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PostPosted: Jun 26, 2015 12:40 pm 
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Kurt Sellner wrote:
E Ireland wrote:
In sweden they use ethanol in diesel engines.

Going to try and find out some more info about that.

While it's possible I doubt it. More likely its a kind of vegetable oil. In the Army I noticed all the trucks on base were fueled with "B-80", a blend of fuel that consisted of 80% corn or soybean oil, the balance a petroleum fuel.
I've met people that have converted diesel vehicles to run on corn oil, it's a fairly trivial process. Running a diesel on ethanol sounds unlikely to me.


Apparently the engine is modified so the ethanol is injected into the cylinder input port where it evaporates, filling the cylinder with ethanol vapour.

Ignition then occurs when a small amount of diesel (something like 5% of the fuel input at minimum) is injected in the conventional manner. The diesel ignites which causes the ethanol to ignite as well.
With computer controlled injectors the engine can be set to run on any combination of diesel and ethanol - but it obviously requires two fuel tanks.


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PostPosted: Jun 27, 2015 8:14 am 
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E. Ireland wrote:
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Ignition then occurs when a small amount of diesel (something like 5% of the fuel input at minimum) is injected in the conventional manner. The diesel ignites which causes the ethanol to ignite as well.
With computer controlled injectors the engine can be set to run on any combination of diesel and ethanol - but it obviously requires two fuel tanks.


What is the advantage of that? Can the engine burn on a leaner mix of ethanol? A normally aspirated spark ignited engine seems much simpler. Using two fuels that must be balanced at varying loads seems like it could be quite a problem. I'm guessing that the ratio of the two fuels would not be a constant and would vary with pressure and temperature conditions. The computer would need to monitor both and compensate.

Are there emissions advantages? I used to have a Honda CVCC engine where a rich mixture of gasoline ignited a leaner mixture. It was supposed to be more environmentally friendly.

Is the engine running under the Otto cycle or the Diesel cycle or some odd combination?

Well - If they start selling these engines, I wouldn't buy the first years models.


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PostPosted: Jun 27, 2015 11:40 am 
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Eino wrote:
What is the advantage of that? Can the engine burn on a leaner mix of ethanol? A normally aspirated spark ignited engine seems much simplr. Using two fuels that must be balanced at varying loads seems like it could be quite a problem. I'm guessing that the ratio of the two fuels would not be a constant and would vary with pressure and temperature conditions. The computer would need to monitor both and compensate.

With controlled (probably common rail) fuel injection of both the ethanol and diesel modern electronics should easily be up to the challenge.
You will get superior fuel consumption because of the inherently higher compression of the engine than an equivalent naturally aspirated spark ignition engine.
I think another advantage is it removes any need to provide some sort of ethanol fueling network that is foolproof prior to rollout -as if you can't get ethanol you can just make it switch to a pure diesel engine until you get pure ethanol - whilst diesel would be consumed even if you were running on ethanol the minimum ratio is so low that a tank of diesel would last for a very very long time.
I imagine it would also be more tolerant of water in the ethanol than a spark ignition engine as the ignition of a small amount of diesel is surer to be a far higher energy process than a puny little spark.
If the engine has trouble igniting the fuel because of "wet" ethanol the engine could detect that and reduce the ethanol:diesel ratio on the fly.
Eino wrote:
Are there emissions advantages? I used to have a Honda CVCC engine where a rich mixture of gasoline ignited a leaner mixture. It was supposed to be more environmentally friendly.

Apparently there are benefits, but I am not sure how it stacks up against an otto cycle engine on that basis.
Eino wrote:
Is the engine running under the Otto cycle or the Diesel cycle or some odd combination?

It is running in a hybrid where the compression ignition is used to ignite the Otto cycle fuel.
But in engineering terms it is certainly closer to a diesel engine than a petrol one.


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PostPosted: Jun 28, 2015 9:23 am 
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E Ireland wrote:
Apparently the engine is modified so the ethanol is injected into the cylinder input port where it evaporates, filling the cylinder with ethanol vapour.

Ignition then occurs when a small amount of diesel (something like 5% of the fuel input at minimum) is injected in the conventional manner. The diesel ignites which causes the ethanol to ignite as well.
With computer controlled injectors the engine can be set to run on any combination of diesel and ethanol - but it obviously requires two fuel tanks.
This can also be done with ammonia rather than ethanol, and ammonia is a great nuclear fuel.

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PostPosted: Jun 28, 2015 12:33 pm 
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Kiteman wrote:
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This can also be done with ammonia rather than ethanol, and ammonia is a great nuclear fuel.


So - Ammonia can be produced easier than ethanol? Ammonia would not produce greenhouse gases? (Other than water vapor)

How would you make ammonia with a reactor? Would you start with air to get the Nitrogen? Maybe just burn the ammonia in an engine if it is cheap enough to make.


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PostPosted: Jun 28, 2015 1:58 pm 
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Use an electrically driven Pressure Swing Adsorption plant to produce a pure nitrogen stream.

Then feed steam and electricity from the reactor and the nitrogen into a Solid State Ammonia Synthesis plant and out drops the ammonia.


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PostPosted: Jun 28, 2015 10:32 pm 
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If you have an ASU on site, there's a good chance it would be a cryogenic ASU, then you also probably have LN2/LOx streams, as well as potentially a CO2 side stream as well.


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PostPosted: Jun 28, 2015 11:12 pm 
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E Ireland wrote:
Apparently the engine is modified so the ethanol is injected into the cylinder input port where it evaporates, filling the cylinder with ethanol vapour.

Ignition then occurs when a small amount of diesel (something like 5% of the fuel input at minimum) is injected in the conventional manner. The diesel ignites which causes the ethanol to ignite as well.
With computer controlled injectors the engine can be set to run on any combination of diesel and ethanol - but it obviously requires two fuel tanks.


I've seen a system like this experimented with but not using ethanol. Where I've seen this before is with the use of natural gas, a fuel that is abundant, inexpensive (relatively anyway), and clean (again relative).

T. Boone Pickens advocated for this as a transition to "greener" technologies for over the road trucking, trains, and perhaps other places where diesel engines are used. It's also been proposed for things like stationary backup generators. They'd still need a diesel supply along with the natural gas supply but the engine could run much longer on the supply it has, and I'd assume that if electricity AND natural gas was lost that the generators could run on diesel alone.

I have to wonder if this could be combined with the B-80 fuels. It appears that in both cases the system is relying on the presence of a sufficient quantity of cetane in the mix to give reliable ignition. Mixing the ethanol with the petro-diesel or bio-diesel should work I would think. I've heard of people in dire situations running a diesel engine from gasoline. As I recall the engine was running before the gasoline was added, meaning the engine was already warm, and afterward the engine was in need of repair.

So, after some thought I'd think that it is possible to run a diesel cycle engine from ethanol but the engine would have to be designed specifically to do so or that there would have to be enough fuel oil in the mix to provide the proper ignition, lubrication, and cooling that diesel fuel provides inherently.

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PostPosted: Jun 28, 2015 11:30 pm 
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Eino wrote:
Kiteman wrote:
Quote:
This can also be done with ammonia rather than ethanol, and ammonia is a great nuclear fuel.


So - Ammonia can be produced easier than ethanol? Ammonia would not produce greenhouse gases? (Other than water vapor)

How would you make ammonia with a reactor? Would you start with air to get the Nitrogen? Maybe just burn the ammonia in an engine if it is cheap enough to make.


It seems to me that whether one is "easier" than the other is dependent on what resources you have on hand. Ethanol is easy to make on both large and small scales as it takes the materials and skill not much different than those to bake bread. People have been "drinking their corn from a jar" for as long as people have had corn and jars.

Ammonia has been produced with relative efficiency for a very long time. I've heard that the hydrogen is most often produced from natural gas as it is cheap and plentiful, but it also means a high carbon output. I'm not sure where the nitrogen comes from but I suspect it comes from the air. Not a very "green" process as it's done now.

With nuclear power the nitrogen would be drawn from the air. The hydrogen could also be drawn from the air as the water vapor is a byproduct of making the nitrogen. The water, from which the hydrogen is derived, could also be from seawater or waste water.

Ammonia has been used as a fuel in cases where natural gas is considered a hazard. Ironically it's also been used as a "green" fuel where regulations require it even though the ammonia is most definitely derived from natural gas. Ammonia as a fuel has also been proposed as a part of municipal natural gas systems by mixing it with the natural gas and other gasses so that properties like energy per volume, line pressures, and so forth are unchanged.

This is all an interesting discussion but the claim being made is that fossil fuels, including natural gas, are not the evil that so many claim. Fossil fuels are good and we should not discount them so quickly as an energy source. So long as petro-fuels can compete with bio-fuels and synthesized fuels on price we should continue to use them. Raising the price of fossil fuels artificially, through mechanisms like taxation, only harms humanity in ways that the status quo could not.

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Disclaimer: I am an engineer but not a nuclear engineer, mechanical engineer, chemical engineer, or industrial engineer. My education included electrical, computer, and software engineering.


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PostPosted: Jun 29, 2015 1:46 am 
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I was re-reading this thread and thought I should address this post.

HolgerNarrog wrote:
If our civilisation will not develop back to the middle age there will be about 20 - 30 bn poeple living on earth in 1 - 2 centuries. They will live on a standard above todays standards in the US or Europe. They will need food, transportation and lots more. They will need about 5 bn tons of plastics and chemicals. If they will use chemical fuel driven cars it will require at least 10 bn tons of diesel equivalents.

How do you think to harvest a sufficient quantity of bio mass from our planet?


The world population is unlikely to reach the levels you predict. First thing is the tendency for people that have reached what we might call a "modern" or "first world" economy to have children at or below replacement rates. This has become a concern in some nations, while population is increasing it does so only because of immigration. These nations fear losing their national identity if this continues since it would not be long before a majority of the population cannot call the nation in which they live as "home".

The second reason that I do not believe that we'd see the population rise as you fear is explained by your question about resources. We'll get one of two scenarios that will keep the population in check. Most likely a population/nation/society will develop a desire to allow their children to have a life free of want and have children at a replacement rate. A less likely possibility is a cycle of resource wars, famine, and epidemics followed by periods of relative peace and plenty.

You also get into what many people see as a problem with any economy that relies on bio-fuels. We just do not have enough fresh water, enough arable land, and sufficient technology to support the population we have now if we rely on wind, solar, and bio-fuels. There is an excellent TED Talk on this that I'm too tired to search for and link to now that describes this in detail. The math he uses is something that I'd think any high school graduate could follow and makes a very compelling case on the problems that a reliance on bio-fuels have. He also makes it clear that he is not advocating for or against anything, he just wants to make it clear to all the obstacles that must be overcome to live in a world free from nuclear power and fossil fuels.

Where do we find all this bio-mass? The answer is we can't. That is why we will rely on fossil fuels for a very long time. There are two ways out of this problem. We can shrink the population to a level the earth can support with bio-mass, which I assume few would advocate. The other solution is nuclear power. Until we develop a nuclear power infrastructure that can replace fossil fuels we MUST continue burning them. Doing otherwise means people die.

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PostPosted: Jun 29, 2015 2:58 am 
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D-methyl ether is considered a good substitute for diesel and it needs to be compressed to keep it liquid. It is obvious that you can have any fuel in the diesel if you can engineer the injection of right quantity of fuel.
http://www.aboutdme.org/

Quote:
Volvo Trucks to Commercialize DME-Powered Vehicles for North America

Volvo Trucks became the first manufacturer to announce plans to commercialize DME-powered heavy-duty commercial vehicles in North America. As the latest step in its comprehensive “Blue Power” alternative fuel strategy, Volvo revealed ongoing U.S. customer field testing of trucks powered by DME, and demonstrated the technology after an announcement at the California State Capitol.

DME mirrors the exceptional performance qualities and energy efficiency of diesel, and burns clean without producing any soot. Converting natural gas to DME is an innovative way to address many of the distribution, storage and fueling challenges otherwise presented by natural gas as a heavy truck fuel.

“With the addition of DME-powered vehicles to our previously announced CNG and LNG offering, Volvo’s Blue Power line-up will offer the industry’s most comprehensive approach to the developing North American alternative fuel market,” said Göran Nyberg, president of Volvo Trucks North American Sales and Marketing.

Read more..
.


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PostPosted: Jun 29, 2015 5:38 am 
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Are there any synthesis routes to create hydrocarbon fuels from water and CO2, that can work at MSR temperatures?

I'm familiar with the Sulfur-iodine cycle, but that happens at 830C and needs heat from a reactor at quite a bit above this.


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PostPosted: Jun 29, 2015 6:12 am 
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The Copper-Chlorine cycle. It's a hybrid thermochemical and electrochemical cycle, the highest temperature it requires is 530 degrees Celsius, which should easily be within the capability of an MSR.


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PostPosted: Jun 29, 2015 7:56 am 
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E Ireland wrote:
The Copper-Chlorine cycle. It's a hybrid thermochemical and electrochemical cycle, the highest temperature it requires is 530 degrees Celsius, which should easily be within the capability of an MSR.


https://en.wikipedia.org/wiki/Copper%E2 ... rine_cycle

It states an overall efficiency of 43%.

Any idea whether that is heat -> chemical energy (43% is a very good efficiency- and probably measured with a CANDU, so a MSR should improve on it)
or
electrical energy -> chemical energy (43% is very poor efficiency)
or
somewhere in between.

A MSR/Cu-cl plant that could switch between generating electricity and making heat for the Cu-Cl process, or even drawing electricity (when Germany is paying to get to get rid of it) could be very useful.


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PostPosted: Jun 29, 2015 8:59 am 
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I've seen estimates for 40-55% efficiency.
These are in terms of thermal energy > chemical energy.
As much of the energy never goes through electricity.


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