PDF Publication Title:
Text from PDF Page: 107
D APPENDIX D: TECHNOLOGY SOLUTIONS FOR ENERGY RECOVERY This same current pumps heat within the thermoelectric device due to the Peltier effect, which lowers the initial temperature differential when the current is zero. Part of the heat energy, H, through the Seebeck-generated current, is converted to Joule heating within the legs of the thermoelectric device. The efficiency, n, for a power generator is the output power, I2RL, divided by H. It can be shown that &T'T#$ 1+ZT'1! (max=$1 0!$ T! (4) &# T % 1 "$1+ZT+0! %1" where the first term is the Carnot efficiency. The second term contains T, which is the average temperature of the leg. The Z is the figure of merit of the semiconductor legs; it represents a “quality factor” of the material to perform as a thermoelectric device. Recent Developments in Thermoelectric Materials Thermoelectric materials are of interest for application as heat pumps and power generators. The performance of thermoelectric devices is quantified by a figure of merit, ZT, as previously described. A material with a figure of merit of around unity was first reported over four decades ago, but since then – despite investigation of various approaches – there has been only modest progress in finding materials with enhanced ZT values at room temperature. In 2001, Rama Venkatasubramanian and co-workers at the Research Triangle Institute in North Carolina reported that thin-film thermoelectric materials demonstrate a significant enhancement of ZT at 300 K, compared to bulk Bi2Te3 alloys. This amounts to a maximum observed factor of 2.4 for p-type Bi2Te3/Sb2Te3 superlattice devices. The enhancement is achieved by controlling the transport of phonons and electrons in the superlattices. High atomic weight reduces the speed of sound in the material, and thereby decreases the thermal conductivity. Although it is possible in principle to develop bulk semiconductors with ZT > 3, there are no candidate materials on the horizon. Preliminary devices exhibit significant cooling (32 K at around RT) and the potential to pump a heat flux of up to 700 W/cm2; the localized cooling and heating occurs some 23,000 times faster than in bulk devices. Most commercial thermoelectric devices are for cooling. Venkatasubramanian’s group has found a way to greatly increase the amount and speed of heating or cooling using superlattices: stacks of very thin films of two alternating superconducting materials. It is reported that the material properties, as measured by ZT, are 2.5 times better than the current state of the art, have been verified by more than one method, and are useful at room temperature. Previously, it had been widely assumed that a thermoelectric “barrier” existed with a ZT = 1. Another encouraging development has been by Hsu et al., in a report describing AgPbmSbTe2+m with a ZT ~2 at 800 K for m = 18. Although the temperature may be too high for refrigeration, it is appropriate for power generation. What is interesting, however, is the discovery that this material contains regions 2 to 4 nm in size that are rich 104 TPDF Image | Analysis for Recovering Energy from Industrial Waste Heat
PDF Search Title:
Analysis for Recovering Energy from Industrial Waste HeatOriginal File Name Searched:
PNNL_15803.pdfDIY PDF Search: Google It | Yahoo | Bing
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
IT XR Project Redstone NFT Available for Sale: NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Be part of the future with this NFT. Can be bought and sold but only one design NFT exists. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Turbine IT XR Project Redstone Design: NFT for sale... NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Includes all rights to this turbine design, including license for Fluid Handling Block I and II for the turbine assembly and housing. The NFT includes the blueprints (cad/cam), revenue streams, and all future development of the IT XR Project Redstone... More Info
Infinity Turbine ROT Radial Outflow Turbine 24 Design and Worldwide Rights: NFT for sale... NFT for the ROT 24 energy turbine. Be part of the future with this NFT. This design can be bought and sold but only one design NFT exists. You may manufacture the unit, or get the revenues from its sale from Infinity Turbine. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Supercritical CO2 10 Liter Extractor Design and Worldwide Rights: The Infinity Supercritical 10L CO2 extractor is for botanical oil extraction, which is rich in terpenes and can produce shelf ready full spectrum oil. With over 5 years of development, this industry leader mature extractor machine has been sold since 2015 and is part of many profitable businesses. The process can also be used for electrowinning, e-waste recycling, and lithium battery recycling, gold mining electronic wastes, precious metals. CO2 can also be used in a reverse fuel cell with nafion to make a gas-to-liquids fuel, such as methanol, ethanol and butanol or ethylene. Supercritical CO2 has also been used for treating nafion to make it more effective catalyst. This NFT is for the purchase of worldwide rights which includes the design. More Info
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
Infinity Turbine Products: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. May pay by Bitcoin or other Crypto. Products Page... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)