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tubeless countercurrent heat exchange

Using vortex currents in counter flowing fluids to efficiently cool or heat
 
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[edited: changed from Oil Only and added second system of air to air]

A vortex can be induced to be stable i.e. in air guns, where a vortex current can travel many meters.

If we cause vortex currents in opposing directions, perhaps even one vortex current inside the other, we may construct a low cost countercurrent heat exchanger.

Probably cheaper than a regular car radiator we would be replacing systems that cool the oil through pipes.

// [Edit: Remarked out:] This is wrong as spidermother noticed: Our system would use oil only - so that there is no need to separate the liquids.

This could work for any two "fluids" oil, air, water or even coolants changing phase.

In order to overcome the mixing, dissolving and evaporation of one flow into the other
[edit: Originally I wrote: could probably be solved (in next halfbidea.]
can be solved by a second system. For example: In a water to air system, the hot water vortices pass heat to the cool air vortices but also evaporating some of the water into the air. This air is kept in a closed cycle, but in a second air to air counter exchange system passes the heat to ambient air with a minimal transfer of water vapor. A final dryer could be added at the exit of the heated ambient air, to drain excess vapor and retain it within the system.

pashute, Jul 14 2011

something like this http://en.wikipedia...e_Ranque-Hilsch.png
[j paul, Jul 14 2011]

Vortex Tube http://en.wikipedia.org/wiki/Vortex_tube
not the same thing but simular [duroncrush, Jul 22 2011]

[link]






       >something like this [vortex tube link by Jean Paul]   

       Er. No.
The [[vortex tube]] has a single input and double output and works at high pressures only.
  

       I'm talking about something SIMILAR to what is shown INSIDE the vortex tube, but has two input sources: One input for the hot flow direction (to be cooled), the other input for the cold flow (to be heated).   

       This would work without the need for high pressures (a simple aquarium pump at typically 2 PSI (0.136 atm) and 70 Lph would be enough to run a good heat exchange system like this).   

       And vortex tubes work (as far as I know) only with gases and not liquids, while I'm talking primarily about liquids, although it would work with a gas too, as proven by the vortex tube.
pashute, Jul 14 2011
  

       There will surely be some mixing, right? So this would be for situations where that doesn't matter too much. Is that what you are thinking?   

       I don't understand how a countercurrent heat exchanger helps when you have a single fluid, though. You need to exchange heat between the oil and the water in a conventional cooling system, because they must be kept strictly apart, but if you only have oil, why not just circulate the hot oil directly through the radiator and back to the engine?   

       This might be more useful, for instance, in ventilating a building, where an imperfect heat exchanger is better than nothing, and a small amount of mixing is not a big problem.
spidermother, Jul 14 2011
  

       Sorry
I got the image of two vortices passing each other and jumped to the wrong conclusion.
what fluids?
if the more dense one is on e out side it might work.
j paul, Jul 14 2011
  

       Countercurrent exchange causes an almost total crossover of hot to cold and cold to hot.   

       I'm trying to eliminate the "radiator" - a device where the hot fluid flows in tubules that allow the fast transfer of heat to a cold source outside these tubules. My radiator will have no tubules in it.   

       Spidermother was correct in asking: If you have a cold source of oil, just recycle it into the system. She's correct. I was half-thinking. So lets discuss an oil to air, or water to air exchange:   

       Instead of going through a radiator, we could have the oil or water come down in pipes in a vortex with air at ambient temperature (I'll soon discuss that) coming up in a countercurrent vortex. The problem of evaporation would have to be dealt with. So oil to air is easier to deal with. I suppose there wouldn't be much loss to evaporation. Am I assuming correctly?   

       Anyway - the air in the system cannot be from the environment, because then air with much of the oil particles or evaporated water will be leaving the system, something we don't want happening.   

       So the hot air will go through a second air-to-air vortex system. The cooling vortex will be with ambient air. The cooled vortex will retain most of the original air. This will ensure that a minimum of water/oil will be lost to the external environment, while the heat is moved out.   

       This second air-to-air heat exchange could have a dryer at the exit of the hot ambient air, with silicon-gel... (Hey: That gives me a new idea: see next week) or using thermal wheel.
pashute, Jul 15 2011
  

       I'm lost - how would 2 complicated vortex guns that don't exist cost less than simple tubes that do?
saedi, Jul 15 2011
  

       Not complicated at all. "Simple tubes" are quite expensive as anyone who wishes to buy a car radiator knows.   

       In large scale applications like industrial chillers, they could be the most significantly costly component. This type of equipment can cost hundreds of thousands of dollars for hospitals or other large buildings.
pashute, Jul 17 2011
  

       I really like this idea, and the more general idea of using vortices to carry one body of fluid within another body of the same fluid. I just love vortices - they are beautiful.   

       So, an uber[+] from me.
MaxwellBuchanan, Jul 17 2011
  

       I have to say I don't hate this, but you are going to get some mixing. Thus it's only going to be appropriate for things where mixing is undesirable but not catastrophic, and even then probably require multi-stage systems as mentioned.   

       There remains the question of can you generate appropriate vortices without a very high pressure or flow rate that makes this prohibitively expensive/difficult.
MechE, Jul 18 2011
  

       I'm lost as to where you're going to get significant heat transfer without convective mixing.
RayfordSteele, Jul 18 2011
  

       Really interesting concept, but I don't think we have yet found an application where this could work. Very half-baked+   

       I think I agree with [Rayford] depending on the definition of "significant". Although there will be heat transfer faster than diffusion due to molecular collision, the mixing at the edge of the vortex might make that effect insignificant.   

       I also worry about that throughput. I think ring vortices travel slower than the air in ductwork. In addition, there would need to be separation between vortices, so the heat exchanger will have to be much wider than a standard heat exchanger with the same capacity.
scad mientist, Jul 18 2011
  

       // significant heat transfer without convective mixing//   

       In a closed-tube system, there's no mixing, and heat is transferred through the tube walls (which, admittedly, are usually copper or the like). In this case, there's direct contact between a doughnut- shaped vortex of cold water and the surrounding body of hot water.   

       I also see lots of difficulties with this, but I still love the idea of using vortex rings to carry one liquid through another, miscible liquid.
MaxwellBuchanan, Jul 18 2011
  

       With tubes present, the radiator acts as a thermal capacitor, albeit one with some resistance, capturing the heat and allowing radiation and convection to do their jobs.   

       Note that the Ranque-Hilsch vortex doesn't seem to transfer much heat from the warmer outer ring at the entrance to the cooler inner one escaping the tube.   

       If you have vastly different fluid densities, you'll end up with vastly different specific heats per volume of fluid, resulting in poor heat transfer efficiencies due to limitations on the side of the less dense fluid.
RayfordSteele, Jul 18 2011
  

       [Rayford] The transfer is the other way. It actually transfers heat from the cold air to the hot air, which is why you get hot and cold streams. Admittedly, I'm not sure the physiscs are clearly understood as to why this happens, but some of the theories do not depend on mixing. If it is possible to construct one that runs dissimilar materials, it might help explain the effect.
MechE, Jul 18 2011
  

       //With tubes present, the radiator acts as a thermal capacitor,//   

       I don't think that's significant, unless the radiator is only acting for very short periods. In continuous operation, the thermal capacity of the metalwork isn't relevant.
MaxwellBuchanan, Jul 18 2011
  

       Thanks Max! Its great having someone on my side.   

       I originally was not thinking of the vortex tube but before talking about how it wont work - take a look at the currently single link (which is NOT my idea, but has two vortices one inside the other in opposite directions - and obviously there IS a total transfer of heat from very cold at one end to extremely hot at the other.   

       Granted this is achieved at high pressure, but has anyone tried the heat exchange concept with low pressure? You say it won't work. I say it probably will.
pashute, Jul 19 2011
  

       [Pashute] The vortex gun/cooler requires the high pressure to generate the vortex. This also provides the energy to perform the anti-entropic separating of hot and cold air. Since you are trying to transfer heat from a hot to cold medium, that energy should not be required, but you are still going to have to generate the vortices, which will require energy from somewhere.
MechE, Jul 19 2011
  

       you should have deleted the link if it is getting in the way!
I would not have minded, it was only posted because I thought it might help.
j paul, Jul 21 2011
  

       j paul, it helps! I'm saying that although its not my idea it does prove my point.
pashute, Jul 21 2011
  

       MechE I agree, I just think its worth checking how much energy is needed for vortices, and I suspect that not too much.
pashute, Jul 21 2011
  
      
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