Navy plans to make jet fuel from sea water

[Joseph Chikva]

Thanks. What about with NO2, the other part of NOx?

NO2 is listed in the link as 51.3 The higher oxides of nitrogen have smaller and eventually negative enthalpies. I assumed pure NO because that produced the reaction most likely to be endothermic. But it just ain't overcoming that much water as a product.

How significant is to consider are those reduction reactions exothermic or endothermic if NOx content in input stream has e,g. 1000 ppm order, while after that catalityc reduction reaction has e.g. 10 ppm order?
If to recall that "ppm" means "part per million".
So, if we have gas flow e.g. 1000 kg/h, input NOx content would be only 1 kg/h and after reduction 0.01 kg/h.
What contribution in energy balance will give the reduced 0.99 kg/h for a stream 1000 kg/h?
All the more if to recall that this process executes outside the engine in exhaust system. So without executing of any useful work.

[Blankbeard]

Thanks. What about with NO2, the other part of NOx?

NO2 is listed in the link as 51.3 The higher oxides of nitrogen have smaller and eventually negative enthalpies. I assumed pure NO because that produced the reaction most likely to be endothermic. But it just ain't overcoming that much water as a product.

How significant is to consider are those reduction reactions exothermic or endothermic if NOx content in input stream has e,g. 1000 ppm order, while after that catalityc reduction reaction has e.g. 10 ppm order?
If to recall that "ppm" means "part per million".
So, if we have gas flow e.g. 1000 kg/h, input NOx content would be only 1 kg/h and after reduction 0.01 kg/h.
What contribution in energy balance will give the reduced 0.99 kg/h for a stream 1000 kg/h?
All the more if to recall that this process executes outside the engine in exhaust system. So without executing of any useful work.

I didn't consider usefulness. Honestly, I got annoyed that a question that could be answered in two minutes with grade school math had been argued about for several forum pages.

Then I felt guilty for being judgmental so I decided to do some back of the envelope calculations and see how practical this idea is.

[Joseph Chikva]

I didn't consider usefulness. Honestly, I got annoyed that a question that could be answered in two minutes with grade school math had been argued about for several forum pages.

Then I felt guilty for being judgmental so I decided to do some back of the envelope calculations and see how practical this idea is.

So, you are agreed that issue is useless when consider energy balance.

I would say you more - this issue is significant only for developers of that catalytic reduction hardware (found by Mr. Kiteman) for making a decision about inclusion there in catalyst bed the cooling loop.

And just wondering to hear "I got annoyed that a question that could be answered in two minutes with grade school math" from person who was mistaken in 500 times speaking about mass of 1 mol.
Sorry.

PS: I never argued is reaction NO+NH3=> N2+ H2O exo or endo, stating that is less significant for energy balance and therefore less interesting for me at this (current) level of discussion.

[Blankbeard]

So, you are agreed that issue is useless when consider energy balance.

No, I can think of ways to use it. If you are extracting heat from your exhaust, adding more heat prior to that point is a good thing. May or may not be efficient depending on application.

Also, let me point out something that should be obvious. Exothermic means to give off heat. If you're hoping to get work out of something (like a FUEL) it has to be exothermic. Endothermic reactions absorb heat from their surroundings. You can't run an engine normally off an endothermic reaction.

If that reaction wasn't exothermic this whole thread would be moot.

And here
http://en.wikipedia.org/wiki/Reaction_Motors_XLR99
That's the rocket motor from the X-15 runs on ammonia and oxygen. Kind a hard to do that unless you have an exothermic reaction.

Also note that production of NOx isn't a big deal in a high temperature ammonia engine. It's mostly N2 and H2O.

I would say you more - this issue is significant only for developers of that catalytic reduction hardware (found by Mr. Kiteman) for making a decision about inclusion there in catalyst bed the cooling loop.

It was you that first posted that image on page 5. That diagram has nothing to do with burning ammonia as a fuel. It's about using ammonia to clean up fossil fuel exhaust. You don't need hardware anything like that on an ammonia burning engine. The issues with that are:

1) Ammonia burns at a temperature lower than its ignition temperature. This can make an engine hard to start. Not an issue for turbines that compress air to high temperatures, or rockets that have powerful ignition systems. Very similar to diesel and solvable the same way.
2) Ammonia is slightly corrosive to a few materials. They should be avoided.
3) Ammonia may require refrigeration or otherwise be harder to store on planes. Requires work.
4) The energy density is 1/3 to 1/2 of current fuels.

And just wondering to hear "I got annoyed that a question that could be answered in two minutes with grade school math" from person who was mistaken in 500 times speaking about mass of 1 mol.
Sorry.

Wait, what is this? Yes, I made a typo once, not any 500 times. And yes, you really should have known better than to argue about such a simple thing that should have been obvious to you, especially when it's not important to your point, as you now say. No offense intended.

PS: I never argued is reaction NO+NH3=> N2+ H2O exo or endo, stating that is less significant for energy balance and therefore less interesting for me at this (current) level of discussion.

That's like saying that you never argued water was wet or dry. Why are you arguing about something obvious? Just saying.

[Joseph Chikva]

So, you are agreed that issue is useless when consider energy balance.

No, I can think of ways to use it. If you are extracting heat from your exhaust, adding more heat prior to that point is a good thing. May or may not be efficient depending on application.

Theoretically that is very easy - only include heat exchanger taking heat from exhaust gas and giving that to air or as an option to fuel. You would increase ΔT in Carnot cycle thus incresing efficiency. And bigger (exchanger) is better. And there are a lot of patents in this field.
Practically, that is less useful. Especially for transport engines. As this solution increases mass and dimensions with little improvement of energy balance.

Also, let me point out something that should be obvious. Exothermic means to give off heat. If you're hoping to get work out of something (like a FUEL) it has to be exothermic. Endothermic reactions absorb heat from their surroundings. You can't run an engine normally off an endothermic reaction.

Are you really think that I don't know what does "exothermic" and "endothermic" mean?
And how does thermal engine work? For your reference, I am a quite skilled engineer.

It was you that first posted that image on page 5. That diagram has nothing to do with burning ammonia as a fuel.

That relates to Mr. Kiteman's proposal to use the so called "Selective catalytic reduction" for decreasing of NOx level in any type of fuel burning exhaust gas. Including fossil fuel, ammonia, hydrogen, etc. As NOx present anywhere where air as an oxidizer is used.
And if you would like too to refuse from hydrocarbons, why do you also not consider e.g. pure hydrogen (I know that passanger aircraft Tu-154 was altered in 70s of last cetury in USSR) and e.g. dimethylether, etc.?

Wait, what is this? Yes, I made a typo once, not any 500 times. And yes, you really should have known better than to argue about such a simple thing that should have been obvious to you....

Your typo (1 kg = 1000 g, while proper number is 2g and 1000/2= 500) in the beginning of your calculations induced me to stop further reading of your post. All the more, if to recall that I consider this issue as less significant.
"I never spoke about taking of extra power from exhaust system"- Kiteman says. In this regard, is the question "does it matter is that reaction exo or endo?" not legit?
All the more if I said:

How significant is to consider are those reduction reactions exothermic or endothermic if NOx content in input stream has e,g. 1000 ppm order, while after that catalityc reduction reaction has e.g. 10 ppm order?
If to recall that "ppm" means "part per million".
So, if we have gas flow e.g. 1000 kg/h, input NOx content would be only 1 kg/h and after reduction 0.01 kg/h.
What contribution in energy balance will give the reduced 0.99 kg/h for a stream 1000 kg/h?
All the more if to recall that this process executes outside the engine in exhaust system. So without executing of any useful work.

Would you still like to extract extra power from exhaust system?

[Blankbeard]

Practically, that is less useful. Especially for transport engines. As this solution increases mass and dimensions with little improvement of energy balance.

First, what do you mean by energy balance? Do you mean energy efficiency? You're not talking about the first law of thermodynamics and that's the only definition relevant to an engine. You should be talking about energy efficiency.

Haven't you ever heard of turbochargers? They sit in the exhaust stream and extract energy from it. They're very light weight and rather efficient. You may have heard that they're all the rage now because they can be used to make more fuel efficient engines. Nearly every manufacturer offers at least one car with a smaller turbocharged engine in place of a larger normally aspirated engine. Ford calls it "Ecoboost" and says it gives the power of a V8 with the efficiency of a V6.

Let's compare Ford's 2 liter Duratec and Ecoboost engines. They're identical except for the Ecoboost is turbocharged. The Duratec develops 160 horsepower while the Ecoboost produces 252. The only difference is the turbocharger, roughly 20 pounds. 92 horsepower for 20 pounds. That doesn't affect your "energy balance?" You can put the Ecoboost in a larger vehicle and still get the good fuel economy of a small engine.

Just because you found a picture with a heat exchanger in it doesn't mean that you have to have a heat exchanger. They're used in fixed installations because they are cheap, have few or no moving parts, require little maintenance, and in a fixed site the weight doesn't matter.

And you originally posted this image in connection with aircraft. There's no need to extract heat from the exhaust of a jet engine. The exhaust turbine has already done that for you. But there's still a reason to inject more ammonia fuel into the exhaust stream after the last turbine. That device is called an afterburner.

Are you really think that I don't know what does "exothermic" and "endothermic" mean?
And how does thermal engine work? For your reference, I am a quite skilled engineer.

Based on your insistence on including a heat exchanger as the only reason to inject a fuel into an exhaust stream, A skilled engineer should know that fuels are exothermic. Maybe you don't deal with fuels in your day to day job. I don't know. It's not my job to determine what you know. I just read what you write.

And if you would like refuse from hedrocarbons why do you also not consider e.g. pure hydrogen (I know that passanger aircraft Tu-154 was altered in 70s of last cetury in USSR) and e.g. dimethylether, etc.?

Is English your first language? I mean no offense.

Pure hydrogen isn't a good aircraft fuel for two reasons: One, it has terrible energy density per unit volume (Great per unit mass though) Two, it's very expensive to produce unless you have a nuclear reactor and it's always hard to store. If's also terribly dangerous as it is colorless, odorless, and highly explosive. Ammonia at least has a strong smell and doesn't sustain a flame in open atmosphere very well, meaning it would be a safer fuel.

DME seems to be an acceptable fuel. It has roughly the same energy density as the ammonia the other guy was talking about. It's also a gas at room temperature, meaning it needs refrigeration to below -24C. That's extra weight for an aircraft to carry. It's also an ether. I don't know if the Navy's process can produce an ether.

Finally, the biggest problem is that it's produced from methanol, which is a liquid at room temperature and has only a slightly lower energy density. Methanol is much easier to produce. There is a direct method but it's apparently very new and it remains to be seen how useful it is.

And your typo (1 kg = 1000 g and 1000/2= 500) in the beginning of your calculations induced me to stop further reading of your post. All the more, if to recall that I consider this issue as less significant.

1000/2 ? What does that have to do with the typo I made. The molar weight of diatomic hydrogen is about 2kg or 2000 grams. I typed 1kg, 1000 grams. There's no 500 anywhere in there.

[Joseph Chikva]

A skilled engineer should know that fuels are exothermic.

Only when you have corresponding quantity of oxidizer. You can inject extra (above stechiometric ratio) fuel into a flame with reducing of temperature.
For example stechiometric ratio for gasoline/air is about 1:13.5 (by mass) and all extra quantity of fuel above this ratio will not be exothermic.

English is my fourth language and is not so good as I wish.

[Joseph Chikva]

The molar weight of diatomic hydrogen is about 2kg or 2000 grams. I typed 1kg, 1000 grams. There's no 500 anywhere in there.

In chemistry and physics, the Avogadro constant (symbols: L, NA) is defined as the number of constituent particles (usually atoms or molecules) in one mole of a given substance. It is a dimensionless number and has the value 6.02214129(27)×10^23 mol^−1

So, diatomic hydrogen molecule consisting of two protons and two electrons if to negnect their binding energy and electron masses has a mass 2 x 1.67 * 10^27 kg = 3.34 * 10^-27 kg

And 6.02214129(27)×10^23 mol^−1 * 3.34 * 10^-27 kg = 20.1139519086E-4 kg/mol =~2E-3 kg/mol = 2 g/mol

[Joseph Chikva]

Haven't you ever heard of turbochargers?

Yes, I aware with turbochargers. Also I aware with belt driven chargers (superchargers). Also I aware with their combination with so called "intercoolers" which dissipates energy into atmosphere, cooling the inflow air, thus increasing its density and so the "air filling coefficient" and so increasing the power per volume or power per cylinder.
If you think that turbochargers improve efficiency in internal combustion engines because they take energy from exhaust gas, that's right. But not totally.
As more significant is dependence of engine's efficiency on compression ratio.
See for example here: http://www.ewp.rpi.edu/hartford/~ernest ... mi2010.pdf

it can be resulted that the effect of combustion efficiency on the thermal efficiency of the cycle is related to compression ratio.

Engines with superchargers (e.g. Mercedes uses) taking charging energy from cranked shaft (so, using useful power) are not less efficient than your (Ford's) Ecoboost engine using wasting with exhaust gases power. Especially at lower turning rate.
Engineering, my friend, is a permanent compromise between mutually exclusive things.
And your wish to use more energy loosing at this moment with exhaust gases does not mean that you able to propose technically attractive solution. For example, I doubt in your or Kiteman's such ability.
Without any offense too.

And once again, here was talk about reduction of NOx, very common number of which is about 1000 ppm.
If you wish to get more power from its reduction reaction - I wish you all the best.
Can you estimate an efficiency improvement - how much extra % can you get in the best case?
As this is a school grade task too.
Good luck in your homework.

Note: the drawing uploaded by me was related namely to "NOx Catalytic reduction" that was proposed by Kiteman. As I understand he strongly advocates this method. See the link in wiki from which that diagram was taken.

[KitemanSA]

Thanks. What about with NO2, the other part of NOx?

NO2 is listed in the link as 51.3 The higher oxides of nitrogen have smaller and eventually negative enthalpies. I assumed pure NO because that produced the reaction most likely to be endothermic. But it just ain't overcoming that much water as a product.

So, higher oxide, more water, more exo?

So we might say that yet again, Joey the jeneous is WRONG?

[KitemanSA]

Even then, this is an expensive proposition.

Yup, but so is shipping oil products all over the world.

[KitemanSA]

PS: I never argued is reaction NO+NH3=> N2+ H2O exo or endo, stating that is less significant for energy balance and therefore less interesting for me at this (current) level of discussion.

]But I am not still not catching up about your belief that injection of ammonia for reduction of NOx emission is exothermic.

I suppose this could just be a language issue, but it could be that yet again "Joey the jeneous" is changing tunes when demonstrated he is yet again WRONG.

[Joseph Chikva]

PS: I never argued is reaction NO+NH3=> N2+ H2O exo or endo, stating that is less significant for energy balance and therefore less interesting for me at this (current) level of discussion.

]But I am not still not catching up about your belief that injection of ammonia for reduction of NOx emission is exothermic.

I suppose this could just be a language issue, but it could be that yet again "Joey the jeneous" is changing toons when demonstrated he is yet again WRONG.

Yes, I am still not catching up about your belief that this is exothermic reaction and never argued and am not arguing even now.
As I am still stating that this reaction is less significant for energy balance.
You have about 0.1% (about 1000 ppm) by mass of NOx in exhaust gas. What improvement in efficiency can give reaction decreasing this number even if that is exothermic?

[KitemanSA]

You can't run an engine normally off an endothermic reaction.

Hate to disagree with you when you have been doing such a nice job proving my points, but a violently ENDOthermic reactant would make a decent fuel too. It just is a matter of which comes first, the turbine or the compressor!

Oh, you said "normally" so I guess you were right.

[KitemanSA]

That relates to Mr. Kiteman's proposal to use the so called "Selective catalytic reduction" for decreasing of NOx level in any type of fuel burning exhaust gas. Including fossil fuel, ammonia, hydrogen, etc. As NOx present anywhere where air as an oxidizer is used.

Not mine, but I could wish it were so.

http://www.amazon.com/BLUE-DEF-DIESEL-E ... rds=adblue