ZetaX Posted October 28, 2015 Share Posted October 28, 2015 As far as I know, nuclear reactors always have their energy extracted by boiling water into steam, turning a turbine generator somewhere. Nuclear reactors generate heat, so is it possible to use it to directly apply the heat to an industrial process - say, seawater desalination, or a blast furnace?Blast furnaces are normally well above the temperatures at which you consider a nuclear recator "safe". Even a https://en.wikipedia.org/wiki/Very-high-temperature_reactor could maybe reach 1000°C, which would not work for, say, iron.Some other things are prohibited by the dangers of radiation leaking and/or induced radiation. But I don't know for sure how it would be for the seawater (yet I think that places that need it are often those that do not have access to nuclear technology). Quote Link to comment Share on other sites More sharing options...
RainDreamer Posted October 28, 2015 Share Posted October 28, 2015 As far as I know, nuclear reactors always have their energy extracted by boiling water into steam, turning a turbine generator somewhere. Nuclear reactors generate heat, so is it possible to use it to directly apply the heat to an industrial process - say, seawater desalination, or a blast furnace?Nuclear powered desalination plants has been proposed, and I am not sure, but might have been implemented.PDF resource about it:https://www.oecd-nea.org/ndd/workshops/nucogen/presentations/8_Khamis_Overview-nuclear-desalination.pdf Quote Link to comment Share on other sites More sharing options...
Rune Posted October 28, 2015 Share Posted October 28, 2015 The real life equivalent of this weapon is the fuel air bomb (thermobaric weapon), it use the surrounding O2 to ignite the fuel it carry. A large number of this weapon can surly burn a large portion of the O2 in a precise area (making the air unbreathable). But an entire atmosphere, I don't know! with enough number may be.... I guess.edit: yeah! Like what NuclearNut says below, the number of fuel air bomb required will be the equivalent of the mass of the atmosphere. That's not a few salvo.Actually, you can do something close to it... and we already have. A firestrom is a front of high-temperature, high-speed winds that ignite all combustibles on their path, and create enough energy from the resulting fires that they sustain themselves. In WWII, we burned a few cities using conventional explosives dropped in a more-or-less precise fashion. Dresden was accidental IIRC, but the effects was deemed useful enough to try to make it on purpose over the mostly wood and paper Japanese cities.For a whole planet? You would need plenty of burnable stuff on the surface and a sufficiently oxygenated atmosphere. And the firestorm would probably die over oceans and such. But I'm thinking Earth has already had conditions that would have allowed for burning a whole continent, for example (at the end of the carboniferous, with a higher O2 content and huge continental-span forests).Rune. Scary, right? Quote Link to comment Share on other sites More sharing options...
MinimumSky5 Posted October 28, 2015 Share Posted October 28, 2015 I was reading about Hawking radiation on wikipedia, and it said this: Vanish? Is that because it's been turned into a singularity, and it can never grow volumetrically again? Why wouldn't it turn back into a star, or some other lump of detectable matter after it evaporated beyond a certain mass?Classical physics breaks down at singularities, so no-one can really say what happens, but he way I understand it, as the black hole already has infinite density, it will always have infinite gravity, keeping it compressed. Quote Link to comment Share on other sites More sharing options...
uncle_jew Posted October 29, 2015 Share Posted October 29, 2015 What is the physical meaning of the specific impulse, expressed in (seconds^-1)?I understand it is proportional to the exhaust velocity and as such indicates the impulse delivered per unit of propellant consumed.But what does the unit of Isp (seconds^-1) mean? If the engine has an Isp of 100 (*seconds^-1), exactly what does this engine do 100x per second? Quote Link to comment Share on other sites More sharing options...
andrewas Posted October 29, 2015 Share Posted October 29, 2015 A given mass of fuel can generate thrust equal to its weight under Earth surface gravity for ISP seconds. Which isn't particularly useful. The primary benefit of giving the ISP in seconds is that it cancels out the length, so american engineers can talk with the rest of the world's engineers with less risk of confusion. Quote Link to comment Share on other sites More sharing options...
K^2 Posted October 29, 2015 Share Posted October 29, 2015 ISP is expressed in seconds, not inverse seconds. The rest is right in adnrewas post. It's worth pointing out that it's measurement units all the way down. US engineers use pounds of weight/mass interchangeably. The exact definition is impulse (lb*s) per weith of the fuel (lb). Pounds cancel, leaving you with seconds. Soviet rocket engineers used a definition of impulse (N*s) per mass of the fuel (kg), leaving ISP in m/s, and different from US definition by exactly the Earth's gravity factor g. Many reference sources still give ISP in m/s, so it's something to keep in mind. Quote Link to comment Share on other sites More sharing options...
shynung Posted October 29, 2015 Share Posted October 29, 2015 Wouldn't it be exhaust velocity if expressed in m/s? Just sayin'. Quote Link to comment Share on other sites More sharing options...
Hary R Posted October 29, 2015 Share Posted October 29, 2015 Wouldn't it be exhaust velocity if expressed in m/s? Just sayin'.Outside of USA, it is the same thing. Quote Link to comment Share on other sites More sharing options...
K^2 Posted October 29, 2015 Share Posted October 29, 2015 Wouldn't it be exhaust velocity if expressed in m/s? Just sayin'.Effective exhaust velocity. Yes. They are one and the same in metric. Quote Link to comment Share on other sites More sharing options...
Hcube Posted October 29, 2015 Share Posted October 29, 2015 I suggest this excellent video about specific impulse : Scott Manley also made a video about it, but it's not very good in my opinion Quote Link to comment Share on other sites More sharing options...
RainDreamer Posted October 31, 2015 Share Posted October 31, 2015 Why are a lot of things in the universe disk/ring shaped? Saturn rings, asteroid belt, flat disk shape galaxies, etc. I know that they are not the only configuration possible, but why we see so many of them? Quote Link to comment Share on other sites More sharing options...
K^2 Posted October 31, 2015 Share Posted October 31, 2015 Why are a lot of things in the universe disk/ring shaped? Saturn rings, asteroid belt, flat disk shape galaxies, etc. I know that they are not the only configuration possible, but why we see so many of them?There are a lot of contributing factors, but the main commonality is conservation of angular momentum. You know how figure scaters pull in arms to get themselves to spin faster? Same principle. The closer things are pulled together, the faster they turn. And as things collide, only one direction of rotation ends up winning out. So larger, older galaxies tend to be disk shaped. Same with protoplanetary disks that turn into planets around new stars. And around these planets, moons form turning in the same direction. Quote Link to comment Share on other sites More sharing options...
magnemoe Posted October 31, 2015 Share Posted October 31, 2015 Nuclear powered desalination plants has been proposed, and I am not sure, but might have been implemented.PDF resource about it:https://www.oecd-nea.org/ndd/workshops/nucogen/presentations/8_Khamis_Overview-nuclear-desalination.pdfYes, its pretty smart as you use the heat directly to distillate water. No need to use steam turbines and generators. An added bonus is that you can run this as an addition to an standard power plant to use power then the demand is low. Quote Link to comment Share on other sites More sharing options...
PB666 Posted October 31, 2015 Share Posted October 31, 2015 There are a lot of contributing factors, but the main commonality is conservation of angular momentum. You know how figure scaters pull in arms to get themselves to spin faster? Same principle. The closer things are pulled together, the faster they turn. And as things collide, only one direction of rotation ends up winning out. So larger, older galaxies tend to be disk shaped. Same with protoplanetary disks that turn into planets around new stars. And around these planets, moons form turning in the same direction.The angular vector of the accretion volumn that represents the greatest angular momentum will be the vector with the least 'drag' or collion related heat or friction. This is going to cause flattening. But non-collisions also matter since they can change the orbital momentum and eccentricity throwing them either into the central star, into an orbit that collides with a larger planet, like jupiter, or out of the system. Quote Link to comment Share on other sites More sharing options...
Hcube Posted November 8, 2015 Share Posted November 8, 2015 NEW QUESTION :Does the "dyne" in "Rocketdyne" come from the CGS system ? That would actually make sense...(If it's obvious, well known by everyone and i'm the only one realizing it just right now, please tell me) Quote Link to comment Share on other sites More sharing options...
Oafman Posted November 9, 2015 Share Posted November 9, 2015 ANOTHER NEW QUESTION:I was daydreaming the other day, thinking about a possible mission plan using the Outer Planets Mod, and wondering about how to perform an orbital insertion on a planet with rings. As any KSP player knows, you make your insertion burn at periapsis to maximise returns from the Oberth Effect, and the lower the periapsis, the better. But with a planet like Saturn, you couldn't get close, or you would risk travelling through the rings, with what I would assume would be a reasonably high probablility of collision with debris. So I figured we must simply have to place the periapsis outside the altitude of the rings, and suck up a more expensive burn because of no Oberth gains. Anyway, later on I did a quick bit of Googling to see what Cassini had done. And it turns out, that Cassini just manned up and piled straight through the middle of the rings!From NASA page on Cassini insertionBefore entering the rings, Cassini did turn it's antenna prograde to shield the spacecraft from particles. So obviously, it was recognised that there was some risk, but I guess that risk was small enough to justify this mission plan.Can anyone expand on why that was the case. Is the debris in the rings (or at least, in the part that Cassini crossed) so spread out that any collision was very unlikely? Are the particles in that section of the ring so small that a collision would not damage the antenna? Quote Link to comment Share on other sites More sharing options...
Hcube Posted November 9, 2015 Share Posted November 9, 2015 I'm no expert, but the picture says "Cassini passes behind ring"... Maybe that answers your question ? Also, can anyone help me about the CGS system and Rocketdyne question ? It just makes a lot of sense and i'd like to know if it's a coincidence ... Quote Link to comment Share on other sites More sharing options...
Kryten Posted November 9, 2015 Share Posted November 9, 2015 Rocketdyne was formed in the 40s, there's not a lot of documentation from that era, and rocketry didn't get much publicity. I don't think you're going to get better than 'maybe'. Quote Link to comment Share on other sites More sharing options...
JJJacksonTyler Posted November 14, 2015 Share Posted November 14, 2015 Question: Do I get some sort of achievement for finally completing the journey to Space Shuttle Mecca?Where is Enterprise? Quote Link to comment Share on other sites More sharing options...
RainDreamer Posted November 14, 2015 Share Posted November 14, 2015 You are now one of the cool kids. Quote Link to comment Share on other sites More sharing options...
benzman Posted November 14, 2015 Share Posted November 14, 2015 Where is Enterprise?In New York:- http://www.intrepidmuseum.org/ Quote Link to comment Share on other sites More sharing options...
Hcube Posted November 14, 2015 Share Posted November 14, 2015 (edited) In New York:- http://www.intrepidmuseum.org/I highly recommend the intrepid museum by the way. Apart from being set on an aircraft carrier, you can see Enterprise (yaaaay) , a 60s submarine (with torpedos, nuclear missiles and all the cool submarine stuff, gauges, tubes and pretty much every cliché ever on submarines). Aaaaand there's a SR-71 Blackbird [EDIT : not really, see post below] wich makes all this 10 times more awesome. Bonus points if you find the aircraft carrier lego replica ^^ And sights on NY ! Honestly a really cool place to visit Edited November 14, 2015 by Hcube Quote Link to comment Share on other sites More sharing options...
Kryten Posted November 14, 2015 Share Posted November 14, 2015 Aaaaand there's a SR-71 Blackbird wich makes all this 10 times more awesome. Not quite; it's an A-12 OXCART, the blackbird's CIA ancestor. Quote Link to comment Share on other sites More sharing options...
WestAir Posted November 14, 2015 Share Posted November 14, 2015 I highly recommend the intrepid museum by the way. Apart from being set on an aircraft carrier, you can see Enterprise (yaaaay) , a 60s submarine (with torpedos, nuclear missiles and all the cool submarine stuff, gauges, tubes and pretty much every cliché ever on submarines). Aaaaand there's a SR-71 Blackbird wich makes all this 10 times more awesome. Bonus points if you find the aircraft carrier lego replica ^^ And sights on NY ! Honestly a really cool place to visitThey also have a Concorde. Quote Link to comment Share on other sites More sharing options...
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