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Advanced Thermoelectric Materials for Efficient Waste Heat Recovery in Process Industries

Description: The overall objective of the project was to integrate advanced thermoelectric materials into a power generation device that could convert waste heat from an industrial process to electricity with an efficiency approaching 20%. Advanced thermoelectric materials were developed with figure-of-merit ZT of 1.5 at 275 degrees C. These materials were not successfully integrated into a power generation device. However, waste heat recovery was demonstrated from an industrial process (the combustion exhaust gas stream of an oxyfuel-fired flat glass melting furnace) using a commercially available (5% efficiency) thermoelectric generator coupled to a heat pipe. It was concluded that significant improvements both in thermoelectric material figure-of-merit and in cost-effective methods for capturing heat would be required to make thermoelectric waste heat recovery viable for widespread industrial application.
Date: January 6, 2009
Creator: Polcyn, Adam & Khaleel, Moe
Partner: UNT Libraries Government Documents Department

High Temperature Integrated Thermoelectric System and Materials

Description: The final goal of this project is to produce, by the end of Phase II, an all ceramic high temperature thermoelectric module. Such a module design integrates oxide ceramic n-type, oxide ceramic p-type materials as thermoelectric legs and oxide ceramic conductive material as metalizing connection between n-type and p-type legs. The benefits of this all ceramic module are that it can function at higher temperatures (> 700 C), it is mechanically and functionally more reliable and it can be scaled up to production at lower cost. With this all ceramic module, millions of dollars in savings or in new opportunities recovering waste heat from high temperature processes could be made available. A very attractive application will be to convert exhaust heat from a vehicle to reusable electric energy by a thermoelectric generator (TEG). Phase I activities were focused on evaluating potential n-type and p-type oxide compositions as the thermoelectric legs. More than 40 oxide ceramic powder compositions were made and studied in the laboratory. The compositions were divided into 6 groups representing different material systems. Basic ceramic properties and thermoelectric properties of discs sintered from these powders were measured. Powders with different particles sizes were made to evaluate the effects of particle size reduction on thermoelectric properties. Several powders were submitted to a leading thermoelectric company for complete thermoelectric evaluation. Initial evaluation showed that when samples were sintered by conventional method, they had reasonable values of Seebeck coefficient but very low values of electrical conductivity. Therefore, their power factors (PF) and figure of merits (ZT) were too low to be useful for high temperature thermoelectric applications. An unconventional sintering method, Spark Plasma Sintering (SPS) was determined to produce better thermoelectric properties. Particle size reduction of powders also was found to have some positive benefits. Two composition systems, specifically 1.0 SrO ...
Date: June 6, 2011
Creator: Chu, Mike S. H.
Partner: UNT Libraries Government Documents Department

RTG Impact Response to Hard Landing During Mars Environmental Survey (MESUR) Mission

Description: The National Aeronautics and Space Administration (NASA) is studying a seven-year robotic mission (MESUR, Mars Environmental Survey) for the seismic, meteorological, and geochemical exploration of the Martian surface by means of a network of ~16 small, inexpensive landers spread from pole to pole. To permit operation at high Martian latitudes, NASA has tentatively decided to power the landers with small RTGs (Radioisotope Thermoelectric Generators). To support the NASA mission study, the Department of Energy's Office of Special Applications commissioned Fairchild to perform specialized RTG design studies. Those studies indicated that the cost and complexity of the mission could be significantly reduced if the RTGs had sufficient impact resistance to survive ground impact of the landers without retrorockets. Fairchild designs of RTGs configured for high impact resistance were reported previously. Since the, the size, configuration, and impact velocity of the landers and the power level and integration mode of the RTGs have changed substantially, and the previous impact analysis has been changed substantially, and the previous impact analysis has been updated accordingly. The analytical results, reported here, indicate that a lander by itself experiences much higher g-loads than the lander with an integral penetrator; but that minor modifications of the shape of the lander can very substantially reduce the maximum g-load during landing, thus eliminating the need for retrorockets for RTG survival. There are three copies in the file and the Original Artwork is stored in the ESD files.
Date: March 6, 1992
Creator: Schock, Alfred & Mukunda, Meera
Partner: UNT Libraries Government Documents Department

Design Optimization of Radionuclide Nano-Scale Batteries

Description: Radioisotopes have been used for power sources in heart pacemakers and space applications dating back to the 50's. Two key properties of radioisotope power sources are high energy density and long half-life compared to chemical batteries. The tritium battery used in heart pacemakers exceeds 500 mW-hr, and is being evaluated by the University of Florida for feasibility as a MEMS (MicroElectroMechanical Systems) power source. Conversion of radioisotope sources into electrical power within the constraints of nano-scale dimensions requires cutting-edge technologies and novel approaches. Some advances evolving in the III-V and II-IV semiconductor families have led to a broader consideration of radioisotopes rather free of radiation damage limitations. Their properties can lead to novel battery configurations designed to convert externally located emissions from a highly radioactive environment. This paper presents results for the analytical computational assisted design and modeling of semiconductor prototype nano-scale radioisotope nuclear batteries from MCNP and EGS programs. The analysis evaluated proposed designs and was used to guide the selection of appropriate geometries, material properties, and specific activities to attain power requirements for the MEMS batteries. Plans utilizing high specific activity radioisotopes were assessed in the investigation of designs employing multiple conversion cells and graded junctions with varying band gap properties. Voltage increases sought by serial combination of VOC s are proposed to overcome some of the limitations of a low power density. The power density is directly dependent on the total active areas.
Date: October 6, 2004
Creator: Schoenfeld, D.W.; Tulenko, J.S.; Wang, J. & Smith, B.
Partner: UNT Libraries Government Documents Department

Thulium-170 heat source

Description: An isotopic heat source is formed using stacks of thin individual layers of a refractory isotopic fuel, preferably thulium oxide, alternating with layers of a low atomic weight diluent, preferably graphite. The graphite serves several functions: to act as a moderator during neutron irradiation, to minimize bremsstrahlung radiation, and to facilitate heat transfer. The fuel stacks are inserted into a heat block, which is encased in a sealed, insulated and shielded structural container. Heat pipes are inserted in the heat block and contain a working fluid. The heat pipe working fluid transfers heat from the heat block to a heat exchanger for power conversion. Single phase gas pressure controls the flow of the working fluid for maximum heat exchange and to provide passive cooling.
Date: September 6, 1990
Creator: Walter, C.E.; Van Konynenburg, R. & VanSant, J.H.
Partner: UNT Libraries Government Documents Department

Radioisotopes for heat-source applications

Description: Potential DOD requirements for noninterruptable power sources could total 1 MW thermal by FY 1990. Of the three isotopes considered, (/sup 90/Sr, /sup 147/Pm, /sup 238/Pu) /sup 90/Sr is the only one available in sufficient amounts to meet this requirement. To meet the DOD FY 1990 requirements, it would be necessary to undertake /sup 90/Sr recovery operations from spent fuel reprocessing at SRP, Hanford, and the Barnwell Nuclear Fuels Plant (BNFP). /sup 90/Sr recovery from the existing alkaline high level waste (HLW) at Hanford and SRP is not attractive because the isotopic purity of the /sup 90/Sr is below that required for DOD applications. Without reprocessing LWR spent fuel, SRP and Hanford could not supply the demand of 1 MW thermal until FY 1996. Between FY 1983 and FY 1996, SRP and Hanford could supply approximately 0.70 MW of /sup 90/Sr and 0.15 MW of /sup 147/Pm. SRP could supply an additional 0.15 MW from the production and recovery of /sup 238/Pu. Strontium-90 is the most economical of the three heat source radionuclides considered. The /sup 90/Sr unit recovery cost from SRP fresh acid waste would be $180/watt. The BNFP /sup 90/Sr recovery cost would be $130/watt to $235/watt depending on the age and burnup of the LWR spent fuel. Hanford /sup 90/Sr recovery costs form Purex fresh acid waste are unavailable, but they are expected to be comparable to the SRP costs. /sup 147/Pm and /sup 238/Pu are considerably more expensive heat source materials. /sup 147/Pm recovery costs at SRP are estimated to be $450/watt. As with /sup 90/Sr, the Hanford /sup 147/Pm recovery costs are expected to be comparabl to the SRP costs. Production of high assay (93.5%) /sup 238/Pu at SRP from excess /sup 231/Np would cost about $1160/watt, while recovery of low assay (27%) /sup 238/Pu ...
Date: October 6, 1982
Creator: Hoisington, J.E.
Partner: UNT Libraries Government Documents Department

Nuclear fuel element

Description: A nuclear fuel element and a method of manufacturing the element. The fuel element is comprised of a metal primary container and a fuel pellet which is located inside it and which is often fragmented. The primary container is subjected to elevated pressure and temperature to deform the container such that the container conforms to the fuel pellet, that is, such that the container is in substantial contact with the surface of the pellet. This conformance eliminates clearances which permit rubbing together of fuel pellet fragments and rubbing of fuel pellet fragments against the container, thus reducing the amount of dust inside the fuel container and the amount of dust which may escape in the event of container breach. Also, as a result of the inventive method, fuel pellet fragments tend to adhere to one another to form a coherent non-fragmented mass: this reduces the tendency of a fragment to pierce the container in the event of impact. 1 fig., 1 tab.
Date: April 6, 1989
Creator: Zocher, R.W.
Partner: UNT Libraries Government Documents Department

Thermionic converter emitter support arrangement

Description: This document discusses a support provided for use in a thermionic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end is supported by a spring structure that includes a pair of Belleville springs, and the spring structure is supported by a support structure fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element at the front end, a larger metal main support at the rear end that is attached to the housing, and with a ceramic layer between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer captured between the Belleville springs. 7 figs.
Date: July 6, 1989
Creator: Allen, D.T.
Partner: UNT Libraries Government Documents Department