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Talk-Polywell.org • cheap, high performance, thermo electric material discoverd
Page 1 of 3

cheap, high performance, thermo electric material discoverd

Posted: Wed Apr 16, 2014 10:26 pm
by ohiovr
http://news.sciencemag.org/chemistry/20 ... oing-waste

Assuming it has a temperature range between 300 and 600 K, efficiency could be as high as 19% which is comparable to an internal combustion engine, but with some not so obvious advantages.

Re: cheap, high performance, thermo electric material discov

Posted: Wed Apr 16, 2014 11:10 pm
by ohiovr
I was wrong:

http://www.nature.com/nature/journal/v5 ... 13184.html

It has a upper temperature limit of 923 K (211 K away from its melting point) and therefor a absolute efficiency of 27%

Re: cheap, high performance, thermo electric material discov

Posted: Wed Apr 16, 2014 11:37 pm
by ladajo
This is definitely something that makes me go "hmmmm".

Re: cheap, high performance, thermo electric material discov

Posted: Thu Apr 17, 2014 12:00 am
by Skipjack

Re: cheap, high performance, thermo electric material discov

Posted: Thu Apr 17, 2014 12:13 am
by ohiovr

Re: cheap, high performance, thermo electric material discov

Posted: Thu Apr 17, 2014 5:35 am
by D Tibbets
Some comparisons might be in order. My recollection is that typical thermoelectric devices are at best 2-3% efficient. If something can increase that 10 fold,that would be tremendous. The poorly performing and power hungry piezoelectric coolers/ heaters would be revolutionized. Spacecraft thermoelectric batteries also.

I suspect such a device may not replace camshafts or turbines for converting fuel energy into mechanical energy, but if they work at appropriate temperatures they could supplement the efficiency considerably. Instead of 30-40% efficiencies a combined efficiency of 50-70% might be possible. A coal fired power plant might increase output by hundreds of Megawatts without burning more coal. The only modification may just be cutting into the steam line past the low pressure turbine and diverting it to thermoelectric converters. The costs may be modest with the added benefit of less waste heat management resources needed. I could even see it applied to spent fuel rods once they cooled some, and provide additional (nuclear battery) power.

Even in a fusion reactor it would narrow the gap between a thermal steam plant and a direct conversion scheme. In a space craft it might eliminate the need for a steam plant in a D-T or D-D reactor, and perhaps decrease the radiator requirements for any given electrical output, even for a direct conversion reactor.. Using the Mars Curiosity rover, or the Saturn and Jupiter or Voyager, or New Dawns probes, the available energy available could be significantly increased while also significantly decreasing the weight and radiator needs of the nuclear batteries.

Dan Tibbets

Re: cheap, high performance, thermo electric material discov

Posted: Thu Apr 17, 2014 7:02 pm
by Diogenes

Re: cheap, high performance, thermo electric material discov

Posted: Fri Apr 18, 2014 2:36 am
by Aero

Re: cheap, high performance, thermo electric material discov

Posted: Fri Apr 18, 2014 12:55 pm
by ladajo
This is an important consdieration. The normal running load of an average vehicle does not come anywhere close to attached generator (alternator) capacity.
It is sized to support battery load and abnormal operating conditions, such as all lighting active and battery charging at high rate.
This flyweight, even unloaded, creates significant drag and efficiency loss on the engine. Alternators do not have clutches like AC Compressors do.

Even placement of conformal solar panels on vehicles has the potential to significant reduce fuel burn in the aggregate. Especially if one attaches this idea to clutching out the alternator (generator) when using solar to supply low to medium system loads.

Note that the idea of using solar with a clutched generator/alternator is my idea alone. I claim rights to it here and now. :)

Re: cheap, high performance, thermo electric material discov

Posted: Fri Apr 25, 2014 7:28 pm
by Tom Ligon
If I didn't have so many things that need doing today, I'd fire up the guarded hot plate sitting next to me with a bismuth telluride peltier device in it. I've already calibrated a handful of them as heat flow sensors, a job they do especially nicely.

What I've been meaning to do is load the devices down to measure power delivery instead of just voltage output. There are a lot of people toying with them as thermoelectric generators, but I've seen very little on their efficiency. I'm thinking of sticking a set on a heatsink and mounting it on the back of one of my photovoltaic arrays to scavenging waste heat.

These are commonly available and about two orders of magnitude cheaper than Omega HFS-3 thin film thermopiles, with about two orders of magnitude better output. But they're only rated to a temperature of about 90 C. Good for solar scavenging, not so good on the wood stove.

Re: cheap, high performance, thermo electric material discov

Posted: Sat Apr 26, 2014 11:22 am
by GIThruster
IIUC, this will operate as a heater, a cooler and a thermal to electric transducer so it's pretty utilitarian stuff. It is essentially a nano-peltier device, that operates as it does because of the staggered n and p junction atoms. Note importantly, that because of this molecular structure, this can only be had in single crystal. Even anisotropic thin films do not display this kind of ordering. So they may call this "cheap" but it's many tens of thousands of crystal growth tanks away from ever being used for something like scavenging energy from an exhaust. Without investment in huge numbers of tanks, which is maybe even a billion dollar investment; these crystals are going to remain on the order of thousands of dollars/cc.

I think N-G has the largest dielectric crystal growth facility in the world and they have a couple hundred tanks. That's not enough to build exhaust systems at an affordable rate.

This has however, a multitude of applications that come before scavenging heat. Just being able to heat and cool in such a tiny package has real value. Look at where peltiers are already being used and you'll find the first applications. If this is really 27% efficient, it would enable the hottest chips to run unhindered on just a watt of power. That's enough for the next breakthrough in computing.

Re: cheap, high performance, thermo electric material discov

Posted: Sun Apr 27, 2014 1:30 am
by Tom Ligon
I did a little more looking into this article yesterday. I know some preppers interested in making thermoelectric generators (make power from you wood stove, etc.) I've got about 20 40 mm Peltier coolers that I've been working with as heat flow sensors. They're thermopiles, and can be used as thermoelectric generators. I've been paying about $5 each for them but you can get under $3.

The common bismuth telluride Peltier devices act as TEGs at about 4% efficiency, and can handle around 250 C. That's enough to be useful. A jump to, what did they say ... 19% ... is revolutionary.

Re: cheap, high performance, thermo electric material discov

Posted: Sun Apr 27, 2014 1:44 am
by ohiovr

Re: cheap, high performance, thermo electric material discov

Posted: Sun Apr 27, 2014 1:47 am
by ohiovr

Re: cheap, high performance, thermo electric material discov

Posted: Sun Apr 27, 2014 2:23 am
by Tom Ligon
I've been getting them here:

http://www.mpja.com/Thermoelectric-Cool ... 30207%20PM

But the TEC1-12706 can be found on e-bay for less.

As a heat flow sensor the output voltage seems to be perfectly linear with heat flow.

I was surprised they can run this hot. As heater/coolers they're rated for 90 C max on the hot side. I've been thinking of putting them on the back of PV panels to use the waste heat to boost overall efficiency. Plus, cooling a PV panel boosts the efficiency a little anyway. But at 19% or better, why bother with the PV?

One digit change in the part number and you get data on it as a TEG in this abstract:

Title: Thermoelectric Power Generation System Using Waste Heat from Biomass Drying
Authors: Maneewan, S.; Chindaruksa, S.

Affiliation: AA(Department of Physics, Faculty of Science, Thermal Energy and Energy Conservation Promotion Research Unit, Naresuan University), AB(Department of Physics, Faculty of Science, Thermal Energy and Energy Conservation Promotion Research Unit, Naresuan University)
Publication: Journal of Electronic Materials, Volume 38, Issue 7, pp.974-980
Publication Date: 07/2009
Origin: CROSSREF; SPRINGER

Keywords: Thermoelectric, power generation, biomass drying
DOI: 10.1007/s11664-009-0820-5

Bibliographic Code: 2009JEMat..38..974M

Abstract
This paper looks at thermoelectric power generation from waste heat from a biomass drier. In this study, the researchers selected four thermoelectric modules: two thermoelectric cooling modules (Model A: MT2-1,6-127 and Model B: TEC1-12708) and two thermoelectric power generation modules (Model C: TEP1-1264-3.4 and Model D: TEG1-1260-5.1) for testing at temperatures between 25°C and 230°C. Test results indicated that the thermoelectric TEC1-12708 could generate a maximum power output of 1 W/module and TEP1-1264-3.4, TEG1-1260-5.1, and MT2-1,6-127 could generate 1.07 W/module, 0.88 W/module, and 0.76 W/module, respectively. Therefore, the thermoelectric cooling of TEC1-12708 was appropriate to use for thermoelectric power generation from waste heat. The experiments used four ventilation fans (6 W, 2.50 m3/s) and 12 thermoelectric modules which were installed in the back of a charcoal brazier. The experiments were conducted and tested in conditions of recycling 100%, 75%, 50%, and 25% of outlet air. Testing results identified that the temperatures of the drying room were 81°C, 76°C, 70°C, and 64°C, respectively. The power generation system could generate about 22.4 W (14 V, 1.6 A) with an air flow of 9.62 m3/s. The thermoelectric module can convert 4.08% of the heat energy to electrical energy.