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Author Topic: Electricity from heat exchangers?  (Read 22056 times)

Low-Q

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Electricity from heat exchangers?
« on: December 06, 2010, 11:34:43 AM »
I read about heat exchangers which have a COP of 4.04. It delivers more energy than you put in from the grid. This extra energy is taken from the surrounding air, so there is no violation of the laws.

If the COP are 4.04, shouldn't it be possible to make a generator which used the energy in thin air to power the heat exchanger WITHOUT using power from the grid at all?

How do we, in the simplest way, convert heat into electric energy so we can run the pump in the exchanger from its own harnessed energy from the air?

What about making an engine which runs from the temperature difference in the heat exchanger, and connect a generator to this motor?

Make this exchanger big enough, and you do not ever have to pay bills for powering your house :)

Vidar

Doug1

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Re: Electricity from heat exchangers?
« Reply #1 on: December 06, 2010, 02:21:19 PM »
You would have to re-develope the entire thing. Temp difference will only be slight unless it is a good distance apart from two objects (below ground to above ground) Typical generator has a high resistance to spin while under a load. The space required to build a system would be larger then most people have space for. While it's a good idea technollogy is just isnt there yet. Find a better form of peltire materials or combinations of them which could boost output then maybe. Or find the holy grail to energy conservation and recycling then you wont need to do much but could if your inclinned to have something to do.
 I still believe the holy grail is something stupid and over looked because it is just too simple and easy to believe.

Low-Q

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Re: Electricity from heat exchangers?
« Reply #2 on: December 06, 2010, 04:34:51 PM »
Increasing the surface area of each poston and cylinder in a Stirling enging should help? Let's say there is a star-shaped piston and cylinder. Let one or several "hot" cylinders be attached to the hot side of the exchanger, and the other cylinders on the old side? Then we let the surrounding air to provide the power we need?

Anyways, sure there is a stupid and simple way to the holy grail - we are just not stupid enough to find out ;) The motto must be: "Keep it simple", or as Einstein said: "Make it as simple as possible, but not simpler than that"

iquant

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Re: Electricity from heat exchangers?
« Reply #3 on: December 06, 2010, 06:19:19 PM »
Why not take advantage of the difference between air and water temp?  ie.  ocean or river based heat exchanger. 

I read about heat exchangers which have a COP of 4.04. It delivers more energy than you put in from the grid. This extra energy is taken from the surrounding air, so there is no violation of the laws.

If the COP are 4.04, shouldn't it be possible to make a generator which used the energy in thin air to power the heat exchanger WITHOUT using power from the grid at all?

How do we, in the simplest way, convert heat into electric energy so we can run the pump in the exchanger from its own harnessed energy from the air?

What about making an engine which runs from the temperature difference in the heat exchanger, and connect a generator to this motor?

Make this exchanger big enough, and you do not ever have to pay bills for powering your house :)

Vidar

Low-Q

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Re: Electricity from heat exchangers?
« Reply #4 on: December 06, 2010, 08:35:58 PM »
Why not take advantage of the difference between air and water temp?  ie.  ocean or river based heat exchanger.
Yes, it is many ways to harness the potential between two temperatures. What you mention are a very good way of doing it. I will consider using the groundwater which is only 2 meters below the surface under my house. Drill a hole and put some pipes down there. Water can circulate with a small pump and supply a sterling engine with constant temperature on one side, and a variable temperature on the other side. The good thing is that the engine works better in the winter time where the temperatures up here reach below -30 degrees celcius some times. The machine will generate enough power to heat up the house :)

crazyoldfart

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Re: Electricity from heat exchangers?
« Reply #5 on: January 15, 2013, 11:43:53 PM »
I have conducted several experiments with heat exchangers and reclaiming heat lost from home electronics. I built a cabinet that pulled the heat off 3 desktop computers with 4 hard drives each. the temperature was a pretty constant 110 degrees. this went thru a heat exchanger with water (closed loop like a car radiator ) water temp was 107 degrees . Now if we replace the water with a technology over a hundred years old, the first refrigerators, we could get pressures that could drive a turbine.
How big a turbine you ask, I have no Idea. it takes money to build brand new untested hardware and make it work.
And unfortunately I don't have a lot of extra money, so it's not developed 
So yes there are many ways to reclaim lost energy from heat, It's a matter of funding that makes it work or not

 

crazyoldfart

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Re: Electricity from heat exchangers?
« Reply #6 on: January 15, 2013, 11:54:58 PM »
Yes, it is many ways to harness the potential between two temperatures. What you mention are a very good way of doing it. I will consider using the groundwater which is only 2 meters below the surface under my house. Drill a hole and put some pipes down there. Water can circulate with a small pump and supply a sterling engine with constant temperature on one side, and a variable temperature on the other side. The good thing is that the engine works better in the winter time where the temperatures up here reach below -30 degrees celcius some times. The machine will generate enough power to heat up the house :)
Peltier devices may be a good alternative to heat exchanger if your outside temp gets real low. heat exchangers also work well with peltier devices when designed properly

Low-Q

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Re: Electricity from heat exchangers?
« Reply #7 on: January 16, 2013, 11:32:17 PM »
You can't.

You can extract energy from an environmental temperature difference, but there is absolutely no way to create a temperature difference using a heat exchanger then use that difference to generate more energy than was required to power the heat exchanger in the first place.
You're right. At least not in a closed insolated loop. I still believe it is possible in open air without violating any laws. Mechanical work out on expence of colder atmosphere - and it's lots of air to take that heat from. I'll bet that someone will figure out how ;-)

Vidar

jfilmmusic

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Re: Electricity from heat exchangers?
« Reply #8 on: January 25, 2013, 11:22:22 PM »
Reading everyone's comments in this thread inspired me to take some basic measurements on a simple heat engine - one that runs constantly in a normal household ambient environment, makes and uses only a ~2 degree temperature difference (by itself), and runs reliably 24/7 for months on end. To break it down I have made no attempt to create or use any available temperature difference to enhance the process, so I hope this is useful data.


Starting at the smallest scale using a tiny 6 inch 'drinking bird', which is successfully able to lift (in addition to it's own weight) a 6g ND magnet twice a minute by 7.62cm verified over several days, (attached underneath it's bottom, just for known weight, not magnetic properties):


Potential Energy (Work):
0.006kg * 9.8m/s * 0.0762m = 0.00448056 J (4.48mJ)


Power:
The lifting occurred on days with 60% average humidity about twice a minute (every 30 seconds):
0.00448056 J / 30s = 0.000149352 Watts  (0.149352mW)


Under these isolated, micro circumstances, it would take roughly 10,000 tiny 6 inch birds to create about 1.5 Watts of electricity. Yes, that would be absurd to scale it that way.


Luckily there are so many physical and chemical principals at play (check out the 'drinking bird' Wiki), it would seem there are many opportunities to re-think a system solely for the purpose of power generation. I read (and saw photos/videos) that an artist built a working 6.5 foot high version (vs the dainty 6 inch one tested here), which was again for 'art and novelty', not power generation. This shows at least the physical scalability.


However small at this level, it does show measurable, clean, free energy that runs reliably over long periods - and dosen't challenge any known science.


Hope this is of some relevance here.




Tom Booth

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Re: Electricity from heat exchangers?
« Reply #9 on: January 26, 2013, 03:53:27 AM »
You can't.

You can extract energy from an environmental temperature difference, but there is absolutely no way to create a temperature difference using a heat exchanger then use that difference to generate more energy than was required to power the heat exchanger in the first place.

Why wouldn't this work?

A heat engine converts heat into work, Right?

If, just for the sake of argument, or a place to start as an example, you have a very efficient heat engine that can convert 70% of the heat delivered to it into useful work output with 30% waste heat and a Heat Pump with a COP of 3 or higher.

The heat pump can remove 3 times more waste heat from the engine than the energy required to run the heat pump. (It can remove the 30% waste heat with just 10% of the heat engines 70% work output).

That leaves 60% work output from the heat engine to be used for other purposes such as generating electricity.

If the heat engine is running directly from ambient heat, then the heat pump is not needed as a source of heat/energy to run the engine. All it has to do is remove the waste heat not converted into work by the engine.

If you had an engine only 40% efficient leaving 60% waste heat to be removed, you would still only need 20% of the work output to remove the waste heat and have 20% left over for the production of electricity.

Heat pumps can have a COP of much grater than 3. Some are as high as 10.

And please say something other than it violates the second law of thermodynamics.

Low-Q

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Re: Electricity from heat exchangers?
« Reply #10 on: January 26, 2013, 11:21:32 PM »
I have been thinking of the very same thing as the drawing above. The heat pump is collecting heat from the air, just like a turbine collects kinetic energy from the waterfall. The waterfall is created by making a dam to collect all that water level, and a heat pump is using fans to collect heat from the air which is "focused" on a small area on the hot side of the pump.
The level below the dams upper edge is the maxium potential you can get from the water fall.
The temperature level between the surrounding air around the heat pump and the hot side of the pump is the maximum potential that is "dammed". The energy spent to make the temperature difference is so small that the environmental air will not be measurable affected by it.
The heat from the sun will be the water in the lake that continuously fill the "heat-dam".


So if a heat pump REALLY can supply 5 or 6 times more heat than what is supplied by the pump-motor itself, the calculation should be pretty straight forward whether this works or not.


I was told once that a heat pump with high COP was accordlingly inefficient as a heat engine. A heat pump with poor COP was accordingly more efficient as a heat engine. I know this because I asked the same question as here. However the answer was "You cannot get a selfrunning energy source because the high COP heat pump works as a very inefficient heat engine". I asked what if one of the heatpumps had very poor COP, and we reversed it to make a heat engine out of it, and ran it with a heat pump with very high COP. What then? I did not got that question answered.


Anyways, no matter how we understand this, energy MUST be conserved. If energy is not conserved with this idea, it will not work. Easy as that. I think it will work, AND that energy is conserved. It works just as well as a heat pump can supply more heat than the energy it consumes from the grid. That is at least my claim. No magic, no overunity, just pure conservative physics that works surprisingly well.


I think most sceptics say no because it appears to be overunity - while it's not. It remain to test this in practice. Anyone with a good and bad heat pump somewhere in Norway (Close to Oslo Airport Gardermoen)?


Vidar

Doug1

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Re: Electricity from heat exchangers?
« Reply #11 on: January 27, 2013, 03:27:52 PM »
Wow a very good line of argument. Havent seen that in a long time.
  Maybe you can use a small natural effect to lock onto a larger natural effect that amounts to something of size. How did they make gasses into liquid before they had liquid gasses in the first place to operate the refrigeration cycle to make the liquid gasses for you to argue about.

jfilmmusic

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Re: Electricity from heat exchangers?
« Reply #12 on: January 27, 2013, 08:42:33 PM »
Wow a very good line of argument. Havent seen that in a long time.
  Maybe you can use a small natural effect to lock onto a larger natural effect that amounts to something of size. How did they make gasses into liquid before they had liquid gasses in the first place to operate the refrigeration cycle to make the liquid gasses for you to argue about.
Nice, inspiring questions.
I like the 'nature bootstrap' concept. Are you hinting of water...(which boils at room temperature around 0.5psi)? A vacuum (anti-compression) evaporative cooling cycle using water as refrigerant, with roughly 0.2 or 0.14 psi (negative atm) vacuum? Kinetic evaporation...? Considering toxicity, ozone depletion, flammability, system efficiency (via modern enhancements) and design considerations...

Doug1

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Re: Electricity from heat exchangers?
« Reply #13 on: January 28, 2013, 02:34:45 PM »
Water gravity earth and solar 2 seperate systems. One above ground and one under it. In the middle under some sort of controled rate of contact in a insulated two sided ratiator plate lay a gang of peltires several layers thick between plates. The system in the air or above ground gainning extra heat from solar radiation in the sun hours and storing it in a mass or in batteries. The ground system rejecting the heat into the same hot storage above turning the ground into a cold reservouir below the frost line level 14 inches should do fine. Two preasure ,vaccume systems placed in two different environments. Controlling the rate of dissapation where the differences combine to act upon the peltires. Shared use of both for other domestic use would require proper size of thermal batteries <earth ,air storage>. Two pond systems have been considered but the soil is dense and generally colder then air in the summer.While it may be considered warm in comparison to the air in the winter it is by no means warm it's just not as cold. Experience dictates that storing heat in the ground is less effective because it dries out the soil eventually making it less effective, it then acts as an insulator.Conversley if water is frozen in the ground it takes it a long time to thaw out before it even has a chance to start drying out. Since each of the two systems runs independantly in a location which favors their individual tendancies it will work less to maintain a greater difference of temperature backed with additional input of the selected environments.Even a small system will be useful. If need be gloycol can be added as an antifreeze or other products. Freon is in my opinion only useful to reduce the size of a system to make a refrigerator for food that will fit in a kitchen. Even that is questionable against an amonia refrigerator considering the lower amount of energy to operate the later. People are wrongly afraid of amonia due to propaganda from chemical companies. More people die due to hart desease from eating fast food then do from stabbing the coils and releasing the gas in a frigde. When there is no more clean water to drink or gas for your car and food is in short supply you wont give a rats ass about what kind of refrigerant is in your house.
   Got off topic sorry.
 If your system is feeble as in it generates too little. Turn your feeble output into a receiver and learn how to amp up your antanna aperature to make a bubble as big as you can at a freq in tune with back ground noise. Its all about the antanna, size matters only in effective aperature. Physical size is a missnomer. You walk around and drive all the while yaking on your cell phone never giving thought to how the little piece of crap can reach out and get a signal and transmit with such ease inspite of how small it is. Or you use a GPS to add to your agrivation think about those distances. Thats a pretty serious antanna. You can do a lot with very little if your pointing it at something really big and they match electrically.