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No doubt, any energy extracted from this should come from the mass of the bird impacting some stop at the end of its travel. It might help to add as much weight to the top and bottom of the bird as possible so there is more mass in motion.

VincentG wrote: ↑Thu Sep 26, 2024 4:22 pm No doubt, any energy extracted from this should come from the mass of the bird impacting some stop at the end of its travel. It might help to add as much weight to the top and bottom of the bird as possible so there is more mass in motion.

Directly.

Ultimately, though, the energy is solar. The sun heats the earth and atmosphere, that heat both "boils" (or evaporates) the fluid inside the bird and also evaporates the water on the outside.

More weight might pump more water per bump, but the bird would need to be able to do more work to lift the additional weight and also probably operate more slowly, but ultimately "consume" more ambient heat.

The point of all this is that ambient heat can be utilized by a heat engine to do work, and that work can be utilized to produce a temperature differential which then makes more ambient heat available to be utilized.

It has to be understood that heat is a form of energy that is "used up".

Heat can be added and used up, then more heat can be added and used up.

There is no real need to remove heat from a heat engine. Heat goes in, heat that goes in is used up. Then more heat can go in to be used, etc. etc.

The Carnot myth that heat is a fluid that must flow through the engine, in one side and out the other is just nonsense.

A greater ∆T allows more heat to be utilized so that more heat can be used up each cycle, but the heat is still all used up.

If it isn't, that is a result of poor engineering not some "universal law".

More weight might pump more water per bump, but the bird would need to be able to do more work to lift the additional weight and also probably operate more slowly, but ultimately "consume" more ambient heat.

If you add equal weight top and bottom so the bird is still perfectly balanced, the only extra work would be to overcome the added friction on the pivot.

VincentG wrote: ↑Thu Sep 26, 2024 4:22 pm No doubt, any energy extracted from this should come from the mass of the bird impacting some stop at the end of its travel. It might help to add as much weight to the top and bottom of the bird as possible so there is more mass in motion.

Adding mass to the bird would be similar to adding mass to a flywheel. Nothing more. It is the change in height of the inside fluid that matters. That is related directly to ∆T.

The bird gets top heavy from the heat entering the bottom, and less but most heat leaving the head. This is seen as rising fluid in the tube and ∆T. Of course we all know that. To rise, the fluid must condense in the inside top, creating a pressure difference. Think partial pressures at specific temperatures.

Tom Booth wrote:Ultimately, though, the energy is solar. The sun heats the earth and atmosphere, that heat both "boils" (or evaporates) the fluid inside the bird and also evaporates the water on the outside.

Without the coldness of space the solar energy would be useless. The Earth is powered by heat coming from the sun and being rejected to deep space. The rejected heat must be equal to the received heat minus energy stored on earth. Stored energy can be in the form of kinetic, potential, thermal, or chemical energy.

The Earth would have no weather without that temperature difference. Humidity would become 100%. The drinking bird would stop. Temperature would be the same everywhere.

Temperature difference is needed for entropy differences. Heat from the sun evaporates water because a higher temperature lowers the relative humidity. The cold of space raises the relative humidity. That causes condensation, clouds, and rain. It then gets warmer again, lowering the relative humidity. This, the drinking bird's head cools from evaporation. Without cooling, rain, and rewarming, humidity will never decrease.

The drinking bird is perfect proof of the second law, and the need for cooling to remove heat. ∆T needed.

Put a bell jar over the drinking bird and water glass. It will stop.

Put ice on top of the bell jar. Let the condensation drip back into the glass. The bird will start drinking as long as heat is provided to the bottom of the bird.

Put the top of the bell jar in the cold of deep space. Let the condensation drip back into the glass. The bird will start drinking as long as heat is provided to the bottom of the bird.

∆T needed. Heat in. Heat out, but less. The difference equals work out.

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VincentG wrote: ↑Fri Sep 27, 2024 6:28 am

More weight might pump more water per bump, but the bird would need to be able to do more work to lift the additional weight and also probably operate more slowly, but ultimately "consume" more ambient heat.

If you add equal weight top and bottom so the bird is still perfectly balanced, the only extra work would be to overcome the added friction on the pivot.

Perhaps it might be worth experimenting with.

The drinking bird is perfect proof of the second law, and the need for cooling to remove heat. ∆T needed.

Evaporation does not "remove heat".

It is a change of state that "locks up" energy in the form of kinetic energy of the gas.

Heat is transformed into motion, a different form of energy. As a result the "heat" disappears and the result is a drop in temperature, but NOT a relocation of "heat" evidenced by an increase in temperature of the water vapor leaving the birds head.

At the point of evaporation, heat is being "consumed" as a result of a change of state from liquid to gas/vapor.

In a Stirling engine a similar but different energy transformation takes place resulting in heat-energy "disappearing" and transforming into motion (of the engine itself). Likewise the "heat" is not relocated, evidenced by an increase in temperature at the "sink" or point of supposed reception of the supposedly "rejected" so-called "heat".

for your direct "removal" of heat to make the bird operate, the "heat" would have to be relocated as heat, to the surrounding air so that the temperature of the air surrounding the birds head would increase.

A change in state does not result in a temperature change or transfer or "removal" of "heat" from one place to another

Evaporation takes energy away in the form of mass transfer. It is an outflow of energy from the system. The system gets colder because it is warmer than the evaporation temperature. Phase change temperature constant only happens at freezing or boiling, this happens between those temperatures. The heat in the warmer bird-head-gas flows outwards to the colder bird-head-skin/felt. Heat transfers out of the system. Second law proof, yet again.

Fool wrote: ↑Fri Sep 27, 2024 11:37 am Evaporation takes energy away in the form of mass transfer. It is an outflow of energy from the system. The system gets colder because it is warmer than the evaporation temperature. Phase change temperature constant only happens at freezing or boiling, this happens between those temperatures. The heat in the warmer bird-head-gas flows outwards to the colder bird-head-skin/felt. Heat transfers out of the system. Second law proof, yet again.

The "system" includes the surrounding air, and the evaporating water, as well as heat from the sun, and as you pointed out earlier, the cold of outer space.

So now by limiting "the system" to what happens within the interior of the glass bulb you are contradicting yourself. You just arbitrarily move the system boundary to arrive at an apparent confirmation of Carnot, but without what happens outside the bulb, you don't have a working engine, you have a paperweight

Eventually, the escaping water vapor might re-condense somewhere releasing the "heat" it "removed", but that is not a given and such remote condensation will have no effect on the operation of the bird.

The "system", logically, should at least include all those things immediately necessary for the operation of the engine cycle which would include the evaporation process.

An "outflow of energy" by evaporation is not the same as "heat removal" or "heat rejection".

But more pointedly, the similar energy conversion in a Stirling engine that results in heat being transformed into the kinetic motion of the engine, accompanied by a drop in temperature, is not "heat rejection " or "heat removal".

All quibbling over what constitutes "the system" or semantics generally, experimentally there is what you call a "temperature anomaly"; no detectable temperature increase at the Stirling engines "sink" in numerous experiments

Instead, like the bird, there is actually a temperature decrease without any "transfer" of "heat" from one location to another. Rather than being "removed", the heat is transformed.

If "heat" is leaving the birds head as heat, then that heat should appear as a temperature increase outside the birds head. But there is no "heat" leaving the birds head or being "rejected".

The cooling is a result of something other than heat transfer.

At the interface between liquid water on the felt on the birds head and the surrounding air you have individual water molecules breaking bonds with other water molecules which takes energy. That energy consumption results in a drop in temperature.

Are those escaping water molecules "hotter"?

Really, there is no such thing as heat. Only different forms of motion

In a Stirling engine the random molecular gas motion is persuaded to oscillate in a rhythmic manner that has an impact on the piston, transferring energy to the piston setting it in motion.

This cyclical transfer of energy reduces the energy of the gas resulting in a drop in temperature and a drop in pressure below atmosphere so the piston can return and complete the cycle, then heat is again added at the start of another cycle.

No "heat" is "rejected" or "removed", unless you define "removed" as transformed.

The energy of the microscopic molecular motion of the gas is transfered to produce the motion of the engine.

The engine could turn a generator that produces electricity that goes through wires and eventually reaches a resistance heating appliance so that the "removed" so-called "heat" then re-emerges, but again, such a remote re-emergence, if you want to look at it that way, has no effect on the local cyclic operation of the engine.

The electrical load would slow it down presumably, but the result is cooling of the working fluid by an energy transfer or transformation, not "heat" transfer to a "sink".

You can view it, or define it however you like to preserve your precious "Carnot theorem" I don't really care

What concerns me is; if I have a Stirling engine "running on ice", does the heat flow through the engine into the ice or can it be transformed so that the energy or "heat" is released or re-emerges at some remote location?

If the heat, derived from the ambient surroundings comes out of a space heater somewhere, but does not directly influence the ice the engine is running on then Tesla's proposed ambient heat powered engine appears doable.

The bird is an example

The heat "removed" may reappear when the evaporating water condenses somewhere. So what?

The bird still runs.

This is simple Mr. Booth. Is the bird's head colder than the bird's bottom? Heat is moving from warm bottom to colder head.

Heat can transfer without temperature change. All that is needed is a temperature difference.

Evaporation only needs to have a temperature above the dew point of the air. The water evaporating will decrease in temperature until it closes in on the dew point.

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Fool wrote: ↑Fri Sep 27, 2024 1:09 pm This is simple Mr. Booth. Is the bird's head colder than the bird's bottom?

Not without the external evaporation, which is part of the "system".

Heat is moving from warm bottom to colder head.

Heat can transfer without temperature change. All that is needed is a temperature difference.

In the case where there is a phase change. Boiling water for example. In that case the heat/energy is transformed so is no longer "heat", as in evaporation, or as in a Stirling engine, converting "heat" into "work". ( Really just transferring molecular motion of the gas/working fluid to "bulk" sensible motion of the engine.)

Otherwise a heat transfer results in a temperature increase in the object or substance the heat is transfered to.

You can put heat into ice and the temperature of the ice will stay the same (phase change). But adding heat to water increases the temperature until the boiling point (phase change).

Evaporation only needs to have a temperature above the dew point of the air. The water evaporating will decrease in temperature until it closes in on the dew point.

So, what's your point? Without tying up energy in phase change resulting in a drop in temperature, (not "heat transfer"), the bird would not operate. The evaporation is part of the "system". Obviously

In an external combustion engine, is the fuel part of the system? If so would a Stirling engine then be labeled as a candle engine? No. A Stirling engine is a temperature difference engine.

A drinking bird is a temperature difference engine of a different kind. Not an evaporation or solar engine. It could use a flame and ice.

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Fool wrote: ↑Fri Sep 27, 2024 4:40 pm In an external combustion engine, is the fuel part of the system?

I should think so.

Could it operate without fuel? Without a fuel pump to deliver the fuel? etc.

If so would a Stirling engine then be labeled as a candle engine? No.

Why not? Most people call an IC engine a "gasoline engine". What does it matter what you call it?

A Stirling engine is a temperature difference engine.

So it is erroneously labeled by some who have an obsolete and possibly erroneous notion of how it operates.

A drinking bird is a temperature difference engine of a different kind. Not an evaporation or solar engine. It could use a flame and ice.

It is not a "temperature difference" engine, because it does not require a pre-existing temperature difference to begin operating.

It does require some mechanical input to get it started and begin the cycle, similar to how most engines of any kind require a starting mechanism of some sort, with few exceptions

The bird by its continued mechanical action, after being started, by energy derived from the surrounding ambient heat (a "single heat "reservoir") generates a temperature difference that allows the process to continue without further intervention.

The bird is the same temperature as the glass of water is the same temperature as the air. In the course of operation a temperature difference is created by mechanical action derived from the surrounding ambient heat.

That's one way of looking at it anyway.

It is a theoretical basis for how a Stirling engine could also use ambient heat to derive energy to continue some cooling process that would provide the means for continued operation.

Not "rejecting" heat to an artificial "sink" would be a key element of such a system, and I think that has been repeatedly demonstrated experimentally.

That is simply my honest opinion, based on my own experiments and observations over the past decade.

The bird proves conclusively that this is possible using a very simple evaporative cooling system.

Admittedly, that does not prove conclusively that it is possible using any other cooling system, such as a common heat pump or refrigerator run by means of a Stirling engine that operates by the ∆T provided by the heat pump, but personally I don't see anything baring the road to such a contraption as Tesla envisioned.

Certainly a scaled up version of the drinking Bird using a Stirling engine + swamp cooler in an appropriate climate is possible, without question.

The bird is in that respect a "proof of concept". It works.

And it only evaporates about a teaspoon of water for 24 hour operation.

A Stirling engine powered swamp cooler could likely do quite a bit better.

Is a Stirling engine running on evaporative cooling not a temperature difference engine? No it still is. How the temperature difference is generated doesn't matter.

Now you are going to have to attempt to run a drinking bird off a "preexisting temperature difference".

Might I suggest putting a five Watt light bulb underneath it. Cycle it on and off, if it gets too hot. Or dim it. Damnit Jim, I'm a doctor not an ornithologist.

Infrared LED or more? Paint the bottom black and put in the sunshine, shade the top with aluminum foil?

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Fool wrote: ↑Fri Sep 27, 2024 6:04 pm Is a Stirling engine running on evaporative cooling not a temperature difference engine? No it still is.

Not as a combined unit. But you can feel free to call it by whatever name you like.

How the temperature difference is generated doesn't matter.

What matters is that it IS. generated by the engine itself, or by its own action. A so-called "Self-Acting Engine" that requires no fuel other than the surrounding ambient heat

Now you are going to have to attempt to run a drinking bird off a "preexisting temperature difference".

Might I suggest putting a five Watt light bulb underneath it. Cycle it on and off, if it gets too hot. Or dim it. Damnit Jim, I'm a doctor not an ornithologist.

Infrared LED or more? Paint the bottom black and put in the sunshine, shade the top with aluminum foil?

Again, feel free to do your own nonsense "experiments". I don't have much time for your foolishness.

Tom Booth wrote:What matters is that it IS. generated by the engine itself, or by its own action. A so-called "Self-Acting Engine" that requires no fuel other than the surrounding ambient heat

It won't work from heat alone. It must also have low humidity.

So you don't think it will work from the heat of a lightbulb and dry head. Have you ever seen a bubble light Christmas tree ornament? Boils on one end condenses on the other.

You come up with magic thermodynamic fantasies all the time, yet still don't recognize how your theory provides a violation of the first law. The second law can't be broken without the first law being broken. Your experiment is inconclusive. Most people would want to do a conclusive experiment. Not Tom, nope. Too foolish.

That avoidance is conclusive enough for me. Just put a bell jar over the drinking bird and glass. See if it needs more than ambient heat. Go ahead, I dare you. I double dog dare you.

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