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1
Science / Re: Tesla's heat engine (split from DDWFTTW)
Last post by spork -
I love oregon for so many reasons.

Great location for hang gliding, paragliding, and kitesurfing.
2
Also
https://youtu.be/3HpVDTEHCYc

Just as a kind of thought experiment. After all the discussion about ammonia refrigeration.

The bird is a heat engine that derives its energy by the use of evaporative cooling.

An ammonia refrigerator cools by evaporating ammonia in a continuous cycle.

So why can a heat engine (the bird) operate by evaporation of water on a toy but it is supposed to be theoretically impossible to run a heat engine on the cold produced by evaporating ammonia, and have the combined heat-engine-refrigerator power itself with ambient heat.

Is it that the bird is so much more efficient? Is it because the bird is an open cycle? because it uses up a drop or two of water?

In principle I would think the ammonia refrigerator would be more efficient than the bird.

I've participated in many forums where someone, usually not me, started a thread about bootstrapping a heat pump with a heat engine in some way shape or form. What I haven't come across is anyone ever following through and putting together such a device.

So how can we be so sure it wouldn't work?

Of course to make a beginning of it, one would need to have a thorough understanding of how a refrigerator works first of all and an understanding of how a heat engine works second of all. The two things, IMO are not the same thing working in reverse at all except perhaps in the most abstract sense. One converts heat into work and the other converts work into heat, but that isn't really true either.

A heat pump does not convert work into heat. It uses work to MOVE heat. The energy expended is used to TRANSPORT heat not create it.

A heat engine on the other hand actually converts heat energy directly into another form of energy. It doesn't move heat in a reverse direction from one reservoir to another it destroys heat energy and re-creates it as something entirely different.

To me this is as different as expending work or energy carrying gasoline in a can from one place to another as opposed to actually putting the gas in an engine and using it to drive an automobile.

Tom, for real, if you think the principle is sound, make one! It really doesn't require that much money or technology to do prototyping like this. It takes a shop with minimal fabrication tools. Mostly it would be a screwdriver, wrenches and a vise. You can find components to adapt and a local machine shop can make most any little thing you need for less than a couple hundred bucks.

This is the deal with what spork did. He was convinced the principle was sound and built models to test the concept. It worked so well they built the blackbird. Now everyone but cranks knows it works. The original little carts weren't complicated to any extreme degree.

Your idea might take a little bit of precision welding which you could get done at a local auto body shop or machine shop if you don't know how to do it yourself. But the point is, it is within the realm of the possible. All it takes is a little initiative. If you can't be motivated to do it yourself, it's still an interesting discussion I guess but the conventional wisdom is king until it's overturned or you can clearly point out both the flaw in the conventional way to model the system and a model which doesn't suffer that flaw. And even at that point, all you've got is a hypothesis that passes the immediate dismissal test. You still need to demonstrate your application to say whether or not it works in any definitive way.

And Stirling engines are cool as shit, so if that's what you are basically getting at you'll be doing something that's cool as shit and who doesn't want to do something that's cool as shit?

https://www.stirlingengine.com/

I tell you what though, the physics of compressed gasses aren't intuitive so if you plan on using adiabatic expansion, you are on your own. .
3
don't you live in california? I thought it was legal there.
It's a weird deal.  Recreational use was voted in at the beginning of 2017.  But apparently it's not possible to buy it without a card until the beginning of 2018.  Something about giving local municipalities 1 year to setup their own rules around zoning, sales, etc.
I love oregon for so many reasons.
4
Well if you think that going from an EROI of 50 down to an EROI of 10 is a "great development" then perhaps you would also think that me granting you the job of "Manager of Dave's Dirty Laundry"  would be "great development" in your career.

I didn't say that going from an EROI of 50 down to an EROI of 10 is a "great development".  I said none of that, including the words you falsely ascribe to me using quotation marks.

I said that the domestication of species, including animals for food and labour, and plants (both annual and perennial) for food was what enabled early civilisations to have time for arts, crafts, science, and leisure and all the other stuff we both agree it's good to have time for.

If you think that annuals didn't play a major role, do you dispute that BREAD played a major role in the development of Middle East culture?  Do you even read the NT?
Yes I know what you are saying. And you are full of shit which is why I made that joke.   Development of "agriculture" -  especially tillage based on annual crops - had nothing to do with the building of "great" cities like Nineveh and Babylon.  Developing a system which requires 5X (or 20X) the amount of work to produce the same amount of food (thank you Father Cain)  is a step backwards, not forwards.
Ignorance and arrogance. As expected.
5
"My point is that EROI numbers are no use unless sorted by energy source. "

 why didn't you just say it that way in the first place?
:facepalm:

Seriously?
6
Science / Re: Tesla's heat engine (split from DDWFTTW)
Last post by Tom Booth -
Also
https://youtu.be/3HpVDTEHCYc

Just as a kind of thought experiment. After all the discussion about ammonia refrigeration.

The bird is a heat engine that derives its energy by the use of evaporative cooling.

An ammonia refrigerator cools by evaporating ammonia in a continuous cycle.

So why can a heat engine (the bird) operate by evaporation of water on a toy but it is supposed to be theoretically impossible to run a heat engine on the cold produced by evaporating ammonia, and have the combined heat-engine-refrigerator power itself with ambient heat.

Is it that the bird is so much more efficient? Is it because the bird is an open cycle? because it uses up a drop or two of water?

In principle I would think the ammonia refrigerator would be more efficient than the bird.

I've participated in many forums where someone, usually not me, started a thread about bootstrapping a heat pump with a heat engine in some way shape or form. What I haven't come across is anyone ever following through and putting together such a device.

So how can we be so sure it wouldn't work?

Of course to make a beginning of it, one would need to have a thorough understanding of how a refrigerator works first of all and an understanding of how a heat engine works second of all. The two things, IMO are not the same thing working in reverse at all except perhaps in the most abstract sense. One converts heat into work and the other converts work into heat, but that isn't really true either.

A heat pump does not convert work into heat. It uses work to MOVE heat. The energy expended is used to TRANSPORT heat not create it.

A heat engine on the other hand actually converts heat energy directly into another form of energy. It doesn't move heat in a reverse direction from one reservoir to another it destroys heat energy and re-creates it as something entirely different.

To me this is as different as expending work or energy carrying gasoline in a can from one place to another as opposed to actually putting the gas in an engine and using it to drive an automobile.
7
Science / Re: Tesla's heat engine (split from DDWFTTW)
Last post by spork -
So. It's not intuitive at all. Goddamnit that sucks. Physics should be intuitive once you get the basic pronciple at work.

Exactly!
8
Science / Re: Tesla's heat engine (split from DDWFTTW)
Last post by spork -
don't you live in california? I thought it was legal there.
It's a weird deal.  Recreational use was voted in at the beginning of 2017.  But apparently it's not possible to buy it without a card until the beginning of 2018.  Something about giving local municipalities 1 year to setup their own rules around zoning, sales, etc.
9
Science / Re: Tesla's heat engine (split from DDWFTTW)
Last post by Testy Calibrate -
So, here it is in HS physics terms.
https://www.grc.nasa.gov/www/k-12/airplane/specheat.html

So. It's not intuitive at all. Goddamnit that sucks. Physics should be intuitive once you get the basic pronciple at work.
10
Arts and Entertainment / Re: Malcolm Young is dead
Last post by Worldtraveller -
:(