the future of car engines?

[Viking]

Originally posted by Angus
Viking:
"Seems like the diesels were about 20-30% more fuel efficient than the steam engines in WWII. However, the diesel's main advantage was probably size back then. Diesels were a relatively new technology while the steam engine was refined over a century of use."

Not really?
Firstly, the fuel consumption is really in the same ballpark. (snip)

Your own figures:

Graf Spee:
Displacement: 12100-16200 t.
Fuel 2523 t.
Range: 8,900 nautical miles at 20 knots (16,500 km at 37 km/h)
or 19,000 nautical miles at 10 knots (35,000 km at 18.5 km/h)

HMS Belfast:
Displacement: "somewhat above 13.000 tons"
Fuel 2375 t.
Range: , 9800 nm done at 15 kts

Seems to me that the Graf Spee is almost as efficient at 20 knots as the Belfast is at 15. At 10 knots there is no contest.

Originally posted by Angus
There is the increased displacement to add to the equation, but also that while the Graf Spee class has a high cruise vs lowe max speed, it can be because of the engines being built for that job, while the boiler cruisers were built for top speed. Just my cents.

The Graf Spee and the Belfast are pretty identical in displacement, and a typical steam turbine engine setup allows you to run on only one or two boilers for cruise speeds, so they could vary their efficiency, so top speed is pretty irrelevant. And the difference in top speed is only 3.5 knots anyway.

At 15 knots which is probably the Belfast's best economic cruise speed it is clearly much less efficient than Graf Spee's diesels. I don't see how you can argue the opposite?

[Angus]

Viking:
"Seems to me that the Graf Spee is almost as efficient at 20 knots as the Belfast is at 15. At 10 knots there is no contest."

Almost but not. At 10 kts we don't have the data from any of the British cruisers. But AFAIK that at the higher speeds the German vessel was more economic, so the tables might actually turn at low speeds. Just another 2 cents.

As for the difference in top speed, you know the drill as with aircraft, you need a lot more energy for increased speeds. The Belfast is what? 15% faster, which would mean a 350 mph aircraft vs a 410 mph one, which is quite a bit. Then you get on to things like acceleration....

Basically:

Belfast/Edinburgh/Exeter have the fuel economy in the same ballpark as the diesels. They have more power and higher top speed. We do not know so much of their lowest speed settings. BTW Belfast has 4 boilers while the other ones have 8.

[Viking]

Originally posted by Angus
Viking:
"Seems to me that the Graf Spee is almost as efficient at 20 knots as the Belfast is at 15. At 10 knots there is no contest."

Almost but not. At 10 kts we don't have the data from any of the British cruisers. But AFAIK that at the higher speeds the German vessel was more economic, so the tables might actually turn at low speeds. Just another 2 cents.

I highly doubt that. But without real data there is no way to be sure. There is also the question what type of oil did they use. Belfast probably burned no. 6 oil or perhaps no. 4. Did Graf Spee run on diesel oil or heavy fuel oil? All this will vary the results.

Originally posted by Angus
As for the difference in top speed, you know the drill as with aircraft, you need a lot more energy for increased speeds. The Belfast is what? 15% faster, which would mean a 350 mph aircraft vs a 410 mph one, which is quite a bit. Then you get on to things like acceleration....

12%, but top speed is irrelevant. Also 115% of 350 is 402.5, not 410, and the actual number should be 392 (112%).

Originally posted by Angus
Basically:

Belfast/Edinburgh/Exeter have the fuel economy in the same ballpark as the diesels. They have more power and higher top speed. We do not know so much of their lowest speed settings. BTW Belfast has 4 boilers while the other ones have 8.

I disagree, but without more data we're only guessing. Also this it completely off topic, and has no relevance to either modern ship engines or future car engines.

[john9001]

car engines, the post was about car engines.

[Holden McGroin]

Originally posted by Viking
Nuclear powered steam turbines are actually even less efficient than conventional steam turbines, both in thermal efficiency and fuel economy. That matters not for military applications of course, but for civilian use they are pointless.

All the turbine cares about  is that it gets good quality steam and a vacuum in the condenser into which it can exhaust. Steam is steam, and all the turbine cares about is the quality of the steam.  It can come from any generating source.

The same turbine design can be used in a nuclear power plant, a coal fired power plant, or in the case of the power station where I work, a combined cycle gas turbine power plant.

[Viking]

I was talking about marine nuclear reactors vs. conventional stream propulsion, not land based power plants. Land based power plants have little or no restrictions in size or weight. Above I posted Al Minyard's brief to support my view.

[Angus]

Viking the diesel. You leave me pondering on this:
"--------------------------------------------------------------------------------
Originally posted by Angus
Basically:

Belfast/Edinburgh/Exeter have the fuel economy in the same ballpark as the diesels. They have more power and higher top speed. We do not know so much of their lowest speed settings. BTW Belfast has 4 boilers while the other ones have 8.
--------------------------------------------------------------------------------



I disagree, but without more data we're only guessing. Also this it completely off topic, and has no relevance to either modern ship engines or future car engines."

What do you disagree about? The power and top speed are absolute figures. As a sidenote, the admiral Hipper was turbo powered and as heavy as the Graf Spee, but with more power (some 100.000 hp) and higher top speed as a result.
 Do you disagree about the fuel econmy? Well, you can always calculate it into Newtons vs a timeframe to find out the total energy. Either way, there is a vast difference between your promoted 8% vs what, - 20%?
And the off topic I regard as a flank, sorry. The future of car engines is with certainty NOT status quo, so that means any method is going to be used to convert all sorts of fuels mankind has into an appliable energy that can be used to propel a car.
Highly efficient powerplants are a part of that chain, and they seem to use fossil fuel for turbos rather than engine sets. Smaller power plants and backups go to the engine sets, probably for the sake of simplicity.
And HoldenMcGroin, I look forward to you pondering on this

[Viking]

Originally posted by Angus
What do you disagree about?

The fuel efficiency!

Originally posted by Angus
Do you disagree about the fuel econmy? Well, you can always calculate it into Newtons vs a timeframe to find out the total energy. Either way, there is a vast difference between your promoted 8% vs what, - 20%?

What are you rambling on about now? I've never "promoted" that 60 YEAR OLD diesels were more efficient than steam, but it seems they were. I've argued that MODERN diesel engines are more efficient than steam engines, AND THEY ARE. Where do you get the 20% number from??? I've been against including these WWII ships in this discussion from the beginning, but it is just like you to bring something completely irrelevant into a discussion, jumping from topic to topic and using numbers and math that have no foundation in logic or reason. I'm seriously starting to wonder if you keep doing this simply to piss people off or if you have some attention deficiency.

[Ghosth]

yes but Viking your talking Apples & oranges.

Your talking Modern Diesel vs ancient steam.

That was my whole original point. we need a MODERN steam engine.
Preferably turbine, preferably sized for car.

[Viking]

Originally posted by Ghosth
Your talking Modern Diesel vs ancient steam.

No, I'm talking modern diesel vs. modern steam. "Modern" as in in use today. And I would think they are exclusively steam turbines. However there are very few left, and I would surmise for good reason.

I don't imagine a practical steam engine for car application will ever be used again. I could be wrong of course.

[Maverick]

The discussion about naval engines might be relevent to the thread some day when they put one in a car.    

[Angus]

Originally posted by Viking
The fuel efficiency!




What are you rambling on about now? I've never "promoted" that 60 YEAR OLD diesels were more efficient than steam, but it seems they were. I've argued that MODERN diesel engines are more efficient than steam engines, AND THEY ARE. Where do you get the 20% number from??? I've been against including these WWII ships in this discussion from the beginning, but it is just like you to bring something completely irrelevant into a discussion, jumping from topic to topic and using numbers and math that have no foundation in logic or reason. I'm seriously starting to wonder if you keep doing this simply to piss people off or if you have some attention deficiency.

Call it rambling if it burns your skin, I am basically comparing 70  years+ old British steam TURBINES to some 67 years old German diesel, and adding another german 67 year old Turbine into the equation.
These were the hottest and newest "powerplants" of the day, and since the money and usage put into them was quite a lot we must look into what was learned.
Irrelevant as it is, which it ISN'T, a powerplant is a powerplant - little ones in cars bigger in ships, and very big ones on land.
So, with rambling put aside, please explain why massive rows of combustion engines are not used to generate electricity from fossil fuels on land?

[john9001]

the induction electric motor is the future, low maintenance, nothing to wear out, only moving parts are the two bearings. and you can eliminate the drive train by putting the motors in the hubs.

only weak point is the need for better batteries, but that is improving every day, DeWalt now has 36 VOLT portable hand tools.

when the people decide they want the simplicity of electricity the cars will be built.

[Nashwan]

only weak point is the need for better batteries, but that is improving every day, DeWalt now has 36 VOLT portable hand tools.

They might be 36 volt, but they only provide a bit more power than batteries did 30 years ago. (The higher voltage is just used for marketing, 36 volts does not necessarily provide more power than 12v. The important thing to look at is the wattage)

when the people decide they want the simplicity of electricity the cars will be built.

The problem for electric cars is batteries have a huge way to go to equal the power to weight of gasoline. The best batteries now store about 0.7 megajoules per kg. Gasoline contains about 44 megajoules per kilogram.

What that means is if you want a battery that stores as much energy as a 20 (us) gallon tank, it will weigh about 4.2 tons. (and cost a fortune)

Whilst an electric car is much more efficient than a gasoline one, a battery that provides enough energy to give the same sort of performance that people are used to is just too heavy for a practical car design. And it has other drawbacks, like it takes a long time to charge.

Batteries have got a long way to go before they are practical for normal cars.

[Viking]

Originally posted by Angus
So, with rambling put aside, please explain why massive rows of combustion engines are not used to generate electricity from fossil fuels on land?

You haven't listened at all; internal combustion engines ARE used to generate electricity on land. An LNG gas turbine IS an internal combustion engine. Secondly, diesel fuel is more expensive than LNG. LNG is now available in Norway as car fuel in city areas and it is popular with bus companies and taxis. The only reason I can think of that prevents LNG from fueling ships is that transporting LNG in such quantities is dangerous. What I predict for the future of car engines is multi-fuel engines based on modern turbo-diesels.