Liquid droplet radiator program at the NASA Lewis Research Center

The NASA Lewis Research Center and the Air Force Rocket Propulsion Laboratory (AFRPL) are jointly engaged in a program for technical assessment of the Liquid Droplet Radiator (LDR) concept as an advanced high performance heat ejection component for future space missions. NASA Lewis has responsibility for the technology needed for the droplet generator, for working fluid qualification, and for investigating the physics of droplets in space; NASA Lewis is also conducting systems/mission analyses for potential LDR applications with candidate space power systems. For the droplet generator technology task, both micro-orifice fabrication techniques and droplet stream formation processes have been experimentally investigated. High quality micro-orifices (to 50 micron diameter) are routinely fabricated with automated equipment. Droplet formation studies have established operating boundaries for the generation of controlled and uniform droplet streams. A test rig is currently being installed for the experimental verification, under simulated space conditions, of droplet radiation heat transfer performance analyses and the determination of the effect radiative emissivity of multiple droplet streams. Initial testing has begun in the NASA Lewis Zero-Gravity Facility for investigating droplet stream behavior in microgravity conditions. This includes the effect of orifice wetting on jet dynamics and droplet formation. Results for both Brayton and Stirling power cycles have identified favorable mass and size comparisons of the LDR with conventional radiator concepts

Structure of bryozoan communities in an Antarctic glacial fjord (Admiralty Bay, South Shetlands)

Bryozoans are among the most important groups of the Southern Ocean benthic macrofauna, both in terms of species richness and abundance. However, there is a considerable lack of ecological research focused on their distribution patterns and species richness on smaller scale, especially in the soft bottom habitats of Antarctic glacial fjords. The aim of this study was to describe those patterns in the Admiralty Bay. Forty-nine Van Veen grab samples were collected at the depth range from 15 to 265 m, in the summer season of 1979/1980, at three sites distributed along the main axis of the fjord. Among 53 identified species of bryozoans, 32 were recorded in the Admiralty Bay for the first time. The most common and abundant species were Himantozoum antarcticum, Inversiula nutrix and Nematoflustra flagellata. Genera such as Arachnopusia, Cellarinella and Osthimosia were the most speciose taxa. It was demonstrated that depth was important for the distribution of the bryozoans. More than half of the recorded species were found only below 70 m. An influence of glacial disturbance was reflected in the dominance structure of colony growth-forms. The inner region of the fjord was dominated almost entirely by encrusting species, while the diversity of bryozoan growth-forms in less disturbed areas was much higher. In those sites the highest percentage of branched, tuft like species represented by buguliform and flustriform zoaria was observed.The study was supported by a grant of Polish Ministry of Science and Higher Education No. 51/N-IPY/2007/0 as well as Census of Antarctic Marine Life Project. Krzysztof Pabis was also partially supported by University of Lodz internal funds. This research was also supported by the Polish Geological Institute-National Research Institute during the realization of the project numbered 40.2900.0903.18.0 titled “Bryozoan assemblage of Admiralty Bay—richness, diversity and abundance.” Urszula Hara is deeply grateful to Leszek Giro (Micro-area Analyses Laboratory at the Polish Geological Institute-National Research Institute, Warsaw), for providing SEM assistance during the project. We also want to thank two anonymous reviewers for their suggestions that helped us improve this article. Thanks are also due to Magdalena Błażewicz-Paszkowycz for language correction and polishing the final version of the manuscript

NOVEL TECHNOLOGIES FOR GASEOUS CONTAMINANTS CONTROL

Overall objective of this project was to develop a technology platform for cleaning/conditioning the syngas from an integrated gasification combined cycle (IGCC) system at elevated temperatures (500-1,000 F) and gasifier pressures to meet the tolerance limits for contaminants, including H{sub 2}S, COS, NH{sub 3}, HCl, Hg, and As. This technology development effort involved progressive development and testing of sorbent/catalytic materials and associated processes through laboratory, bench, pilot, and demonstration testing phases, coupled with a comprehensive systems analysis at various stages of development. The development of the regenerable RTI-3 desulfurization sorbent - a highly attrition-resistant, supported ZnO-based material - was the key discovery in this project. RTI-3's high attrition resistance, coupled with its high reactivity, effectively allowed its application in a high-velocity transport reactor system. Production of the RTI-3 sorbent was successfully scaled up to an 8,000-lb batch by Sued-Chemie. In October 2005, RTI obtained U.S Patent 6,951,635 to protect the RTI-3 sorbent technology and won the 2004 R&D 100 Award for development of this material. The RTI-3 sorbent formed the basis for the development of the High-Temperature Desulfurization System (HTDS), a dual-loop transport reactor system for removing the reduced sulfur species from syngas. An 83-foot-tall, pilot HTDS unit was constructed and commissioned first at ChevronTexaco's gasification site and later at Eastman's gasification plant. At Eastman, the HTDS technology was successfully operated with coal-derived syngas for a total of 3,017 hrs over a 12-month period and consistently reduced the sulfur level to <10 ppmv. The sorbent attrition rate averaged {approx}31 lb/MM lb of circulation. To complement the HTDS technology, which extracts the sulfur from syngas as SO{sub 2}, RTI developed the Direct Sulfur Recovery Process (DSRP). The DSRP, operating at high pressure and high temperature, uses a small slipstream of syngas to catalytically reduce the SO{sub 2} produced in the warm syngas desulfurization process to elemental sulfur. To demonstrate this process at Eastman, RTI constructed and commissioned a skid-mounted pilot DSRP unit. During its 117-h operation, the DSRP system achieved 90% to 98% removal of the inlet sulfur. The DSRP catalyst proved very robust, demonstrating consistent reaction rates in multiple experiments over a 3-year period. Sorbent materials for removing trace NH{sub 3}, Hg, and As impurities from syngas at high temperature and high pressure were developed and tested with real syngas. A Li{sub 4}SiO{sub 4} sorbent for removal of CO{sub 2} from syngas at high temperature was also developed and tested. The Li{sub 4}SiO{sub 4} material demonstrates excellent CO{sub 2} removal, but its regeneration was found to be technically challenging. Additionally, reverse-selective polymer membrane materials were investigated for the bulk removal of CO{sub 2} and H{sub 2}S from syngas. These materials exhibited adequate separation at ambient conditions for these acid gases. Field testing of these membrane modules with real syngas demonstrated potential use for acid-gas separation from syngas. The HTDS/DSRP technologies are estimated to have a significant economic advantage over conventional gas cleanup technologies such as Selexol{trademark} and Rectisol. From a number of system studies, use of HTDS/DSRP is expected to give a 2-3 percentage point increase in the overall IGCC thermal efficiency and a significant reduction in capital cost. Thus, there is significant economic incentive for adaptation of these warm gas cleanup technologies due to significantly increased thermal efficiency and reduction in capital and operating costs. RTI and Eastman are currently in discussions with a number of companies to commercialize this technology

Novel Technologies for Gaseous Contaminants Control

Overall objective of this project was to develop a technology platform for cleaning/conditioning the syngas from an integrated gasification combined cycle (IGCC) system at elevated temperatures (500-1,000 F) and gasifier pressures to meet the tolerance limits for contaminants, including H{sub 2}S, COS, NH{sub 3}, HCl, Hg, and As. This technology development effort involved progressive development and testing of sorbent/catalytic materials and associated processes through laboratory, bench, pilot, and demonstration testing phases, coupled with a comprehensive systems analysis at various stages of development. The development of the regenerable RTI-3 desulfurization sorbent - a highly attrition-resistant, supported ZnO-based material - was the key discovery in this project. RTI-3's high attrition resistance, coupled with its high reactivity, effectively allowed its application in a high-velocity transport reactor system. Production of the RTI-3 sorbent was successfully scaled up to an 8,000-lb batch by Sued-Chemie. In October 2005, RTI obtained U.S Patent 6,951,635 to protect the RTI-3 sorbent technology and won the 2004 R&D 100 Award for development of this material. The RTI-3 sorbent formed the basis for the development of the High-Temperature Desulfurization System (HTDS), a dual-loop transport reactor system for removing the reduced sulfur species from syngas. An 83-foot-tall, pilot HTDS unit was constructed and commissioned first at ChevronTexaco's gasification site and later at Eastman's gasification plant. At Eastman, the HTDS technology was successfully operated with coal-derived syngas for a total of 3,017 hrs over a 12-month period and consistently reduced the sulfur level to <10 ppmv. The sorbent attrition rate averaged {approx}31 lb/MM lb of circulation. To complement the HTDS technology, which extracts the sulfur from syngas as SO{sub 2}, RTI developed the Direct Sulfur Recovery Process (DSRP). The DSRP, operating at high pressure and high temperature, uses a small slipstream of syngas to catalytically reduce the SO{sub 2} produced in the warm syngas desulfurization process to elemental sulfur. To demonstrate this process at Eastman, RTI constructed and commissioned a skid-mounted pilot DSRP unit. During its 117-h operation, the DSRP system achieved 90% to 98% removal of the inlet sulfur. The DSRP catalyst proved very robust, demonstrating consistent reaction rates in multiple experiments over a 3-year period. Sorbent materials for removing trace NH{sub 3}, Hg, and As impurities from syngas at high temperature and high pressure were developed and tested with real syngas. A Li{sub 4}SiO{sub 4} sorbent for removal of CO{sub 2} from syngas at high temperature was also developed and tested. The Li{sub 4}SiO{sub 4} material demonstrates excellent CO{sub 2} removal, but its regeneration was found to be technically challenging. Additionally, reverse-selective polymer membrane materials were investigated for the bulk removal of CO{sub 2} and H{sub 2}S from syngas. These materials exhibited adequate separation at ambient conditions for these acid gases. Field testing of these membrane modules with real syngas demonstrated potential use for acid-gas separation from syngas. The HTDS/DSRP technologies are estimated to have a significant economic advantage over conventional gas cleanup technologies such as Selexol{trademark} and Rectisol. From a number of system studies, use of HTDS/DSRP is expected to give a 2-3 percentage point increase in the overall IGCC thermal efficiency and a significant reduction in capital cost. Thus, there is significant economic incentive for adaptation of these warm gas cleanup technologies due to significantly increased thermal efficiency and reduction in capital and operating costs. RTI and Eastman are currently in discussions with a number of companies to commercialize this technology