Timeline for Why can't an ocean liner be powered by an engine that takes heat from the ocean water and eject ice cubes?
Current License: CC BY-SA 3.0
12 events
| when toggle format | what | by | license | comment | |
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| May 23, 2016 at 20:22 | vote | accept | Fine Man | ||
| Apr 18, 2016 at 20:15 | comment | added | Fine Man | Let us continue this discussion in chat. | |
| Apr 18, 2016 at 20:14 | comment | added | CuriousOne | Nothing stops you from putting a nuclear reactor on the ship to propel if forward and that reactor will have to use sea water for its cooling system. Why you would also want to make large amounts of ice cubes along the way would remain a mystery, of course. | |
| Apr 18, 2016 at 20:12 | comment | added | Fine Man | @CuriousOne -- OK, that makes sense. Of course, now I won't attempt engineering such an ocean liner, but would there be some source of energy it could use (equivalent to the electricity from the fridge's power cord)? | |
| Apr 18, 2016 at 20:10 | comment | added | CuriousOne | Because a fridge has a power chord which powers it. That's why it can make ice cubes. For every unit of heat that it takes from the cubes to deposit in the room, somewhere else several units of heat flow from a hot to a colder temperature bath. In total the net heat flow is always from hot to cold. Unplug the fridge and nothing happens. | |
| Apr 18, 2016 at 20:06 | comment | added | Fine Man | @CuriousOne -- Hmm... I'm now a bit more confused than when I ask the question (darn entropy :-]). If a fridge can do a similar process, why can't an ocean liner? Also, what makes such an ocean liner different than one that uses heated water that ejects steam? | |
| Apr 18, 2016 at 20:05 | answer | added | White Knight_wk | timeline score: 1 | |
| Apr 18, 2016 at 20:01 | comment | added | CuriousOne | :-) Nothing stops you from trying (except for common sense, that is). The point is that the second law of thermodynamics reflects the experience that nobody has been able to find physical processes that violate it, which reflects the scientific method: science observes and then derives descriptions. We don't have postulates around here. Laws are simply short hand notations that summarize large classes of unchallenged evidence. Find one counterexample and the law is gone. In this case you would, in my honest opinion, be wasting your time, though. | |
| Apr 18, 2016 at 19:57 | comment | added | Fine Man | @CuriousOne -- Oh. So, is it possible to make such an ocean liner? | |
| Apr 18, 2016 at 19:55 | comment | added | CuriousOne | These are very sloppy examples of the second law of thermodynamics in the Clausius formulation, which basically says that heat only flows from hot to cold, unless something else happens. The latter is simply an observation. Nobody has ever observed heat flow against a temperature gradient unless there was a second physical process that caused it (which is what the electric motor/compressor in a fridge does all day). That an ocean liner can't run on heat from seawater by making ice cubes is simply based on the observation that nobody has ever seen such a machine (or any of its equivalents). | |
| Apr 18, 2016 at 19:53 | review | First posts | |||
| Apr 18, 2016 at 19:56 | |||||
| Apr 18, 2016 at 19:50 | history | asked | Fine Man | CC BY-SA 3.0 |