Perpetual Ideas

[Tom Booth]

I don't really see how regenerators in the general sense do anything else than basically change the timing of heating and cooling. So the most work would be done at a different crank angle.

For my idea I'm trying to store some heat in the fluid so I can use it to extend the heating cycle. Haven't fully figured it out yet though.

I won't say anything is "impossible" though in this case I'm tempted.

If you add heat to the working fluid it wants to expand, and the expanding is the means of extracting power. So it sounds like you are endeavoring to "store" heat in the working fluid but somehow inhibit expansion.

To a degree I guess that happens at or near TDC when the piston is holding the gas back under pressure throughout the heating process. So, I have to say it's not only possible, but happens to some extent in all engines during "isochoric" heating

https://en.m.wikipedia.org/wiki/Isochoric_process

To some extent I also think a "thermal lag" or the popular little so-called "thermoacoustic" engines with the long relatively voluminous chamber partially plugged with a stopper, partially isolated from the power cylinder, at TDC is effectively an isochoric heating chamber, especially with the piston held firmly down over the opening by a connecting rod attached to a crank, like a lid on a pressure cooker getting ready to explode. A boiler in a steam engine stores the hot working fluid under pressure until the valve opens allowing the high pressure steam to rush into the power cylinder to expand and drive the piston. Similar isochoric heating process.

I'm not sure there is any other way to store heat in the working fluid except as described here - under PRESSURE.

With steam, high pressure tends to raise the boiling point, inhibiting phase change, so I think when released the "wet" steam flashes to a "dryer" more expansive gaseous state.

Storing heat in metal is a way of putting the heat into a latent form using the high heat capacity and low expansion coefficient. The heat is "stored" in the metal with little expansion, but transfered into the gas the gas expands a lot.

An ammonia absorption refrigerator is getting pretty far afield but the ammonia gas is "stored" in water. It greatly expands when released from the water by a relatively low grade application of heat.

So my initial knee jerk response, that it would be "impossible" to store heat in the working fluid itself as it would expand and become useless, I have to think again, not impossible, but tricky. There may be other possibilities I haven't thought of, of course.

[Jack]

I'm approaching it from the rotary vane angle. It allows me to create chambers where I hold the fluid and move it to where I need it.

Right now I'm at the point where I use the fluid at its hottest to power my cold rotor. There will be excess fluid that, in stead of pushing it with the hot rotor through the cold rotor, I hold and bring together with a new "load" of fresh fluid in my "regenerator" rotor.

It seems like a nice idea on paper, but I'm not sure it works the same way in real life. I might have to start learning how to work with CFD software.

[Tom Booth]

For a long time I've been wanting to give the gravity pump idea posted early on in this thread a fair try.

I couldn't imagine it could actually work as presented, but, I couldn't really figure out exactly why not.

As water runs out, it creates a vacuum that draws more water in.

Well I finally decided to set up a little test in the kitchen.

gravity-pump.jpg (267.22 KiB) Viewed 896 times

As can be seen from the collapsed bottle, the setup certainly does result in a vacuum.

Actually I did, with a little poking at the inlet tube, get water to start running, up and out of a bowl in the sink into the milk bottle then out a tube in the bottom of the.bottle back into the sink drain... Continuously...

But, cheating a little, so far.

The siphon outlet is still lower than the water level in the bowl. So, just a siphon with this contraption in the middle. No pumping water up hill so far

But the water is still running and the vacuum increasing, presumably, but the milk bottle is also being crushed by the vacuum/pressure.

I'm going to call it inconclusive at this point. It isn't really a fair test as A LOT of potential vacuum is being lost due to the flimsy container. Also the sizing and length of the tubing, and those upright tubes that look like some kind of vapor traps are not included in the setup

Would making some "improvements" get it to work to pump water up hill? I very very much doubt it.

Unfortunately just now I hear air being sucked into the milk bottle from a leak around the hole where the tubing is inserted on the bottom

All I can say is a surprisingly high vacuum has been generated without air bubbles getting drawn in backwards from the end of the bottom drain tube

[Tom Booth]

A bit of video:

https://youtu.be/83wjLTWKXDk?si=Umo82cShViQOqXc1

This (the following, not mine) video does a good job of explaining all the necessary elements, many of which my test experiment is obviously lacking.

https://youtu.be/xXJAkQscS2A?si=nMNDVQWzehQnFGYG

Some videos include a foot valve on the bottom of the inlet pipe.

My test shows at least that a container with air, in line in a siphon does not break the siphon.

The upright tubes are apparently to trap air bubbles that presumably, will eventually get drawn in through the end of the outlet pipe to rejuvenate the flow. Presumably this could only work until the upright pipes become full of air, if it works at all.

At best I think it can only prolong the inevitable and the "siphon" will eventually be broken.

On the other hand... As water flows out, more flows in.

Also, the inlet pipe is supposed to be of a narrower diameter than the outlet, until the end, My test uses only one size tubing throughout.

Does the weight of all this additional water in the larger outlet pipe help in some way?

[Fool]

Pressure in a column of water is calculated by the following equation :

Pressure = density of water times g gravity times height

P = d•g•h

The equation doesn't have diameter in it, only height and density. A bigger diameter will have a higher flow at the same pressure.

In other words, whether it works or not depends only on height, not total mass.