Diesel Electric Propulsion

popobowa · Apr 3, 2021

Hi gentlemen,
I was just reminded that ,many years back, I had intensely looked into a free piston Sterling motor powered by the Suns rays...via big trough collectors....and yhis Freepiston was supposed to move a linear generator...
Nowadays , especially the latter, had become " the dogs bollocks" as a range extender . Toyota has released news of having made one with ,I believe it was over 45% thermal to kW efficiency,and 20kW output and at DLR, a German Areospace research Institute, they also have some running ..with 35 and 60kW el..their combustionchamber is in the middle of 2 oscillating pistons bouncing against a gasspring. Further combustionchambers instead of those springs should increase efficiency....

Long story short: those would make very light, small AND very efficient generators. And with an efficiency of 45% equalling 190 g/kWh.....better than any small boat diesel which lies @ 220 for the best Commonrail and close to 300 for normal inj.

The DLR models are rather small, app 80cm long and 15cmx15cm square...35kW, dont look heavy at all. 30 to 50kg maybe.

Now with this tech I would go for serial hybrid, and still only need the same fuel per nm as the most ideal diesel setup.

Any one of you having better knowledge of this tech?
S

costalive · Apr 10, 2021

YachtForums said: ↑

It's ironic you should ask. I'm currently writing a a 40 page / 120 hour feasability study for a major transportation manufacturer on this very subject. In answer to your question... YES.

The steerable podded propulsor provides the greatest potential due to favorable hydrodynamics and control, while being competitive with conventional propulsion systems.

The benefits of diesel electrific propulsion (podded) are many...

1. Integrated electric power and propulsion systems enable design flexibility and save space, by eliminating gear trains and propeller shafts.

2. Hydrocoustic dampening is increased by eliminating the mechanical link between the power plant and the propeller. Essentially, electric drives will enable the reduction of noise and vibration.

3. Improved operational flexibility and reliability. With a diesel electric power-station concept, power is supplied by a set of primary gensets that provide power to propulsion and other designated loads. This approach provides the flexibility to shift power between propulsion, onboard services, and other electrical loads. It also enables improved speed control and maneuverability over conventional propellor and rudder configurations. Pods can rotate 360 degrees for directional thrust, eliminating thrusters.

4. Increased space. Eliminating gears and shafts from the propulsion system will make more space available for other uses. Also, the primary power (engines) will no longer be tied to the propeller shaft line, so the gensets can be distributed to more idealistic locations throughout the yacht, i.e. more favorable C.G. locations.

6. Reduced Crew. Due to digital control and automation, which will be an integral part of the yachts electrification, the requirements for additional engineering staff are reduced.

7. Reduced logistics. Common power and propulsion modules can be used across a variety of hull types and model lines.

8. Reduced costs. Commercial technology is likely to be available for many of the system elements.

9. Life-cycle cost. Overall operational efficiency is greatly improved as electric motors are able to sustain higher RPM's with less maintenance throughout their operational parameters.

10. Redundancy. Instead of one or two primary engine sources, multiple gensets can be utilized, both on-line and off-line, as power is needed. If one fails or is down for maintenance, the other gensets can provide power to the propulsors as needed.

11. Fuel-consumption savings. The diesel electric concept has been proven over a wide range of applications, from trains to ships, as a more economical source of propulsion.

I could continue, but you are probably falling asleep by now...
Click to expand...

Not bored keep going!

popobowa · Apr 20, 2021

Costalive....youre working on linear freepiston el. generation? Or are you referring to another post?
IThe good thing about FPLG is that the basics cant be protected by patents anymore...of course, it seems to me, that the devil lies in the detail here.
Controlling heat, keeping it away from magnets, making strongest poss. magnets as pistontravel isnt very long, combustiontiming, metering of fuel and control of gas spring rebound force to enable var. compressionratio etc. etc.

A fair bit of headache for the developers..but a lot of knowledge and tech is availiable and needs "only" to be adapted......throw us a hint if something in the 20 to 100kW powerenvelope is on its way...for me to be a guineapig mounting it in a fast cruising cat..which has to stay light.
Very curious...

popobowa · Apr 20, 2021

I forgot to ask... as you might know:
it seems to me that the gas spring side could theoretically be replaced by 2 additional combustionchambers which, in theory, should make the mashine even more efficient as the heat (frictionloss) of the gassprings replaced by working pistons?! of course more timing complications and heat buildup problems...but maybe for future experiments. Then i wonder why air is used as springmedia and not.. Nitrogen, as in the better gas shocks and all Aircraft gassprings..as it doesnt heat up.

popobowa · Apr 26, 2021

Searching the .www , I found only 2 companies with seemingly working prototype FPLG's, and one that doent look mechanically sound...
Thr promising ones as far as I can tell are:
Libertine from UK
Mainspring from USA

The other is an Israeli company, not giving any specs, only bold claims, and their method of joining the linear motors,4 at each corner, via a plate.. which must get very stressed if one LM creates slightly different resistance...

I am really curious to see who has a viable product out first....

Anyone of you know about other such projects ?

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