View Full Version : Waste heat in to energy using Magnetic Piston Generator
10th Aug 05, 3:02 PM
This little gadget I found at Free Energy News (http://freeenergynews.com/), it "can use fuel combustion or low-boiling-point working fluids to convert heat energy into high-pressure gases that propel its "Magnetic Piston" at high velocities, back-and-forth, through a linear alternator to generate usable electricity." Full Article (http://peswiki.com/index.php/Directory:Accelerated_Magnetic_Piston_Generator)
I see this as being able to help make a lot of places, like power plants, factories or anything that makes a lot of heat, more energy efficent. Since they would be making some power not just taking in power, cutting down power bills and making things cheaper. What do you all think?
10th Aug 05, 5:54 PM
Heh, that's pretty sexy. I spent about ten minutes trying to take out the valves but I don't think it can be done without making some kind of gravity design which you'd have trouble with anyway because the piston would tend to find an equilibrium point somewhere in a vertical situation. Seeing as it's basically "free energy," that is, waste heat, it's nice that someone is capitalizing on it.
10th Aug 05, 6:14 PM
Perhaps I'm missing something, but apart from requiring a more complicated setup how is this any better than a regular ol' generator? Both move magnets in wire coils, but the generator has the advantage of only needing the gas to flow in one direction to maintain rotational velocity.
From the website:
In a typical internal combustion piston engine (which powers virtually every car and truck in the world), pistons are attached to a crankshaft via connecting rods, which transform the linear reciprocating motion of the pistons into steady rotary crankshaft motion.
This rotary power take-off may be useful to turn gears, drive vehicles and power factory processes, but if the primary purpose of the internal combustion engine is to generate electric power, then this linear-to-rotary transformation is unnecessary and inherently inefficient, because a substantial portion of the mechanical work produced is lost due to the lateral forces imposed by the crankshaft and the internal friction generated by these variously moving parts, which in turn must then be separately connected to a generator rotor to produce electricity.
By eliminating the complex piston-crank mechanism of an internal combustion engine, the MPG's simpler linear motor/generator configuration directly utilizes and transforms the linear motion of its accelerated magnetic piston into electrical power, thus eliminating the need for multiple pistons, connecting rods, the crankshaft and other friction-causing, energy-consuming rotating components required by conventional combustion engines. With fewer moving parts, the MPG can offer increased engine fuel-efficiency and operating reliability in a smaller, yet more powerful and lower-weight engine/generator package that can be manufactured at a lower cost.Now I'm just confused.
10th Aug 05, 9:17 PM
A part of the force created in an internal combution engine is bled off in the process of turning the crank shaft, some of the energy is lost in that conversion, also heat is a by product of not just the combustion but also the turning/moving parts.
What this device does is allow for MORE of the energy to be captured but the way the device is built.
10th Aug 05, 10:09 PM
There are actually numerous designs for machines that can convert waste heat back to useable energy. I think a cooler one is this (http://www.sciencedaily.com/releases/1999/05/990527043210.htm).
10th Aug 05, 10:14 PM
That's what's confusing: the article isn't talking about building a better engine-generator, the only application where the quoted paragraphs would make sense. Despite that fact, such engine-generator setups are only useful when economies of scale prohibit the use of intermediary liquids, nullifying the claim that "any heat source" could be used.
11th Aug 05, 3:38 AM
Polly, if you were to plug this onto, say, a car's tailpipe it would decrease the efficiency of the car because it effectively backs up the exhaust and makes it harder to clear from the cylinder. However, slap it onto a coal or paper plant, say, where the exhaust is put to pasture twelve ways to Sunday before being released into the atmosphere anyway (that is, the hot gas is processed through scrubbers and whatnot) and backup is less of an issue, and you're just taking good advantage of a steady and otherwise wasted supply of hot gas.
The whole tie-in to rotary engines is just an explanation that there are fewer steps in the conversion of pressure to mechanical energy to electricity because you're not trying to make anything spin, so it's (I guess) significantly more efficient than trying to process waste gas through a turbine to generate electricity.
Put it on top of a CPU and use the 100W of thermal waste power to gain some extra juice for your gfx card...
Meh.. Sink the computer into liquid nitrogen, and overclock everythg 5GHz past the recomended operating speed... :P
Anywho, this looks like it could have some cool uses.
11th Aug 05, 7:08 AM
I think you all are missing the point. This engine requires volatile gases, just as other heat engines do. You can't slap it onto anything that makes heat, because it still must obey the efficiency limitations that every other (http://en.wikipedia.org/wiki/Heat_engines) heat engine abides by. Want to put it on your CPU? Sure, but on a cold day (0 C) with an average CPU temp (37 C) you're looking at a theoretical max of 12% efficiency. So even with a Carnot heat engine, (http://en.wikipedia.org/wiki/Carnot_cycle) the best of all possible engines, you'll get no more than 12W back. The energy savings won't even pay for the cost to maintain the thing, much less pay back your investment in purchasing it. Paper plants and other industries probably already have looked into attaching turbines to their waste heat outputs but it wouldn't be economically viable.
This is not a revolutionary idea, people. This is not a solid-state generator, it obeys the laws and limitations that all other heat engines do. It's no magic bullet, useful in every situation. It gives us nothing that is better or worse than any other engine on the market. Neat though it is to contemplate, there is no free lunch.
11th Aug 05, 7:43 AM
Who said there was, Polly?
Your assertion that turbines wouldn't be economically viable is evidenced by the lack of turbines everywhere. However this device is more cost effective than a turbine, because under the best cirumstances where the valves are automatically timed by the movement of the piston, it has like eight simple moving parts. It still may not be economically viable, but without numbers it's impossible to judge.
As far as volatile gases go, it'd be nice to see one of thes run a hybrid electric car, unfortunately the best models will rely on the torque from the rotary engine when it's needed.
Edit: got it down to four simple moving parts.
11th Aug 05, 11:52 AM
This won't reduce emissions at all, at least, not significantly. What it will do is increase the return on those emissions.
Use any large factory putting something out a smokestack, and plug one of these into the flow. It won't add anything to the emissions since that's what it's using to power the turbine, but it will generate some more electricity off the discharge. There's no combustion or anything.
11th Aug 05, 1:39 PM
I think Polly was arguing that in order for it to be remotely useful you'd have to turn the cylinder into an internal combustion engine. I'm saying he might be right but we don't know. Again, it will work as described, in line with exhaust from a factory, but we don't know if it would be worth the time and effort to buy them, hook them up, and maintain them. Which is fair, but a little poo-headed. :p
11th Aug 05, 1:59 PM
There would be a limit on the amount of power you could attract from the exhaust too. If you pipe away too much heat from something like a chimney stack, it stops working as a chimney because there isn't sufficient convection to maintain a draft/suction. If you take too much pressure out of an exhaust to power these pistons, then something bad will happen (not sure what though).
11th Aug 05, 4:51 PM
Why in sam hell would you need to turn it into a combustion engine? Are windmills combustion engines? Hydro power?
You wouldn't solve the worlds problems forever with this, but you might get a little extra energy for your emission. Every little bit of efficiency helps, especially since this is a very very simple mechanism. It's not like you're going to need a PHD to make sure the valves are clean once every few months, and the device is one of the simplest current generators.
The website oversells it, sure. But that doesn't mean the idea is invalid and the creators should be burned at the stake for their crimes against thermodynamics. It will work, just not as well as advertised. Is that really a surprise?
11th Aug 05, 5:19 PM
It may actually work, but at what cost to efficiency of the carnot cycle of the heat engine it is attached to? There is always a cost, a coil around a hot exhaust system will generate electrical power, but it causes the exhaust to slow down, which can back things up and adversely affect the heat source.
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