Stirlingengineforum.com

Sippy Bird Experiments.

There is a little, not much, debate as to how the sippy bird works. Most agree in the following:

The bird is bottom heavy and tips up.
Cooling in the head rases the level of liquid.
At some point the bird becomes too heavy from the raising liquid level.
It tips it's head down into a water container.
The level lowers.
The bird's head get rewet.
The bird tips back up.
The fluid inside is usually special.

Things that are obvious to me but not debated:

The liquid drops because the inner tube is at the correct angle to break the air lock, and it pours out. This requires a water glass of the correct height.
The head is wet and evaporative cooling is a factor.
No process is adiabatic because the bird moves too slowly and is not insulated.
It is an open system and heat is carried away by evaporative mass flow, causing a lower temperature.

Debated theories:

1: Evaporative cooling cools the head enough to condense the fluid causing a reduction in pressure inside the head allowing the fluid to be pushed up from the higher pressure in the bird's bottom. The fluid drains back into the bottom after the airlock is broken. The process starts over again. That is similar to the, boiling water with ice, vacuum chamber. This theory requires very tight temperatures, fluid type, and internal pressure.

2. I've heard the following theory, although not common. The bobbing of the bird produces work that cools the head more than evaporative cooling can.

3. The bobbing causes the evaporative cooling to be faster because of forced convection. Like having a fan on it. The bird will work, but more slowly, even if the bobbing is suppressed.

Experiments:

Ice in the water. Prediction, it will work faster. Question, does the bird's head freeze from any 'extra cooling', work or evaporation?

Hotter room. Will it have a room temperature range or stop working outside the range? Humidity maximum? Prediction, none, just a curiosity.

Damped bobbing. Use a dampener to stop the bobbing. Could be as simple as an, upper range stop, rubber band, or a generator made from magnets and coils. Prediction, it will keep working with no bobbing, but slower.

Sealed in a glass dome. Prediction, stop running if only evaporative cooling. Or keep running if cooling from work. Avoid uneven temperatures on dome. No, strong lights heating, nor strong cooling of dome. Could require a very long undisturbed run. With or without bobbing or damped bobbing.

Sealed glass dome with ice on top. With atmospheric pressure inside, and or partial vacuum (Caution, may explode the bird.). Prediction, it may keep working. Again, its just for curiosity's sake. Evaporation and condensation, outside bird and inside dome, will continue. This produces a temperature difference for a heat engine theory.

Open experiment with a fan blowing to increase evaporation, such that it won't affect bird movement much, maybe from the side.

I hope someone is equipped to do those simple experiments. I would do them but have zero equipment. No bird, no glass dome, no infrared camera, thermometers, vacuum chamber. I do have glasses the right height, rubber bands and could build a vacuum chamber. Furthermore, I'm satisfied with the evaporative cooling classical theory, #1 above, as are most scientists. To deviate would require the extra investigation recorded here.

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Fool wrote: ↑Sun Sep 08, 2024 4:27 am ....

2. I've heard the following theory, although not common. The bobbing of the bird produces work that cools the head more than evaporative cooling can.

...

Really? I've never heard or read anyone say that, and I've certainly never said it.

Another attempt at strawmanning.

The swinging of the head is the result of heat converted to motion or "work". The "bobbing of the head" does not "produce work". That doesn't make any sense.

The work or motion assists or speeds up the evaporative cooling.

I don't think that is even controversial:


https://youtu.be/wC_P2gBwms0

From about 8:30 a demonstration of taking wet bulb temperature.

https://youtu.be/PmZCRgad3wc

Without the swinging to greatly speed up evaporation, the ambient heat heats up the water as fast as it evaporates so that there is no significant temperature difference.

The swinging is necessary to make the evaporative cooling take place more rapidly than the ambient heat can warm it back up or keep it warm.

But do some experiments, those birds only cost about $6.00

Here is a simple test to determine how much the "work" of swinging or bobbing back and forth contributes to the birds functioning vs. evaporative cooling alone.

Leave the bird with a glass of water to all equalize to room temperature.

Maybe 2 birds.

Starting with the birds upright, dunk one in the water allowing it to swing upright and continue swinging freely.

Using an eye dropper, take some of the water and wet the second birds head with the room temperature water, leaving the bird standing upright without swinging.

Certainly the felt alone is intended to increase surface area for greater potential for evaporation, but without air movement, swinging of the bird, wind or a fan, probably the cooling would not be rapid enough to get the bird started. The cooling from evaporation would be mostly offset by continual warming by the surrounding ambient.

There are probably already videos online of many of your proposed experiments.

Just to be clear, I do not think "work" in the bird directly results in cooling in the same way that adiabatic expansion of a gas doing work in a Stirling engine does. That is a misrepresentation.

The slow gas expansion or actually phase change in the bird is clearly, if anything, isothermal not adiabatic. There is no significant cooling as a direct result of conversion of heat into work.

The heat is converted to work isothermally, without cooling, the work is then used to operate a simple evaporative cooler.

Nobody ever claimed the bird is cooled by: "The bobbing of the bird produces work that cools the head more than evaporative cooling can." as far as I know.

All I ever said, anyway, is that the work output is used to drive the evaporative cooler. The swinging motion (work output) produces "wind" that greatly accelerates evaporation.

Let us look at what you actually said, bolding added:

Tom Booth at another site wrote:This infrared video of the "drinking Bird" ambient heat engine demonstrates the principle I have argued before, which actually got me banned from a popular physics forum.

What is apparent from the infrared image is that the glass of water is actually hotter than the birds head. Only slightly cooler perhaps than the ambient environment

What this means IMO, is that the motion of the bird swinging its head about in the air greatly accelerates the cooling process.

So, contrary to what is claimed, that the bird operates purely on the basis of passive evaporative cooling is false.

Heat from the environment powers the bird. The heat is converted to motion or thermodynamic "work" output, and that work output is used to power a quite ACTIVE refrigeration system.

This is IMO, a clear example of a "perpetual" heat engine + heat pump combination. That it is supposedly only taking advantage of an existing environmental temperature difference is not true. The toy is using environmental heat to do work to drive its own active cooling system, as evidenced by the fact that the birds head is obviously much colder than the glass of water, due to its own mechanical action and not a pre-existing environmental temperature difference.

Your strawman attack on a poorly written sentence, 'bobbing causes work' verses 'work induced bobbing'. Has left the main point out. It is the following.

The main point is that active evaporation requires mass flow. Water evaporates and is carried away from the birds head by air flow leaving colder water behind. It has little to do with the internal processes of the bird. It is completely environmental.

The air flow can be forced or natural convection. Bobbing is a form of forced air flow, and has little to do with work related thermodynamic refrigeration.

Evaporative cooling is not refrigeration.

Furthermore, there is no evidence that the glass of water in the video has any chance of developing a colder surface temperature from natural evaporative cooling in the time allotted. Bulk size verses thin skin bird head cooling. Furthermore, the inside of the bird head should be warmer than the outside if heat is flowing outwardly.

I've heard that a sling psychrometer indicates the same temperature drop sitting stationary as it has when spun. It just takes longer to stabilize. So bobbing just increases speed not maximum temperature drop.

Anyway you've indicated that the temperature drop is a result of evaporation, not refrigeration, and I agree that the bobbing may speed it up a little bit. So I guess this is a done deal.

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OK but you have your points numbered:

2. I've heard the following theory, although not common. The bobbing of the bird produces work that cools the head more than evaporative cooling can.

3. The bobbing causes the evaporative cooling to be faster because of forced convection. Like having a fan on it. ...

Why different numbers? A different number just to repeat the same thing, #2 "poorly worded" and #3 worded correctly?

Makes a lot of sense.

You stalk me across the internet to pull something I said from another forum and misrepresent it here. That's more than simply a "poorly worded" completely innocent mistake.

Get a life.

Fool wrote: ↑Mon Sep 09, 2024 12:56 pm ...

Evaporative cooling is not refrigeration.
...

In your opinion.

Here is a professional opinion:

https://www.cafcoservices.com/blog/hvac ... n-systems/

"Types of refrigeration systems"

What's #1 at the top of the list?

Maybe you can find a reference to back up your opinion that evaporative cooling is NOT a type of refrigerating system.

Perhaps you should start with the dictionary definition of refrigeration.

Vapor-compression is not the only type of refrigeration.

Technically even vapor-compression uses evaporation in a closed loop. Probably why the evaporator is called an "evaporator".

Oh, yeah, I forgot, you prefer your own terminology and want it to be called a boiler.

Good luck getting the world to follow you in renaming the parts and processes of a refrigeration system in your ongoing campaign to prove me wrong somehow.

I've heard that a sling psychrometer indicates the same temperature drop sitting stationary as it has when spun

Unsubstantiated assertion. Probably another lie, as is your habit. The video I provided demonstrates otherwise.

you've indicated that the temperature drop is a result of evaporation, not refrigeration

False.

There is a difference between passive evaporation, as from a glass of water, and an engineered evaporative refrigeration SYSTEM, as in the drinking Bird or a swamp cooler.

The first does not require work input. That is what makes it "passive". The second requires work input, which makes it "active".

The drinking Bird is an ACTIVE refrigeration system. That it utilizes evaporation does not nullify that fact. A household refrigerator also utilizes evaporation, as already stated.

I suppose by your definition an ice cube is refrigeration system.

One of these days you will use engineering definitions when talking engineering principals.

Colloquially, frigid means cold, refrigeration means cold. But in engineering refrigeration means, 'artificial refrigeration machine and cycle. Leaving out cooling machine.

Colloquially the separation between cooler and refrigerator is the depth of cooling. A few degrees, aka evaporative cooling, cooling. Significantly more than a couple dozen degrees, refrigeration. I have yet to see anyone call it a swamp refrigerator. It seems evaporative cooling a few degrees is commonly separated from the deeper cooling machines called refrigerators.

You're missing the point. The bird operates between ambient temperature and evaporatively cooled temperature. It is an open system heat engine continuously heated and cooled by natural processes.

It produces microwatts of power.

Scaling it up won't work because the temperature differential only allows the liquid to rise about a half inch. A bigger machine will only have the same temperature difference.

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Fool wrote: ↑Mon Sep 09, 2024 7:36 pm I suppose by your definition an ice cube is refrigeration system.

One of these days you will use engineering definitions when talking engineering principals.

Colloquially, frigid means cold, refrigeration means cold. But in engineering refrigeration means, 'artificial refrigeration machine and cycle. Leaving out cooling machine.

Colloquially the separation between cooler and refrigerator is the depth of cooling. A few degrees, aka evaporative cooling, cooling. Significantly more than a couple dozen degrees, refrigeration. I have yet to see anyone call it a swamp refrigerator. It seems evaporative cooling a few degrees is commonly separated from the deeper cooling machines called refrigerators.

You're missing the point. The bird operates between ambient temperature and evaporatively cooled temperature. It is an open system heat engine continuously heated and cooled by natural processes.

It produces microwatts of power.

Scaling it up won't work because the temperature differential only allows the liquid to rise about a half inch. A bigger machine will only have the same temperature difference.

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As usual, your entitled to your opinions, as wrong as they may be.

The pressure vapor refrigeration (PCR) cycle is different from evaporative swamp coolers.

The PVR Cycle uses two pressures, one to condense, and the other to boil. Boils is the difference.

An evaporative cooler requires atmospheric temperature and low humidity and air flow to evaporated the water.

The first is good for decades of temperature drop. Evaporative is good for less than ten or so, no matter how much it's waved around, or blown on.

If more drop is desired in the PVR Cycle, just increase the pressure difference.

"As usual, your entitled to your
opinions, as wrong as they may be."

"As usual, your entitled to other people's opinions, as wrong as they may be."

Fool wrote: ↑Mon Sep 09, 2024 7:49 pm "As usual, your entitled to other people's opinions, as wrong as they may be."

So you say, but the world goes on using evaporative cooler and refrigeration interchangeably. For example:

EVAPORATIVE COOLING

A very energy-efficient and effective use of water as a refrigerant occurs in the evaporative cooling process. By evaporating water, the temperature of the air in contact with the evaporating liquid water is lowered. Liquid water needs heat to phase-change (evaporate) from a liquid state to a vapor state. Thus, as each pound of liquid water is evaporated, it will absorb 970 Btu. This is an endothermic reaction, meaning heat energy is absorbed in the evaporation or phase-change process. The heat energy absorbed comes from the air in contact with the water, which will, in turn, become cooler during the process. The end product is cooler air with some water vapor entrained.

A portable evaporative cooler essentially works off this principle by acting as a cooling fan that uses water, a water pump, and a wetted surface to create the naturally occurring process of evaporation to cool warm air and drop its temperature. By pulling air across water,

https://www.achrnews.com/articles/13311 ... efrigerant

Please cite an "engineering" reference that backs up your made up BS that proper engineering language excludes water evaporation or evaporative cooling from refrigeration processes or systems. Or admit your full of shit

Tim Booth wrote:You stalk me across the internet to pull something I said from another forum and misrepresent it here.

Tom, you have no legs to stand on. You are often mistaken about how classical theory works. You don't have a cohesive alternate theory. Your analogies are wrong and inapplicable.

How is quoting you a misrepresentation? Its what you said. The fact that it is nonsense isn't my fault.

You have complained of being banned in several forums. You still don't get why. It is your abrasive banter name calling and fraudulent descriptions.

It is blatantly obvious why this bird machine works. You are wrong. Ruled false by things I've learned over many years. Years of learning that you obviously never got.

If you want to promote your own theories, get the data necessary to support it. Otherwise, prepare to be disagreed with by those that have more knowledge on the subject. I very sorry your ignorance causes you such poor means for debate.

The Sippy Bird is not perpetual motion. It doesn't generate enough work to lift water up to the height of the glass rim to fill it.

It requires two energy inputs. Ambient heat, and dry ambient air flow. It's an open system.



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