out?

[Tom Booth]

I'm working with open atmosphere engines. For "buffer pressure" you need a sealed engine with a buffer space not open to atmosphere.

Perhaps one day you'll learn to be consistent with your own definitions.

viewtopic.php?p=16567&hilit=Senft+buffer#p16567

He introduces a modification of the old PV (pressure / volume) diagram. Again, something I've never seen before. He includes the "buffer" or atmospheric pressure (designated by the horizontal line Pb = buffer pressure) and makes a distinction between "effective work" which translates into useful shaft work, or mechanical work output of the engine and "forced work" which is really negative work that has to be subtracted from the effective work to get the net work output of the engine.

And Senft's. But please continue with late posts, and entertaining errors.

Perhaps Dr. Senft considers Earth's atmosphere to be a closed pressured sealed engine.

He includes the "buffer" or atmospheric pressure.

Two different things. As in coffee OR tea.

In a sealed engine you have only "buffer pressure". In an open engine you have atmospheric pressure.

The vertical line in Senft's PV diagrams refers to one or the other as the case may be but "buffer pressure" and "atmospheric pressure" are not synonyms.

It's one of the other.

You've been on this forum how long?

You still need such simple and obvious matters explained to you?

Yet you continually present yourself as some kind of authority who knows better than everyone else.

The word "OR" could be ambiguous in that context, but not to anyone who knew the first thing about Stirling engines.