silvrsvt Posted October 18, 2012 Share Posted October 18, 2012 http://io9.com/5952805/will-cars-of-the-future-run-on-liquid-nitrogen Quote Link to comment Share on other sites More sharing options...
xr7g428 Posted October 18, 2012 Share Posted October 18, 2012 (edited) You do realize that nitrogen is not an energy source. The energy here has to be produced else where, and then used to compress the nitrogen. Nitrogen is not a fuel, it is just a gas that is compressed. Edited October 18, 2012 by xr7g428 Quote Link to comment Share on other sites More sharing options...
RichardJensen Posted October 18, 2012 Share Posted October 18, 2012 True, but the same is true of battery powered cars. The question is whether this form of energy storage is cheaper/more efficient than batteries. Given the physics of batteries, in which you are attempting to store a glut of electrons in a medium capable of holding them, it doesn't seem much of a stretch to imagine that there are other more efficient ways of storing energy obtained elsewhere. Quote Link to comment Share on other sites More sharing options...
rkisler Posted October 18, 2012 Share Posted October 18, 2012 (edited) True, but the same is true of battery powered cars. The question is whether this form of energy storage is cheaper/more efficient than batteries. Given the physics of batteries, in which you are attempting to store a glut of electrons in a medium capable of holding them, it doesn't seem much of a stretch to imagine that there are other more efficient ways of storing energy obtained elsewhere. This would have the same inneficiencies as compressed air cars, but even worse due to having to keep the nitrogen at cyrogenic temps (liquid at atmospheric is -196C/-321F). Not gonna happen. Edited October 18, 2012 by Austin Quote Link to comment Share on other sites More sharing options...
battyr Posted October 18, 2012 Share Posted October 18, 2012 Yeah, nitrogen is not a fuel. Nitrogen is what you have left after you remove the oxygen from air. Except that you need extra energy to cool and compress it into a liquid. In this case case it would be easier just to use water instead of liquid nitrogen. It would be called a steam engine. Quote Link to comment Share on other sites More sharing options...
akirby Posted October 18, 2012 Share Posted October 18, 2012 Maybe the next gen Volt will use an onboard ICE to compress and liquify the nitrogen so it can then be used to run another engine that can turn a generator that can charge a battery pack that can then turn the wheels via electric motors. That's efficient, right? 3 Quote Link to comment Share on other sites More sharing options...
Edstock Posted October 19, 2012 Share Posted October 19, 2012 Maybe the next gen Volt will use an onboard ICE to compress and liquify the nitrogen so it can then be used to run another engine that can turn a generator that can charge a battery pack that can then turn the wheels via electric motors. That's efficient, right? As long as it stays in one place. 1 Quote Link to comment Share on other sites More sharing options...
xr7g428 Posted October 19, 2012 Share Posted October 19, 2012 True, but the same is true of battery powered cars. The question is whether this form of energy storage is cheaper/more efficient than batteries. Given the physics of batteries, in which you are attempting to store a glut of electrons in a medium capable of holding them, it doesn't seem much of a stretch to imagine that there are other more efficient ways of storing energy obtained elsewhere. The thread title says this: Will cars of the future run on Liquid Nitrogen? The article fails to mention that liquid nitrogen in not a fuel. Battery vehicles run on electricity. Typically to compress liquid nitrogen you use electricity. The process of using electricity to first strip the oxygen through electrolysis, and then use more electricity to compress the nitrogen, makes this a very ineffecient process. Quote Link to comment Share on other sites More sharing options...
Kris Kolman Posted October 19, 2012 Share Posted October 19, 2012 Obviously no one who wrote this ever worked with cryogenics... Liquid nitrogen continues to boil and as such doesn't stick around for long (even in vacuum jacketed tanks) and if leaked onto non-heated steel will break the steel (due to thermal stress concentrations). Let alone the issues of needing specialized mechanical and electrical systems to work in the super cold environment. Stored energy might be similar, but the collateral impacts make it impracticable. Quote Link to comment Share on other sites More sharing options...
jpd80 Posted October 19, 2012 Share Posted October 19, 2012 The author is mistaken and confused. Compressed industrial nitrogen is different to Liquefied nitrogen gas. As others have already said, cryogenic fluids require huge pressures and heavy walled vessels for storage, It's also the main reason why no one even contemplates Liquefied natural Gas a a fuel for vehicles Quote Link to comment Share on other sites More sharing options...
RangerM Posted October 19, 2012 Share Posted October 19, 2012 We maintain a liquid Nitrogen dewar (Google: Dewar Flask) at our office; capable of storing the liquid for weeks. While it is large, it does an effective job maintaining the nitrogen with minimal losses. There is a spring valve to prevent over-pressurizing the chamber, that rarely vents. While I think the idea of N2-powered cars isn't practical, you CAN store it quite effectively for longer periods of time. I don't think you could make a dewar capable of storing enough liq-N2 and be strong enough to endure riding in a car (without losing the vacuum). Quote Link to comment Share on other sites More sharing options...
jpd80 Posted October 19, 2012 Share Posted October 19, 2012 We maintain a liquid Nitrogen dewar (Google: Dewar Flask) at our office; capable of storing the liquid for weeks. While it is large, it does an effective job maintaining the nitrogen with minimal losses. There is a spring valve to prevent over-pressurizing the chamber, that rarely vents. While I think the idea of N2-powered cars isn't practical, you CAN store it quite effectively for longer periods of time. I don't think you could make a dewar capable of storing enough liq-N2 and be strong enough to endure riding in a car (without losing the vacuum). A Dewar Flask stores at Vacuum, not pressure, so while it preserves the liquid, there no real energy there.Vacuum flasks are used to maintain their contents (often but not always liquid) at a temperature higher or lower than ambient temperature, at ambient pressure Quote Link to comment Share on other sites More sharing options...
RangerM Posted October 19, 2012 Share Posted October 19, 2012 A Dewar Flask stores at Vacuum, not pressure, so while it preserves the liquid, there no real energy there. Vacuum flasks are used to maintain their contents (often but not always liquid) at a temperature higher or lower than ambient temperature, at ambient pressure The energy an N2-powered car derives is from the evaporation/expansion of liquid to gas. You don't need (or want) the storage chamber to be pressurized. Once you allow the liquid to escape, it boils quickly (expanding from liquid to gas). Ideally, you would want the N2 to enter the piston as a liquid so evaporation occurs there, extracting maximum work. Quote Link to comment Share on other sites More sharing options...
jpd80 Posted October 19, 2012 Share Posted October 19, 2012 The energy an N2-powered car derives is from the evaporation/expansion of liquid to gas. You don't need (or want) the storage chamber to be pressurized. Once you allow the liquid to escape, it boils quickly (expanding from liquid to gas). Ideally, you would want the N2 to enter the piston as a liquid so evaporation occurs there, extracting maximum work. There's not enough energy there to make that work in a vehicle, it's like a low temperature steam engine with a boiler full of liquid. Quote Link to comment Share on other sites More sharing options...
RangerM Posted October 19, 2012 Share Posted October 19, 2012 There's not enough energy there to make that work in a vehicle, it's like a low temperature steam engine with a boiler full of liquid. I disagree. The vapor pressure of liquid water at ambient conditions is low. The vapor pressure of liquid nitrogen is essentially 1 atmosphere (14.7 psi). Nitrogen gas cylinders are typically 2300 PSI. If you inject enough liquid into the chamber, you can make about as much pressure as you'd ever need to operate a piston. Quote Link to comment Share on other sites More sharing options...
SoonerLS Posted October 19, 2012 Share Posted October 19, 2012 Once you allow the liquid to escape, it boils quickly (expanding from liquid to gas). Ideally, you would want the N2 to enter the piston as a liquid so evaporation occurs there, extracting maximum work. It seems to me that it'd be better to use it with a turbine to generate electricity rather than using it to drive pistons. Quote Link to comment Share on other sites More sharing options...
RangerM Posted October 19, 2012 Share Posted October 19, 2012 (edited) It seems to me that it'd be better to use it with a turbine to generate electricity rather than using it to drive pistons. I wouldn't consider it practical either way. The theory is the same regardless; obtaining work from expansion of a gas either from combustion (gasoline) or evaporation (N2) of a liquid. Edited October 19, 2012 by RangerM Quote Link to comment Share on other sites More sharing options...
Mark B. Morrow Posted October 19, 2012 Share Posted October 19, 2012 Maybe the next gen Volt will use an onboard ICE to compress and liquify the nitrogen so it can then be used to run another engine that can turn a generator that can charge a battery pack that can then turn the wheels via electric motors. That's efficient, right? I hear a certain R. Goldberg is the Chief Engineer on that project. 1 Quote Link to comment Share on other sites More sharing options...
All-Or-Nothing Posted October 19, 2012 Share Posted October 19, 2012 Maybe the next gen Volt will use an onboard ICE to compress and liquify the nitrogen so it can then be used to run another engine that can turn a generator that can charge a battery pack that can then turn the wheels via electric motors. That's efficient, right? Ha Ha...good one They should put alternators in the wheel hubs. Battery for initial takeoff then alternators keep the wheels turning. while charging the battery for the next takeoff. Quote Link to comment Share on other sites More sharing options...
jpd80 Posted October 21, 2012 Share Posted October 21, 2012 (edited) I disagree. The vapor pressure of liquid water at ambient conditions is low. The vapor pressure of liquid nitrogen is essentially 1 atmosphere (14.7 psi). Nitrogen gas cylinders are typically 2300 PSI. If you inject enough liquid into the chamber, you can make about as much pressure as you'd ever need to operate a piston. But how do you get to 2300 psi in a N2 Gas cylinder when liquid nitrogen is at atmospherics pressure? What they're talking about is using liquid N2 sprayed into the inlet manifold with water spray used to "boil" the liquid N2 and turn it into a gas, that is th part I have a problem with, as you evaporate the liquid, it sucks in huge amounts of energy freezing the delivery pipes. This idea has been going round and round for decades but if it was any good it would have been reality by now. Edited October 21, 2012 by jpd80 Quote Link to comment Share on other sites More sharing options...
RangerM Posted October 21, 2012 Share Posted October 21, 2012 (edited) But how do you get to 2300 psi in a N2 Gas cylinder when liquid nitrogen is at atmospherics pressure? Liquid N2 exists under ambient pressure only at a temperature of -321 F. Once exposed to a temperature greater than this, its volume expands 700x as it evaporates from liquid to gas. The reason a nitrogen cylinder is 2300 PSI (at ambient temperature) is it is WAY above nitrogen's "critical temperature" (Google: Critical Temperature) of -233 F. What they're talking about is using liquid N2 sprayed into the inlet manifold with water spray used to "boil" the liquid N2 and turn it into a gas,that is th part I have a problem with, as you evaporate the liquid, it sucks in huge amounts of energy freezing the delivery pipes. This idea has been going round and round for decades but if it was any good it would have been reality by now. I'm not defending the practicality of the system, however I'm not sure why water spray would even be necessary. Exposure to ambient air temperature (alone) would boil the Liq N2 to gas. Friction inside the piston I'd think would provide additional heat energy to further boil the N2 to gas. No doubt that the external surfaces of such an engine would turn white as the ambient water vapor would freeze on the surface. But to even slow down the boiling of the N2, the engine would have to get below the critical point of Nitrogen which is -233 F. Not likely. Edited October 21, 2012 by RangerM Quote Link to comment Share on other sites More sharing options...
theoldwizard Posted October 22, 2012 Share Posted October 22, 2012 <sarcasm=on> I always read the Economist for science/engineering breakthroughs <sarcasm=off> Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.