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#22
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Vision of the three Rs: Regular, Reliable and Reusable
In article .com,
Totorkon wrote: Just as important will be the electrolysis and liquification hardware. Cooling and storing H2 and O should be easier given the temperature of space and vacuum for the thermous effect. Actually, electrolyzing water is not a very good way to get fuel. Electrolysis is *grossly* energy-intensive; a kilowatt-*year* of energy electrolyzes only about a ton of water. Moreover, dealing with the results is not that easy, especially for LH2, which needs active refrigeration at all times -- a headache not only for a fuel depot, but for its customers. (There are people who claim that LH2 could be kept liquid with passive cooling, but that's a rather ambitious claim. LOX is much easier.) And both LOX and LH2 probably need active refrigeration to cool and liquify them in the first place -- passive cooling doesn't work very well for getting rid of large amounts of heat at low temperatures, because the radiator areas become enormous. It is almost certainly preferable to just launch LOX and kerosene (or perhaps some lighter hydrocarbon, like chilled propane). The one big advantage of hydrogen is that it's *light*, but if you're picking it up in orbit, that no longer matters very much. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
#23
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Vision of the three Rs: Regular, Reliable and Reusable
In article ,
Fred J. McCall wrote: Hint: You don't try to 'create demand'. You service the ones that exist and let the new ones come as they will. -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw Interesting juxtaposition of text and signature quote there, Fred. The big changes -- and hence the big chances to get rich or do good -- come not from servicing existing markets, but from servicing markets which *don't* already exist and have to be built along with your business. On FedEx's first day, a fleet of over a dozen aircraft carried a grand total of six packages. Aiming at a hypothetical market is a risky thing to do, but the payoff can be huge. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
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Vision of the three Rs: Regular, Reliable and Reusable
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#25
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Vision of the three Rs: Regular, Reliable and Reusable
On Feb 17, 11:23 am, (Henry Spencer) wrote:
In article .com, Totorkon wrote: Just as important will be the electrolysis and liquification hardware. Cooling and storing H2 and O should be easier given the temperature of space and vacuum for the thermous effect. Actually, electrolyzing water is not a very good way to get fuel. Electrolysis is *grossly* energy-intensive; a kilowatt-*year* of energy electrolyzes only about a ton of water. I will have to google this subject again. I thought that a kg of water represented about two Kwh of thermal energy, enough to split about three tons per Kwyr at 75% efficiency. A single 138 m^2 solar 'blanket' on the ISS generates 16 Kwh. Of course the collector would have to be near geosynchronous altitude for 24 hours of sun, or be in a polar orbit, which would further limit its usefulness. Moreover, dealing with the results is not that easy, especially for LH2, which needs active refrigeration at all times -- a headache not only for a fuel depot, but for its customers. (There are people who claim that LH2 could be kept liquid with passive cooling, but that's a rather ambitious claim. LOX is much easier.) And both LOX and LH2 probably need active refrigeration to cool and liquify them in the first place -- passive cooling doesn't work very well for getting rid of large amounts of heat at low temperatures, because the radiator areas become enormous. Zubrin has plans to land a tank of LH2 on mars to react with CO2, guess that might not be a great idea given the time of transit. It is almost certainly preferable to just launch LOX and kerosene (or perhaps some lighter hydrocarbon, like chilled propane). The one big advantage of hydrogen is that it's *light*, but if you're picking it up in orbit, that no longer matters very much. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | Truth can be a bitter medicine, but it is the only cure for a foolish notion. Thankyou for the dose, Doctor Spencer. |
#26
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Vision of the three Rs: Regular, Reliable and Reusable
On Feb 17, 11:23 am, (Henry Spencer) wrote:
In article .com, Totorkon wrote: Just as important will be the electrolysis and liquification hardware. Cooling and storing H2 and O should be easier given the temperature of space and vacuum for the thermous effect. Actually, electrolyzing water is not a very good way to get fuel. Electrolysis is *grossly* energy-intensive; a kilowatt-*year* of energy electrolyzes only about a ton of water. Moreover, dealing with the results is not that easy, especially for LH2, which needs active refrigeration at all times -- a headache not only for a fuel depot, but for its customers. (There are people who claim that LH2 could be kept liquid with passive cooling, but that's a rather ambitious claim. LOX is much easier.) And both LOX and LH2 probably need active refrigeration to cool and liquify them in the first place -- passive cooling doesn't work very well for getting rid of large amounts of heat at low temperatures, because the radiator areas become enormous. It is almost certainly preferable to just launch LOX and kerosene (or perhaps some lighter hydrocarbon, like chilled propane). The one big advantage of hydrogen is that it's *light*, but if you're picking it up in orbit, that no longer matters very much. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | I see my mistake. I read that 1kg of H2 generates about 30 thermal Kwh, which would correspond to about 9kg of water. If you were in charge of the space program, with a gaurenteed budget of say 20 or 30 billion per year, how would you spend it? |
#27
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Vision of the three Rs: Regular, Reliable and Reusable
Totorkon wrote:
On Feb 17, 11:23 am, (Henry Spencer) wrote: In article .com, Totorkon wrote: Just as important will be the electrolysis and liquification hardware. Cooling and storing H2 and O should be easier given the temperature of space and vacuum for the thermous effect. Actually, electrolyzing water is not a very good way to get fuel. Electrolysis is *grossly* energy-intensive; a kilowatt-*year* of energy electrolyzes only about a ton of water. Moreover, dealing with the results is not that easy, especially for LH2, which needs active refrigeration at all times -- a headache not only for a fuel depot, but for its customers. (There are people who claim that LH2 could be kept liquid with passive cooling, but that's a rather ambitious claim. LOX is much easier.) And both LOX and LH2 probably need active refrigeration to cool and liquify them in the first place -- passive cooling doesn't work very well for getting rid of large amounts of heat at low temperatures, because the radiator areas become enormous. It is almost certainly preferable to just launch LOX and kerosene (or perhaps some lighter hydrocarbon, like chilled propane). The one big advantage of hydrogen is that it's *light*, but if you're picking it up in orbit, that no longer matters very much. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | I see my mistake. I read that 1kg of H2 generates about 30 thermal Kwh, which would correspond to about 9kg of water. If you were in charge of the space program, with a gaurenteed budget of say 20 or 30 billion per year, how would you spend it? You realize of course that you are discussing rocket science with an elderly senile has been, right? -- Get A Free Orbiter Space Flight Simulator : http://orbit.medphys.ucl.ac.uk/orbit.html |
#28
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Vision of the three Rs: Regular, Reliable and Reusable
On Feb 17, 10:40 pm, kT wrote:
Totorkon wrote: On Feb 17, 11:23 am, (Henry Spencer) wrote: In article .com, Totorkon wrote: Just as important will be the electrolysis and liquification hardware. Cooling and storing H2 and O should be easier given the temperature of space and vacuum for the thermous effect. Actually, electrolyzing water is not a very good way to get fuel. Electrolysis is *grossly* energy-intensive; a kilowatt-*year* of energy electrolyzes only about a ton of water. Moreover, dealing with the results is not that easy, especially for LH2, which needs active refrigeration at all times -- a headache not only for a fuel depot, but for its customers. (There are people who claim that LH2 could be kept liquid with passive cooling, but that's a rather ambitious claim. LOX is much easier.) And both LOX and LH2 probably need active refrigeration to cool and liquify them in the first place -- passive cooling doesn't work very well for getting rid of large amounts of heat at low temperatures, because the radiator areas become enormous. It is almost certainly preferable to just launch LOX and kerosene (or perhaps some lighter hydrocarbon, like chilled propane). The one big advantage of hydrogen is that it's *light*, but if you're picking it up in orbit, that no longer matters very much. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | I see my mistake. I read that 1kg of H2 generates about 30 thermal Kwh, which would correspond to about 9kg of water. If you were in charge of the space program, with a gaurenteed budget of say 20 or 30 billion per year, how would you spend it? You realize of course that you are discussing rocket science with an elderly senile has been, right? -- Get A Free Orbiter Space Flight Simulator :http://orbit.medphys.ucl.ac.uk/orbit.html- Hide quoted text - - Show quoted text - Henry's point about the difficulty of liquifying hydrogen makes sense, on earth it takes close to 40% of the energy inherent in the H2 to liquify. In space as the temperature drops, an exponetially larger radiating area is required to drop it further. I get a bit more than a ton of H2&O per Kwyr, but electrolysis is notoriously inefficient. I think he would get an argument from Zubrin about the ease of keeping H2 liquid in space. I would argue that the process of recovering water from a pole of the moon, or from phobos, and then generating propellants is so important, and the establishment of regular access to orbit is so fundamental, that developing these capabilities is a worthier goal than putting people on the moon again. |
#29
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Vision of the three Rs: Regular, Reliable and Reusable
Totorkon wrote:
On Feb 17, 10:40 pm, kT wrote: Totorkon wrote: On Feb 17, 11:23 am, (Henry Spencer) wrote: In article .com, Totorkon wrote: Just as important will be the electrolysis and liquification hardware. Cooling and storing H2 and O should be easier given the temperature of space and vacuum for the thermous effect. Actually, electrolyzing water is not a very good way to get fuel. Electrolysis is *grossly* energy-intensive; a kilowatt-*year* of energy electrolyzes only about a ton of water. Moreover, dealing with the results is not that easy, especially for LH2, which needs active refrigeration at all times -- a headache not only for a fuel depot, but for its customers. (There are people who claim that LH2 could be kept liquid with passive cooling, but that's a rather ambitious claim. LOX is much easier.) And both LOX and LH2 probably need active refrigeration to cool and liquify them in the first place -- passive cooling doesn't work very well for getting rid of large amounts of heat at low temperatures, because the radiator areas become enormous. It is almost certainly preferable to just launch LOX and kerosene (or perhaps some lighter hydrocarbon, like chilled propane). The one big advantage of hydrogen is that it's *light*, but if you're picking it up in orbit, that no longer matters very much. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | I see my mistake. I read that 1kg of H2 generates about 30 thermal Kwh, which would correspond to about 9kg of water. If you were in charge of the space program, with a gaurenteed budget of say 20 or 30 billion per year, how would you spend it? You realize of course that you are discussing rocket science with an elderly senile has been, right? -- Get A Free Orbiter Space Flight Simulator :http://orbit.medphys.ucl.ac.uk/orbit.html- Hide quoted text - - Show quoted text - Henry's point about the difficulty of liquifying hydrogen makes sense, on earth it takes close to 40% of the energy inherent in the H2 to liquify. When launching from the Earth, fuel costs are insignificant compared to the cost of the launcher, engines and payloads, so energy for fuel manufacture, and the costs of the fuel itself, is irrelevant. When you come up with a launch scheme where fuel costs are important, please let us all know about it, as soon as you possibly can. In space as the temperature drops, an exponetially larger radiating area is required to drop it further. You realize you are talking to a condensed matter physicist, right? I get a bit more than a ton of H2&O per Kwyr, but electrolysis is notoriously inefficient. That's a myth. Electrolysis is one of the most efficient operations imaginable, almost, but not quite, as efficient as rocket engines. We are talking about attainable efficiency in the mid 90s. I just don't know where people get crackpot ideas that electrolysis is inefficient. I think he would get an argument from Zubrin about the ease of keeping H2 liquid in space. In space we have solar power. Clearly reaction engines aren't necessary. I would argue that the process of recovering water from a pole of the moon, or from phobos, and then generating propellants is so important, and the establishment of regular access to orbit is so fundamental, that developing these capabilities is a worthier goal than putting people on the moon again. I agree. However, most of it can be automated, and reaction engines aren't necessary for automated operations, when you have solar power, and especially with very low microgravity of small moons and asteroids. Reaction engines are only really necessary for Earth to LEO, and clearly hydrogen wins. Plus, there are added advantages that Henry never speaks of, being the corrupt old school ******* that he is. For instance - water and oxygen for breathing, drinking, growing plants, and hydrogen being the lightest element (molecule) for solar powered acceleration. Any intensive research and development into solar conversion and hydrogen manipulation will easily pay for itself in commerce, the commerce necessary to solve real problems right here on Earth -- Get A Free Orbiter Space Flight Simulator : http://orbit.medphys.ucl.ac.uk/orbit.html |
#30
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Vision of the three Rs: Regular, Reliable and Reusable
kT wrote:
We are talking about attainable efficiency in the mid 90s. I just don't know where people get crackpot ideas that electrolysis is inefficient. People equate large energy inputs with inefficiency. Only those with some scientific background will know that they should be comparing the actual energy input with the theoretical minimum. Sylvia. |
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