Re: @ seatarosa | Posts 16+

garth.brooks wrote:

The earlier NSU formula 3=6 was intended to express that the 3-cylinder 2-stroke engine operates with a vibration level similar to that of a 6-cylinder 4-stroke engine, just as a 2-cylinder 2-stroke engine operates similarly to a 4-cylinder 4-stroke engine.

That was originally DKW, not NSU.

http://1949car1985.piranho.de/technische-daten/dkw3-6.htm

Regarding the topic of speed, I'd like to add a few words.

mass
acceleration
(piston) speed
mass forces (centrifugal force)
volume (gas exchange)

Let's do a quick calculation for a 98' hub.
Is everything clear?


btw: two-stroke engines still have a significant advantage in shipbuilding!
You can simply reverse its direction, meaning it runs either clockwise or counterclockwise.


CU Gremlin.

A small addition from Hein Seemann:

Here is some additional information about the world's largest diesel engine:
980 mm cylinder bore, 2660 mm stroke, mean effective pressure 18.2 bar.
Ignition pressure: 200 bar (already 155 bar in the new Mercedes-Benz E-Class), which consequently results in...
The peak piston pressure of 6000 tons occurs at approximately top dead center, with 14 cylinders, resulting in approximately 8000 horsepower per cylinder.
Fuel consumption: 126 g/hp, which means at 90% constant load (normal).
300 tons of heavy fuel oil per day, plus approximately 10 kg of cylinder lubricating oil per cylinder, 24 hours a day.

The heavy oil is injected at approximately 120 degrees Celsius and higher, up to 160 degrees Celsius, depending on...
Fuel quality, three fuel injectors next to the exhaust valve, one fuel pump. Common rail systems are also available, here are just two examples.
'parallel-connected high-pressure pumps (1000 bar; higher pressures resulted in...'
no reduction in consumption). Common rail systems also offer the following advantages.
regarding fuel consumption, there is also no improvement in the full load range.
However, at the minimum speed. For standard engines, the speed is typically around 25-30 RPM.
The rule is that it will stop if it stays below this speed. Common rail systems are...
But with 15 revolutions, it is definitely drivable.

When a large container ship enters the harbor, traveling at a speed of 6 knots, it requires...
The ship uses approximately 1000 horsepower for propulsion, which is only about 1% of its total power output.
Engines, on the other hand, don't just start; they deliver more power. By repeatedly stopping and...
Restarting the main machine is the only option. Common rail.
However, it's almost possible, and people are already considering cylinder deactivation.
The latest engines from both MAN&BW and Wärtsilä (Sulzer) can...
fully electrically controlled, without a camshaft, and can be ordered.
The injectors are also controlled piezoelectrically in this case.

The weight of this largest engine is 2500 tons, with a length of 28 meters.
and 13 meters in height.

You can also order this engine with up to 18 cylinders, which would result in 140,000 horsepower, but there are limitations.
There are currently no ships available for this. In approximately 10 years, container ships with a capacity of 18,000 TEU are expected to be deployed.
Ships with a speed of 25 knots, powered by this technology, navigate the world's oceans. These ships.
They are approximately 400 meters long and, at present, cannot call at any German port.
The Weser-Jade port is being built specifically for this purpose.

Let's go together to the engine room and start this up.
Monstrum, powered by Motor.
The lubricating oil must be at least 50 degrees Celsius (only single-grade oil, lubricating oil -).
approximately 1 liter per kilowatt of installed power, so for our engine, that's 80 liters of oil.
never replaced, only cleaned with separators). The lubricating oil is also used for...
Piston cooling is used. Coolant temperature for cylinders and cylinder head.
approximately the same as in vehicle engines, 83 degrees. Lubricating oil pump pressure on.
approximately 4 bar (pressure), (for electric drive systems), and a variety of other pumps and units.

Starting the electric blower, the two-stroke engine needs to be supplied with air from the outside.
'forced induction' (either mechanically or via turbocharger), generally speaking, formerly.
the undersides of the pistons were used as scavenging air pumps with a variety of.
'Flush air valves used in the past are no longer available today.' Through this high...
Excess air ensures that this ship's diesel engine operates smoke-free, even during startup.

Starting the diesel engine from the bridge using starter air pressure of 30 bar, reducing to approximately 25-30 bar.
UPM, and then fuel is automatically injected, which causes the diesel engine to run.
independent. The turbochargers are starting to spool up slowly, and the air they're producing...
it would not be nearly enough for normal combustion. From the bridge.
The ship is only steered based on engine speed, as directed by the navigation officer.

When the coastline is no longer visible, and the turbochargers are running at full speed...
When the system is operating at full capacity, the electric forced-air blowers will be turned off.
The turbochargers must be cleaned every 2 days using approximately 2-3 kg of walnut shell granules.
to be cleaned on the exhaust side. Soot particles cause wear and tear on the turbines.
to start digging, which is evident due to the increasing exhaust gas temperature of the cylinders.
The engine is getting less air. The turbocharger has a diameter on the air side.
approximately 3 meters, for example, in the case of a 28,000 kW diesel engine. Largest turbochargers available.
Air can generate up to 32,000 kW of power. This means that our largest engine requires three turbochargers to operate at its maximum power output, with a maximum wash air pressure of 4 bar (absolute).

For those who like to tinker: One exhaust valve is located in a basket within the cylinder head.
It needs to be replaced every 6,000 operating hours and takes 4 hours to change. All Dehn-
The screws are loosened or tightened hydraulically. Pistons are all being [something].
Operated for 12,000 hours and newly tagged. A cylinder liner holds.
approximately 40,000 operating hours. Container ships typically operate for around 7,000 hours.
per year.

The efficiency of a ship's diesel engine is currently around 52%, not 60% as previously stated.
Compression ratio is crucial (25 years ago, the ignition pressure was 64 bar).
normal, at 164 g/portion).

The GUD system offers the highest efficiency for a drive machine.
(Gas and steam cycle) with 59% efficiency (electrical), supplied by Siemens, but only...
using gas or light heating oil.



Cu.
Peter.

Hello Peter,

I once heard that valves and pistons can also be replaced while the machine is running. I can imagine that the crosshead could be disengaged if the machine is stopped briefly. I think it's not much for the exhaust valve to only last less than a year. Is it due to the impurities in the heavy fuel oil? (see turbocharger cleaning).

Sincerely,
Christian

Hello Christian,

This is like a normal car engine, where work is done while it's running.
excluded. With the massive, back-and-forth movements, not...
imaginable.

Despite the use of valve rotation devices, valve leaks can develop over time.
(to install, with a pressure of 200 bar!). When disassembled, the valve seat in the valve cage and the valve seat itself are precision-ground using machinery, and this process can be repeated multiple times. If the dimensions are too small, the areas will be welded back up.
On board, there are 2 to 3 spare exhaust valve heads, and the removed valves will be...
repaired by the deck crew (mostly Filipinos).

You might find 6000 operating hours to be a short lifespan, while your car might only last 2500 operating hours.
The exchange will be completed in 4 hours. Sure, heavy fuel oil has a...
The lifespan is greatly influenced by factors such as the sulfur content, which affects it in several ways.
Percentages can be included. Currently, heavy fuel oil costs only about $140 per ton.

Turbocharger cleaning has nothing to do with the exhaust valves. All gas emissions.
'They lead into a common exhaust manifold and from there into the turbochargers.' The
Walnut granules are blown into the turbocharger.

Christian, once you send me your email address, I can send you some pictures.
Then everything will become clearer.

Best regards,

Peter.

Hello Peter,

The issue of charging in a 2-stroke marine diesel engine still bothers me. In this case, the intake ports are only open for a short period. During this time, a) the exhaust gases must be flushed out through the exhaust valve, and b) boost pressure must be built up. However, for the boost pressure to be generated, the exhaust valve must be closed. I can't quite imagine that there's enough time for that. On the other hand, to gain time, one could open the exhaust valve before opening the intake ports. However, this would again sacrifice efficiency because the expansion pressure could not be utilized up to the ultimate tensile strength (or just before it).

I hope I've managed to express myself reasonably clearly, as I mentioned earlier, I'm not an expert. What one certainly can't say about you.

I'm just surprised that Hein Seeman isn't from Hamburg, Büsum, or Schlicktown (Wilhelmshaven), but rather from Essen.

mcgregg

The topic of charging in 2-stroke marine diesel engines still bothers me. In this case, the intake ports are only open for a short time. During this period, a) the exhaust gases must be flushed out through the exhaust valve, and b) boost pressure must be built up. However, for the boost pressure to be generated, the exhaust valve must be closed again. I can't quite imagine that there is enough time for that. On the other hand, to gain time, one could open the exhaust valve before the intake ports open. However, this would again sacrifice efficiency because the expansion pressure could not be utilized up to the ultimate tensile strength (or just before it).


uff

Here's the translation:

'Consider the valve-controlled two-stroke engine (with scavenging) and the four-stroke engine side by side. You will notice that only slightly more time is available for the charge exchange in the four-stroke engine, and this is only because the exhaust gases are being pushed out.'

The time available for the actual charging process is very short, because, as you correctly pointed out, the exhaust port must be closed during charging. The gas volumes are not a problem, because in a two-stroke engine, I have significantly more cross-sectional area available than in a four-stroke engine. I can use the entire cylinder head for the exhaust and the cylinder foot for the intake. In a four-stroke engine, both must be located in the cylinder head. Consequently, the turbocharger in the two-stroke engine must be able to deliver high volumetric flow rates.

Indeed, the exhaust valve opens much too early, but this is also the case with four-stroke engines.
You need to open the exhaust before the residual gas is completely relaxed, otherwise you may get a vacuum in the cylinder. Check the corresponding valve timing.

Is everything clear?

CU Gremlin.

"Regarding the 4-stroke engine, I have 180° of crankshaft rotation for each working stroke (simplified). So, for the exhaust and intake strokes, there are still 360° available. However, in a 2-stroke engine, all of that has to happen within a few degrees around the top dead center (TDC). And I'm having a hard time visualizing that right now, especially when comparing it." Or am I making a mistake in my thinking?

*bittenichhaun* has its knowledge gaps, but I am very interested.

mcgregg

Or am I making a mistake in my thinking?


a small.

It's true that in a two-stroke engine, the gas exchange only occurs in the upper part of the cylinder, and it needs to happen very quickly. However (and this is the key point!), I have incredibly large flow cross-sections available, which makes it easier.
if we convert a 4-valve four-stroke engine into a two-stroke engine, I have 4 valves available for the exhaust instead of only two. Accordingly, I can dimension the intake ports in the UT (Unified Topology) simulation. Take a look at the Junkers aircraft diesel engine under http://www.ralfhandel.de/images/fragebild.jpg. 'As' and 'Es' are inlet and outlet openings, arranged completely around the circumference. It is easily conceivable that such an opening would never be achievable with plate valves.

'For both concepts, the time available for charging (i.e., forcing air into the cylinder) is equally limited. I need to inject the mixture correctly between the exhaust closing and the intake closing. The intake closing occurs at a time when the cylinder is still rising and hasn't yet generated enough pressure to exceed the boost pressure (otherwise, it wouldn't work). This is also possible in a two-stroke engine with a port control system, but then I would need a device to close the exhaust port ('supercharging slide'). It was used before, but abandoned in favor of valve control in the cylinder head.'

CU Gremlin.

Okay, Gremlin, let me summarize. Turbocharging in a 2-stroke diesel engine works as follows:

Towards the end of the combustion process, just before the intake ports are opened by the descending piston, the exhaust valve opens. A large portion of the exhaust gases now escapes because there is still considerable pressure in the cylinder. Afterwards, the intake channels open, where there is also considerable pressure due to the turbocharger. Therefore, it's not really stupid to open the exhaust valve beforehand. The incoming fresh air now displaces a significant portion of the exhaust gases. The exhaust valve is closed, but the intake channels are still open. Now, the boost pressure enters the cylinder until the intake channels are closed again by the piston. The mixture is compressed tightly, and around the optimal timing (OT), the fuel is injected. The expanding flame front then forcefully pushes the piston downwards. Just before the end of the ultrasound (UT), the gas exchange process starts again from the beginning.

I think I've got it now. But knowing the Gremlin, something is probably wrong with my implementation again.

Anyway, I find the walnut method quite strange.

mcgregg

I think I've got it now. But knowing the Gremlin, something is probably wrong with my implementation again.

No, now it fits .


You must not forget: even with a 4-stroke engine, the expansion stroke is not fully utilized; here too, the exhaust valve opens long before the top dead center (TDC). In the area around TDC, the pressure in the cylinder can hardly be used anymore (due to the crankshaft!). In turbo engines, the remaining energy in the exhaust is also used effectively .

CU Gremlin.

Gremlin wrote:

mcgregg wrote: I think I've got it now. But knowing the Gremlin, something is probably wrong with my implementation again. No, now it fits .

Uff, I'm so relieved.

I think I'm slowly getting to the point where I'm ready for "diesel engine management." I still have a lot to learn. I probably need to give my dear some advice.

Regards,
mcgregg

Hello Rudolf, also known as mcgregg! Well, I can understand your thirst for knowledge, especially after being out of the loop for 90 years. You're amazed at what they've done with your invention, aren't you?

What I'd like to know now is: What really happened in 1913 on the ship where you suddenly disappeared without a trace?

By the way, judging by the photo, it looks like you're doing great. Do you use an anti-aging cream?

Sure, here's the translation:

'Hello.'

@SeatArosa1.7SDI:

Okay, the picture is of Rudolf Diesel. I thought it was quite fitting for the topic. But I would never dare to represent the old Rudolf here. Besides, if I did, I would have called myself "Rudi_D" instead of "mcgregg." And I wouldn't pretend to understand the 2-stroke diesel engine in public.

But was he on the ship in 1913? I only remember something about a premature death. I think I should find out more about my "idol" .

How about including a profile of Rudolf Diesel in the technical articles, for example, like this one about Felix Wankel. I find his developments much more fascinating than the Diesel engine. Despite that, as a fuel efficiency enthusiast, I prefer diesel.

Regards,
mcgregg

Hello to mcgregg and all the other friends of the big diesel engine.


I hope the attached image arrives correctly.
A lot has been added and clarified in the meantime. Please keep in mind that...
The exhaust gases from the cylinder are purged by a scavenging air pressure.
from 4 bar (absolute) at full load (ships operate at 90% MCR) and a huge...
Buffers for channels that are also under the same (slightly fluctuating) pressure.
to stand. The exhaust system consists of the exhaust path, including the exhaust valve, diffuser (not shown in the image), exhaust manifold (which can be quite large, almost allowing a person to stand underneath on larger engines), turbocharger, waste heat boiler, and chimney.
For reference: At a critical pressure differential of 5.3 bar (ideal gas), the following occurs:
Speed of sound at the narrowest point. It's quite a buzz in there.
Intake ports and the exhaust valve. If you can't hear it, it's being overwritten.
'Due to the noise from the turbochargers, it is impossible to access the cylinder station without hearing protection.'
enter.

Over the past 25 years, the efficiency of large two-stroke diesel engines has been approximately...
41, approximately 52% (167g/kWh at a stroke of 3.2 meters, cylinder bore of 800 mm, 76 RPM).
Engine for tankers or bulk carriers, 15 knots; (4-stroke engines have a consumption of 180 g/kWh).
Cylinder power approximately 1000 kW, at MAK 425/120 RPM. These engines are used in the...
Height is approximately 1/3 lower compared to 2-stroke engines.
A significant contribution to this comes from the intensive improvement of turbochargers, with considerably increased efficiency. This efficiency is so high that the exhaust gas temperature (around 280 degrees) is just sufficient to generate enough steam for the general operation of the ship during transit, using the waste heat boiler.
Okay, so for our largest ship diesel engine, we need 300 tons of heavy fuel oil per 24 hours.
approximately 10 degrees to 130 degrees.

Regarding your comment: 'I definitely find the walnut method quite strange.'
I don't understand. If necessary, rice will do, since there are already enough Filipinos.
aboard.
In the 1960s, the Starfighter used a specific method for cleaning the engine.
Walnut shells (granulate) were used.

A great resource for information on 2-stroke and 4-stroke marine diesel engines:
http://www.marinediesels.info/entry2.htm
Unfortunately, I can only provide translations in English. You can use Google Translate or other translation tools for a raw translation.
allow. If you absolutely need to know the meaning of any technical terms, please email me.

It's surprising that Hein Seemann settled down in Essen.
After working on 16 ships, I wanted a land-based job, and I found one here.
I have been involved with significantly larger energy systems, such as...
Turboset with a capacity of 1300 MW (1,700,000 horsepower), 65 meters long. I'm retired now.
and I occasionally go sailing, preferably on boats with 2-stroke engines, and that's about me.
Guest student at the local university, with a focus, as one might expect.
be different, engine technology. (I also remember hearing that term before on the...)
Ship engineering school), a long time ago.

cu

Hein Seemann.

Peter.

@Peter: Wow, your post answers a lot of questions, but it also raises new ones. I'll take some time to go through the link when I have a quiet moment. Very interesting. Thank you.

Given the current climate where we are constantly being impressed with "high-tech" solutions from all directions, the idea of using walnut shells seems rather rustic. One could, with a serious expression, try to sell expensive chemical products to ship operators. Toll systems and diesel particulate filters, despite significant development efforts, are not working very well. And the turbocharger in the ship's diesel engine is simply cleaned with walnut shells. Brilliant.

I've actually always been interested in ships and their propulsion systems. When I was a teenager, I came across the book "Everything about a ship" about the "Cap San" ships. I visited the Cap San Diego in the Hamburg harbor; it was very interesting.

Okay, here's the translation:

"Okay, one more question. What country is the company Sulzer from?" It sounds somehow German, but I haven't found anything online that indicates the nationality of this company.

Regards,
mcgregg