Space Storable Propellants

[willpittenger]

The melting and boiling points hydrogen peroxide are not that far from Water's.<br /><br />Water:<li>Freezing: 0°C<li>Melting: 100°C<br /><br />Hydrogen Peroxide:<li>Freezing: -11°C<li>Melting: 150.2°C<br /><br />So here on hear hydrogen peroxide would make a good antifreeze, but in space... Sorry.</li></li></li></li> <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[gunsandrockets]

"...speaking of LUNOX, this website: http://www.space-rockets.com/moon1.html has the interesting idea of using a LUNOX/Aluminum monopropellant."<br /><br />How about a liquid aluminum/liquid oxygen rocket? How wild is that? A couple years ago saw an XCOR engineer discuss this concept which XCOR was planning to present to NASA.

 

[gunsandrockets]

"not to get too far off topic, but any gas should work for an ion engine correct?"<br /><br />I have heard argon mentioned as well as xenon.<br /><br />Xenon should provide an excellent storable propellant since it is liquid at a higher temperature than liquid oxygen and it is much denser.

 

[montmein69]

If I go back to the first post [Holmec] :<br /><br /> /> Ares IV post brought up a good question.<br /><br /> />What propellants can be used to store in space so a<br /> /> booster can sit in an orbit for months (possibly years) to<br /> /> be used when a crew is ready to use them.?(Thinking of<br /> /> Mars mission and beyond).<br /><br />I conclude than :<br /><br />1 - there is no way to prepare a Moon mission with Ares 1 and Ares V scenario :<br />- LH2/LOX is needed to go to the Moon (we need the best .../cut/...thrust for the payload .../cut/... <font color="orange">performance for the propulsion system</font><img src="/images/icons/blush.gif" />)<br />- Big issue to get the cryo-propellants on Earth Orbit. No solution -at the moment- to adapt a cooling system on the EDS<br />Finally the combo Ares IV launching all the stuff directly on a Moon orbit must be used<br /><br />2- The Moon mission is buy far different of a Mars Mission. The issue of cryo conservation must be fixed and specific experiments must be done in that area.<br /><br />And my final question<br /> .... is the Moon mission a real milestone for this technical problem ? <div class="Discussion_UserSignature"> </div>

 

[propforce]

<font color="yellow">"H2O2/Kerosene is non-toxic and therefore easier to handle." <br /><br />Do you know what happens if you put your hand into a vat of H2O2? </font><br /><br />Instant "rapid oxidation", e.g., burn of your bare hands which may result in a complete explosion of H2O2. It is very reactive with the oil that occurs naturally on our skins.<br /><br />Rocket propellant grade H2O2 is very unstable, almost like a nitroglycerin explosive, a pot hole on the road could set it off while transporting. <div class="Discussion_UserSignature"> </div>

 

[propforce]

<font color="yellow">Big issue to get the cryo-propellants on Earth Orbit. No solution -at the moment- to adapt a cooling system on the EDS </font><br /><br />Big issue is to design an <i>insulation system</i> for cryogenic propellants. You'll need a pretty fancy "cooling system" to cool a LH2 tank. <br /><br />Does anyone know how fast hydrogen boil off in a LH2 tank? Imagine a pot of boiling water on top of stove, that's how fast.... Now how much do we need to replenish if we let it boil like that for hours... days... or months ? <div class="Discussion_UserSignature"> </div>

 

[nyarlathotep]

<font color="yellow">- LH2/LOX is needed to go to the Moon (we need the best thrust for the payload) </font><br /><br />We need minimum overall system cost to go to the moon. Thrust or Isp of the lander stage isn't really that important.<br /><br />This may mean we use storable cryogens (lox and propane/methane) hauled from LEO using SEP. It may mean using hypergolics. Perhaps hydrogen really is best. But cost analysis hasn't been done because NASA is doing all transport in house to support their welfare program, and the NASA high templars have an idiotic "Hydrogen Is Best" religion.<br /><br /><font color="yellow">Does anyone know how fast hydrogen boil off in a LH2 tank?</font><br /><br />Depends on the tank.

 

[edkyle98]

"Perhaps hydrogen really is best. But cost analysis hasn't been done because NASA is doing all transport in house to support their welfare program, and the NASA high templars have an idiotic "Hydrogen Is Best" religion. "<br /><br />For TLI, hydrogen IS best. (And yes, a forest's worth of studies have completed and presented during the past 40 years repeatedly reaching this conclusion.) If storables were used for the TLI burn instead, twice as much mass would have to be placed in low earth orbit, which either means twice as many launches (twice the cost) or bigger launchers (twice the cost).<br /><br /> - Ed Kyle

 

[willpittenger]

I think most of the topic has concerned propellants for use once we are in lunar orbit. They were talking about propellants that can sit around in the vehicle for long periods of time. That would never be the case with a TLI system. However, it might be true for a lander. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[montmein69]

I don't know what other people writing on the thread mean but for me the point is :<br /><br />http://tinyurl.com/y9ehpz<br /><br />and especially this :<br /><br /><font color="yellow"><br />The operational problem of Ares V's Earth departure stage (EDS), and its lunar lander, staying in low Earth orbit (LEO) for up to three months. This requirement, revealed in October on Flightglobal.com, adds mass and complexity to the EDS because of the need for long-term cryogenic propellant storage. That is necessary as under the Constellation architecture Ares V would be launched first and delays in sending the Ares I could see a period of weeks or even months before Orion docks with the EDS and its lunar module in preparation for trans-lunar injection from LEO. </font>/safety_wrapper> <div class="Discussion_UserSignature"> </div>

 

[montmein69]

<blockquote><font class="small">In reply to:</font><hr /><p><br />Big issue is to design an insulation system for cryogenic propellants. You'll need a pretty fancy "cooling system" to cool a LH2 tank. <p><hr /></p></p></blockquote><br /><br />I'm not a specialist and always openminded if I'm wrong.<br /><br />I found the term here :<br /><br />http://tinyurl.com/ydb8vk<br /><br /><font color="yellow"> To keep the LH2 cold enough, to stop it boiling off, the EDS would need cryocoolers, but none exist.</font><br /><br />I supposed it means that a passive insulation would not be enough to avoid a loss of LH2.<br /><br />If the LH2 boils some exit valve is needed to keep the pressure in the tank in the correct range ... and .. the propellant is lost<br /><br />To keep it below the boiling point ....they have to invent <img src="/images/icons/smile.gif" /> <br /><br /> <div class="Discussion_UserSignature"> </div>

 

[josh_simonson]

Here are two useful plots for considering the storability of propellants in various earth orbits and around the solar system.<br /><br />They demonstrate how close LOX is to being passively storable (particularly in high earth orbit), as well as hydrogen and hydrazine. <br />

 

[josh_simonson]

second figure<br />

 

[propforce]

<font color="yellow"><i>"...To keep the LH2 cold enough, to stop it boiling off, the EDS would need cryocoolers, but none exist. ..."</i><br /><br />I supposed it means that a passive insulation would not be enough to avoid a loss of LH2. <br /><br />If the LH2 boils some exit valve is needed to keep the pressure in the tank in the correct range ... and .. the propellant is lost <br /><br />To keep it below the boiling point ....they have to invent </font><br /><br /><br />There're some research going on with cryocoolers for large tanks. Smaller cryocoolers do exist today for satellites' sensors & instrumentation payloads. <br /><br />The variety approach to cryocoolers are largely based on the concept to "minimize boil-off" as oppose to use a "refrigerant" to provide additional cooling to the LH2. The do this with a small recirculation pump to circulate LH2 through the tank, thereby minimizing "thermal stratification" effect (different temperature gradients) with the LH2.<br /><br />Bottom line is that LH2 is not a good candiate for long term storage in space, but maybe viable on the surface of Moon or Mars. <div class="Discussion_UserSignature"> </div>

 

[scottb50]

Helium is a good working fluid to keep Hydrogen liquified. The mechanics are basically the same as any refrigerator, compress and expand.<br /><br />I remember reading, a long time ago about a system that forced a gas into a micro-etched plate device. As the gas is pushed through it is repeatedly compressed and expanded getting colder and colder every cycle until it comes out liquid. Something like this could simply vent the boil off gas back to the beginninng of the cycle and re-liquify it.<br /><br />As I have pointed out before it would also be simpler to keep the amount of cryogenic gasses to a minimum until they are actually needed. You would still need the capability of short term storage of large amounts for a specific burn, but long term cryogenic storage could be avoided by using liquid water.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[willpittenger]

So, in the Neptune/Pluto area, we would not have a problem with keeping hydrogen in a liquid state -- but might have a problem keeping oxygen from freezing? <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[no_way]

<blockquote><font class="small">In reply to:</font><hr /><p>You would still need the capability of short term storage of large amounts for a specific burn, but long term cryogenic storage could be avoided by using liquid water. <p><hr /></p></p></blockquote><br />Electrolysis isnt terribly good idea because it requires lots of power to get significant amounts of propellant in short time.<br /><br />I remember a figure of 20 mWhrs for a ton of hydrogen. Thats either a lot of solar panels, or a looong time to fill your tanks ( which will experience boiloff all the while ) <br /><br />EDIT: just found a source that says 50kWhrs per kilogram of hydrogen, which is 50mWhrs for a ton ..<br /><br />EDIT2: Just FYI, ISS solar arrays combined at peak power, around 100Kw, would produce 2 kgs of hydrogen per hour. 40 days to get a ton. Thats a long time to wait to fuel up a lunar stack.

 

[nyarlathotep]

<blockquote><font class="small">In reply to:</font><hr /><p>Here are two useful plots for considering the storability of propellants in various earth orbits and around the solar system. <p><hr /></p></p></blockquote><br /><br />The vertical axis on your charts seems to be labeled in some sort of archaic dead language.

 

[rocketman5000]

obviously not a "new" NASA chart....

 

[josh_simonson]

The names have been changed to protect the innocent. <img src="/images/icons/wink.gif" />

 

[halman]

spacester,<br /><br />Your post regarding paraffin as a rocket propellant got me to thinking about diesel fuel. It has more heat energy per unit of volume than gasoline, because of the paraffin content. However, the paraffin has a nasty habit of coagulating into clumps, which makes high performance engines hiccup. Heating and agitating the diesel fuel will prevent this, or even just heating, if the temperature is raised enough. Properly atomized, diesel is capable of highly efficient combustion, with very little soot. Of course, the carbon is the drawback, but rockets have been built which can deal with that. Storage tanks would not have to be very large, as would be the case with methane.<br /><br />For my money, either kerosene or diesel and liquid oxygen would be the best propellants for long term storage on orbit. Once we have reached orbit, the high IsP value of hydrogen is no longer required, as longer burns will compensate for lower IsP values. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[willpittenger]

Do you know what happens to Diesel fuel when the temperature falls below -40C? You get something with the consistancy of Vasoline. In lunar orbit, you have to assume the temperature will be at least that cold. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[comga]

In reply to: "The vertical axis on your charts seems to be labeled in some sort of archaic dead language."<br /><br />Rankine: Fahrenheit degrees above absolute zero (FWIW).<br /><br />From Wikipedia<br /> <br />Rankine is a thermodynamic (absolute) temperature scale named after the Scottish engineer and physicist William John Macquorn Rankine, who proposed it in 1859. As with the Kelvin scale (symbol: K), zero on the Rankine scale is absolute zero, but the Rankine degree is defined as equal to one degree Fahrenheit, rather than the one degree Celsius used by the Kelvin scale. A temperature of 459.67 °R is precisely equal to 0 °F.<br /><br />Not a common scale but easily converted to Kelvin by multiplying with 5/9. <br /><br />Definitely not the "New NASA" but "I'm not dead yet!" <br /><br />PS Space qualified, long lived, moderate volume cryocoolers have been tested since the 90's. At least some of these are based on Sterling cycle systems, not Joule-Thompson expansion coolers used for small loads like detectors. With cryocoolers, maintaining liquid H2 is (a non-trivial) exercise in scaling, insulation, power, and system weight.<br /><br />Methane makes the refrigeration easier at the expense of burdening every two Hydrogen molecules with a Carbon atom.

 

[spacester]

Thanks, comga, and this "metric luddite" LOL notes that if that log scale was degrees Kelvin the lines would be flatter and there would be less resolution in actual usage as a reference. <img src="/images/icons/laugh.gif" /><br /><br />halman, my thinking on Paraffin is pretty much limited to lunar surface operations in my thinking. It's part of my lunar dome thing. I can't resist so allow me to describe it briefly then y'all can get back OT.<br /><br />The idea is that it would be a multi-use commodity. It appears to be the easiest to store hydrogen-carrier with enough chemical energy to be a rocket fuel. (Note: water is a feedstock for rocket propellants). <br /><br />So that's the base thought, paraffin is interesting just for that, but then I found another use for it and the development of a 'paraffin infrastructure' follows from there.<br /><br />One of the huge challenges facing a lunar habitat is permanence, meaning spending the long lunar night without freezing to death. One needs energy reserves and multiple redundancy to do that. I was contemplating the absolute most brute simple background/backup energy source for heating the habitat and I envisioned a big vat of molten Paraffin providing that capability. <br /><br />I haven't run any numbers on it yet, so at this point it's just another silly idea. The idea is to deliver one big chunk of wax and get multiple uses out of it, including as part of a local trading economy with other commodities. <div class="Discussion_UserSignature"> </div>

 

[halman]

willpittenger,<br /><br />Perhaps I am mistaken, but I have always understood that any object exposed to the Sun in Earth orbit will quickly reach a surface temperature of around 500 degrees F. OF course, the side that is in shadow will also very quickly reach about minus 300 degrees F. but that is beside the point. (Or behind it.) By warming the diesel with sunlight, it can be brought up to a temperature where the paraffin will liquify. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>