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Tom Booth

Heat engine experiments and 2nd law of thermodynamics.

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Posted (edited)
23 minutes ago, swansont said:

Heat converted to work to drive a piston is not how a refrigeration cycle works

 

"Driving the engine mechanically" is not a conversion of heat into work.

Hot things cooling off/cool things warming up requires no engine; it happens spontaneously. A refrigerator takes the cold bit and makes it colder. This requires and engine, as it will not happen spontaneously.

Expansion engines are used in cryogenic refrigeration. It IS a variety or type of refrigeration, just not one many people are familiar with.

 

Screenshot_20200617-013647_crop_10_resize_23.jpg

Screenshot_20200617-013706_crop_88_resize_46.jpg

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This is from a public domain document: https://operations.fnal.gov/rookie_books/Cryo_Primer.pdf

Edited by Tom Booth
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3 hours ago, Tom Booth said:

Expansion engines are used in cryogenic refrigeration. It IS a variety or type of refrigeration, just not one many people are familiar with.

 

We were discussing Stirling engines. One example at a time, remember?

From your link: (pp 14-15, emphasis added)

“It's important to understand that a refrigerator is a heat engine that operates in reverse. Energy is transferred from a low level to high level, which is contrary to
the spontaneous processes that occur in nature. To accomplish this transfer, an amount of work must be supplied dependent on the temperatures involved. Energy must be added to this workload to compensate for the inefficiencies inherent in heat transfer, inefficiencies that arise from heat exchange equipment and the irreversible behavior of compression or expansion equipment.”

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17 hours ago, Tom Booth said:

I've been looking for some kind of "authoritative" confirmation of my statement, that a Stirling cryo-cooler is THE SAME as a Stirling engine running in The SAME direction as a Stirling engine, as very often, there is quite a bit of misinformation on the internet that a Stirling cooler runs in the opposite direction from a Stirling engine.

What do you mean by direction ?

What happens if you reverse the hot and cold plates in your machine ; Does the machine then run counter clockwise, if it ran clockwise before ?

Now what happens if you do nothing but monitor the plate temperatures and drive the flywheel first clockwise and then counter clockwise with say a small electric motor?

 

I don't see the difficulty measuring these temperatures - for a first ball park run you do not need to be very accurate.

You will also gain so much more by conducting these simple experiments for yourself, than by posting details of exotic machinery.

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1 hour ago, swansont said:

We were discussing Stirling engines. One example at a time, remember?

It has been my observation that the Stirling engine cycle is functionally equivalent to the expansion refrigerating engine described above. The comparison is appropriate.

4 minutes ago, studiot said:

exotic machinery.

What exotic machinery?

A Stirling cryo-cooler is essentially the same machine as a Stirling engine 

An expansion engine is similarly not at all "exotic" or complicated. It is simply any piston in a cylinder driven by the expansion of a gas.

 

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Posted (edited)
16 minutes ago, Tom Booth said:

What exotic machinery?

A Stirling cryo-cooler is essentially the same machine as a Stirling engine 

An expansion engine is similarly not at all "exotic" or complicated. It is simply any piston in a cylinder driven by the expansion of a gas.

So you will have no difficulty providing the answers by using a kitchen thermometer and winding your stirling engine backwards.

When you boil the water in your #dewar, mine is two sugars and cream please.

:)

Edited by studiot

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15 minutes ago, studiot said:

What do you mean by direction ?.

Direction of rotation.

In other words, if a Stirling engine were operated, turning clockwise, putting energy into a big giant external flywheel, then the heat source was removed, and the flywheel continued to drive the engine, in the same clockwise direction, the engine would then be functioning as a refrigerator.

This is not any different than what takes place, or can, take place, as a result of a Stirling engine storing energy in its own flywheel, then proceeding through the remainder of the cycle on that stored momentum.

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6 minutes ago, Tom Booth said:

the engine would then be functioning as a refrigerator.

You are welcome to demonstrate this in practice, which is why I invited you to do just that (theatrically large flywheels are unneccessary).

What would be refrigerated?

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"demonstrate"?

How?

Quote

Please stop using videos as support for your ideas...

I was recording experiments so the results could be known to everyone, with as little interpretation on my part as possible, but apparently posting video is frowned upon here, if not outright grounds for expulsion, so, who can possibly demonstrate anything with such restrictions?

 

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2 minutes ago, Tom Booth said:

"demonstrate"?

How?

I was recording experiments so the results could be known to everyone, with as little interpretation on my part as possible, but apparently posting video is frowned upon here, if not outright grounds for expulsion, so, who can possibly demonstrate anything with such restrictions?

!

Moderator Note

Gosh, yes. How on earth did anyone communicate science and technology before the invention of video!?

Just try writing. You know, words. With some diagrams, if necessary.

If you want to reference other peoples work, then find published "words" and "pictures". It really isn't that hard. (If you can only find videos, then that means that there is no good, reliable information available.)

If you don't want to follow the rules of the forum, we can close the thread.

 

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29 minutes ago, studiot said:

You are welcome to demonstrate this in practice, which is why I invited you to do just that (theatrically large flywheels are unneccessary).

What would be refrigerated?

I believe I already have.

By simply insulating the cold plate, which is where the engine's refrigeration winds up, to prevent ambient heat infiltration, the same way an ice box is insulated, the "sink" or cold plate getting colder, demonstrably causes the engine to run better and faster.

8 minutes ago, Strange said:
!

Moderator Note

Gosh, yes. How on earth did anyone communicate science and technology before the invention of video!?

Just try writing. You know, words. With some diagrams, if necessary.

If you want to reference other peoples work, then find published "words" and "pictures". It really isn't that hard. (If you can only find videos, then that means that there is no good, reliable information available.)

If you don't want to follow the rules of the forum, we can close the thread.

 

Why not just carve it out on some stone tablets?

Sorry, but I don't need this, there ia a multitude of forums I could be posting to that don't have such nonsensical restrictions.

Close the thread if you want boo hoo. Your loss.

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24 minutes ago, Tom Booth said:

Sorry, but I don't need this, there ia a multitude of forums I could be posting to that don't have such nonsensical restrictions.

!

Moderator Note

I hardly think that asking you to present your ideas in writing (a technology that has been around for thousands of years) is "nonsensical". 

Trying to present technical information via a video is pretty nonsensical. It is a terrible medium for the task.

 
24 minutes ago, Tom Booth said:

Close the thread if you want boo hoo. Your loss.

!

Moderator Note

OK. But I can't see that anyone is losing anything. 

Do not start another thread on this subject.

 

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