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Hehe. The problem with internal combustion engines oxygen requirement for use on mars is not "Dook's problem". It's just math. I didn't create it. It's always been there. I just pointed it out.
In the previous discussion of this topic I did the math assuming CO2 mixed in and it still used too much oxygen. Internal combustion engines are just not efficient when compared to fuel cell's on mars. Here is the math once again.
Okay, the 152 cu in engine at it's maximum torque at 1,950 rpm uses 148,200 cu in of fuel/oxygen/CO2 per minute (4 cycle engine). Now if only 20% of that is oxygen that is 29,640 cu in used per minute.
A 50 gallon LOX tank provides 11,948,624 cu in of oxygen gas which would last you 403.1 minutes or 6.7 hours. You could go just over 100 miles then turn around and head back.
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But Dook, why do you assume 20% oxygen? If you are reburning hot exhaust gasses, you could probably dilute both the fuel and oxidizer way down to 2% or so. The partial combustion products would go round and round and get reburned, thereby increasing the efficency of the burning. Furthermore, if you are going to use regenerative braking, you'll already have batteries on board. The Honda Prius and other hybred vehicles shut the engine off entirely and run on batteries for a while, then turn the small, efficient engine back on and recharge the batteries. The number of hours an engine runs tells you nothing about how far a good hybred engine can go.
Euler, yes, it may very well be that some of these new technologies will prove better. Who knows.
-- RobS
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2%?? I'm not sure where you got that from but I would like to see the reference. Just a quick look online about exhaust gas recirculation on modern engines shows that EGR is usually less than 10% of the total mixture. That means 90% is oxygen and fuel, mostly oxygen.
http://www.xse.com/leres/efidiag/egr.ht … g/egr.html
I did find the reference below which shows a diesel engine that had 45% EGR but the test was to see how emissions changed and does not say how performance was affected.
http://www-chaos.engr.utk.edu/pap/crg-a … ma2000.pdf
Nevertheless if a diesel can run with as much as 45% EGR that would be the way to go but in my opinion it still cannot compete with fuel cell/solar powered vehicle in terms of efficiency and redundancy. Fuel cell's also provide fresh water for the crew. With an internal combustion engine you have to carry it all. Also if your engine fails the crew dies.
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Has anyone considered a blimp?
It can go places (or deposit people) were a rover can't go. The power required to move around would be considerably less, and could be augmented by putting solar panels on top.
"Yes, I was going to give this astronaut selection my best shot, I was determined when the NASA proctologist looked up my ass, he would see pipes so dazzling he would ask the nurse to get his sunglasses."
---Shuttle Astronaut Mike Mullane
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Thank you for the links, Dook. I wasn't suggesting 2% as much as questioning 20%. From these links, it appears one can run an engine on about 10% oxygen (in other words, half the usual terrestrial levels, which would correspond to a mix of 55% air and 45% recirculated exhaust). And I agree--did agree all along--that fuel cells are more efficient.
-- RobS
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The problem with your numbers Dook, is that your method of calculation is simply incorrect. Combustion only takes place in a small fraction of the space a cylinder, the rest of the space is taken up by other gases which are heated by the combustion and expand. Only a small spurt of fuel is injected every cycle, and even in our terrestial atmosphere (which is only ~20%) oxygen, only a small fraction of that is actualy combusted. On a mars rover, the vast majority of the volume of the cylinder will be filled with inert CO2 gas from the surrounding atmosphere.
Here is a better way to calculate the fuel consumption of a combustion engine.
I'm not sure what you have calcualted for daily energy requirments for a martian rover, but the estimates I have seen tend to run around 50 kWh/day or 180 MJ/day. Combustion of methanol yeilds 20 MJ/kg, giving a daily energy requirment of only 9kg/day or 126kg over a 2 week expadition.
Methanol combusts according to the following equation:
2CH3OH + 3O2 -> 2CO2 + 4H2O
giving you a ratio of 3O2 atoms for every 2 Methanol atoms. Since the atomic weights of methanol and oxygen are the same, the necessary ratio of oxygen to methanol is a simple 1.5. Thus, you need 189kg of oxygen for a expidition.
All of this assumes 100% efficency in your engine. Of course, ICE while they have other possative attributes, the best of them only average around 40% efficenct due to a number of issues (friction, incomplete combustion, ect...). However, even with this rather large inefficency taken into acount, ICE still do fairly well, needing 315kg of Methanol and 473kg of O2. For a total tankage of 788kg of fuel over a 2 week stay. This is a little heavy, but certianly do able. Even with higher inefficency figures for a ICE engine of 25% it is still a achiveable 1260kg.
Now, I'm not sure how that ~12 million in^3 of O2 is measured (is that 12 million cu. in at STP?), but in any case the the ammount of fuel necessary for a ICE is certianly do able.
Now, I did all these calculations for Methanol, but methane gets slighly better results (due to it's higher combustion energy), however the tank for will probably be heavier. Which one is actualy supperior probably depends upon the exact specifications of the vehicle.
He who refuses to do arithmetic is doomed to talk nonsense.
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Back from my midterm marathon mini-sabatical...
Of course fuel cells are superior in efficency, they don't involve throwing so much energy overboard as waste heat, I am simply stating that an ICE engine isn't entirely impractical on Mars. A fuel cell system will have longer range, lower mass, fewer moving parts and is obviously preferable but what I am stating is that an ICE system isn't entirely impractical. In fact, I think that Doc Zubrin even considerd them early in the life of MarsDirect.
As Austin points out your fuel volume fraction figure is too high, and makes sense since regular Earth vehicles powerd by liquid methane would get better milage then your hypothetical engine. With less gravity combined with hybrid drive, I think the range can be attained with one ton of fuel or so and is not insane.
As for your engineering,
-I have doubts about your choices of materials for the drivetrain, that carbon composits will flex too much compared to metals, and isn't worth the reduced weight.
-The combination of batteries AND fuel cells doesn't make much sense either unless the small efficency advantage of batteries is worthwhile, which I doubt it given the extra mass.
-Your vehicle is pretty small. It would not have enough room for work/storage space and an airlock and tries to cram too much equipment (even LSS gasses) into the pressure hull.
-Pretty low assumtions about the amount of horsepower needed to get around on Mars, even at low speeds. And you do need to be able to go fairly fast to get anywhere.
-Blanket condemnation of the concept of using electric motors to power the wheels directly, which affords far more agility and climbing power, and was used on the Apollo lunar rover. The motor isn't IN the wheel either, so there is no power connection to the spinning wheel, and affords redundancy if one of the motors fails. This method apears favored by many design teams.
-Ignoring advantage of using liquified oxygen tankage instead of pressurized for density and lower tank pressures, and probobly overestimating pressurized tank weight.
-Overall, excessively optimistic mass estimates about the whole vehicle, making the whole thing dangerously too simple (cabin cooling system?), definatly less useful, and a likly victim of weight creep.
I would like to reaffirm my opinion that MarsDirect is too small for the sake of saving a buck and a few years in development in a rush to get there. The system doesn't have a large enough crew, six people ought to be a minimum to stay psychologicly glued together and get real work done besides flags/footprints. The system isn't large enough volume wise, both the HAB and ERV don't offer enough room for the crew and nessesarry work & equipment space. The system doesn't carry enough payload mass such that reasonable equipment can be carried, too much capability is sacrificed to save a few kilos, like a real rover and not a Martian VW Bug.
I think that a nuclear fuel plant will weigh on the order of 3-4MT or so... around 0.5MT for the reactor, ~1MT for support hardware (turbine, cooling, etc), then the ISRU system, control hardware, structure & plumbing, and of or two loads worth of fuel. I think its a better idea to leave the thing stationary as much as possible, so that you don't need to lug along tonnes of radiation shielding (not included in the above estimate) and don't need to carry ~2MT of reactor with you where ever you go. I'm not a fan of the nuke truck idea.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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The problem with your numbers Dook, is that your method of calculation is simply incorrect. Combustion only takes place in a small fraction of the space a cylinder, the rest of the space is taken up by other gases which are heated by the combustion and expand.
I'm sorry you don't like my calculations but they are correct and they do take into account other gasses in the oxygen/fuel mixture. The problem with internal combustion engines is not fuel but oxygen to burn the fuel. My calculation is based upon a very small engine and assumes that only 20% of the cylinders gas intake is oxygen.
How does combustion of methanol yeild 20 MJ/kg? Combustion in what size engine?
What size engine do you plan on using to get 50 kw a day and what percent of that engines intake volume do you think will be oxygen/fuel?
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As Austin points out your fuel volume fraction figure is too high, and makes sense since regular Earth vehicles powerd by liquid methane would get better milage then your hypothetical engine. With less gravity combined with hybrid drive, I think the range can be attained with one ton of fuel or so and is not insane.
My fuel volume fraction figure is too high? Well what's yours then? How much of an engine's intake is oxygen and fuel? The fuel is not the problem, supplying the oxygen is!
-I believe carbon composite driveshafts would be fine for use on mars and would not flex too much however making the driveshafts out of metal would not be much of a problem. Only a little more weight.
-The batteries provide extra (perhaps excessive) redundancy. The fuel cells can be operated at night to recharge the batteries and create heat but if necessary the batteries can be charged entirely from the mounted and emergency solar panels and then the batteries can be used to operate the vehicle. If I was way over the weight limit then the batteries would go but since I'm only a few hundreds pounds over they provide extra redundancy. I could get within weight easy by halving the number of batteries.
-The vehicle is not small, the Apollo capsule was small. Mine is an 8' x 17' area. One will be driving most of the time and the other can be in the back getting ready for outside excursions or napping or whatever.
-A mouse can move a ton if you gear his wheel enough. As I said I can easily add more electric motors to the design but it's all in the gearing. Also, how are you going to go fast on mars? Much of it is entirely covered in basketball sized rocks!
-I ignore LOX because it's not necessary and it has it's own problems. If you can't keep it at -298 F it evaporates. Also my numbers are correct for each oxygen tank weight. See the website reference I included under that paragraph.
-How can you suggest my weights are overly optimistic when I've included references for everything? If you would check them you will see that the weight is given for each item on the web sites except for the carbon composite structure and the CO2 removal system but I believe they are in the ballpark.
Dangerously too simple? There is no such thing. Dangerously complex is though. My idea has multiple redundancies and many things can be fixed easily, without the need for computerized diagnostics.
Less useful? Than what?
Weight creep. Maybe, maybe not. As I said I have included website references for almost everything in my idea, the weights are given.
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I don't think i'm getting through to you... let me clarify... if you use less fuel per firing of the cylinder, then you therefore need less oxygen per firing, overall reducing the consumption of oxygen too. Your hypothetical engine fills the cylinder with what, 10% by volume of methane fuel gas? That is a pretty high figure... Say you inject only 2%, then you only need 4% oxygen to combust instead of 20% per cycle. You would need more RPMs or cylinders, but the relationship isn't nessesarrily linear, and you ought to only use so much fuel as you can derive useful cylinder expansions.
The 21MJ/kg figure I assume comes from the thermodynamic calculation about how much energy is actually released in combustion between MeOH & O2. This is thermodynamics, and doesn't concern the engine size, the engine is tailored to meet the output needs and nothing more, and it is fairly reasonable to assume engines of different sizes can burn similar fuel mixtures. Its just the middle man, its only concern is conversion efficency.
A good ICE engine ought to be able to capture about 30-33% of this energy as mechanical work, with quite a bit left over for heat to keep the cabin warm, boost the efficency of an onboard electrolyzer, and operate equipment (water distiller?).
Running the fuel cells to recharge the batteries is also a pretty redundant and silly thing to do. Why would you do that? Why wouldn't you just route the power from the cells directly? That makes no sense at all. As previously established, the solar arrays don't make enough power to keep your crew alive and move the vehicle, so you wouldn't have enough solar power left over from the LSS to recharge an emergency propulsion battery anyway.
Liquid Oxygen would save you so much gas tank trouble that its well worth it. If you keep the tank in the shade and insulated, it would be much lighter then gas tanks since it doesn't have to be under high pressure and LOX is only a little more dense then water. Yes it will boil off, but if it is well protected the boiloff will be quite slow, and you can feed this boiloff directly to the power plant instead of venting it overboard.
Any rover ought to be able to manage at least a few kilometers an hour, so you could make several hundred kilometers in two weeks with 8hrs of driving per Sol, preferably able to go a bit faster on even terrain with low research value.
The vehicle IS too small. If it is a roughly cylinder-shaped vessel, since it must be kept under high pressure, then only being 8ft in diameter leaves you with little room to stand up... The lab module on the ISS has a diameter 14 feet wide. You vehicle will need a cockpit with two seats that will take up the front 3ft or so, your two cots (which can be subbed for four extra seats) with ~7ft more, toilet/hygene/cooking station along one side taking up ~6ft on one side and LSS gear/foodstuffs taking the same on the other, and the last 4ft being the two-suit airlock. Since the thing needs somewhat dome-shapped endcaps, that brings the vehicle to around 25 feet long or a little less, say 22ft... No room for lab space, not enough room for sample storage, physicly cramped, not enough room for HP LSS gas bottles and propulsion equipment internaly.
I'm thinking more of a mobile lab rather then a rolling HAB, in which case the thing needs to be at least 26ft long, maybe a little more, to accomodate a glove box, Electron & Optical Microscopes, and a Mass Spectrometer along with a "chemistry set" for them on one side, and a large storage cabinate on the other for (environmentally regulated?) sample containers, sterilization/biology stuff perhaps, and a hydraulic press to break rocks. Extra LSS tankage in the floorboards, perhaps stretch the airlock a foot for extra gear and spares storage. This is a science mission after all, not a "yay look! we're on Maaars!" mission.
So yes, the thing will need to weigh more too... but overall, I think your baseline vehicle is too optimistic because you haven't added anything except basic pieces, and there is going to be more stuff needed to make it safe and effective to operate. Electrical busses, control equipment, spare parts, LSS consumeables, comm gear, cabin cooling, basic radiation shielding, thick windows, metal airlock hatches, LSS/FCU plumbing, and on and on. You can't just "forget" about this kind of thing, your vehicle is much heavier then you think it is...
From a design philosophy point of view, if you build it too simple and leave out too much, then the vehicle is as best pretty worthless and just a rolling HAB with little rock boxes on the outside. At worst under-equipped to be safe, if you omit too much equipment.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I'm sorry you don't like my calculations but they are correct and they do take into account other gasses in the oxygen/fuel mixture. The problem with internal combustion engines is not fuel but oxygen to burn the fuel. My calculation is based upon a very small engine and assumes that only 20% of the cylinders gas intake is oxygen.
How does combustion of methanol yeild 20 MJ/kg? Combustion in what size engine?
What size engine do you plan on using to get 50kw day and what percent of that engines intake volume do you think will be oxygen/fuel?
You are just simply incorrect on this. My method of calculation comes from simple stochiometric analisis of the situation. The only variables are the necessary energy consumption of the rover, and the efficency of the engine. Good estimates can be found for both of these figures. Where do your estimates for oxygen taking up 20% of the cylinder come from? At what pressure is the oxygen at? And in what condition is oxygen storred in the tank (pressure, temp, ect)? Knowing that volume of the tank is nice, but without some more data, I cannot figure out how much oxygen is actualy in there. I would be happy to do some calculations to show how your figures for combustion and fuel consumption work out, but without this data, I cannot even attempt it.
The combustion of methanol yeilds 20 MJ/kg. This is based upon the bond energies in the rectants (methanol) and the products (CO2 and Oxygen). It is a simple thermodynamic constant. It is the same on Mars as it is on Earth. And it is the same in a small engine as it is a large. It would take quite a lot of space to work out the calculations, but here is http://www.avogadro.co.uk/calculations/ … tm]website that shows how it works out. It gives a value in kJ/mol, I'll convert it to MJ/kg for you here.
680kJ/mol x 1mol/32g x 1MJ/1000kJ x 1000g/1kg = 21.25MJ/kg
Yout take the enthalpy of combustion -680kJ/mol (from the website). It's value is negative because the combustion gives of heat, but we can disregard that for our purpouses. Dividing by the molar mass of Methanol, 32g/mol gives us the amount of energy in kJ/g the conversion from kJ to MJ and g to kg cancle out, so our answer comes out to 21.25, even better than my initial estimate of 20MJ/kg. I should also point out that the enthalpy of combustion of methanol is EXACTLY the same as that of the reaction that occurs inside a methanol-oxygen fuel cell. In fact, while the method of reaction is diffrent, the equation is exactly the same.
I did not discuss engine size, in my post, because it is not relevant to the amount methanol and oxygen you need to combust to get 50 kWh/day, which is strictily an issue of efficency and thermodynamics. However, it's mass and volume would be considerably lower than that of the fuel cells you would need to get a amount of energy. A ICE can generate as much as 1000W/kg of mass (including transmition), but a heavy duty and more complex engine such as on the rover might get only 500W/kg. Turbine engines can perform much better, as much as 1-6kW/kg, but there design could be tricky, and there transmitions are typical much heavier. A Methanol-Oxygen fuel cell can only generate about 100W/kg, 5 times less than an ICE.
Anyways to Generate 50kWh/day you need an engine capable of generating 2kW. An ICE that could do this would mass only 2kg! The fuel cells would mass 20kg. I do not have figures for size on hand, but it is fairly obvious that the ICE would be smaller as well.
As to the specifics of the engine design, I'll admit, I have little clue. I am an chemistry student, not an engineer. However all the engineering is in the end based upon the chemistry I illustrated above. The fuel consumption is dependant upon the efficency of the engine, the amount of power that you need to generate, and thermodynamic constants. With good estimates for all these, a good estimation of fuel consumption can be generate without actualy designing the engine.
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While doing some research for this post, I did come across some intresting statistics. It may turn out that a turbine engine may be one of the best energy generation methods. Not only can they potentialy offer the greatest power density, a turbine engine also has greater efficency than a ICE, potetialy comparable or even greater than that of fuel cells.
Another thought that came to me is that methanol is probably generaly supperior to methane as a chemical fuel, regardless of the method of how it is used. Not only is methanol easier to store than methane, it's also allows you to shift more of the fuel mass over to methanol, since less oxygen is need for combustion per unit of methanol. Now overal, you do need more fuel, due to methanol's lower energy density, but it is certianly a very viable option.
He who refuses to do arithmetic is doomed to talk nonsense.
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Turbines are pretty efficent, considerably more then piston engines, and would couple to a generator for indirect/hybrid drives easily but I think they have a few drawbacks... They rely heavily on expanding inert gas in the combustion chaimber, and consume huge volumes of inert gas, which I think might be hard to provide in the thin air versus a "ultra turbocharged" regenerative piston engine. If it could work though, it would probobly be superior to piston or fuel cell engines for high-output applications. Exhaust water recyling might also be problematic given the large volume of exhaust gas.
I am still a big fan of fuel cells... they are still quite efficent, easily packaged for vehicle-size applications, and have few moving parts for maximum reliability. No pressurized inert gas is required, no excess oxidizer needed, and no need to lug a generator along to produce electricity. Methane isn't the ideal fuel as far as efficency, cell life, or fuel storage headaches, but as far as ISRU goes its easier to make then Methanol and won't freeze... Mars gets pretty cold at night, but mild heating and insulation would fix that problem.
Reforming of Methanol might be an efficency concern too, but there has been progress recently with catalyst systems that promises to greatly improve efficency, perhaps to the point of not needing anything except the catalyst and some selective membranes.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Methanol combusts according to the following equation:
2CH3OH + 3O2 -> 2CO2 + 4H2O
giving you a ratio of 3O2 atoms for every 2 Methanol atoms. Since the atomic weights of methanol and oxygen are the same, the necessary ratio of oxygen to methanol is a simple 1.5. Thus, you need 189kg of oxygen for a expidition.
You are assuming that all of the oxygen in an ICE gets combusted. ICEs always use much more oxygen than stochiometric analysis would indicate. Look up air independent propulsion or closed-cycle diesels for some examples of how much oxygen engines actually need.
Running the fuel cells to recharge the batteries is also a pretty redundant and silly thing to do. Why would you do that? Why wouldn't you just route the power from the cells directly? That makes no sense at all. As previously established, the solar arrays don't make enough power to keep your crew alive and move the vehicle, so you wouldn't have enough solar power left over from the LSS to recharge an emergency propulsion battery anyway.
It is not completely redundant. Using the batteries, you can give the rover much more power. The fuel cells would then only need to be large enough to deliver the average power usage, rather than the peak power usage. You could also use the batteries with a regenerative breaking system. However, I think that a capacitor could probably do the job better than an actual battery.
Liquid Oxygen would save you so much gas tank trouble that its well worth it. If you keep the tank in the shade and insulated, it would be much lighter then gas tanks since it doesn't have to be under high pressure and LOX is only a little more dense then water. Yes it will boil off, but if it is well protected the boiloff will be quite slow, and you can feed this boiloff directly to the power plant instead of venting it overboard.
Another option would be to just use hydrogen peroxide. That would give you a non-cryogenic liquid oxidizer.
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If the fuel/oxidizer can be ignited following injection rapidly enough, the gas mixture would not have time to diffuse into the inert gas, so the oxidizer efficency would be much higher. This would probobly be more difficult for larger engines with low-volitility liquid fuels and wouldn't work at all for diesel engines since they don't have spark plugs.
A small battery or ultracapacitor bank sure, but the one Dook outlined for his vehicle seems to be able to handle a signifigant amount of power requirements for periods of hours, not minutes.
Hydrogen peroxide isn't cryogenic, but it is chemically kinda unstable. The water byproduct would be quite a bit of dead weight if you just extracted O2 from it, and getting it to break down catalyticly into the crazy Hydroxyl radicals and trying to (somehow...) burn it your fuel rapidly it might cost signifigant efficency. Not really useful for fuel cells either, not that easy to make in an ISRU plant, and i'm wondering what happens when the stuff gets cold in the Martian night.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Well stochiometricly, yes I am making that assumtion of complete combustion, but the inefficencies due to incomplete combustion are already accounted for when the inefficencie of the engine is factored in. I know this is kind of a cop-out, but there is no simple way to calculate what amount of methanol is combusted without knowing the specifics of the actual engine, and even then it would be a factor you would half to test for to get a realy good answer.
However, a methanol (or methane) powered closed cycle engine, such as a would be on a martian rover would probably perform better than a more conventional disel or gasoline powered engine in terms of incomplete combustion. This is due to several factors, first methanol and methane are much smaller molecules than those in traditional fuels, meaning there are fewer bonds to break per unit of fuel.
Secoundly, methanol contains within it some of the oxygen for combustion already within it, which leads to less formation of CO, and less incomplete combustion. This is why methanol and ehtanol are somtimes added to conventional fuels as "cleaning agents."
Thirdly, by the very nature of a closed cycle engine, any products that are not fully combusted the first time around cycle through the engine and are combusted again.
I did not mean to imply that air was injected into the cylinder at a 2:3 ratio, only that that was approximatly the ratio at which it was consumed. However most spark ignited engines approach equilivency ratios of 1, or stochiometric ratios, as I indicated earlier. Indeed, the only statistics I could find for the performance of a closed cycle engine was for a diesel engine, which had a equivilence ratio (in this case of consumption to actual consompution) I calculated to be 1.2, which is typical for a normal chemical ignited engine. A methanol engine should perform better than this, but even so 1.2 is well within the amount I compinsated for with inefficency.
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Another factor in the martian enviroment which favors the combustion engines, is the abscence of nitrogen in the atmosphere. Without nitrogen, no energy is wasted forming various nitrous oxide compounds (NO, NO2, ect...)
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Another note about methanol, pure methanol has a freezing point of -98*C, which should rarely be a problem in an insulted tank. But the methanol/h20 mixture we are likely to use (<90% methanol) has an even lower freezing point of -145*C, and is not likely to ever freeze.
As for forming methanol, it is fairly easily done with methane and water vapor in the presence of a nickle catylist. I can go into the specifics if you like.
He who refuses to do arithmetic is doomed to talk nonsense.
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I suppose making Methanol wouldn't be terribly difficult, its just adding more weight/complexity to the ISRU plant. The relative ease of extracting hydrogen from methanol and the efficency of using Hydrogen in the fuel cell is pretty attractive though. There is a "neat trick" where Methanol, Water, and Oxygen are passed over a Rhodium/Cerium catalyst: Water and Methanol are converted to Hydrogen and Carbon Monoxide with heat, which is supplied by the reaction of small amounts of Methanol and Oxygen... So, at the expense of a little extra fuel, the reformer is all but eliminated as a bulky/heavy/electricity hungry device, and I bet you could recycle the waste heat too.
Good point about diluting a Methanol mixture to depress its freezing point, that should work just fine.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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an old thread from 20 years back maybe worth looking at again
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Nuclear spaceflight: igniting the next era of exploration
https://physicsworld.com/a/nuclear-spac … ploration/
If we want to send humans to Mars, and launch more science missions to the outer solar system, then we need the firepower to get there. One technology that could usher in this new era is nuclear-propelled rockets. This video traces the history of the nuclear spaceflight concept and looks at two complementary approaches being developed today: nuclear thermal propulsion (NTP) and nuclear electric propulsion (NEP).
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