Author Topic: NASA Tests New Breed Of Propulsion Engine And System In Support Of VSE  (Read 6158 times)

Offline AndyMc

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As 'hinted at' by Dr. Stanley in answer to my question here: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=1258&start=141 NASA are considering Lox/Ethanol for the CEV SM propulsion and reaction control system.

http://www.nasa.gov/centers/marshall/news/news/releases/2006/06-010.html

So, the CLV looks like eventually being a 5 segment SRB,  5m diameter Lox/H2 second stage, powered by a single J2-s (J2-x) and Lox/Ethanol fuelled CSM (CEV).

Of course it could all change..........




Offline gladiator1332

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Sounds really interesting. It seems that developing enviromentally friendly stuff is the new thing. We are seeing cleaner jet engines, and now were getting clean spacecraft. I also like the part about a safer environment for workers at the pad and whatnot. There are some really nasty chemicals in some of the stuff associated with the Shuttle.  

Hmm....this might be something NASA PR would want to go with. "It may look old, but this is the most environmentally friendly spacecraft ever built". People love stuff like that.

Offline Dogsbd

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So we could be growing corn on the Moon to fuel these ethanol powered vehicles?

:)


Offline AndyMc

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Dogsbd - 1/2/2006  3:17 PM

So we could be growing corn on the Moon to fuel these ethanol powered vehicles?

:)

Now there's a thought. I think I read somewhere that the temperature near the Lunar south pole was around 20 degrees C. If there's water ice there too plus abundant sunlight.....what's stopping this from working. Seems to good to be true.

Offline AndyMc

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I could only find this brief piece: http://www.space.edu/spacegrant/Eric%20Hanson.doc It mainly refers to fuel cells using Ethanol made from sweet potato
Quote:
"Reforming Fuel Cells that Require Hydrogen for Opposition  by Eric Hanson


Research on integrated power systems and fuel reforming is based on concepts that researchers at the EERC have been developing. The purpose of this study is to demonstrate that fuel cell technology can be incorporated into a crewed space base station. The fuel cell and energy systems that are currently being evaluated are the solid oxide fuel cell (SOFC) and autothermal or catalytic partial oxidation reforming (CPOx) of an ethanol fuel derived from sweet potatoes.
   
NASA is working on a project called INTEGRITY, which is a test simulation facility for an actual mars or lunar base. The research done on a mars base was all based around this simulation facility and papers describing the theoretical systems. There are several issues related to the fuel cell technology that still needs to be addressed. Fuel sources that are available on the base would be methane and grown crops, and the reforming process, which would be located outside the facility, would be CPOx. The limiting factor for the fuel cell and its systems is weight. The one thing to direct the most attention to about this system is its power-to-weight ratio.

The conclusions are that an SOFC would be the most attractive due to relatively similar operating temperatures with the CPOx reforming process. Also, the SOFC can tolerate amounts of trace gases that would poison other cells. Ethanol, derived from sweet potatoes, is the most premium fuel to use in a reformer because the hydrogen has no other sulfur or poisoning gases within it. Also, methane is available through the Sabatier process that comes from the solid and liquid waste streams on the station. It is recommended that more research is needed in the area of fuel cells and integrated power systems that work in a closed loop system like that on a mars or lunar base.
"


Offline Daniel Handlin

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Dogsbd - 1/2/2006  4:17 PM

So we could be growing corn on the Moon to fuel these ethanol powered vehicles?

:)


If methane isn't available, LOX/ethanol (PURE ethanol, mind you...)  is still superior to hypergolics or LOX/LH2. It's immeasurably less toxic than hypergolics and doesn't require the safety protocols that hypergolic propellants do. You can DRINK ethanol - and many people do in alcoholic beverages - while even a few breaths of N204 or hydrazine will kill you. Ethanol is even more storable than the 'storables', i.e. hypergolics, as it's liquid over a much wider temperature range. While at 330 sec ISP, ethanol is not nearly as efficient as efficient as LOX/LH2 and is significantly less efficient than LOX/CH4 (which is about 370 sec), it's also somewhat better than hypergolics at 310 sec or so. So ethanol is not nearly as efficient as CH4, but it's more efficient, safer, and more storable than hypergolics, and it's ten times more dense than hydrogen (and also about twice as dense as methane, which should help to offset the Isp difference a little). So if we're not going with methane, I think that ethanol is the second best; a safe, fairly dense, and comparatively efficient storable fuel.

While you obviously wouldn't be growing corn on the Moon anytime in the near future, LOX/ethanol also offers another benefit over hypergolic storables, namely that you could at least make the LOX on the moon from the purported ice. I have to go look up whether anyone's done any studies on producing ethanol in-situ anywhere, but I doubt it. But it's another advantage over storables.

Offline Dobbins

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An Ethanol engine can be converted to a Methanol engine without too much trouble. Commercial production of Methanol from Methane is a proven technology and uses similar processes to those that have been proposed for producing Methane in space. You can even look at Methanol as an easily stored form of Methane since it is basically partially oxidized Methane.

John B. Dobbins

Offline BogoMIPS

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Dobbins - 3/2/2006  8:19 AM

An Ethanol engine can be converted to a Methanol engine without too much trouble. Commercial production of Methanol from Methane is a proven technology and uses similar processes to those that have been proposed for producing Methane in space. You can even look at Methanol as an easily stored form of Methane since it is basically partially oxidized Methane.


Interesting, so an Ethanol engine might be a "baby step" towards an engine that can be fueled with ISRU resources.  This seems like an all-too-sensible approach.

There's got to be some signifigant downside somewhere, right? :)

Offline Dobbins

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It's more than a baby step, it's an alcohol engine. It's more a matter of which type of alcohol is in the fuel tank than something radically different. Methanol has a slightly lower ISP and requires stricter handling procedures because it is toxic, though no where near as toxic as hypergolics. If you design the alcohol engine with the ISP of Methanol in mind then you wind up with one that has extra performance when you use it with Ethanol. That is a win/win situation.

John B. Dobbins

Offline Daniel Handlin

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Dobbins - 3/2/2006  8:19 AM
An Ethanol engine can be converted to a Methanol engine without too much trouble. Commercial production of Methanol from Methane is a proven technology and uses similar processes to those that have been proposed for producing Methane in space. You can even look at Methanol as an easily stored form of Methane since it is basically partially oxidized Methane.

An interesting idea. Although methanol is toxic and is a lot less efficient than methane. It would make a heck of a lot more sense to just use the methane you've already made and spend the methane engine R&D money than to make methanol for a methanol engine; the Isp and nontoxicity advantages are well worth it. Methanol isn't really any more efficient than hypergolics, and is just about as toxic.

Quote
Interesting, so an Ethanol engine might be a "baby step" towards an engine that can be fueled with ISRU resources.  This seems like an all-too-sensible approach.

There's got to be some signifigant downside somewhere, right? :)

Yeah- the alcohol fuels are significantly lower-perfoming than methane. Still, if we can't have methane, ethanol is the next best thing (though it's a distant second best, to be sure, in my opinion).

Offline Dobbins

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Methanol isn't nearly as toxic as hypergolic fuels and it has been used a a fuel for race cars for decades without the special handling needed for hypergolics. The Indy type race cars have run methanol since the 1960s, and there are classes of drag racing cars that are limited to methanol fuel, and these are considered hobby classes by the sanctioning bodies as opposed to the similar pro classes that use nitromethane as a fuel. It certainly requires some care in handling, but so does gasoline, another toxic fuel, and the procedures for handling methanol fuel are similar to those used for gasoline.

John B. Dobbins

Offline CuddlyRocket

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Daniel Handlin - 4/2/2006  2:31 AM
Still, if we can't have methane, ethanol is the next best thing (though it's a distant second best, to be sure, in my opinion).
One advantage of ethanol is that there have already been examples of rocket engines using this as propellant - so we know it works! I seem to recall that there are potential problems with methane as a fuel (something to do with the igniters?), so we don't actually know if a methane engine can be made to work - to the required reliability anyway.

A methane engine needs to be developed as part of a research project, not as part of an operational vehicle development.

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