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Author Topic: Ambient heat engine  (Read 16970 times)

memoryman

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Re: Ambient heat engine
« Reply #15 on: January 01, 2017, 10:31:40 PM »
Peltier devices have a low efficiency (~10%?) and are expensive.

Philip Hardcastle

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Re: Ambient heat engine
« Reply #16 on: January 01, 2017, 10:55:04 PM »
There are some free energy possibilities that can be explored, one that I think is overlooked is the temperature difference between the ground and the sky.


A reliable source of warm is in the ground, the deeper the better, and on clear days and nights the sky is a reliable cold.


The sky temperature in most places is about 1C (34F), though it can be much colder, and the ground temperature is typically 21C at modest depth, this gives a 20C differential. Such a temperature difference is the basis for OTEC (Ocean Thermal Energy Conversion).


For people living off grid and in desert locations a mix of solar and OTEC is ideal, but then the new 21-70 batteries make storing PV now cost effective

gotoluc

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Re: Ambient heat engine
« Reply #17 on: January 02, 2017, 04:34:54 AM »

An ambient heat engine was something I pondering on for a while during the build of my 28 foot Solar electric catamaran house boat with 2.5Kw of solar panels on the roof to drive the 2 electric motors (one per pontoon) with about 2Kw/hr of lithium battery backup.


Here's what I was thinking of. Solar panels are heat collector which drives their efficiency down. I was thinking of adding solar pool roof heaters (tubing) at the back of the panels and pump glycol through them to copper tubing attached to the pontoons (below water line) to cool the fluid. I'm sure the gain in electrical power from the 2.5Kw array would be greater then what the pump would use.
I then thought, what if I add a heat pump between this heat source and sink. There could easily 30 degrees F or much greater temperature difference between the back of the solar panels and the sea water.
So the idea is, could we not use the electricity from the now cooled and better performing solar array to power the heat pump which would create steam and use steam engines to power the houseboat instead of electric motors. Could the steam engines possibly be a greater propulsion power then using the 2Kw directly to electric motors?


I'm no expert at heat pumps and refrigerants but I'm good at thinking up ideas like these ;)


Please let me know your thoughts on this.


Regards


Luc

Philip Hardcastle

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Re: Ambient heat engine
« Reply #18 on: January 02, 2017, 05:47:14 AM »
Hi Luc,


Your ideas are interesting, but alas the gains are not likely to be as good as you would hope.


A few things, we are all talking about heat engines etc, the hated Carnot limit is a guide we should all observe when considering the engineering of differential temperature heat engines. The formula is know to all and it says that if you have 20C delta then you can only get a maximum efficiency of about 6%, and probably only 4% when you take into account real world losses such as electric pumps.


That you have solar and li-ion is the way to go for value for money, and having a large towable pontoon deck with a large solar array would be a cool thing to do. Remember that long pontoons have less drag than short fat ones.


The 21-70 batteries I mentioned are predicted to drop to $100 per kWh, so that will be awesome.


Solar PV efficiency at say 15% is always going to beat a thermal alternative, as memoryman pointed out most peltier devices are low efficiency.


Whilst OTEC is low efficiency it relies upon having massive reservoirs of heat to work with, so even 5% efficiency makes sense, but in the case of a marine vessel you need maximum bang for the buck. Better to invest in the pontoon or some sort of PV wings that can be lowered in smooth conditions (perhaps with a simple outrider).


If you do want to consider thermal as a secondary generation matter the cost is likely to be much higher than that of more PV.


My view of solar sailing, and I am a keen observer having a desire to build a round the World vessel one day, is that the hulls of a catamaran can be super slippery through water and can be well filled with 21-70 batteries to have a capacity of say 1MWh, this coupled to a large foldout PV array of say 50kW would mean that by the time you have spent a few days in port you can make a 24 hour crossing to the next port or anchorage.


The issues of low drag seem to be best dealt with by the idea of having the hulls essentially open bottomed such that they trap air, the pumps needed to keep them filled needing less power than that needed to push ordinary hulls through the water. The obvious additional benefit being that the hulls are barnacle free.


The idea of 50kW arrays that can fold away in rough conditions seems sensible, and in smooth seas 50kW will give you good speed during the day. Depending on your desire to make long distance voyages you can of course run 24/7 at a lower speed and so match input energy to motor usage. I think the super slippery hulls and due care to make the above water areas aerodynamic could have a 24/7 cruiser maintaining 10 knots.


For people interested in getting a higher efficiency out of simple Stirling engines might I point out that the temperature of some collectors can get much higher than others, in fact one of the best solar collectors is black nickel, this can achieve an equilibrium temperature of over 200C, if in vacuum, and if such a high temperature is used than Carnot would predict about 40% efficiency (but say 30% real world - 2 x most PV).


Anyhow Luc, I hope my comments are of interest to you, happy sailing.

gotoluc

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Re: Ambient heat engine
« Reply #19 on: January 02, 2017, 06:51:54 AM »

Hi Philip,

glad I caught your attention... thanks to your boating interests.

BTW, the catamaran solar powered houseboat was an all in one (not something I towed)
I chose a catamaran hull for best displacement characteristics (speed and efficiency)
The ideal is to navigate during sunlight at the speed (watts) the panels provide in real time. The batteries were just a backup in case you need a little extra power for maneuvering in and out of port.

So a 28 feet x 8 feet array of vacuum tubes with black nickle collector plates would do a better job then photovoltaic panels. Not a bad idea!
I guess parabolic concentrators (mirror polished stainless steel) could be used to reduce the amount of tubes and cost?

Interesting stuff!

Thanks for sharing

Luc

Philip Hardcastle

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Re: Ambient heat engine
« Reply #20 on: January 02, 2017, 07:33:51 AM »

So a 28 feet x 8 feet array of vacuum tubes with black nickle collector plates would do a better job then photovoltaic panels. Not a bad idea!
I guess parabolic concentrators (mirror polished stainless steel) could be used to reduce the amount of tubes and cost?



Hi again Luc


The trade offs that are needed depend on the situation (of course), my guess is that for a house boat a large covered area could be used as a solar collector, if vacuum tubes collectors are used (and they can be bought cheap from China) then a simple polished foil back sheet with formed parabolic troughs would be good and cheap, and it would not make it heavy or particularly thick. Fresnel lenses have been proposed and can make a thin and lightweight collector that can be used as an insulated roof / awning.


Consider that if you achieve 250C+ you can store energy in salts for night operation.


Not that I am an expert but..... one very good source of heat is that of various PCM materials such as waxes, a Sterling engine could easily be integrated to work in conjunction with a pcm reservoir, imagine that you pump the black nickel collector heat into a ton of pcm with a phase change of 200C+, it can hold an amazing amount of energy to drive the Stirling all nigh long, the 1,00kg of pcm storage being highly lagged.


Like I said to John a number of posts ago, there is much that can be pursued that is possible, worthwhile but challenging, and a lot of things that are just going to burn money with a certain futility.


I applaud all that pursue ideas and will always offer help to anyone that seeks my advice (such as it is - according to memoryman).


Best
Phil


P.S pcm for temp 200C+ is probably going to be a salt, not sure what the best ones currently are, obviously the large latent heat at the phase change temperature is what you want to match your heat engine. IIRC paraffin wax as a pcm is ideal for keeping your house cool / warm, but not much use for heat engines power production systems. Of course those interested in the amazing uses of pcm can research on Google.

Philip Hardcastle

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Re: Ambient heat engine
« Reply #21 on: January 02, 2017, 08:18:19 AM »
Hello! The use of low-grade heat and transfer it into electricity is a reality today. I have developed a pattern, working on phase transition and generating 0.085 Watts of power. The device environmentally friendly and can be operated for a long time. This is only the beginning.
Here is a link to the video: https://www.youtube.com/watch?v=0rPQvTyXxqA&t=4s


Hi, not sure what you are showing, is it a peltier cell with an alcohol evaporator on top?


Please explain.

sm0ky2

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Re: Ambient heat engine
« Reply #22 on: January 02, 2017, 02:43:01 PM »
@ Luc

about your boat:
rather than wasting a lot of time/$$ trying to generate power from the waste heat,
it might be more beneficial to simply remove the heat
scoops placed just below the water line, in the forward direction
will automatically circulate water through the cooling lines.

This cooling action will come at no additional costs (after initial installation of the lines)
However, the gain in efficiency of the PV array will give you extra power out of your set-up.

sm0ky2

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Re: Ambient heat engine
« Reply #23 on: January 02, 2017, 02:46:32 PM »

Hi, not sure what you are showing, is it a peltier cell with an alcohol evaporator on top?


Please explain.

that's what it looks like to me.
the black board to absorb heat
some sort of heat-transfer medium caked on the top side of the modules.
 --- might be semiconductor grade thermal grease? (the kind you use on a CPU)
the liquid appears to be a low grade isopropyl (the cheap green kind)
evaporation process quickly removes heat from the cold side of the modules.

[replicators - I would suggest using a higher grade alcohol, so there is less water left behind]

memoryman

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Re: Ambient heat engine
« Reply #24 on: January 02, 2017, 04:02:50 PM »
Philip, you and I exchanged many emails in your Quenco period; you made ridiculous power claims  which I showed to be orders of magnitude too high. In addition, I had two very well connected persons contact you, with unpleasant results for them (and therefore me).
I am also well aware of your interactions with Simon D. who is a very good friend of me.
I respect your opinions on many subjects, but you can stand to improve your people skills.
As to the sailboat idea, using superhydrophobic coating will both reduce the friction and keep the hull free of barnacles.
And I am very aware of the Carnot limit.

Philip Hardcastle

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Re: Ambient heat engine
« Reply #25 on: January 02, 2017, 06:54:36 PM »
Philip, you and I exchanged many emails in your Quenco period; you made ridiculous power claims  which I showed to be orders of magnitude too high. In addition, I had two very well connected persons contact you, with unpleasant results for them (and therefore me).
I am also well aware of your interactions with Simon D. who is a very good friend of me.
I respect your opinions on many subjects, but you can stand to improve your people skills.
As to the sailboat idea, using superhydrophobic coating will both reduce the friction and keep the hull free of barnacles.
And I am very aware of the Carnot limit.


Bill you are really a low life liar, you have little to no understanding of engineering and you never never never showed me any such thing, moreover the facts are, and remain, that I never made a ridiculous power claim but rather it is you that cannot understand the math.


As to your well connected people, they were as full of BS as you are, but if you insist on attacking me I am prepared to defend myself by publishing the emails, your call..


People skills? read back and see who has the issues, you used this forum to make a low and uncalled for attack on me, and now you escalate just because I gave you some ribbing back.


Now I came here in good faith to offer some advice to a guy that seemed hell bent on wasting his time on a dead end topic but then you jumped in with your ridiculous uninformed opinion, dressed up as a stated factual claim, that told him it was possible. You Bill are a danger to him, and if you do truly understand the Carnot theory then your advice to him is all the more outrageous.


Now this forum should not be a place for this sort of exchange, and I would offer to you a truce, again your call.


As to hull coatings, there are coatings and even shark skin patterns, but air bubble is better AFAIK from reading research, it also is open source and so free to use.

Bronepoezd

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Re: Ambient heat engine
« Reply #26 on: January 02, 2017, 07:59:06 PM »
I showed only the principle of the generators. You can collect the plant, which will run continuously and generate 100 watts or more. However, the question of creating such a device in the size and money. Search phase transitions - they key. I continue to work in this direction. There are also ideas for parametric resonance with the proof of the energy gain. Perhaps among you there are people with more advanced technical equipment, you can share an idea.

memoryman

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Re: Ambient heat engine
« Reply #27 on: January 02, 2017, 08:08:00 PM »
First of all, my first post on this:
"John, looking at your site, I see some good ideas. The idea of using heat pumps to 'self-loop' is possible, but not yet practical. Imho, the obstacle is the refridgerant.
I'll be happy to comment further after spending more time reading your ideas. Bill"

was addressed to the poster, not you. YOU responded with: "John please ignore Bill's opinion about what is possible, he won't be there to compensate you for the time and money you will waste." so, who started this?
I still have all 63 emails we exchanged between 5/29/2012 and 8/9/2012; publish any you want.
The two contacts I supplied were: my son's father in law (a very connected physician) and a billionaire aquintance.
Both were stunned by your rude responses.
Here is one quote from the old website: "These tiles will be 1.5V (DC) with a minimum output current of 1,000Amps/cm2". That translates into 1.5kW/cm^2...
Draw your own conclusions.