A MTD Liquid Piston Stirling Engine

Moderator: stan.hornbaker

Forum rules
Be nice!

A MTD Liquid Piston Stirling Engine

Postby stan.hornbaker » Fri Apr 07, 2006 12:08 pm

A MTD (200 C) Liquid Piston Stirling Engine has been built with
information posted on the internet.
The basic page:
More detais:
There are many links to more information.
Do not miss movie and animation links at bottom of the prototype page.

The liquid pistons are liquids in the "u" tubes which oscillate at
about 1 Hz! The small pistons in the horizontal tubes are for
extracting power.
The basic unit can be connected to operate as an integral engine-cooler.
Two of the four cylinder units make a better engine-cooler.
stan.hornbaker
 
Posts: 532
Joined: Thu Jun 20, 2002 6:01 pm
First Name: William S.
Last Name: Hornbaker

Response to A MTD Liquid Piston Stirling Engine

Postby np___8146 » Wed Dec 03, 2008 6:52 pm

What is the efficiency of this system?
np___8146
 
Posts: 1
Joined: Wed Dec 03, 2008 6:52 pm
First Name: Nicholas
Last Name: Papadopoulos

Response to A MTD Liquid Piston Stirling Engine

Postby stan.hornbaker » Wed Dec 03, 2008 7:38 pm

Peter Fette has not seen fit to publish output power nor efficiency figures.
If you take note of the size and construction, it is unlikely to be much more than an interesting implementation of a heat engine and not a commercially viable product.
stan.hornbaker
 
Posts: 532
Joined: Thu Jun 20, 2002 6:01 pm
First Name: William S.
Last Name: Hornbaker

Response to A MTD Liquid Piston Stirling Engine

Postby bptdude___2569 » Wed Dec 03, 2008 7:46 pm


Wow, this thing is amazing.
Somebody really sat down and did some serious machine creation.

"liquid piston" is a concept to be made a note of...

My two cents worth?

Well, my pet peave with typical Stirling designs, that they can't break the mentality of internal combustion engines, and really ignore the cold side, is not true here. This engine is designed from the group up to be a perfectly balanced engine, thermal wise. I like it, a lot.

It also uses the concept of internal cooling and heating of the working gas, not the concept people are also stuck on, of heating the containment cyclinder. Using fluid to spray mist the working gas is extremely clever. These guys are great.

Also, look at the use of "regenerator". Here you can clearly see the "regenerators" have nothing to do with saving heat or cold, saving fuel, etc. The purpose of the regenerator, something that is required for most typical Stirlings to even move, is really to play a trick with pressure and volume. Here is where I ponder what would be better to do this. I have seen a couple of other concepts, but that is another tangent.

Somebody just asked about efficiency. It may not be efficient, due to the requirements of the heat and cold side, to provide the exchangers, etc. It is obvious to me, this is purely a concept engine, and anybody who loves Stirlings should stare at this thing until they understand it. It probably has a negative efficiency, but that matters not.

Huge kudos to these guys, and pooh on people who dismiss it too easily.

- Joe


bptdude___2569
 
Posts: 177
Joined: Sat Jan 13, 2007 3:31 am
First Name: Joe
Last Name: McLean

Response to A MTD Liquid Piston Stirling Engine

Postby stan.hornbaker » Thu Dec 04, 2008 9:46 am

Joe: Fine for research. But still a clunker at 1 Hz.

Do you really think that this is a practical solution to a competitive commercial engine??
stan.hornbaker
 
Posts: 532
Joined: Thu Jun 20, 2002 6:01 pm
First Name: William S.
Last Name: Hornbaker

Response to A MTD Liquid Piston Stirling Engine

Postby bptdude___2569 » Thu Dec 04, 2008 3:53 pm


Clunker? maybe.
A practcal solution? no, not yet at least.

But am I wrong at saying the Stirling is in dire need of research, because it has the theory, but so far has eluded practical engineering for commercial use? The few serious attempts require extreme engineering and cost, thus killing it for widespread use?

I could be totally wrong about my ideas about the regenerator and obsession with the cold side, but these areas are things that even the best minds that publish on the Internet are having difficulty even explaining.

Just "fine for research" ? IMHO, we are in dire need of research, going back to the drawing board, for Stirlings to be practical and mass produced. These people who designed and built this did something fundamental, a nice new place to begin, with several fantastic new concepts in a working machine, even a "clunker". And, it was published on the web!

I do understand there are people and companies who will groan to know things may start changing, finally, coming from newbies. These people are smart, devoted, and put up capitol. But don't we want somebody, somehow, to break this enigma open, and provide the ability to realize the Stirling theory of thermal efficiency?

The only concept missing from the design, is the ability to provide heating and cooling timed to the cycle of the engine, which is a concept that will greatly increase power output. *wink wink, nudge nudge*

This would not be my final design type, but I love it still. I have trouble explaining my concepts to people sometimes, but here is a very different design, that promotes more research. When you see Stirlings sold in Home Depot, you will know enough basic research was done.


- Joe
bptdude___2569
 
Posts: 177
Joined: Sat Jan 13, 2007 3:31 am
First Name: Joe
Last Name: McLean

Response to A MTD Liquid Piston Stirling Engine

Postby stan.hornbaker » Thu Dec 04, 2008 8:19 pm

The Stirling engine is deceivingly simple yet is an engineering nightmare to make into a power producing machine except at excessive expense,use of exotic materials, and therefore has been restricted to space applications, submarines, and mass use as CHP on limited leases to some regions or area. Otherwise the price is prohibitive. Even Phillips found limited sales for their product.
stan.hornbaker
 
Posts: 532
Joined: Thu Jun 20, 2002 6:01 pm
First Name: William S.
Last Name: Hornbaker

Response to A MTD Liquid Piston Stirling Engine

Postby bptdude___2569 » Thu Dec 04, 2008 10:21 pm


That is the current status, yes.

What they do is grossly overkill the hot end, and spend what it takes to make it work.

For a military submarine, cost is no object, really. I really am suprised nobody sold some to the Unites States Marine Corps. They are sometimes very forward thinking, and having an isolated fire base not require truck deliveries of fuel has both human life and other military advantages, where again, price is not really such a problem, especially if you see what they pay for final cost of fuel delivery.

Anyways, when people figure out, I mean really figure out the Stirling engine, using what is available here in the 21st century for design and materials, then building one will be simple. We should not settle for the current state. We just have not solved the puzzle yet.

Hence, any unique design that does something new that works at all, is more valuable than an overpriced brute-force current design.

Well, I think so... *smiles*

- Joe
bptdude___2569
 
Posts: 177
Joined: Sat Jan 13, 2007 3:31 am
First Name: Joe
Last Name: McLean

Response to A MTD Liquid Piston Stirling Engine

Postby stan.hornbaker » Fri Dec 05, 2008 10:25 am

To produce a modern Stirling engine at reasonable cost requires overcoming the heat transfer film factors on the inside and outside of the hot and cold surfaces with all that is therein implied. Have fun!
stan.hornbaker
 
Posts: 532
Joined: Thu Jun 20, 2002 6:01 pm
First Name: William S.
Last Name: Hornbaker

Response to A MTD Liquid Piston Stirling Engine

Postby bptdude___2569 » Fri Dec 05, 2008 6:42 pm


To produce a profitable engine, first one has to prove high power can be obtained, and then some clever and cheap way to doing it engineered.

Did it ever occur to people to tear apart this puzzle, conflicting interest by conflicting interest? For example:

Stirlings take silly amounts of heat on the hot end, to heat the containment casing to near cherry red { for metal }, but at the same time keeping metal that hot causes failure when put under stress for not too long. Thus, very expensive materials and manufacuring methods are used to compensate, driving the cost beyond practical.

So, if you start a whole new Stirling specialty of design, thinking of ways to heat the working gas { fluid } on the inside some other way using heat from the outside, you could require less heat and not require extreme materials for the casing.

Then it just becomes a matter of finding the heat transfer method that does not eat its young efficiency wise or cost wise.

That is what is novel about the design presented. They sprayed a mist inside the cylinder to change the temperature of the gas. The reverse should work too, blowing air into a fluid.

I have seen other examples too, including one that took blazing concentrated solar heat and beamed it through a window in the cylinder. I liked that one because it allowed a green renewable energy source to be used and made switching the heat on and off quite possible with some sort of shutter system, thus allowing timing to the engine cycle.

- Joe
bptdude___2569
 
Posts: 177
Joined: Sat Jan 13, 2007 3:31 am
First Name: Joe
Last Name: McLean


Return to Power-producing Stirling Engines

Who is online

Users browsing this forum: No registered users and 1 guest

cron