# Hot water (energy conversion)

hot water!! (energy conversion)

Hello colleagues I´m new here and I'm from delicias, Chihuahua, Mexico and the reason of my post is that I want to do something with the water that is discarded of the mine of Naica, Chihuahua because this water from the mine has a lot of energy, I mean the water is 75°C!!! (167°F). I would like to help me with ideas to use that energy.:shy:
if you want to meet the mine go ahead http://www.naica.com.mx/

Wow those caves look amazing.

Well the immediate thoughts are to use it as a source of hot water, how close do you live?

Aside from that, there's not much else it's good for really.

I'm live very close to it, 30 min and my partner live in that small town, he is physicist too.
I was wondering if i can use somehow the Stirling cycle?? do you thing is a good idea...

I'm live very close to it, 30 min and my partner live in that small town, he is physicist too.
I was wondering if i can use somehow the Stirling cycle?? do you thing is a good idea...

You need a good temperature difference to get any useful work out of it.

What is the ambient temperature?

well, the ambient temperature is around of 25°C to 38°C almost always, at nights the temperature downs to 15°C but i think that energy is completely wasted

Well you haven't got a very good temperature difference to do much more than use it as a hot water source. Although how you'd transport it over the distance I don't know.

If a shallow well (50 to 100 feet or so) would reach the water table there, then you could get 50-60 degree water. That delta might be enough to make decent use of a sterling engine... But, the energy required to get the water up from the shallow well may be more than you could harness from the sterling engine... Not sure, I'm not an expert on sterling engines...

If a shallow well (50 to 100 feet or so) would reach the water table there, then you could get 50-60 degree water. That delta might be enough to make decent use of a sterling engine... But, the energy required to get the water up from the shallow well may be more than you could harness from the sterling engine... Not sure, I'm not an expert on sterling engines...

I don't think the temperature difference is enough to operate a stirling engine.

yeah, as I said, I'm not an expert on sterling engines, it was just a thought... but now that i think about it, the one sterling engine i have seen in person was the single piston type that used an alcohol burner, significantly hotter than 160F... but i have seen novelty versions sold, like one that sits on top of a computer monitor (CRT presumable) and will spin. http://www.ltd-stirling.de/id46.htm

Another thought is using a peltier junction device?? But they are very inefficient. But I seem to remember a recent advancement with them (just in the lab for now, i think)...

http://en.wikipedia.org/wiki/Thermoelectric_generator

Mech_Engineer
Gold Member

This is a pretty cool idea, it would basically be a small-scale geothermal plant operating at a somewhat lower temperature.

Based on what you're looking to do with the energy, there are a few methods for utilizing it. To convert to mechanical energy, a stirling engine might be a solution but a better one could be a rankine cycle system which utilizes a working fluid other than water (maybe a refrigerant for example). Sourcing the turbine and pump might be difficult however. It might also be possible to combine a refrigeration system with a standard steam-based rankine system, although that may be getting too complex.

If you want to convert to electrical energy, the most direct (simplest) solution would probably be a peltier stack. Yes it would be inefficient, but efficiency isn't a huge concern since you're harvesting from an abundance of heat. The other options would basically involve attaching a generator to the mechanical energy options.

If this is the cave system I'm thinking of, isn't the water being pumped out of the mine and once the pumps turn off the water will stop flowing? Does water flow out of the mine naturally?

Interesting case. Too deep to siphon, too impure to use directly for domestic hot water. Since it has to be pumped out anyhow, there may be geothermal uses, but I suspect it's best applied to pre-heat a working fluid going to some other superheater (e.g. solar). I assume it's presently being dumped into the river system flowing eventually to the Gulf of Mexico. If it's flowing downhill through pipes to do that, I'd consider a coaxial counterflow heat exchanger (pipe within a pipe) to evaporate (e.g.) alcohol, but you're probably better off with a localized plant. Is there a refinery, distillery, or sewage plant that could use the heat industrially? Alternatively, there may be something you can do with thermoacoustic generators. They are Stirling generators with no moving parts, where the heat difference drives an acoustic resonator which in turn can drive an acoustoelectric transducer. Have a look at the SCORE (Stove for Cooking, Refrigeration and Electricity) project and at Orest Symko's work in Utah.