Could this be a game-changer?

[socaldmax]

Originally Posted by Don C L

Actually Beetron makes the same point that this is best thought of as a transitional power source, but it is so much more efficient, and able to run on different fuels, and small, I thought it had "sailboat auxiliary" in its future.

Or even a primary power source. Everybody talks about how reliable their diesel engines are, except when they're covered in filth up to their elbows replacing injectors or rebuilding the block or replacing valves or rebuilding the injection pump or resurfacing the cylinder head or....


the fact is, diesel engines are low power, heavy, not all that reliable and don't get into decent efficiency territory until they're turbocharged, supercharged and on a really massive scale. Something like that free piston design has only 2 moving parts. That has to be far more reliable.

There was another design linked from that page that was a flat disc design that used internal combustion and shockwaves to produce power at 60% efficiency with only 1 moving part - the disc, which was fixed to the shaft. When we get to designs like that which produce large amounts of power, very efficiently, with no reciprocating vibration and only a spinning shaft, now you're really talking!

https://www.youtube.com/watch?v=tAALrU0iHHo

[socaldmax]

Originally Posted by Stumble

It's technically possible but not very efficient. Batteries sacrafice a lot of density to things like electrical channels, liquids, and housings. None of which a solid lead keel have to mess with. Just to run quick numbers... A Rolls-Surretre 4000 series deep cycle battery weighs in at 125lbs (wet) and has a volume of 1,547.1 in^3. A solid lead mass the same size would weigh 634.3lbs. So you would need to increase the volume of your keel by about five times.

Secondly you would need some way to remove the batteries after 5-7 years and replace them with new ones. You had also better use a pretty standard industry casing for them so down the road you aren't locked into one manufacturers battery. Probably a 2v battery she'll of some sort.

Third it would no longer even be possible to upgrade to new battery technology. You would be locked into these batteries.

Fourth, I hope you have finally figured out a way to finally waterproof your bilge, because any water intrusion could easily short out your battery compartment, which is now fully below waterline in the bilge of the boat. Even small leaks could cohort out your entire battery system.

Nuclear subs use their battery system as the ballast. Since the hull is basically a sausage shape, they need a lot of ballast down low in the pressure hull to prevent excessive rolling in rough seas. The reactor is also mounted low as well, but is much taller than the battery, so it's not really a good source of ballast.

They also get about 15 - 20yrs out of them.

[socaldmax]

Originally Posted by hamburking

StuM, you are so right.

But think about all the hydrogen locked into a gallon of water!
Trouble is...water don't burn.

Actually...

https://www.youtube.com/watch?v=aGg0ATfoBgo

[RaymondR]

Originally Posted by valhalla360

Other than the alternator belt...haven't had any of those fail on me. Alternator belts are usually good for a few years, so while technically less maintenance, not really much of a difference.

Of course, we don't know the failure methods of this engine. The wankle was supposed to simpler and thus more reliable also. Reality is it had different failure methods and the latest mazda version hasn't proven to be any more reliable.

The problem with all the Wankle style engines is the rectangular shape of the combustion chamber proved very difficult to effectively seal and there is no separation of combustion area from lubricant reservoir. Not a problem with a circular combustion chamber, all problems solved decades (centuries?) ago.

I can see a few problems with the free piston engine, one of which is the linear reactions created with compression and combustion, however this may be the sort of thing which maybe could be solved using ceramics technology which would also allow the free piston to run at very high temperatures which improves the thermal efficiency.

Nukes biggest problem is that it evolved from weapons technology and aroused the ire of the antiwar mob. If uranium and it's by products could not be used for weapons, nuclear power technology would be much further down the development road and we would probably have safe fission power by now.

[socaldmax]

Originally Posted by RaymondR

The problem with all the Wankle style engines is the rectangular shape of the combustion chamber proved very difficult to effectively seal and there is no separation of combustion area from lubricant reservoir. Not a problem with a circular combustion chamber, all problems solved decades (centuries?) ago.

I can see a few problems with the free piston engine, one of which is the linear reactions created with compression and combustion, however this may be the sort of thing which maybe could be solved using ceramics technology which would also allow the free piston to run at very high temperatures which improves the thermal efficiency.

Nukes biggest problem is that it evolved from weapons technology and aroused the ire of the antiwar mob. If uranium and it's by products could not be used for weapons, nuclear power technology would be much further down the development road and we would probably have safe fission power by now.

Can you elaborate more on the linear reactions created with compression and combustion? Sounds interesting.



On the nuclear topic, a lot of the behind the scenes problem with nuclear reactor design and development has to do with the incestuous relationship between Westinghouse, GE and the regulatory agencies. Both W and GE are heavily invested in light water reactor design, even though the inventor of the early light water designs later pointed out that LFTR was a much cheaper, safer design requiring no pressurized coolant, no containment vessel, no expensive and complicated backup systems which always seem to fail, etc. That's all in addition to the ability of a LFTR reactor to "burn up" waste fuel from LW reactors.

Yet the LFTR design has met with resistance that can only be traced to large profits and larger corporations with access to gov't officials and their oversight.

[glenn.225]

Originally Posted by RaymondR

Diesel pile driving hammers are two stroke, free piston engines in which the free falling, cylindrical mass in a cylinder concurrently delivers a blow to the head of the pile and compresses a volume of air into which diesel is injected. The expanding burning fuel air mix then drives the piston upwards to reset for the next stroke.


With it's extreme simplicity and minimalist construction the generator in the illustration looks like it could provide a useful alternator in a very compact and light weight, less expensive package than the orthodox equivalent. I wonder how it compares with a conventional genset on a fuel usage/cost/power output basis?

But would you want one in your boat? I once worked in an office about 300 Metres from a place that made them, test day was almost unbearable.

[RaymondR]

Originally Posted by socaldmax

Can you elaborate more on the linear reactions created with compression and combustion? Sounds interesting.

.

When the fuel charge ignites and accelerates the free piston there is a reaction driving the cylinder in the opposite direction. Since the entire engine is likely to be very light in comparison to a normal IC engine the vibration is likely to be extreme.

However since the free piston may be fairly lightly constructed and will not have to absorb the relatively high loads that a piston connected to a con rod and crankshaft do this would tend to alleviate the vibrations somewhat.

It's a very interesting concept and if it could be implemented successfully might be a game changer.

[RaymondR]

Originally Posted by glenn.225

But would you want one in your boat? I once worked in an office about 300 Metres from a place that made them, test day was almost unbearable.

The comment was offered as an example of a practical implementation of the free piston concept. The noise created by the hammers is primarily from two sources, the exhaust and the piston sucking in a fresh air charge and the falling hammer striking the drive plate.

We used them on drill rigs to drive 30" dia 1" wall conductors. Since the drillers position on the drill floor is close to the hole centre and the hammer top about 65' above the floor I hated using them as my fairly vivid imagination could see 7 ton of flying out the top of the drive casing and falling on me, there is generally nothing retaining the piston in the cylinder except gravity.

[Juho]

Originally Posted by RaymondR

When the fuel charge ignites and accelerates the free piston there is a reaction driving the cylinder in the opposite direction. Since the entire engine is likely to be very light in comparison to a normal IC engine the vibration is likely to be extreme.

However since the free piston may be fairly lightly constructed and will not have to absorb the relatively high loads that a piston connected to a con rod and crankshaft do this would tend to alleviate the vibrations somewhat.

It's a very interesting concept and if it could be implemented successfully might be a game changer.

I got interested in this German design because of the two pistons that balance each others, and the gas springs. This approach could reduce vibrations quite a bit when compared to some other designs.

DLR Portal - News - DLR researchers unveil a new kind of range extender for electric cars

[valhalla360]

Originally Posted by RaymondR

The problem with all the Wankle style engines is the rectangular shape of the combustion chamber proved very difficult to effectively seal and there is no separation of combustion area from lubricant reservoir. Not a problem with a circular combustion chamber, all problems solved decades (centuries?) ago.

I can see a few problems with the free piston engine, one of which is the linear reactions created with compression and combustion, however this may be the sort of thing which maybe could be solved using ceramics technology which would also allow the free piston to run at very high temperatures which improves the thermal efficiency.

Nukes biggest problem is that it evolved from weapons technology and aroused the ire of the antiwar mob. If uranium and it's by products could not be used for weapons, nuclear power technology would be much further down the development road and we would probably have safe fission power by now.

The point wasn't that it would have the same issues as the wankle but that issues you wouldn't expect may show up when you move from experimental to mass production.

This may be the greatest thing since sliced bread but I will be happily extremely surprised if it is.

[RaymondR]

Originally Posted by valhalla360

The point wasn't that it would have the same issues as the wankle but that issues you wouldn't expect may show up when you move from experimental to mass production.

This may be the greatest thing since sliced bread but I will be happily extremely surprised if it is.

The Wankle concept failed because the seal problem could not be overcome as have most other engine concepts which have non cylindrical combustion chambers. All the sealing problems with circular section cylinders have been long overcome so this should not be a problem in the development of the free piston engines.

The linear motion generator is also fairly well developed and is in use in a couple of commercially available Stirling cycle generators so it appears that this will not be a serious problem.

The analogue to the engine is the compressor and the linear compressor has been successfully implemented in the compressors used in some portable, low voltage refrigerators.

The primary use of electricity is as a power transmission mechanism. It's major advantage over other forms of power transmission is it's flexibility in both the placement of the power generator and the particular end use and the almost infinite divisibility of the product from the generator.

There are numerous threads in the forum wherein the various power transmission, storage and end use systems are discussed, each of which have their pro's and con's. I believe that were on to digest them all, the one which provided the ability to position simple and sturdy components around the vessel in a manner to most efficiently use the available volume whilst having the least negative effects upon vessel stability and liveability and allowing the use of a single low cost, safe fuel would attract the most approval.

From idea, through development, to commercialization is a long process but with the interest in hybrid and electric cars to provide the commercial impetus for it's development I perceive the linear generator as a probability rather than just a dream.

[ranchero76]

I don't see why this engine wouldn't be in the production in near future. There're no space technologies in it. Cooling is no problem at all - it's 2 simple 2-cycle engines without connecting rods, crankshaft and bunch of other junk. The only thing that should be done (and it's mentioned in video) - in production engine pistons must be synchronized and balanced to avoid vibration. So maybe these rods WILL be connected to each other via balancing linkage.

[K_V_B]

Originally Posted by StuM

If you are talking about the fuel cells that use hydrogen as the fuel, you are right back up against the same old energy density problem. It takes a lot of room to store the energy equivalent of a gallon of diesel.

The future is a fuel cell that operates on Diesel... (Or some other high density synthetic fuel).

[StuM]

Originally Posted by K_V_B

The future is a fuel cell that operates on Diesel... (Or some other high density synthetic fuel).

See post #68

[socaldmax]

Originally Posted by StuM

See post #68

08-04-2015, 12:29 #17
socaldmax

I'm waiting on the diesel fuel cell. Diesel is fairly safe to transport, has plenty of energy in it, and if it's burned in a fuel cell @ 85% efficiency, it will revolutionize power generation and propulsion.

Looks like a Swedish company and a Norwegian company are both making progress with prototypes.