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Sample records for supercritical brayton cycle

  1. Advanced Supercritical Carbon Dioxide Brayton Cycle Development

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Mark [Univ. of Wisconsin, Madison, WI (United States); Sienicki, James [Argonne National Lab. (ANL), Argonne, IL (United States); Moisseytsev, Anton [Argonne National Lab. (ANL), Argonne, IL (United States); Nellis, Gregory [Univ. of Wisconsin, Madison, WI (United States); Klein, Sanford [Univ. of Wisconsin, Madison, WI (United States)

    2015-10-21

    -through labyrinth seals was proposed. A stepped labyrinth seal, which mimics the behavior of the labyrinth seal used in the Sandia National Laboratory (SNL) S-CO2 Brayton cycle, was also tested in the experiment along with simulations performed. The rest of this study demonstrates the difference of valves' behavior under supercritical fluid and normal fluid conditions. A small-scale valve was tested in the experiment facility using S-CO2. Different percentages of opening valves were tested, and the measured mass flow rate agreed with simulation predictions. Two transients from a real S-CO2 Brayton cycle design provided the data for valve selection. The selected valve was studied using numerical simulation, as experimental data is not available.

  2. Thermodynamic Optimization of Supercritical CO{sub 2} Brayton Cycles

    Energy Technology Data Exchange (ETDEWEB)

    Rhim, Dong-Ryul; Park, Sung-Ho; Kim, Su-Hyun; Yeom, Choong-Sub [Institute for Advanced Engineering, Yongin (Korea, Republic of)

    2015-05-15

    The supercritical CO{sub 2} Brayton cycle has been studied for nuclear applications, mainly for one of the alternative power conversion systems of the sodium cooled fast reactor, since 1960's. Although the supercritical CO{sub 2} Brayton cycle has not been expected to show higher efficiency at lower turbine inlet temperature over the conventional steam Rankine cycle, the higher density of supercritical CO{sub 2} like a liquid in the supercritical region could reduce turbo-machinery sizes, and the potential problem of sodium-water reaction with the sodium cooled fast reactor might be solved with the use of CO{sub 2} instead of water. The supercritical CO{sub 2} recompression Brayton cycle was proposed for the better thermodynamic efficiency than for the simple supercritical CO{sub 2} Brayton cycle. Thus this paper presents the efficiencies of the supercritical CO{sub 2} recompression Brayton cycle along with several decision variables for the thermodynamic optimization of the supercritical CO{sub 2} recompression Brayton cycle. The analytic results in this study show that the system efficiency reaches its maximum value at a compressor outlet pressure of 200 bars and a recycle fraction of 30 %, and the lower minimum temperature approach at the two heat exchangers shows higher system efficiency as expected.

  3. Enhancing power cycle efficiency for a supercritical Brayton cycle power system using tunable supercritical gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Steven A.; Pickard, Paul S.; Vernon, Milton E.; Radel, Ross F.

    2017-08-29

    Various technologies pertaining to tuning composition of a fluid mixture in a supercritical Brayton cycle power generation system are described herein. Compounds, such as Alkanes, are selectively added or removed from an operating fluid of the supercritical Brayton cycle power generation system to cause the critical temperature of the fluid to move up or down, depending upon environmental conditions. As efficiency of the supercritical Brayton cycle power generation system is substantially optimized when heat is rejected near the critical temperature of the fluid, dynamically modifying the critical temperature of the fluid based upon sensed environmental conditions improves efficiency of such a system.

  4. Operation and analysis of a supercritical CO2 Brayton cycle.

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Steven Alan; Radel, Ross F.; Vernon, Milton E.; Pickard, Paul S.; Rochau, Gary Eugene

    2010-09-01

    Sandia National Laboratories is investigating advanced Brayton cycles using supercritical working fluids for use with solar, nuclear or fossil heat sources. The focus of this work has been on the supercritical CO{sub 2} cycle (S-CO2) which has the potential for high efficiency in the temperature range of interest for these heat sources, and is also very compact, with the potential for lower capital costs. The first step in the development of these advanced cycles was the construction of a small scale Brayton cycle loop, funded by the Laboratory Directed Research & Development program, to study the key issue of compression near the critical point of CO{sub 2}. This document outlines the design of the small scale loop, describes the major components, presents models of system performance, including losses, leakage, windage, compressor performance, and flow map predictions, and finally describes the experimental results that have been generated.

  5. Supercritical Carbon Dioxide Brayton Cycle Energy Conversion System

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jae Eun; Kim, S. O.; Seong, S. H.; Eoh, J. H.; Lee, T. H.; Choi, S. K.; Han, J. W.; Bae, S. W

    2007-12-15

    This report contains the description of the S-CO{sub 2} Brayton cycle coupled to KALIMER-600 as an alternative energy conversion system. For system development, a computer code was developed to calculate heat balance of 100% power operation condition. Based on the computer code, the S-CO{sub 2} Brayton cycle energy conversion system was constructed for the KALIMER-600. Using the developed turbomachinery models, the off-design characteristics and the sensitivities of the S-CO{sub 2} turbomachinery were investigated. For the development of PCHE models, a one-dimensional analysis computer code was developed to evaluate the performance of the PCHE. Possible control schemes for power control in the KALIMER-600 S-CO{sub 2} Brayton cycle were investigated by using the MARS code. Simple power reduction and recovery event was selected and analyzed for the transient calculation. For the evaluation of Na/CO{sub 2} boundary failure event, a computer was developed to simulate the complex thermodynamic behaviors coupled with the chemical reaction between liquid sodium and CO{sub 2} gas. The long term behavior of a Na/CO{sub 2} boundary failure event and its consequences which lead to a system pressure transient were evaluated.

  6. Dry Air Cooler Modeling for Supercritical Carbon Dioxide Brayton Cycle Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Moisseytsev, A. [Argonne National Lab. (ANL), Argonne, IL (United States); Sienicki, J. J. [Argonne National Lab. (ANL), Argonne, IL (United States); Lv, Q. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-07-28

    Modeling for commercially available and cost effective dry air coolers such as those manufactured by Harsco Industries has been implemented in the Argonne National Laboratory Plant Dynamics Code for system level dynamic analysis of supercritical carbon dioxide (sCO2) Brayton cycles. The modeling can now be utilized to optimize and simulate sCO2 Brayton cycles with dry air cooling whereby heat is rejected directly to the atmospheric heat sink without the need for cooling towers that require makeup water for evaporative losses. It has sometimes been stated that a benefit of the sCO2 Brayton cycle is that it enables dry air cooling implying that the Rankine steam cycle does not. A preliminary and simple examination of a Rankine superheated steam cycle and an air-cooled condenser indicates that dry air cooling can be utilized with both cycles provided that the cycle conditions are selected appropriately

  7. Task Order 20: Supercritical Carbon Dioxide Brayton Cycle Energy Conversion Study

    Energy Technology Data Exchange (ETDEWEB)

    Murray, Paul [AREVA Federal Services, LLC, Charlotte, NC (United States); Lindsay, Edward [AREVA Federal Services, LLC, Charlotte, NC (United States); McDowell, Michael [AREVA Federal Services, LLC, Charlotte, NC (United States); Huang, Megan [AREVA Federal Services, LLC, Charlotte, NC (United States)

    2015-04-23

    AREVA Inc. developed this study for the US Department of Energy (DOE) office of Nuclear Energy (NE) in accordance with Task Order 20 Statement of Work (SOW) covering research and development activities for the Supercritical Carbon Dioxide (sCO2) Brayton Cycle energy conversion. The study addresses the conversion of sCO2 heat energy to electrical output by use of a Brayton Cycle system and focuses on the potential of a net efficiency increase via cycle recuperation and recompression stages. The study also addresses issues and study needed to advance development and implementation of a 10 MWe sCO2 demonstration project.

  8. Preheating of fluid in a supercritical Brayton cycle power generation system at cold startup

    Science.gov (United States)

    Wright, Steven A.; Fuller, Robert L.

    2016-07-12

    Various technologies pertaining to causing fluid in a supercritical Brayton cycle power generation system to flow in a desired direction at cold startup of the system are described herein. A sensor is positioned at an inlet of a turbine, wherein the sensor is configured to output sensed temperatures of fluid at the inlet of the turbine. If the sensed temperature surpasses a predefined threshold, at least one operating parameter of the power generation system is altered.

  9. Scaling considerations for a multi-megawatt class supercritical CO2 brayton cycle and commercialization.

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, Darryn D.; Holschuh, Thomas Vernon,; Conboy, Thomas M.; Pasch, James Jay; Wright, Steven A; Rochau, Gary E; Fuller, Robert Lynn

    2013-11-01

    Small-scale supercritical CO2 demonstration loops are successful at identifying the important technical issues that one must face in order to scale up to larger power levels. The Sandia National Laboratories supercritical CO2 Brayton cycle test loops are identifying technical needs to scale the technology to commercial power levels such as 10 MWe. The small size of the Sandia 1 MWth loop has demonstration of the split flow loop efficiency and effectiveness of the Printed Circuit Heat Exchangers (PCHXs) leading to the design of a fully recuperated, split flow, supercritical CO2 Brayton cycle demonstration system. However, there were many problems that were encountered, such as high rotational speeds in the units. Additionally, the turbomachinery in the test loops need to identify issues concerning the bearings, seals, thermal boundaries, and motor controller problems in order to be proved a reliable power source in the 300 kWe range. Although these issues were anticipated in smaller demonstration units, commercially scaled hardware would eliminate these problems caused by high rotational speeds at small scale. The economic viability and development of the future scalable 10 MWe solely depends on the interest of DOE and private industry. The Intellectual Property collected by Sandia proves that the ~10 MWe supercritical CO2 power conversion loop to be very beneficial when coupled to a 20 MWth heat source (either solar, geothermal, fossil, or nuclear). This paper will identify a commercialization plan, as well as, a roadmap from the simple 1 MWth supercritical CO2 development loop to a power producing 10 MWe supercritical CO2 Brayton loop.

  10. Corrosion of Structural Materials for Advanced Supercritical Carbon- Dioxide Brayton Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Sridharan, Kumar [Univ. of Wisconsin, Madison, WI (United States)

    2017-05-13

    The supercritical carbon-dioxide (referred to as SC-CO2 hereon) Brayton cycle is being considered for power conversion systems for a number of nuclear reactor concepts, including the sodium fast reactor (SFR), fluoride saltcooled high temperature reactor (FHR), and high temperature gas reactor (HTGR), and several types of small modular reactors (SMR). The SC-CO2 direct cycle gas fast reactor has also been recently proposed. The SC-CO2 Brayton cycle (discussed in Chapter 1) provides higher efficiencies compared to the Rankine steam cycle due to less compression work stemming from higher SC-CO2 densities, and allows for smaller components size, fewer components, and simpler cycle layout. For example, in the case of a SFR using a SC-CO2 Brayton cycle instead of a steam cycle would also eliminate the possibility of sodium-water interactions. The SC-CO2 cycle has a higher efficiency than the helium Brayton cycle, with the additional advantage of being able to operate at lower temperatures and higher pressures. In general, the SC-CO2 Brayton cycle is well-suited for any type of nuclear reactor (including SMR) with core outlet temperature above ~ 500°C in either direct or indirect versions. In all the above applications, materials corrosion in high temperature SC-CO2 is an important consideration, given their expected lifetimes of 20 years or longer. Our discussions with National Laboratories and private industry early on in this project indicated materials corrosion to be one of the significant gaps in the implementation of SC-CO2 Brayton cycle. Corrosion can lead to a loss of effective load-bearing wall thickness of a component and can potentially lead to the generation of oxide particulate debris which can lead to three-body wear in turbomachinery components. Another environmental degradation effect that is rather unique to CO2 environment is the possibility

  11. Thermoeconomic Analysis and Optimization of a New Combined Supercritical Carbon Dioxide Recompression Brayton/Kalina Cycle

    Directory of Open Access Journals (Sweden)

    S. Mohammad S. Mahmoudi

    2016-10-01

    Full Text Available A new combined supercritical CO2 recompression Brayton/Kalina cycle (SCRB/KC is proposed. In the proposed system, waste heat from a supercritical CO2 recompression Brayton cycle (SCRBC is recovered by a Kalina cycle (KC to generate additional electrical power. The performances of the two cycles are simulated and compared using mass, energy and exergy balances of the overall systems and their components. Using the SPECO (Specific Exergy Costing approach and employing selected cost balance equations for the components of each system, the total product unit costs of the cycles are obtained. Parametric studies are performed to investigate the effects on the SCRB/KC and SCRBC thermodynamic and thermoeconomic performances of key decision parameters. In addition, considering the exergy efficiency and total product unit cost as criteria, optimization is performed for the SCRBC and SCRB/KC using Engineering Equation Solver software. The results indicate that the maximum exergy efficiency of the SCRB/KC is higher than that of the SCRBC by up to 10%, and that the minimum total product unit cost of the SCRB/KC is lower than that of the SCRBC by up to 4.9%.

  12. Coupling a Supercritical Carbon Dioxide Brayton Cycle to a Helium-Cooled Reactor.

    Energy Technology Data Exchange (ETDEWEB)

    Middleton, Bobby [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pasch, James Jay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kruizenga, Alan Michael [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Walker, Matthew [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2016-01-01

    This report outlines the thermodynamics of a supercritical carbon dioxide (sCO2) recompression closed Brayton cycle (RCBC) coupled to a Helium-cooled nuclear reactor. The baseline reactor design for the study is the AREVA High Temperature Gas-Cooled Reactor (HTGR). Using the AREVA HTGR nominal operating parameters, an initial thermodynamic study was performed using Sandia's deterministic RCBC analysis program. Utilizing the output of the RCBC thermodynamic analysis, preliminary values of reactor power and of Helium flow rate through the reactor were calculated in Sandia's HelCO2 code. Some research regarding materials requirements was then conducted to determine aspects of corrosion related to both Helium and to sCO2 , as well as some mechanical considerations for pressures and temperatures that will be seen by the piping and other components. This analysis resulted in a list of materials-related research items that need to be conducted in the future. A short assessment of dry heat rejection advantages of sCO2> Brayton cycles was also included. This assessment lists some items that should be investigated in the future to better understand how sCO2 Brayton cycles and nuclear can maximally contribute to optimizing the water efficiency of carbon free power generation

  13. Potential Improvements of Supercritical CO2 Brayton Cycle by Modifying Critical Point of CO2

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Woo Seok; Lee, Jeong Ik; Jeong, Yong Hoon; No, Hee Cheon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2009-10-15

    A Sodium-cooled Fast Reactor (SFR) is one of strong candidates for a next generation nuclear reactor. However, the conventional design of a SFR concept with an indirect Rankine cycle is subjected to a sodium water reaction, which can deteriorate the safety of a SFR. To prevent any hazards from sodium-water reaction, a SFR with the Brayton cycle using Helium or Supercritical Carbon dioxide (S-CO2) as working fluids can be an alternative approach to improve the current SFR design. As in a helium cycle, there has been an investigation to modify thermo-physical properties to increase the efficiency of the cycle and reduce the size of turbomachineries. Particularly, He-Xe or He-N2 binary mixture were successful to decrease the stages of turbomachines due to the increment of molecular weight of gas mixture than that of pure helium. Similar to the case of helium, CO2 has a potential to modify its thermo-physical properties by mixing with other gases. For instance, it was reported that critical point of CO2 can be shifted by mixing with different gases. Since, the efficiency of a S-CO2 cycle is limited to the critical point of CO2, the shift in critical point implies that there is a possibility of improving the cycle efficiency than the current design. This paper presents the results of a preliminary analysis to identify the effects of CO2 critical point modification on the Brayton cycle performance.

  14. Counter flow induced draft cooling tower option for supercritical carbon dioxide Brayton cycle

    Energy Technology Data Exchange (ETDEWEB)

    Pidaparti, Sandeep R., E-mail: sandeep.pidaparti@gmail.com [Georgia Institute of Technology, George W. Woodruff School of Mechanical Engineering, Atlanta, GA 30332 (United States); Moisseytsev, Anton; Sienicki, James J. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Ranjan, Devesh, E-mail: devesh.ranjan@me.gatech.edu [Georgia Institute of Technology, George W. Woodruff School of Mechanical Engineering, Atlanta, GA 30332 (United States)

    2015-12-15

    Highlights: • A code was developed to investigate the various aspects of using cooling tower for S-CO{sub 2} Brayton cycles. • Cooling tower option to reject heat is quantitatively compared to the direct water cooling and dry air cooling options. • Optimum water conditions resulting in minimal plant capital cost per unit power consumption are calculated. - Abstract: A simplified qualitative analysis was performed to investigate the possibility of using counter flow induced draft cooling tower option to reject heat from the supercritical carbon dioxide Brayton cycle for advanced fast reactor (AFR)-100 and advanced burner reactor (ABR)-1000 plants. A code was developed to estimate the tower dimensions, power and water consumption, and to perform economic analysis. The code developed was verified against a vendor provided quotation and is used to understand the effect of ambient air and water conditions on the design of cooling tower. The calculations indicated that there exists optimum water conditions for given ambient air conditions which will result in minimum power consumption, thereby increasing the cycle efficiency. A cost-based optimization technique is used to estimate the optimum water conditions which will improve the overall plant economics. A comparison of different cooling options for the S-CO{sub 2} cycle indicated that the cooling tower option is a much more practical and economical option compared to the dry air cooling or direct water cooling options.

  15. Dynamic modelling and simulation of CSP plant based on supercritical carbon dioxide closed Brayton cycle

    Science.gov (United States)

    Hakkarainen, Elina; Sihvonen, Teemu; Lappalainen, Jari

    2017-06-01

    Supercritical carbon dioxide (sCO2) has recently gained a lot of interest as a working fluid in different power generation applications. For concentrated solar power (CSP) applications, sCO2 provides especially interesting option if it could be used both as the heat transfer fluid (HTF) in the solar field and as the working fluid in the power conversion unit. This work presents development of a dynamic model of CSP plant concept, in which sCO2 is used for extracting the solar heat in Linear Fresnel collector field, and directly applied as the working fluid in the recuperative Brayton cycle; these both in a single flow loop. We consider the dynamic model is capable to predict the system behavior in typical operational transients in a physically plausible way. The novel concept was tested through simulation cases under different weather conditions. The results suggest that the concept can be successfully controlled and operated in the supercritical region to generate electric power during the daytime, and perform start-up and shut down procedures in order to stay overnight in sub-critical conditions. Besides the normal daily operation, the control system was demonstrated to manage disturbances due to sudden irradiance changes.

  16. NERI Quarterly Progress Report -- April 1 - June 30, 2005 -- Development of a Supercritical Carbon Dioxide Brayton Cycle: Improving PBR Efficiency and Testing Material Compatibility

    Energy Technology Data Exchange (ETDEWEB)

    Chang Oh

    2005-07-01

    The objective of this research is to improve a helium Brayton cycle and to develop a supercritical carbon dioxide Brayton cycle for the Pebble Bed Reactor (PBR) that can also be applied to the Fast Gas-Cooled Reactor (FGR) and the Very-High-Temperature Gas-Cooled Reactor (VHTR). The proposed supercritical carbon dioxide Brayton cycle will be used to improve the PBR, FGR, and VHTR net plant efficiency. Another objective of this research is to test materials to be used in the power conversion side at supercritical carbon dioxide conditions. Generally, the optimized Brayton cycle and balance of plant (BOP) to be developed from this study can be applied to Generation-IV reactor concepts. Particularly, we are interested in VHTR because it has a good chance of being built in the near future.

  17. The feasibility study on supercritical methane Recuperated Brayton Cycle for waste heat recovery

    KAUST Repository

    Dyuisenakhmetov, Aibolat

    2017-05-01

    Recuperated Brayton Cycle (RBC) has attracted the attention of research scientists not only as a possible replacement for the steam cycle at nuclear power plants but also as an efficient bottoming cycle for waste heat recovery and for concentrated solar power. RBC’s compactness and the ease at which it can be integrated into existent power plants for waste heat recovery require few modifications. Methane, carbon dioxide and trifluoromethane are analyzed as possible working fluids. This work shows that it is possible to achieve higher efficiencies using methane under some operating conditions. However, as it turns out, the performance of Recuperated Brayton Cycle should be evaluated based on net output work. When the performance is assessed on the net output work criteria carbon dioxide still proves to be superior to other gases. This work also suggests that piston engines as compressors and expanders may be used instead of rotating turbines since reciprocating pistons have higher isentropic efficiencies.

  18. Development of a Supercritical Carbon Dioxide Brayton Cycle: Improving VHTR Efficiency and Testing Material Compatibility - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Chang H. Oh

    2006-06-01

    Generation IV reactors will need to be intrinsically safe, having a proliferation-resistant fuel cycle and several advantages relative to existing light water reactor (LWR). They, however, must still overcome certain technical issues and the cost barrier before it can be built in the U.S. The establishment of a nuclear power cost goal of 3.3 cents/kWh is desirable in order to compete with fossil combined-cycle, gas turbine power generation. This goal requires approximately a 30 percent reduction in power cost for stateof-the-art nuclear plants. It has been demonstrated that this large cost differential can be overcome only by technology improvements that lead to a combination of better efficiency and more compatible reactor materials. The objectives of this research are (1) to develop a supercritical carbon dioxide Brayton cycle in the secondary power conversion side that can be applied to the Very-High-Temperature Gas-Cooled Reactor (VHTR), (2) to improve the plant net efficiency by using the carbon dioxide Brayton cycle, and (3) to test material compatibility at high temperatures and pressures. The reduced volumetric flow rate of carbon dioxide due to higher density compared to helium will reduce compression work, which eventually increase plant net efficiency.

  19. Development of a Supercritical Carbon Dioxide Brayton Cycle: Improving PBR Efficiency and Testing Material Compatibility - 2004 Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    Chang Oh; Thomas Lillo; William Windes; Terry Totemeier; Richard Moore

    2004-10-01

    The U.S. and other countries address major challenges related to energy security and the environmental impacts of fossil fuels. Solutions to these issues include carbon-free electricity generation and hydrogen production for fuel cell car, fertilizer synthesis, petroleum refining, and other applications. The Very High Temperature Gas Reactor (HTGR) has been recognized as a promising technology for high efficiency electricity generation and high temperature process heat applications. Therefore, the U.S. needs to make the HTGR intrinsically safe and proliferation-resistant. The U.S. and the world, however, must still overcome certain technical issues and the cost barrier before it can be built in the U.S. The establishment of a nuclear power cost goal of 3.3 cents/kWh is desirable in order to compete with fossil combined-cycle, gas turbine power generation. This goal requires approximately a 30% reduction in power cost for state-of-the-art nuclear plants. It has been demonstrated that this large cost differential can be overcome only by technology improvements that lead to a combination of better efficiency and more compatible reactor materials. The objectives of this research are (1) to develop a supercritical carbon dioxide Brayton cycle in the secondary power conversion side that can be applied to some Generation-IV reactors such as the HTGR and supercritical water reactor, (2) to improve the plant net efficiency by using the carbon dioxide Brayton cycle, and (3) to test material compatibility at high temperatures and pressures. The reduced volumetric flow rate of carbon dioxide due to higher density compared to helium will reduce compression work, which eventually increase turbine work enhancing the plant net efficiency.

  20. RANS simulation of a radial compressor for supercritical CO{sub 2} Brayton cycle

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Gu; Cho, Seong Kuk; Lee, Jekyoung; Lee, Jeong Ik [KAIST, Daejeon (Korea, Republic of); Cha, Jae Eun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Si Woo [Jinsol Turbo, Daejeon (Korea, Republic of)

    2016-10-15

    S-CO{sub 2} cycle has a small footprint due to the compact turbomachine and heat exchanger. It was found that the S-CO{sub 2} compressor consumes small compression work if the operating conditions approach to the critical point (7.38MPa, 31.1℃). Therefore, this reduced compression work contributes to high cycle efficiency. Due to the above mentioned advantages, the S-CO{sub 2} cycle can be applied to various heat sources such as coal power, bottoming cycle of fuel cells, and the next generation nuclear systems. To demonstrate the S-CO{sub 2} cycle performance, an integral test facility is necessary. Therefore, the joint research team of KAERI, KAIST, POSTECH designed a supercritical CO{sub 2} integral experiment loop (SCIEL). The experimental data from this loop are accumulating in various conditions, rotational speed. The design of a S-CO{sub 2} compressor operating near the critical point is one of the major technical challenges in the development of cycle components. A radial compressor geometry designed for supercritical CO{sub 2} loop was utilized for CFD analysis. The preliminary results were compared to the experimental data. In this study, the authors present a CFD approach with accurate CSV type property table. Compared results showed reasonable difference between CFD and experiment except for efficiency curve at 35,000rpm. In future works, the loss models used for the design of S-CO{sub 2} compressor will be validated, and established with CFD results.

  1. Compressor Modeling for Transient Analysis of Supercritical CO2 Brayton Cycle by using MARS code

    Energy Technology Data Exchange (ETDEWEB)

    Park, Joo Hyun; Park, Hyun Sun; Kim, Tae Ho; Kwon, Jin Gyu [POSTECH, Pohang (Korea, Republic of); Bae, Sung Won; Cha, Jae Eun [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    In this study, SCIEL (Supercritical CO{sub 2} Integral Experimental Loop) was chosen as a reference loop and the MARS code was as the transient cycle analysis code. As a result, the compressor homologous curve was developed from the SCIEL experimental data and MARS analysis was performed and presented in the paper. The advantages attract SCO{sub 2}BC as a promising next generation power cycles. The high thermal efficiency comes from the operation of compressor near the critical point where the properties of SCO{sub 2}. The approaches to those of liquid phase, leading drastically lower the compression work loss. However, the advantage requires precise and smooth operation of the cycle near the critical point. However, it is one of the key technical challenges. The experimental data was steady state at compressor rotating speed of 25,000 rpm. The time, 3133 second, was starting point of steady state. Numerical solutions were well matched with the experimental data. The mass flow rate from the MARS analysis of approximately 0.7 kg/s was close to the experimental result of 0.9 kg/s. It is expected that the difference come from the measurement error in the experiment. In this study, the compressor model was developed and implemented in MARS to study the transient analysis of SCO{sub 2}BC in SCIEL. We obtained the homologous curves for the SCIEL compressor using experimental data and performed nodalization of the compressor model using MARS code. In conclusions, it was found that numerical solutions from the MARS model were well matched with experimental data.

  2. Development of the ANL plant dynamics code and control strategies for the supercritical carbon dioxide Brayton cycle and code validation with data from the Sandia small-scale supercritical carbon dioxide Brayton cycle test loop.

    Energy Technology Data Exchange (ETDEWEB)

    Moisseytsev, A.; Sienicki, J. J. (Nuclear Engineering Division)

    2011-11-07

    Significant progress has been made in the ongoing development of the Argonne National Laboratory (ANL) Plant Dynamics Code (PDC), the ongoing investigation and development of control strategies, and the analysis of system transient behavior for supercritical carbon dioxide (S-CO{sub 2}) Brayton cycles. Several code modifications have been introduced during FY2011 to extend the range of applicability of the PDC and to improve its calculational stability and speed. A new and innovative approach was developed to couple the Plant Dynamics Code for S-CO{sub 2} cycle calculations with SAS4A/SASSYS-1 Liquid Metal Reactor Code System calculations for the transient system level behavior on the reactor side of a Sodium-Cooled Fast Reactor (SFR) or Lead-Cooled Fast Reactor (LFR). The new code system allows use of the full capabilities of both codes such that whole-plant transients can now be simulated without additional user interaction. Several other code modifications, including the introduction of compressor surge control, a new approach for determining the solution time step for efficient computational speed, an updated treatment of S-CO{sub 2} cycle flow mergers and splits, a modified enthalpy equation to improve the treatment of negative flow, and a revised solution of the reactor heat exchanger (RHX) equations coupling the S-CO{sub 2} cycle to the reactor, were introduced to the PDC in FY2011. All of these modifications have improved the code computational stability and computational speed, while not significantly affecting the results of transient calculations. The improved PDC was used to continue the investigation of S-CO{sub 2} cycle control and transient behavior. The coupled PDC-SAS4A/SASSYS-1 code capability was used to study the dynamic characteristics of a S-CO{sub 2} cycle coupled to a SFR plant. Cycle control was investigated in terms of the ability of the cycle to respond to a linear reduction in the electrical grid demand from 100% to 0% at a rate of 5

  3. Thermodynamic optimisation of supercritical CO2 Brayton power cycles coupled to Direct Steam Generation Line-Focusing solar fields

    OpenAIRE

    Coco Enriquez, Luis; Muñoz Antón, Javier; Martínez-Val Peñalosa, Jose Maria

    2016-01-01

    In this paper a new generation line-focusing solar plants coupled to a s-CO2 Brayton power cycles are studied. These innovative CSP will increase the plant energy efficiency, and subsequently optimizing the SF effective aperture area and SF investment cost for a fixed power output. Two SF configurations were assessed: the Configuration 1 with a condenser between the SF and the Balance Of Plant (BOP), for Turbine Inlet Temperatures (TIT) up to 400oC, and the Configuration 2, for higher TIT up ...

  4. Comparison between s-CO2 and other supercritical working Fluids (s-Ethane, s-SF6, s-Xe, s-CH4, s-N2) in Line-Focusing Solar Power Plants with supercritical Brayton power cycles

    OpenAIRE

    Coco Enríquez, Luis; Muñoz Antón, Javier; Martínez-Val Peñalosa, Jose Maria

    2016-01-01

    Thermosolar power plants with linear solar collectors and Rankine or Brayton power cycles are maturing as a competitive solution for reducing CO2 emissions in power plants as an alternative to traditional fossil and nuclear fuels. In this context, nowadays a great effort is being invested in supercritical Carbon Dioxide Brayton (s-CO2) power cycles for optimizing the line-focusing solar plants performance and reducing the cost of renewable energy. However, there are other working fluids with ...

  5. Modeling and sizing of the heat exchangers of a new supercritical CO{sub 2} Brayton power cycle for energy conversion for fusion reactors

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, I.P.; Cantizano, A.; Linares, J.I., E-mail: linares@upcomillas.es; Moratilla, B.Y.

    2014-10-15

    Highlights: •We propose a procedure to model the heat exchangers of a S-CO2 Brayton power cycle. •Discretization in sub-heat exchangers is performed due to complex behavior of CO{sub 2}. •Different correlations have been tested, verifying them with CFD when necessary. •Obtained sizes are agree with usual values of printed circuit heat exchangers. -- Abstract: TECNO{sub F}US is a research program financed by the Spanish Government to develop technologies related to a dual-coolant (He/Pb–Li) breeding blanket design concept including the auxiliary systems for a future power reactor (DEMO). One of the main issues of this program is the optimization of heat recovery from the reactor and its conversion into electrical power. This paper is focused on the methodology employed for the design and sizing of all the heat exchangers of the supercritical CO{sub 2} Brayton power cycle (S-CO2) proposed by the authors. Due to the large pressure difference between the fluids, and also to their compactness, Printed Circuit Heat Exchangers (PCHE) are suggested in literature for these type of cycles. Because of the complex behavior of CO{sub 2}, their design is performed by a numerical discretization into sub-heat exchangers, thus a higher precision is reached when the thermal properties of the fluids vary along the heat exchanger. Different empirical correlations for the pressure drop and the Nusselt number have been coupled and assessed. The design of the precooler (PC) and the low temperature recuperator (LTR) is also verified by simulations using CFD because of the near-critical behavior of CO{sub 2}. The size of all of the heat exchangers of the cycle have been assessed.

  6. Exergy analysis for combined regenerative Brayton and inverse Brayton cycles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zelong; Chen, Lingen; Sun, Fengrui [College of Naval Architecture and Power, Naval University of Engineering, Wuhan 430033 (China)

    2012-07-01

    This paper presents the study of exergy analysis of combined regenerative Brayton and inverse Brayton cycles. The analytical formulae of exergy loss and exergy efficiency are derived. The largest exergy loss location is determined. By taking the maximum exergy efficiency as the objective, the choice of bottom cycle pressure ratio is optimized by detailed numerical examples, and the corresponding optimal exergy efficiency is obtained. The influences of various parameters on the exergy efficiency and other performances are analyzed by numerical calculations.

  7. Exergy analysis for combined regenerative Brayton and inverse Brayton cycles

    Directory of Open Access Journals (Sweden)

    Zelong Zhang, Lingen Chen, Fengrui Sun

    2012-01-01

    Full Text Available This paper presents the study of exergy analysis of combined regenerative Brayton and inverse Brayton cycles. The analytical formulae of exergy loss and exergy efficiency are derived. The largest exergy loss location is determined. By taking the maximum exergy efficiency as the objective, the choice of bottom cycle pressure ratio is optimized by detailed numerical examples, and the corresponding optimal exergy efficiency is obtained. The influences of various parameters on the exergy efficiency and other performances are analyzed by numerical calculations.

  8. Back Work Ratio of Brayton Cycle

    Directory of Open Access Journals (Sweden)

    Malaver de la Fuente M.

    2010-07-01

    Full Text Available This paper analizes the existing relation between temperatures, back work ratio and net work of Brayton cycle, a cycle that describes gas turbine engines performance. The application of computational soft ware helps to show the influence of back work ratio or coupling ratio, compressor and turbine in let temperatures in an ideal thermodynamical cycle. The results lead to deduce that the maximum value reached in back work ratio will depend on the ranges of maximum and minimal temperatures of Brayton cycle.

  9. 超临界二氧化碳布雷顿循环热力学特性研究%Thermodynamic Analysis of Coupling Supercritical Carbon Dioxide Brayton Cycles

    Institute of Scientific and Technical Information of China (English)

    黄潇立; 王俊峰; 臧金光

    2016-01-01

    Based on the first law of thermodynamics,a thermodynamic investigation was carried out on the coupling supercritical carbon dioxide Brayton cycles.The thermodynamic behavior and parameter limitations of the recompression cycle have been analyzed for a heat source system on the basis of equipment model and assumed initial conditions.A new cycle layout,named the cascaded partial flow cycle,was proposed for a high temperature difference heat source system.The thermodynamic behavior of the cascaded partial flow cycle was analyzed and evaluated.The applicable target of the recompression cycle and the cascaded partial flow cycle were proposed based on quantitative comparisons.%基于热力学第一定律,开展超临界二氧化碳(S-CO2)布雷顿循环的热力学特性研究.在设备模型构建和初始条件假设的基础上,研究系统采用再压缩循环的热力学特性和参数限制条件.针对进出口温差较大的热源系统,提出了复叠式分流循环方案,开展热力学特性分析和评价,并与再压缩循环进行定量比较,得出各自的适用对象.

  10. Brayton-cycle heat exchanger technology program

    Science.gov (United States)

    Killackey, J. J.; Coombs, M. G.; Graves, R. F.; Morse, C. J.

    1976-01-01

    The following five tasks designed to advance this development of heat exchanger systems for close loop Brayton cycle power systems are presented: (1) heat transfer and pressure drop data for a finned tubular heat transfer matrix. The tubes are arranged in a triangular array with copper stainless steel laminate strips helically wound on the tubes to form a disk fin geometry; (2) the development of a modularized waste heat exchanger. Means to provide verified double containment are described; (3) the design, fabrication, and test of compact plate fin heat exchangers representative of full scale Brayton cycle recuperators; (4) the analysis and design of bellows suitable for operation at 1600 F and 200 psia for 1,000 cycles and 50,000 hours creep life; and (5) screening tests used to select a low cost braze alloy with the desirable attributes of a gold base alloy. A total of 22 different alloys were investigated; the final selection was Nicrobraz 30.

  11. Off-design performance prediction of Radial Compressor of Supercritical CO{sub 2} Brayton Cycle for KAIST Micro Modular Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Seongkuk; Lee, Jekyoung; Kim, Seong Gu; Lee, Jeong Ik [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-10-15

    KAIST research team suggested a new concept of SMR, which utilizes S-CO{sub 2} as the operating fluid and coolant. It was named as KAIST MMR(Micro Modular Reactor). Compared with existing SMR concepts, this reactor has advantages of achieving smaller volume of power conversion unit (PCU) containing the core and PCU in one vessel for the complete modularization passive air-cooling system more flexible installation in the inland area. In previous study, performance of turbomachinery in PCU was considered only on-design. But, off-design performances of each component can affect not only PCU but also the core because this reactor adopts the direct S-CO{sub 2} loop in GFR. Nuclear system is applied by relatively conservative criteria of safety. Thus, off-design performances of each component should be considered in order to be more realistic reactor. The suggested turbomachinery size of the S-CO{sub 2} cycle is relatively smaller than those of helium Brayton cycle and steam Rankine cycle. Performance analysis of compressor is conducted by KAIST-TMD in case of on-design and off-design. Compressor efficiency in on-design conditions is obtained 84.51 %. But compressor performance in off-design conditions decreases certainly. This means that more heat than existing prediction is rejected by air-cooling system. KAIST-TMD will be verified with more experiment data for providing the results of more accurate analysis. Also, this code will be modified to couple with safety analysis codes and S-CO{sub 2} cycle analysis codes in the future. Furthermore, authors will consider aerodynamic performance analysis and various losses for more realization.

  12. Sensitivity study on nitrogen Brayton cycle coupled with a small ultra-long cycle fast reactor

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Seok Bin; Seo, Han; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2014-10-15

    The main characteristics of UCFR are constant neutron flux and power density. They move their positions every moment at constant speed along with axial position of fuel rod for 60 years. Simultaneously with the development of the reactors, a new power conversion system has been considered. To solve existing issues of vigorous sodium-water reaction in SFR with steam power cycle, many researchers suggested a closed Brayton cycle as an alternative technique for SFR power conversion system. Many inactive gases are selected as a working fluid in Brayton power cycle, mainly supercritical CO{sub 2} (S-CO{sub 2}). However, S-CO{sub 2} still has potential for reaction with sodium. CO{sub 2}-sodium reaction produces solid product, which has possibility to have an auto ignition reaction around 600 .deg. C. Thus, instead of S-CO{sub 2}, CEA in France has developed nitrogen power cycle for ASTRID (Advanced Sodium Technological Reactor for Industrial Demonstration). In addition to inactive characteristic of nitrogen with sodium, its thermal and physical similarity with air enables to easily adopt to existing air Brayton cycle technology. In this study, for an optimized power conversion system for UCFR, a nitrogen Brayton cycle was analyzed in thermodynamic aspect. Based on subchannel analysis data of UCFR-100, a parametric study for thermal performance of nitrogen Brayton cycle was achieved. The system maximum pressure significantly affects to the overall efficiency of cycle, while other parameters show little effects. Little differences of the overall efficiencies for all cases between three stages (BOC, MOC, EOC) indicate that the power cycle of UCFR-100 maintains its performance during the operation.

  13. A comparison between molten carbonate fuel cells based hybrid systems using air and supercritical carbon dioxide Brayton cycles with state of the art technology

    Science.gov (United States)

    Sánchez, D.; Muñoz de Escalona, J. M.; Chacartegui, R.; Muñoz, A.; Sánchez, T.

    A proposal for high efficiency hybrid systems based on molten carbonate fuel cells is presented in this paper. This proposal is based on adopting a closed cycle bottoming gas turbine using supercritical carbon dioxide as working fluid as opposed to open cycle hot air turbines typically used in this type of power generators. First, both bottoming cycles are compared for the same operating conditions, showing that their performances do not differ as much as initially expected, even if the initial objective of reducing compression work is accomplished satisfactorily. In view of these results, a profound review of research and industrial literature is carried out in order to determine realistic specifications for the principal components of the bottoming systems. From this analysis, it is concluded that an appropriate set of specifications must be developed for each bottoming cycle as the performances of compressor, turbine and recuperator differ significantly from one working fluid to another. Thus, when the operating conditions are updated, the performances of the resulting systems show a remarkable advantage of carbon dioxide based systems over conventional air units. Actually, the proposed hybrid system shows its capability to achieve 60% net efficiency, what represents a 10% increase with respect to the reference system.

  14. Development of a plant dynamics computer code for analysis of a supercritical carbon dioxide Brayton cycle energy converter coupled to a natural circulation lead-cooled fast reactor.

    Energy Technology Data Exchange (ETDEWEB)

    Moisseytsev, A.; Sienicki, J. J.

    2007-03-08

    STAR-LM is a lead-cooled pool-type fast reactor concept operating under natural circulation of the coolant. The reactor core power is 400 MWt. The open-lattice core consists of fuel pins attached to the core support plate, (the does not consist of removable fuel assemblies). The coolant flows outside of the fuel pins. The fuel is transuranic nitride, fabricated from reprocessed LWR spent fuel. The cladding material is HT-9 stainless steel; the steady-state peak cladding temperature is 650 C. The coolant is single-phase liquid lead under atmospheric pressure; the core inlet and outlet temperatures are 438 C and 578 C, respectively. (The Pb coolant freezing and boiling temperatures are 327 C and 1749 C, respectively). The coolant is contained inside of a reactor vessel. The vessel material is Type 316 stainless steel. The reactor is autonomous meaning that the reactor power is self-regulated based on inherent reactivity feedbacks and no external power control (through control rods) is utilized. The shutdown (scram) control rods are used for startup and shutdown and to stop the fission reaction in case of an emergency. The heat from the reactor is transferred to the S-CO{sub 2} Brayton cycle in in-reactor heat exchangers (IRHX) located inside the reactor vessel. The IRHXs are shell-and-tube type heat exchangers with lead flowing downwards on the shell side and CO{sub 2} flowing upwards on the tube side. No intermediate circuit is utilized. The guard vessel surrounds the reactor vessel to contain the coolant, in the very unlikely event of reactor vessel failure. The Reactor Vessel Auxiliary Cooling System (RVACS) implementing the natural circulation of air flowing upwards over the guard vessel is used to cool the reactor, in the case of loss of normal heat removal through the IRHXs. The RVACS is always in operation. The gap between the vessels is filled with liquid lead-bismuth eutectic (LBE) to enhance the heat removal by air by significantly reducing the thermal

  15. Systems Analyses of Advanced Brayton Cycles

    Energy Technology Data Exchange (ETDEWEB)

    A.D. Rao; D.J. Francuz; J.D. Maclay; J. Brouwer; A. Verma; M. Li; G.S. Samuelsen

    2008-09-30

    The main objective is to identify and assess advanced improvements to the Brayton Cycle (such as but not limited to firing temperature, pressure ratio, combustion techniques, intercooling, fuel or combustion air augmentation, enhanced blade cooling schemes) that will lead to significant performance improvements in coal based power systems. This assessment is conducted in the context of conceptual design studies (systems studies) that advance state-of-art Brayton cycles and result in coal based efficiencies equivalent to 65% + on natural gas basis (LHV), or approximately an 8% reduction in heat rate of an IGCC plant utilizing the H class steam cooled gas turbine. H class gas turbines are commercially offered by General Electric and Mitsubishi for natural gas based combined cycle applications with 60% efficiency (LHV) and it is expected that such machine will be offered for syngas applications within the next 10 years. The studies are being sufficiently detailed so that third parties will be able to validate portions or all of the studies. The designs and system studies are based on plants for near zero emissions (including CO{sub 2}). Also included in this program is the performance evaluation of other advanced technologies such as advanced compression concepts and the fuel cell based combined cycle. The objective of the fuel cell based combined cycle task is to identify the desired performance characteristics and design basis for a gas turbine that will be integrated with an SOFC in Integrated Gasification Fuel Cell (IGFC) applications. The goal is the conceptualization of near zero emission (including CO{sub 2} capture) integrated gasification power plants producing electricity as the principle product. The capability of such plants to coproduce H{sub 2} is qualitatively addressed. Since a total systems solution is critical to establishing a plant configuration worthy of a comprehensive market interest, a baseline IGCC plant scheme is developed and used to study

  16. Use of dissociating gases in Brayton cycle space power systems

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.M.; Govind, R. (Univ. of Cincinnati, Cincinnati, OH (US))

    1988-05-01

    In this paper an analysis of the use of dissociating gases in Brayton Cycle Space Power Systems has been presented. It has been shown that the development of higher efficiency cycles is necessary for minimizing isotope costs which have a dominant influence on total cycle economics. A dissociating gas Brayton cycle has been optimized for maximum efficiency and minimum radiator surface area. Results show that 40% higher thermal efficiencies and 25% reduction in radiator area can be achieved with a dissociating gas cycle when compared with a nondissociating gas cycle.

  17. Back work ratio of Brayton cycle; La relacion de trabajo de retroceso de un ciclo Brayton

    Energy Technology Data Exchange (ETDEWEB)

    Malaver de la Fuente, M. [Universidad Maritima del Caribe (Venezuela)]. E-mail: mmf_umc@hotmail.com

    2010-07-15

    This paper analyzes the existing relation between temperatures, back work ratio and net work of Brayton cycle, a cycle that describes gas turbine engines performance. The application of computational software helps to show the influence of back work ratio or coupling ratio, compressor and turbine inlet temperatures in an ideal thermodynamical cycle. The results lead to deduce that the maximum value reached in back work ratio will depend on the ranges of maximum and minimal temperatures of Brayton cycle. [Spanish] En este articulo se estudia la relacion que existe entre las temperaturas, la relacion de trabajo de retroceso y el trabajo neto en el ciclo Brayton, que es el ciclo ideal que describe el comportamiento de los motores de turbina de gas. La aplicacion de programas computarizados ayuda a mostrar la influencia de la relacion de trabajo de retroceso o relacion de acoplamiento, la temperatura de entrada al compresor y la temperatura de entrada a la turbina en este ciclo termodinamico ideal. Los resultados obtenidos permiten deducir que el valor maximo que alcanza la relacion de trabajo de retroceso dependera de los limites de temperatura maxima y minima impuestos en el ciclo Brayton.

  18. Preliminary design of S-CO{sub 2} Brayton cycle for APR-1400 with power generation and desalination process

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Seong Jun; Lee, Won Woong; Jeong, Yong Hoon; Lee, Jeong Ik [KAIST, Daejeon (Korea, Republic of); Yoon, Ho Joon [KUSTAR, Abu Dhabi (United Arab Emirates)

    2015-10-15

    This study was conducted to explore the capabilities of the S-CO{sub 2} Brayton cycle for a cogeneration system for APR-1400 application. Three concepts of the S-CO{sub 2} simple recuperated co-generation cycle were designed. A supercritical CO{sub 2} (S-CO{sub 2}) Brayton cycle is recently receiving significant attention as a promising power conversion system in wide range of energy applications due to its high efficiency and compact footprint. The main reason why the S-CO{sub 2} Brayton cycle has these advantages is that the compressor operates near the critical point of CO{sub 2} (30.98 .deg. C, 7.38MPa) to reduce the compression work significantly compared to the other Brayton cycles. In this study, the concept of replacing the entire steam cycle of APR-1400 with the S-CO{sub 2} Brayton cycle is evaluated. The power generation purpose S-CO{sub 2} Brayton cycles are redesigned to generate power and provide heat to the desalination system at the same time. The performance of these newly suggested cycles are evaluated in this paper. The target was to deliver 147MW heat to the desalination process. The thermal efficiencies of the three concepts are not significantly different, but the 3{sup rd} concept is relatively simpler than other cycles because only an additional heat exchanger is required. Although the 2{sup nd} concept is relatively complicated in comparison to other concepts, the temperatures at the inlet and outlet of the DHX are higher than that of the others. As shown in the results, the S-CO{sub 2} Brayton cycles are not easy to outperform the steam cycle with very simple layout and general design points under APR-1400 operating condition. However, this study shows that the S-CO{sub 2} Brayton cycles can be designed as a co-generation cycle while producing the target desalination heat with a simple configuration. In addition, it was also found that the S-CO{sub 2} Brayton cycle can achieve higher cycle thermal efficiency than the steam power cycle under

  19. Optimization and Comparison of Direct and Indirect Supercritical Carbon Dioxide Power Plant Cycles for Nuclear Applications

    Energy Technology Data Exchange (ETDEWEB)

    Edwin A. Harvego; Michael G. McKellar

    2011-11-01

    There have been a number of studies involving the use of gases operating in the supercritical mode for power production and process heat applications. Supercritical carbon dioxide (CO2) is particularly attractive because it is capable of achieving relatively high power conversion cycle efficiencies in the temperature range between 550 C and 750 C. Therefore, it has the potential for use with any type of high-temperature nuclear reactor concept, assuming reactor core outlet temperatures of at least 550 C. The particular power cycle investigated in this paper is a supercritical CO2 Recompression Brayton Cycle. The CO2 Recompression Brayton Cycle can be used as either a direct or indirect power conversion cycle, depending on the reactor type and reactor outlet temperature. The advantage of this cycle when compared to the helium Brayton cycle is the lower required operating temperature; 550 C versus 850 C. However, the supercritical CO2 Recompression Brayton Cycle requires an operating pressure in the range of 20 MPa, which is considerably higher than the required helium Brayton cycle operating pressure of 8 MPa. This paper presents results of analyses performed using the UniSim process analyses software to evaluate the performance of both a direct and indirect supercritical CO2 Brayton Recompression cycle for different reactor outlet temperatures. The direct supercritical CO2 cycle transferred heat directly from a 600 MWt reactor to the supercritical CO2 working fluid supplied to the turbine generator at approximately 20 MPa. The indirect supercritical CO2 cycle assumed a helium-cooled Very High Temperature Reactor (VHTR), operating at a primary system pressure of approximately 7.0 MPa, delivered heat through an intermediate heat exchanger to the secondary indirect supercritical CO2 Brayton Recompression cycle, again operating at a pressure of about 20 MPa. For both the direct and indirect cycles, sensitivity calculations were performed for reactor outlet temperature

  20. On the reversed Brayton cycle with high speed machinery

    Energy Technology Data Exchange (ETDEWEB)

    Backman, J.

    1996-12-31

    This work was carried out in the laboratory of Fluid Dynamics, at Lappeenranta University of Technology during the years 1991-1996. The research was a part of larger high speed technology development research. First, there was the idea of making high speed machinery applications with the Brayton cycle. There was a clear need to deepen the knowledge of the cycle itself and to make a new approach in the field of the research. Also, the removal of water from the humid air seemed very interesting. The goal of this work was to study methods of designing high speed machinery for the reversed Brayton cycle, from theoretical principles to practical applications. The reversed Brayton cycle can be employed as an air dryer, a heat pump or a refrigerating machine. In this research the use of humid air as a working fluid has an environmental advantage, as well. A new calculation method for the Brayton cycle is developed. In this method especially the expansion process in the turbine is important because of the condensation of the water vapour in the humid air. This physical phenomena can have significant effects on the level of performance of the application. Also, the influence of calculating the process with actual, achievable process equipment efficiencies is essential for the development of future machinery. The above theoretical calculations are confirmed with two different laboratory prototypes. (53 refs.)

  1. Power conversion systems based on Brayton cycles for fusion reactors

    Energy Technology Data Exchange (ETDEWEB)

    Linares, J.I., E-mail: linares@upcomillas.es [Rafael Marino Chair on New Energy Technologies. Comillas Pontifical University, Alberto Aguilera, 25-28015 Madrid (Spain); Herranz, L.E. [Unit of Nuclear Safety Research. CIEMAT, Madrid (Spain); Moratilla, B.Y.; Serrano, I.P. [Rafael Marino Chair on New Energy Technologies. Comillas Pontifical University, Alberto Aguilera, 25-28015 Madrid (Spain)

    2011-10-15

    This paper investigates Brayton power cycles for fusion reactors. Two working fluids have been explored: helium in classical configurations and CO{sub 2} in recompression layouts (Feher cycle). Typical recuperator arrangements in both cycles have been strongly constrained by low temperature of some of the energy thermal sources from the reactor. This limitation has been overcome in two ways: with a combined architecture and with dual cycles. Combined architecture couples the Brayton cycle with a Rankine one capable of taking advantage of the thermal energy content of the working fluid after exiting the turbine stage (iso-butane and steam fitted best the conditions of the He and CO{sub 2} cycles, respectively). Dual cycles set a specific Rankine cycle to exploit the lowest quality thermal energy source, allowing usual recuperator arrangements in the Brayton cycle. The results of the analyses indicate that dual cycles could reach thermal efficiencies around 42.8% when using helium, whereas thermal performance might be even better (46.7%), if a combined CO{sub 2}-H{sub 2}O cycle was set.

  2. Control system options and strategies for supercritical CO2 cycles.

    Energy Technology Data Exchange (ETDEWEB)

    Moisseytsev, A.; Kulesza, K. P.; Sienicki, J. J.; Nuclear Engineering Division; Oregon State Univ.

    2009-06-18

    The Supercritical Carbon Dioxide (S-CO{sub 2}) Brayton Cycle is a promising alternative to Rankine steam cycle and recuperated gas Brayton cycle energy converters for use with Sodium-Cooled Fast Reactors (SFRs), Lead-Cooled Fast Reactors (LFRs), as well as other advanced reactor concepts. The S-CO{sub 2} Brayton Cycle offers higher plant efficiencies than Rankine or recuperated gas Brayton cycles operating at the same liquid metal reactor core outlet temperatures as well as reduced costs or size of key components especially the turbomachinery. A new Plant Dynamics Computer Code has been developed at Argonne National Laboratory for simulation of a S-CO{sub 2} Brayton Cycle energy converter coupled to an autonomous load following liquid metal-cooled fast reactor. The Plant Dynamics code has been applied to investigate the effectiveness of a control strategy for the S-CO{sub 2} Brayton Cycle for the STAR-LM 181 MWe (400 MWt) Lead-Cooled Fast Reactor. The strategy, which involves a combination of control mechanisms, is found to be effective for controlling the S-CO{sub 2} Brayton Cycle over the complete operating range from 0 to 100 % load for a representative set of transient load changes. While the system dynamic analysis of control strategy performance for STARLM is carried out for a S-CO{sub 2} Brayton Cycle energy converter incorporating an axial flow turbine and compressors, investigations of the S-CO{sub 2} Brayton Cycle have identified benefits from the use of centrifugal compressors which offer a wider operating range, greater stability near the critical point, and potentially further cost reductions due to fewer stages than axial flow compressors. Models have been developed at Argonne for the conceptual design and performance analysis of centrifugal compressors for use in the SCO{sub 2} Brayton Cycle. Steady state calculations demonstrate the wider operating range of centrifugal compressors versus axial compressors installed in a S-CO{sub 2} Brayton Cycle as

  3. Comparison Between helium cycle and Supercritical CO{sub 2} Cycle for MMR and AMR

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Seong Jun; Lee, Jeong Ik; Ahn, Yoon Han; Lee, Je Kyoung [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2013-05-15

    Korea Atomic Energy Research Institute (KAERI) started the development of Mobile Multi-Purpose Reactor (MMR), which is a 10MWth gas-cooled reactor. MMR is aiming for maximizing mobility, high performance, durability and safety. This is in order to use the MMR for many purposes such as ship propulsion, train engine and so on. MMR generally uses helium Brayton cycle as a power conversion system since it can obtain very simple system arrangement with direct cycle. However, some researchers have proposed that the supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle can be more efficient energy converting cycle for the high temperature gas cooled reactor (HTGR) and the very high temperature reactor (VHTR) system as well. Thus, this paper is to compare helium Brayton cycle to the S-CO{sub 2} Brayton cycle in terms of the efficiency while varying turbine inlet temperature (T. I. T). A cascaded S-CO{sub 2} cycle which had been proposed by Argonne National laboratory (ANL) was used as the S-CO{sub 2} Brayton cycle configuration. This cycle is to overcome the mismatch of temperature drop between reactor coolant and CO{sub 2} through the reactor heat exchanger (RHX). Our research team reviewed the ANL research by using the in-house codes developed by the Korea Advanced institute of Science and Technology (KAIST) research team. The calculation error between the in-house code and previous result was -0.36%.

  4. Status of Brayton cycle power conversion development at NASA GRC

    Science.gov (United States)

    Mason, Lee S.; Shaltens, Richard K.; Dolce, James L.; Cataldo, Robert L.

    2002-01-01

    The NASA Glenn Research Center is pursuing the development of Brayton cycle power conversion for various NASA initiatives. Brayton cycle power systems offer numerous advantages for space power generation including high efficiency, long life, high maturity, and broad salability. Candidate mission applications include surface rovers and bases, advanced propulsion vehicles, and earth orbiting satellites. A key advantage is the ability for Brayton converters to span the wide range of power demands of future missions from several kilowatts to multi-megawatts using either solar, isotope, or reactor heat sources. Brayton technology has been under development by NASA since the early 1960's resulting in engine prototypes in the 2 to 15 kW-class that have demonstrated conversion efficiency of almost 30% and cumulative operation in excess of 40,000 hours. Present efforts at GRC are focusing on a 2 kW testbed as a proving ground for future component advances and operational strategies, and a 25 kW engine design as a modular building block for 100 kW-class electric propulsion and Mars surface power applications. .

  5. Performance evaluation of space solar Brayton cycle power systems

    Science.gov (United States)

    Diao, Zheng-Gang

    1992-06-01

    Unlike gas turbine power systems which consume chemical or nuclear energy, the energy consumption and/or cycle efficiency should not be a suitable criterion for evaluating the performance of space solar Brayton cycle power. A new design goal, life cycle cost, can combine all the power system characteristics, such as mass, area, and station-keeping propellant, into a unified criterion. Effects of pressure ratio, recuperator effectiveness, and compressor inlet temperature on life cycle cost were examined. This method would aid in making design choices for a space power system.

  6. Thermodynamic Modeling for Open Combined Regenerative Brayton and Inverse Brayton Cycles with Regeneration before the Inverse Cycle

    Directory of Open Access Journals (Sweden)

    Lingen Chen

    2012-01-01

    Full Text Available A thermodynamic model of an open combined regenerative Brayton and inverse Brayton cycles with regeneration before the inverse cycle is established in this paper by using thermodynamic optimization theory. The flow processes of the working fluid with the pressure drops and the size constraint of the real power plant are modeled. There are 13 flow resistances encountered by the working fluid stream for the cycle model. Four of these, the friction through the blades and vanes of the compressors and the turbines, are related to the isentropic efficiencies. The remaining nine flow resistances are always present because of the changes in flow cross-section at the compressor inlet of the top cycle, regenerator inlet and outlet, combustion chamber inlet and outlet, turbine outlet of the top cycle, turbine outlet of the bottom cycle, heat exchanger inlet, and compressor inlet of the bottom cycle. These resistances associated with the flow through various cross-sectional areas are derived as functions of the compressor inlet relative pressure drop of the top cycle, and control the air flow rate, the net power output and the thermal efficiency. The analytical formulae about the power output, efficiency and other coefficients are derived with 13 pressure drop losses. It is found that the combined cycle with regenerator can reach higher thermal efficiency but smaller power output than those of the base combined cycle at small compressor inlet relative pressure drop of the top cycle.

  7. Closed Brayton cycle power conversion systems for nuclear reactors :

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Steven A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lipinski, Ronald J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vernon, Milton E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sanchez, Travis [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2006-04-01

    This report describes the results of a Sandia National Laboratories internally funded research program to study the coupling of nuclear reactors to gas dynamic Brayton power conversion systems. The research focused on developing integrated dynamic system models, fabricating a 10-30 kWe closed loop Brayton cycle, and validating these models by operating the Brayton test-loop. The work tasks were performed in three major areas. First, the system equations and dynamic models for reactors and Closed Brayton Cycle (CBC) systems were developed and implemented in SIMULINKTM. Within this effort, both steady state and dynamic system models for all the components (turbines, compressors, reactors, ducting, alternators, heat exchangers, and space based radiators) were developed and assembled into complete systems for gas cooled reactors, liquid metal reactors, and electrically heated simulators. Various control modules that use proportional-integral-differential (PID) feedback loops for the reactor and the power-conversion shaft speed were also developed and implemented. The simulation code is called RPCSIM (Reactor Power and Control Simulator). In the second task an open cycle commercially available Capstone C30 micro-turbine power generator was modified to provide a small inexpensive closed Brayton cycle test loop called the Sandia Brayton test-Loop (SBL-30). The Capstone gas-turbine unit housing was modified to permit the attachment of an electrical heater and a water cooled chiller to form a closed loop. The Capstone turbine, compressor, and alternator were used without modification. The Capstone systems nominal operating point is 1150 K turbine inlet temperature at 96,000 rpm. The annular recuperator and portions of the Capstone control system (inverter) and starter system also were reused. The rotational speed of the turbo-machinery is controlled by adjusting the alternator load by using the electrical grid as the load bank. The SBL-30 test loop was operated at

  8. A global optimization method synthesizing heat transfer and thermodynamics for the power generation system with Brayton cycle

    Science.gov (United States)

    Fu, Rong-Huan; Zhang, Xing

    2016-09-01

    Supercritical carbon dioxide operated in a Brayton cycle offers a numerous of potential advantages for a power generation system, and a lot of thermodynamics analyses have been conducted to increase its efficiency. Because there are a lot of heat-absorbing and heat-lossing subprocesses in a practical thermodynamic cycle and they are implemented by heat exchangers, it will increase the gross efficiency of the whole power generation system to optimize the system combining thermodynamics and heat transfer theory. This paper analyzes the influence of the performance of heat exchangers on the actual efficiency of an ideal Brayton cycle with a simple configuration, and proposes a new method to optimize the power generation system, which aims at the minimum energy consumption. Although the method is operated only for the ideal working fluid in this paper, its merits compared to that only with thermodynamic analysis are fully shown.

  9. Use of Multiple Reheat Helium Brayton Cycles to Eliminate the Intermediate Heat Transfer Loop for Advanced Loop Type SFRs

    Energy Technology Data Exchange (ETDEWEB)

    Haihua Zhao; Hongbin Zhang; Samuel E. Bays

    2009-05-01

    The sodium intermediate heat transfer loop is used in existing sodium cooled fast reactor (SFR) plant design as a necessary safety measure to separate the radioactive primary loop sodium from the water of the steam Rankine power cycle. However, the intermediate heat transfer loop significantly increases the SFR plant cost and decreases the plant reliability due to the relatively high possibility of sodium leakage. A previous study shows that helium Brayton cycles with multiple reheat and intercooling for SFRs with reactor outlet temperature in the range of 510°C to 650°C can achieve thermal efficiencies comparable to or higher than steam cycles or recently proposed supercritical CO2 cycles. Use of inert helium as the power conversion working fluid provides major advantages over steam or CO2 by removing the requirement for safety systems to prevent and mitigate the sodium-water or sodium-CO2 reactions. A helium Brayton cycle power conversion system therefore makes the elimination of the intermediate heat transfer loop possible. This paper presents a pre-conceptual design of multiple reheat helium Brayton cycle for an advanced loop type SFR. This design widely refers the new horizontal shaft distributed PBMR helium power conversion design features. For a loop type SFR with reactor outlet temperature 550°C, the design achieves 42.4% thermal efficiency with favorable power density comparing with high temperature gas cooled reactors.

  10. Operational Results of a Closed Brayton Cycle Test-Loop

    Science.gov (United States)

    Wright, Steven A.; Fuller, Robert; Lipinski, Ronald J.; Nichols, Kenneth; Brown, Nicholas

    2005-02-01

    A number of space and terrestrial power system designs plan to use nuclear reactors that are coupled to Closed-loop Brayton Cycle (CBC) systems to generate electrical power. Because very little experience exists regarding the operational behavior of these systems, Sandia National Laboratories (through its Laboratory Directed Research and Development program) is developing a closed-loop test bed that can be used to determine the operational behavior of these systems and to validate models for these systems. Sandia has contracted Barber-Nichols Corporation to design, fabricate, and assemble a Closed-loop Brayton Cycle (CBC) system. This system was developed by modifying commercially available hardware. It uses a 30 kWe Capstone C-30 gas-turbine unit (www.capstoneturbine.com) with a modified housing that permits the attachment of an electrical heater and a water cooled chiller that are connected to the turbo-machinery in a closed loop. The test-loop reuses the Capstone turbine, compressor, and alternator. The Capstone system's nominal operating point is 1150 K turbine inlet temperature at 96,000 rpm. The annular recuperator and portions of the Capstone control system (inverter) and starter system are also reused. The rotational speed of the turbo-machinery is controlled either by adjusting the alternator load by either using the electrical grid or a separate load bank. This report describes the test-loop hardware SBL-30 (Sandia Brayton Loop-30kWe). Also presented are results of early testing and modeling of the unit. The SBL-30 hardware is currently configured with a heater that is limited to 80 kWth with a maximum outlet temperature of ˜1000 K.

  11. Simulation of CO2 Brayton Cycle for Engine Exhaust Heat Recovery under Various Operating Loads

    Institute of Scientific and Technical Information of China (English)

    舒歌群; 张承宇; 田华; 高媛媛; 李团兵; 仇荣赓

    2015-01-01

    A bottoming cycle system based on CO2 Brayton cycle is proposed to recover the engine exhaust heat. Its performance is compared with the conventional air Brayton cycle under five typical engine conditions. The results show that CO2 Brayton cycle proves to be superior to the air Brayton cycle in terms of the system net output power, thermal efficiency and recovery efficiency. In most cases, the recovery efficiency of CO2 Brayton cycle can be higher than 9%and the system has a better performance at the engine’s high operating load. The thermal efficiency can be as large as 24.83%under 100%operating load, accordingly, the net output power of 14.86 kW is obtained.

  12. Experimental Validation of a Closed Brayton Cycle System Transient Simulation

    Science.gov (United States)

    Johnson, Paul K.; Hervol, David S.

    2006-01-01

    The Brayton Power Conversion Unit (BPCU) is a closed cycle system with an inert gas working fluid. It is located in Vacuum Facility 6 at NASA Glenn Research Center. Was used in previous solar dynamic technology efforts (SDGTD). Modified to its present configuration by replacing the solar receiver with an electrical resistance heater. The first closed-Brayton-cycle to be coupled with an ion propulsion system. Used to examine mechanical dynamic characteristics and responses. The focus of this work was the validation of a computer model of the BPCU. Model was built using the Closed Cycle System Simulation (CCSS) design and analysis tool. Test conditions were then duplicated in CCSS. Various steady-state points. Transients involving changes in shaft rotational speed and heat input. Testing to date has shown that the BPCU is able to generate meaningful, repeatable data that can be used for computer model validation. Results generated by CCSS demonstrated that the model sufficiently reproduced the thermal transients exhibited by the BPCU system. CCSS was also used to match BPCU steady-state operating points. Cycle temperatures were within 4.1% of the data (most were within 1%). Cycle pressures were all within 3.2%. Error in alternator power (as much as 13.5%) was attributed to uncertainties in the compressor and turbine maps and alternator and bearing loss models. The acquired understanding of the BPCU behavior gives useful insight for improvements to be made to the CCSS model as well as ideas for future testing and possible system modifications.

  13. Brayton-Cycle Baseload Power Tower CSP System

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Bruce [Wilson Solarpower Corporation, Boston, MA (United States)

    2013-12-31

    The primary objectives of Phase 2 of this Project were:1. Engineer, fabricate, and conduct preliminary testing on a low-pressure, air-heating solar receiver capable of powering a microturbine system to produce 300kWe while the sun is shining while simultaneously storing enough energy thermally to power the system for up to 13 hours thereafter. 2. Cycle-test a high-temperature super alloy, Haynes HR214, to determine its efficacy for the system’s high-temperature heat exchanger. 3. Engineer the thermal energy storage system. This Phase 2 followed Wilson’s Phase 1, which primarily was an engineering feasibility study to determine a practical and innovative approach to a full Brayton-cycle system configuration that could meet DOE’s targets. Below is a summary table of the DOE targets with Wilson’s Phase 1 Project results. The results showed that a Brayton system with an innovative (low pressure) solar receiver with ~13 hours of dry (i.e., not phase change materials or molten salts but rather firebrick, stone, or ceramics) has the potential to meet or exceed DOE targets. Such systems would consist of pre-engineered, standardized, factory-produced modules to minimize on-site costs while driving down costs through mass production. System sizes most carefully analyzed were in the range of 300 kWe to 2 MWe. Such systems would also use off-the-shelf towers, blowers, piping, microturbine packages, and heliostats. Per DOE’s instructions, LCOEs are based on the elevation and DNI levels of Daggett, CA, for a 100 MWe power plant following 2 GWe of factory production of the various system components.

  14. Calculation principles of humid air in a reversed Brayton cycle

    Energy Technology Data Exchange (ETDEWEB)

    Backman, J. [Lappeenranta Univ. of Technology (Finland). Dept. of Energy Technology

    1997-12-31

    The article presents a calculation method for reversed Brayton cycle that uses humid air as working medium. The reversed Brayton cycle can be employed as an air dryer, a heat pump or a refrigerating machine. In this research the use of humid air as a working fluid has an environmental advantage, as well. In this method especially the expansion process in the turbine is important because of the condensation of the water vapour in the humid air. This physical phenomena can have significant effects on the level of performance of the application. The expansion process differs physically from the compression process, when the water vapour in the humid air begins to condensate. In the thermodynamic equilibrium of the flow, the water vapour pressure in humid air cannot exceed the pressure of saturated water vapour in corresponding temperature. Expansion calculation during operation around the saturation zone is based on a quasistatic expansion, in which the system after the turbine is in thermodynamical equilibrium. The state parameters are at every moment defined by the equation of state, and there is no supercooling in the vapour. Following simplifications are used in the calculations: The system is assumed to be adiabatic. This means that there is no heat transfer to the surroundings. This is a common practice, when the temperature differences are moderate as here; The power of the cooling is omitted. The cooling construction is very dependent on the machine and the distribution of the losses; The flow is assumed to be one-dimensional, steady-state and homogenous. The water vapour condensing in the turbine can cause errors, but the errors are mainly included in the efficiency calculation. (author) 11 refs.

  15. Innovative open air brayton combined cycle systems for the next generation nuclear power plants

    Science.gov (United States)

    Zohuri, Bahman

    The purpose of this research was to model and analyze a nuclear heated multi-turbine power conversion system operating with atmospheric air as the working fluid. The air is heated by a molten salt, or liquid metal, to gas heat exchanger reaching a peak temperature of 660 0C. The effects of adding a recuperator or a bottoming steam cycle have been addressed. The calculated results are intended to identify paths for future work on the next generation nuclear power plant (GEN-IV). This document describes the proposed system in sufficient detail to communicate a good understanding of the overall system, its components, and intended uses. The architecture is described at the conceptual level, and does not replace a detailed design document. The main part of the study focused on a Brayton --- Rankine Combined Cycle system and a Recuperated Brayton Cycle since they offer the highest overall efficiencies. Open Air Brayton power cycles also require low cooling water flows relative to other power cycles. Although the Recuperated Brayton Cycle achieves an overall efficiency slightly less that the Brayton --- Rankine Combined Cycle, it is completely free of a circulating water system and can be used in a desert climate. Detailed results of modeling a combined cycle Brayton-Rankine power conversion system are presented. The Rankine bottoming cycle appears to offer a slight efficiency advantage over the recuperated Brayton cycle. Both offer very significant advantages over current generation Light Water Reactor steam cycles. The combined cycle was optimized as a unit and lower pressure Rankine systems seem to be more efficient. The combined cycle requires a lot less circulating water than current power plants. The open-air Brayton systems appear to be worth investigating, if the higher temperatures predicted for the Next Generation Nuclear Plant do materialize.

  16. Parametric Investigation and Thermoeconomic Optimization of a Combined Cycle for Recovering the Waste Heat from Nuclear Closed Brayton Cycle

    Directory of Open Access Journals (Sweden)

    Lihuang Luo

    2016-01-01

    Full Text Available A combined cycle that combines AWM cycle with a nuclear closed Brayton cycle is proposed to recover the waste heat rejected from the precooler of a nuclear closed Brayton cycle in this paper. The detailed thermodynamic and economic analyses are carried out for the combined cycle. The effects of several important parameters, such as the absorber pressure, the turbine inlet pressure, the turbine inlet temperature, the ammonia mass fraction, and the ambient temperature, are investigated. The combined cycle performance is also optimized based on a multiobjective function. Compared with the closed Brayton cycle, the optimized power output and overall efficiency of the combined cycle are higher by 2.41% and 2.43%, respectively. The optimized LEC of the combined cycle is 0.73% lower than that of the closed Brayton cycle.

  17. Supercritical Water Reactor Cycle for Medium Power Applications

    Energy Technology Data Exchange (ETDEWEB)

    BD Middleton; J Buongiorno

    2007-04-25

    Scoping studies for a power conversion system based on a direct-cycle supercritical water reactor have been conducted. The electric power range of interest is 5-30 MWe with a design point of 20 MWe. The overall design objective is to develop a system that has minimized physical size and performs satisfactorily over a broad range of operating conditions. The design constraints are as follows: Net cycle thermal efficiency {ge}20%; Steam turbine outlet quality {ge}90%; and Pumping power {le}2500 kW (at nominal conditions). Three basic cycle configurations were analyzed. Listed in order of increased plant complexity, they are: (1) Simple supercritical Rankine cycle; (2) All-supercritical Brayton cycle; and (3) Supercritical Rankine cycle with feedwater preheating. The sensitivity of these three configurations to various parameters, such as reactor exit temperature, reactor pressure, condenser pressure, etc., was assessed. The Thermoflex software package was used for this task. The results are as follows: (a) The simple supercritical Rankine cycle offers the greatest hardware simplification, but its high reactor temperature rise and reactor outlet temperature may pose serious problems from the viewpoint of thermal stresses, stability and materials in the core. (b) The all-supercritical Brayton cycle is not a contender, due to its poor thermal efficiency. (c) The supercritical Rankine cycle with feedwater preheating affords acceptable thermal efficiency with lower reactor temperature rise and outlet temperature. (d) The use of a moisture separator improves the performance of the supercritical Rankine cycle with feedwater preheating and allows for a further reduction of the reactor outlet temperature, thus it was selected for the next step. Preliminary engineering design of the supercritical Rankine cycle with feedwater preheating and moisture separation was performed. All major components including the turbine, feedwater heater, feedwater pump, condenser, condenser pump

  18. Brayton-Cycle Baseload Power Tower CSP System

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Bruce

    2013-12-31

    The primary objectives of Phase 2 of this Project were: 1. Engineer, fabricate, and conduct preliminary testing on a low-pressure, air-heating solar receiver capable of powering a microturbine system to produce 300kWe while the sun is shining while simultaneously storing enough energy thermally to power the system for up to 13 hours thereafter. 2. Cycle-test a high-temperature super alloy, Haynes HR214, to determine its efficacy for the system’s high-temperature heat exchanger. 3. Engineer the thermal energy storage system This Phase 2 followed Wilson’s Phase 1, which primarily was an engineering feasibility study to determine a practical and innovative approach to a full Brayton-cycle system configuration that could meet DOE’s targets. Below is a summary table of the DOE targets with Wilson’s Phase 1 Project results. The results showed that a Brayton system with an innovative (low pressure) solar receiver with ~13 hours of dry (i.e., not phase change materials or molten salts but rather firebrick, stone, or ceramics) has the potential to meet or exceed DOE targets. Such systems would consist of pre-engineered, standardized, factory-produced modules to minimize on-site costs while driving down costs through mass production. System sizes most carefully analyzed were in the range of 300 kWe to 2 MWe. Such systems would also use off-the-shelf towers, blowers, piping, microturbine packages, and heliostats. Per DOE’s instructions, LCOEs are based on the elevation and DNI levels of Daggett, CA, for a 100 MWe power plant following 2 GWe of factory production of the various system components. Success criteria DOE targets Wilson system LCOE DOE’s gas price $6.75/MBtu 9 cents/kWh 7.7 cents/kWh LCOE Current gas price $4.71/MBtu NA 6.9 cents/kWh Capacity factor 75% (6500hr) 75-100% Solar fraction 85% (5585hr) >5585hr Receiver cost $170/kWe $50/kWe Thermal storage cost $20/kWhth $13/kWhth Heliostat cost $120/m2 $89.8/m2

  19. Identified corrosion and erosion mechanisms in SCO2 Brayton Cycles.

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, Darryn D.; Kruizenga, Alan Michael

    2014-06-01

    Supercritical Carbon Dioxide (S-CO2) is an efficient and flexible working fluid for power production. Research to interface S-CO2 systems with nuclear, thermal solar, and fossil energy sources is currently underway. To proceed, we must address concerns regarding compatibility of materials, at high temperature, and compatibility between significantly different heat transfer fluids. Dry, pure S-CO2 is thought to be relatively inert [1], while the addition of ppm levels of water and oxygen result in formation of a protective chromia layer and iron oxide [2]. Thin oxides are favorable as diffusion barriers, and for their minimal impact on heat transfer. While S-CO2 is typically understood to be the secondary fluid, many varieties of primary fluids exist for nuclear applications. Molten salts, for use in the Molten Salt Reactor concept, are given as an example to contrast the materials requirements of primary and secondary fluids. Thin chromia layers are soluble in molten salt systems (nitrate, chloride, and fluoride based salts) [3-8], making materials selection for heat exchangers a precarious balancing act between high temperature oxidation (S-CO2) and metal dissolution (salt side of heat exchanger). Because concerns have been raised regarding component lifetimes, S-CO2 work has begun to characterize starting materials and to establish a baseline by analysis of 1) as-received stainless steel piping, and 2) piping exposed to S-CO2 under typical operating conditions with Sandia National Laboratories Brayton systems. A second issue discovered by SNL involves substantial erosion in the turbine blade and inlet nozzle. It is believed that this is caused by small particulates that originate from different materials around the loop that are entrained by the S-CO2 to the nozzle, where they impact the inlet nozzle vanes, causing erosion. We believe that, in some way, this is linked to the purity of the S-CO2, the corrosion contaminants, and the metal particulates that

  20. A Comparison of Supercritical Carbon Dioxide Power Cycle Configurations with an Emphasis on CSP Applications (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Neises, T.; Turchi, C.

    2013-09-01

    Recent research suggests that an emerging power cycle technology using supercritical carbon dioxide (s-CO2) operated in a closed-loop Brayton cycle offers the potential of equivalent or higher cycle efficiency versus supercritical or superheated steam cycles at temperatures relevant for CSP applications. Preliminary design-point modeling suggests that s-CO2 cycle configurations can be devised that have similar overall efficiency but different temperature and/or pressure characteristics. This paper employs a more detailed heat exchanger model than previous work to compare the recompression and partial cooling cycles, two cycles with high design-point efficiencies, and illustrates the potential advantages of the latter. Integration of the cycles into CSP systems is studied, with a focus on sensible heat thermal storage and direct s-CO2 receivers. Results show the partial cooling cycle may offer a larger temperature difference across the primary heat exchanger, thereby potentially reducing heat exchanger cost and improving CSP receiver efficiency.

  1. Nuclear Air-Brayton Combined Cycle Power Conversion Design, Physical Performance Estimation and Economic Assessment

    Science.gov (United States)

    Andreades, Charalampos

    fourth section lays out the cost structure of the Mk1 Pebble-Bed Fluoride-salt-cooled High-temperature Reactor (FHR) with the NACC, since the NACC cannot be treated separately from its heat source. The fifth section evaluates the cost structure of a twelve-unit Mk1 FHR and NACC, including capital construction costs, operating costs, fuel and decommissioning costs in bottom up methodology. The sixth section proposes alternative NACC configurations and scales (mobile, remote NACC) or alternative power cycles to the NACC that can be coupled to the FHR (supercritical carbon dioxide Brayton cycle).

  2. Exergy analyses of an endoreversible closed regenerative Brayton cycle CCHP plant

    Directory of Open Access Journals (Sweden)

    Bo Yang, Lingen Chen, Yanlin Ge, Fengrui Sun

    2014-01-01

    Full Text Available An endoreversible closed regenerative Brayton cycle CCHP (combined cooling, heating and power plant coupled to constant-temperature heat reservoirs is presented using finite time thermodynamics (FTT. The CCHP plant includes an endoreversible closed regenerative Brayton cycle, an endoreversible four-heat-reservoir absorption refrigerator and a heat recovery device of thermal consumer. The heat-resistance losses in the hot-, cold-, thermal consumer-, generator-, condenser-, evaporator- and absorber-side heat exchangers and regenerator are considered. The performance of the CCHP plant is studied from the exergetic perspective, and the analytical formulae about exergy output rate and exergy efficiency are derived. Through numerical calculations, the pressure ratio of regenerative Brayton cycle is optimized, the effects of heat conductance of regenerator and ratio of heat demanded by the thermal consumer to power output on dimensionless exergy output rate and exergy efficiency are analyzed.

  3. Preliminary Study of the Supercritical CO{sub 2} Hybrid Cycle for the HTGR Application

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Seong Jun; Ahn, Yoonhan; Lee, Jeong Ik [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-05-15

    This study was conducted to explore the potential of Supercritical Carbon Dioxide (S-CO{sub 2}) Brayton cycle for the HTGR application. The S-CO{sub 2} cycle is being considered as a PCS due to its high thermal efficiency, simplicity, compactness and so on. Generally, the S-CO{sub 2} Brayton cycle is characterized as a highly recuperated cycle which means that to achieve high thermal efficiency, the cycle requires a highly effective recuperator. Argonne National Laboratory (ANL) showed that direct application of the standard S-CO{sub 2} recompressing Brayton cycle to the HTGR or the Very High Temperature Reactor (VHTR) is difficult to achieve high thermal efficiency due to the mismatch of the temperature difference between the temperature drop of helium as the primary reactor coolant and the temperature rise of CO{sub 2} as the PCS coolant through an Intermediate Heat Exchanger (IHX). Therefore, our research team suggests a novel S-CO{sub 2} cycle configuration, the S-CO{sub 2} Brayton and Rankine hybrid cycle, to solve this limitation. This S-CO{sub 2} hybrid concept is utilizing the waste heat of the S-CO{sub 2} Brayton cycle as heat input to the S-CO{sub 2} Rankine cycle. Dividing the thermal capacity of the heat source in to the Brayton cycle part and Rankine cycle part of the S-CO{sub 2} hybrid cycle appropriately, the temperature difference at the IHX could be reduced, therefore the net system performance and operating range can be improved. In this study, the ANL research is reviewed by the in-house cycle analysis codes developed by the Korea Advanced Institute of Science and Technology (KAIST) research team. And the S-CO{sub 2} Brayton and Rankine hybrid cycle is studied as a PCS for the VHTR condition which was utilized by ANL research team; it was assumed that the core outlet temperature to be 850 .deg. C and the core inlet temperature of 400 .deg. C.

  4. Exergy Analysis and Second Law Efficiency of a Regenerative Brayton Cycle with Isothermal Heat Addition

    Directory of Open Access Journals (Sweden)

    Naser M. Jubeh

    2005-07-01

    Full Text Available Abstract: The effect of two heat additions, rather than one, in a gas turbine engine is analyzed from the second law of thermodynamics point of view. A regenerative Brayton cycle model is used for this study, and compared with other models of Brayton cycle. All fluid friction losses in the compressor and turbine are quantified by an isentropic efficiency term. The effect of pressure ratio, turbine inlet temperature, ambient temperature, altitude, and altitude with variable ambient temperature on irreversibility "exergy destroyed" and second law efficiency was investigated and compared for all models. The results are given graphically with the appropriate discussion and conclusion.

  5. Research and Technology Activities Supporting Closed-Brayton-Cycle Power Conversion System Development

    Science.gov (United States)

    Barrett, Michael J.

    2004-01-01

    The elements of Brayton technology development emphasize power conversion system risk mitigation. Risk mitigation is achieved by demonstrating system integration feasibility, subsystem/component life capability (particularly in the context of material creep) and overall spacecraft mass reduction. Closed-Brayton-cycle (CBC) power conversion technology is viewed as relatively mature. At the 2-kWe power level, a CBC conversion system Technology Readiness Level (TRL) of six (6) was achieved during the Solar Dynamic Ground Test Demonstration (SD-GTD) in 1998. A TRL 5 was demonstrated for 10 kWe-class CBC components during the development of the Brayton Rotating Unit (BRU) from 1968 to 1976. Components currently in terrestrial (open cycle) Brayton machines represent TRL 4 for similar uses in 100 kWe-class CBC space systems. Because of the baseline component and subsystem technology maturity, much of the Brayton technology task is focused on issues related to systems integration. A brief description of ongoing technology activities is given.

  6. Optimal analysis on the performance of an irreversible harmonic quantum Brayton refrigeration cycle.

    Science.gov (United States)

    Lin, Bihong; Chen, Jincan

    2003-11-01

    An irreversible model of a quantum refrigeration cycle working with many noninteracting harmonic oscillators is established. The refrigeration cycle consists of two adiabatic and two constant-frequency processes. The general performance characteristics of the cycle are investigated, based on the quantum master equation and the semigroup approach. The expressions for several important performance parameters such as the coefficient of performance, cooling rate, power input, and rate of entropy production are derived. By using numerical solutions, the cooling rate of the refrigeration cycle subject to finite cycle duration is optimized. The maximum cooling rate and the corresponding parameters are calculated numerically. The optimal region of the coefficient of performance and the optimal ranges of temperatures of the working substance and times spent on the two constant-frequency processes are determined. Moreover, the optimal performance of the cycle in the high-temperature limit is compared with that of a classical Brayton refrigerator working with an ideal gas. The results obtained here show that in the high-temperature limit a harmonic quantum Brayton cycle may be equivalent to a classical Brayton cycle.

  7. Neon turbo-Brayton cycle refrigerator for HTS power machines

    Science.gov (United States)

    Hirai, Hirokazu; Hirokawa, M.; Yoshida, Shigeru; Nara, N.; Ozaki, S.; Hayashi, H.; Okamoto, H.; Shiohara, Y.

    2012-06-01

    We developed a prototype turbo-Brayton refrigerator whose working fluid is neon gas. The refrigerator is designed for a HTS (High Temperature Superconducting) power transformer and its cooling power is more than 2 kW at 65 K. The refrigerator has a turboexpander and a turbo-compressor, which utilize magnetic bearings. These rotational machines have no rubbing parts and no oil-components. Those make a long maintenance interval of the refrigerator. The refrigerator is very compact because our newly developed turbo-compressor is volumetrically smaller than a displacement type compressor in same operating specification. Another feature of the refrigerator is a wide range operation capability for various heat-loads. Cooling power is controlled by the input-power of the turbo-compressor instead of the conventional method of using an electric heater. The rotational speed of the compressor motor is adjusted by an inverter. This system is expected to be more efficient. We show design details, specification and cooling test results of the new refrigerator in this paper.

  8. Recuperative supercritical carbon dioxide cycle

    Science.gov (United States)

    Sonwane, Chandrashekhar; Sprouse, Kenneth M; Subbaraman, Ganesan; O'Connor, George M; Johnson, Gregory A

    2014-11-18

    A power plant includes a closed loop, supercritical carbon dioxide system (CLS-CO.sub.2 system). The CLS-CO.sub.2 system includes a turbine-generator and a high temperature recuperator (HTR) that is arranged to receive expanded carbon dioxide from the turbine-generator. The HTR includes a plurality of heat exchangers that define respective heat exchange areas. At least two of the heat exchangers have different heat exchange areas.

  9. Closed-Cycle Engine Program Used to Study Brayton Power Conversion

    Science.gov (United States)

    Johnson, Paul K.

    2005-01-01

    One form of power conversion under consideration in NASA Glenn Research Center's Thermal Energy Conversion Branch is the closed-Brayton-cycle engine. In the tens-of-kilowatts to multimegawatt class, the Brayton engine lends itself to potential space nuclear power applications such as electric propulsion or surface power. The Thermal Energy Conversion Branch has most recently concentrated its Brayton studies on electric propulsion for Prometheus. One piece of software used for evaluating such designs over a limited tradeoff space has been the Closed Cycle Engine Program (CCEP). The CCEP originated in the mid-1980s from a Fortran aircraft engine code known as the Navy/NASA Engine Program (NNEP). Components such as a solar collector, heat exchangers, ducting, a pumped-loop radiator, a nuclear heat source, and radial turbomachinery were added to NNEP, transforming it into a high-fidelity design and performance tool for closed-Brayton-cycle power conversion and heat rejection. CCEP was used in the 1990s in conjunction with the Solar Dynamic Ground Test Demonstration conducted at Glenn. Over the past year, updates were made to CCEP to adapt it for an electric propulsion application. The pumped-loop radiator coolant can now be n-heptane, water, or sodium-potassium (NaK); liquid-metal pump design tables were added to accommodate the NaK fluid. For the reactor and shield, a user can now elect to calculate a higher fidelity mass estimate. In addition, helium-xenon working-fluid properties were recalculated and updated.

  10. Review of supercritical CO2 power cycle technology and current status of research and development

    Directory of Open Access Journals (Sweden)

    Yoonhan Ahn

    2015-10-01

    Full Text Available The supercritical CO2 (S-CO2 Brayton cycle has recently been gaining a lot of attention for application to next generation nuclear reactors. The advantages of the S-CO2 cycle are high efficiency in the mild turbine inlet temperature region and a small physical footprint with a simple layout, compact turbomachinery, and heat exchangers. Several heat sources including nuclear, fossil fuel, waste heat, and renewable heat sources such as solar thermal or fuel cells are potential application areas of the S-CO2 cycle. In this paper, the current development progress of the S-CO2 cycle is introduced. Moreover, a quick comparison of various S-CO2 layouts is presented in terms of cycle performance.

  11. Malone-Brayton Cycle Engine/Heat Pump.

    Science.gov (United States)

    A machine, such as a heat pump , and having an all liquid heat exchange fluid, operates over a more nearly ideal thermodynamic cycle by adjustment of...difference in axial lengths of rotary pumps of the gear or vane type to achieve the adjustment of volumetric capacity. Adjustment of the heat pump system

  12. Development of a Novel Brayton-Cycle Cryocooler and Key Component Technologies

    Science.gov (United States)

    Nieczkoski, S. J.; Mohling, R. A.

    2004-06-01

    Brayton-cycle cryocoolers are being developed to provide efficient cooling in the 6 K to 70 K temperature range. The cryocoolers are being developed for use in space and in terrestrial applications where combinations of long lifetime, high efficiency, compactness, low mass, low vibration, flexible interfacing, load variability, and reliability are essential. The key enabling technologies for these systems are a mesoscale expander and an advanced oil-free scroll compressor. Both these components are nearing completion of their prototype development phase. The emphasis on the component and system development has been on invoking fabrication processes and techniques that can be evolved to further reduction in scale tending toward cryocooler miniaturization.

  13. Supercritical CO2 Power Cycles: Design Considerations for Concentrating Solar Power

    Energy Technology Data Exchange (ETDEWEB)

    Neises, Ty; Turchi, Craig

    2014-09-01

    A comparison of three supercritical CO2 Brayton cycles: the simple cycle, recompression cycle and partial-cooling cycle indicates the partial-cooling cycle is favored for use in concentrating solar power (CSP) systems. Although it displays slightly lower cycle efficiency versus the recompression cycle, the partial-cooling cycle is estimated to have lower total recuperator size, as well as a lower maximum s-CO2 temperature in the high-temperature recuperator. Both of these effects reduce recuperator cost. Furthermore, the partial-cooling cycle provides a larger temperature differential across the turbine, which translates into a smaller, more cost-effective thermal energy storage system. The temperature drop across the turbine (and by extension, across a thermal storage system) for the partial-cooling cycle is estimated to be 23% to 35% larger compared to the recompression cycle of equal recuperator conductance between 5 and 15 MW/K. This reduces the size and cost of the thermal storage system. Simulations by NREL and Abengoa Solar indicate the partial-cooling cycle results in a lower LCOE compared with the recompression cycle, despite the former's slightly lower cycle efficiency. Advantages of the recompression cycle include higher thermal efficiency and potential for a smaller precooler. The overall impact favors the use of a partial-cooling cycle for CSP compared to the more commonly analyzed recompression cycle.

  14. Combined Reverse-Brayton Joule Thompson Hydrogen Liquefaction Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Shimko, Martin A. [Gas Equipment Engineering Corporation, Milford, CT (United States); Dunn, Paul M. [Gas Equipment Engineering Corporation, Milford, CT (United States)

    2011-12-31

    The following is a compilation of Annual Progress Reports submitted to the DOE’s Fuel Cell Technologies Office by Gas Equipment Engineering Corp. for contract DE-FG36-05GO15021. The reports cover the project activities from August 2005 through June 2010. The purpose of this project is to produce a pilot-scale liquefaction plant that demonstrates GEECO’s ability to meet or exceed the efficiency targets set by the DOE. This plant will be used as a model to commercialize this technology for use in the distribution infrastructure of hydrogen fuel. It could also be applied to markets distributing hydrogen for industrial gas applications. Extensive modeling of plant performance will be used in the early part of the project to identify the liquefaction cycle architecture that optimizes the twin goals of increased efficiency and reduced cost. The major challenge of the project is to optimize/balance the performance (efficiency) of the plant against the cost of the plant so that the fully amortized cost of liquefying hydrogen meets the aggressive goals set by DOE. This project will design and build a small-scale pilot plant (several hundred kg/day) that will be both a hardware demonstration and a model for scaling to larger plant sizes (>50,000 kg/day). Though an effort will be made to use commercial or near-commercial components, key components that will need development for either a pilot- or full-scale plant will be identified. Prior to starting pilot plant fabrication, these components will be demonstrated at the appropriate scale to demonstrate sufficient performance for use in the pilot plant and the potential to achieve the performance used in modeling the full-scale plant.

  15. Supercritical CO2 direct cycle Gas Fast Reactor (SC-GFR) concept.

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Steven Alan; Parma, Edward J., Jr.; Suo-Anttila, Ahti Jorma (Computational Engineering Analysis, Albuquerque, NM); Al Rashdan, Ahmad (Texas A& M University, College Station, TX); Tsvetkov, Pavel Valeryevich (Texas A& M University, College Station, TX); Vernon, Milton E.; Fleming, Darryn D.; Rochau, Gary Eugene

    2011-05-01

    This report describes the supercritical carbon dioxide (S-CO{sub 2}) direct cycle gas fast reactor (SC-GFR) concept. The SC-GFR reactor concept was developed to determine the feasibility of a right size reactor (RSR) type concept using S-CO{sub 2} as the working fluid in a direct cycle fast reactor. Scoping analyses were performed for a 200 to 400 MWth reactor and an S-CO{sub 2} Brayton cycle. Although a significant amount of work is still required, this type of reactor concept maintains some potentially significant advantages over ideal gas-cooled systems and liquid metal-cooled systems. The analyses presented in this report show that a relatively small long-life reactor core could be developed that maintains decay heat removal by natural circulation. The concept is based largely on the Advanced Gas Reactor (AGR) commercial power plants operated in the United Kingdom and other GFR concepts.

  16. Exergetic efficiency optimization for an irreversible heat pump working on reversed Brayton cycle

    Indian Academy of Sciences (India)

    Yuehong Bi; Lingen Chen; Fengrui Sun

    2010-03-01

    This paper deals with the performance analysis and optimization for irreversible heat pumps working on reversed Brayton cycle with constant-temperature heat reservoirs by taking exergetic efficiency as the optimization objective combining exergy concept with finite-time thermodynamics (FTT). Exergetic efficiency is defined as the ratio of rate of exergy output to rate of exergy input of the system. The irreversibilities considered in the system include heat resistance losses in the hot- and cold-side heat exchangers and non-isentropic losses in the compression and expansion processes. The analytical formulas of the heating load, coefficient of performance (COP) and exergetic efficiency for the heat pumps are derived. The results are compared with those obtained for the traditional heating load and coefficient of performance objectives. The influences of the pressure ratio of the compressor, the allocation of heat exchanger inventory, the temperature ratio of two reservoirs, the effectiveness of the hot- and cold-side heat exchangers and regenerator, the efficiencies of the compressor and expander, the ratio of hot-side heat reservoir temperature to ambient temperature, the total heat exchanger inventory, and the heat capacity rate of the working fluid on the exergetic efficiency of the heat pumps are analysed by numerical calculations. The results show that the exergetic efficiency optimization is an important and effective criterion for the evaluation of an irreversible heat pump working on reversed Brayton cycle.

  17. Concept Design for a High Temperature Helium Brayton Cycle with Interstage Heating and Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Steven A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vernon, Milton E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pickard, Paul S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2013-12-01

    The primary metric for the viability of these next generation nuclear power plants will be the cost of generated electricity. One important component in achieving these objectives is the development of power conversion technologies that maximize the electrical power output of these advanced reactors for a given thermal power. More efficient power conversion systems can directly reduce the cost of nuclear generated electricity and therefore advanced power conversion cycle research is an important area of investigation for the Generation IV Program. Brayton cycles using inert or other gas working fluids, have the potential to take advantage of the higher outlet temperature range of Generation IV systems and allow substantial increases in nuclear power conversion efficiency, and potentially reductions in power conversion system capital costs compared to the steam Rankine cycle used in current light water reactors. For the Very High Temperature Reactor (VHTR), Helium Brayton cycles which can operate in the 900 to 950 C range have been the focus of power conversion research. Previous Generation IV studies examined several options for He Brayton cycles that could increase efficiency with acceptable capital cost implications. At these high outlet temperatures, Interstage Heating and Cooling (IHC) was shown to provide significant efficiency improvement (a few to 12%) but required increased system complexity and therefore had potential for increased costs. These scoping studies identified the potential for increased efficiency, but a more detailed analysis of the turbomachinery and heat exchanger sizes and costs was needed to determine whether this approach could be cost effective. The purpose of this study is to examine the turbomachinery and heat exchanger implications of interstage heating and cooling configurations. In general, this analysis illustrates that these engineering considerations introduce new constraints to the design of IHC systems that may require

  18. Second-law analysis and optimization of reverse brayton cycles of different configurations for cryogenic applications

    Science.gov (United States)

    Streit, James Ryder; Razani, Arsalan

    2012-06-01

    Second-law of thermodynamics (2nd law) and exergy analyses and optimization offour Reverse Brayton Refrigeration (RBR) cryogenic cycle configurations: Conventional 1-stage compression cycle; Conventional 2-stage compression cycle; 1-stage compressionModified cycle with intermediate cooling of the recuperator using an auxiliary cooler; andan Integrated 2-stage expansion RBR cycle are performed. The conventional RBR cyclesare analyzed for low and high pressure ratio applications using multistage compressorswith intercooling. Analytical solutions for the conventional cycles are developed includingthermal and fluid flow irreversibilities of the recuperators and all heat exchangers inaddition to the compression and expansion processes. Analytical solutions are used to findthe thermodynamic bounds for the performance of the cycles. Exergy irreversibilitydiagrams of the cycles are developed and the effects of important system parameters onRBR cycle performance are investigated. 2nd law/exergy analyses, and optimization of thecycles with intermediate cooling of the recuperator, considering the cooling temperatureand the recuperator effectiveness and pressure drop, are included. The effect of the 2ndlaw/exergy efficiency of the auxiliary cooler on the total system efficiencies is presented.

  19. Advanced Turbomachinery Components for Supercritical CO2 Power Cycles

    Energy Technology Data Exchange (ETDEWEB)

    McDowell, Michael [Gas Technology Inst., Woodland Hills, CA (United States)

    2016-03-31

    Six indirectly heated supercritical CO2 (SCO2 ) Brayton cycles with turbine inlet conditions of 1300°F and 4000 psia with varying plant capacities from 10MWe to 550MWe were analyzed. 550 MWe plant capacity directly heated SCO2 Brayton cycles with turbine inlet conditions of 2500°F and 4000 psia were also analyzed. Turbomachinery configurations and conceptual designs for both indirectly and directly heated cycles were developed. Optimum turbomachinery and generator configurations were selected and the resulting analysis provides validation that the turbomachinery conceptual designs meet efficiency performance targets. Previously identified technology gaps were updated based on these conceptual designs. Material compatibility testing was conducted for materials typically used in turbomachinery housings, turbine disks and blades. Testing was completed for samples in unstressed and stressed conditions. All samples exposed to SCO2 showed some oxidation, the extent of which varied considerably between the alloys tested. Examination of cross sections of the stressed samples found no evidence of cracking due to SCO2 exposure.

  20. Tensile and Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials

    Science.gov (United States)

    Gabb, Timothy P.; Gayda, John

    2006-01-01

    This paper represents a status report documenting the work on creep of superalloys performed under Project Prometheus. Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, are being screened to compare their respective capabilities for impeller applications. Several wrought superalloys including Hastelloy X, (Haynes International, Inc., Kokomo, IN), Inconel 617, Inconel 740, Nimonic 263, and Incoloy MA956 (Special Metals Corporation, Huntington, WV) are also being screened to compare their capabilities for duct applications. These proposed applications would require sufficient strength and creep resistance for long term service at temperatures up to 1200 K, with service times to 100,000 h or more. Conventional tensile and creep tests were performed at temperatures up to 1200 K on specimens extracted from the materials. Initial microstructure evaluations were also undertaken.

  1. Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials

    Science.gov (United States)

    Gabb, Timothy P.; Gayda, john; Garg, Anita

    2007-01-01

    Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, have been screened to compare their respective capabilities for impeller applications. Mar-M247LC has been selected for additional long term evaluations. Initial tests in helium indicate this inert environment may debit long term creep resistance of this alloy. Several wrought superalloys including Hastelloy(Registered TradeMark) X, Inconel(Registered TradeMark) 617, Inconel(Registered TradeMark) 740, Nimonic(Registered TradeMark) 263, Incoloy(Registered TradeMark) MA956, and Haynes 230 are also being screened to compare their capabilities for duct applications. Haynes 230 has been selected for additional long term evaluations. Initial tests in helium are just underway for this alloy. These proposed applications would require sufficient strength and creep resistance for long term service at temperatures up to 1200 K, with service times to 100,000 h or more. Therefore, long term microstructural stability is also being screened.

  2. Optimum distribution of heat exchanger inventory for power density optimization of an endoreversible closed Brayton cycle

    Energy Technology Data Exchange (ETDEWEB)

    Lingen Chen; Junlin Zheng; Fengrui Sun [Naval Univ. of Engineering, Faculty 306, Wuhan (China); Chih Wu [U.S. Naval Academy, Mechanical Engineering Dept., Annapolis, MD (United States)

    2001-02-07

    In this paper, the power density (defined as the ratio of the power output to the maximum specific volume in the cycle) is taken as the objective for performance optimisations of an endoreversible closed Brayton cycle coupled to constant-temperature heat reservoirs in the viewpoint of finite-time thermodynamics (FTT) or entropy generation minimisation (EGM). The optimum heat conductance distribution corresponding to the optimum power density of the hot- and cold-side heat exchangers for the fixed heat exchanger inventory is analysed using numerical examples. The influence of some design parameters on the optimum heat conductance distribution and the maximum power density and the optimum pressure ratio corresponding to the maximum power density are provided. The power plant design with optimisation leads to higher efficiency and smaller size. (Author)

  3. Method for controlling start-up and steady state performance of a closed split flow recompression brayton cycle

    Energy Technology Data Exchange (ETDEWEB)

    Pasch, James Jay

    2017-02-07

    A method of resolving a balanced condition that generates control parameters for start-up and steady state operating points and various component and cycle performances for a closed split flow recompression cycle system. The method provides for improved control of a Brayton cycle thermal to electrical power conversion system. The method may also be used for system design, operational simulation and/or parameter prediction.

  4. Brayton-cycle heat recovery-system characterization program. Subatmospheric-system test report

    Energy Technology Data Exchange (ETDEWEB)

    Burgmeier, L.; Leung, S.

    1981-07-31

    The turbine tests and results for the Brayton cycle subatmospheric system (SAS) are summarized. A scaled model turbine was operated in the same environment as that which a full-scale SAS machine would experience from the hot effluent flue gas from a glass container furnace. The objective of the testing was to evaluate the effects of a simulated furnace flue gas stream on the turbine nozzles and blades. The following specific areas were evaluated: erosion of the turbine nozzles and blades from the dust in the flue gas, hot corrosion from alkali metal salts in the dust and acid vapor (sulfur trioxide and hydrogen chloride) in the flue gas, and fouling and flow blockage due to deposition and/or condensation from the flue gas constituents.

  5. Application of exergetic sustainability index to a nano-scale irreversible Brayton cycle operating with ideal Bose and Fermi gasses

    Energy Technology Data Exchange (ETDEWEB)

    Açıkkalp, Emin, E-mail: eacikkalp@gmail.com [Department of Mechanical and Manufacturing Engineering, Engineering Faculty, Bilecik S.E. University, Bilecik (Turkey); Caner, Necmettin [Department of Chemistry, Faculty of Arts and Sciences, Eskisehir Osmangazi University, Eskisehir (Turkey)

    2015-09-25

    Highlights: • An irreversible Brayton cycle operating quantum gasses is considered. • Exergetic sustainability index is derived for nano-scale cycles. • Nano-scale effects are considered. • Calculation are conducted for irreversible cycles. • Numerical results are presented and discussed. - Abstract: In this study, a nano-scale irreversible Brayton cycle operating with quantum gasses including Bose and Fermi gasses is researched. Developments in the nano-technology cause searching the nano-scale machines including thermal systems to be unavoidable. Thermodynamic analysis of a nano-scale irreversible Brayton cycle operating with Bose and Fermi gasses was performed (especially using exergetic sustainability index). In addition, thermodynamic analysis involving classical evaluation parameters such as work output, exergy output, entropy generation, energy and exergy efficiencies were conducted. Results are submitted numerically and finally some useful recommendations were conducted. Some important results are: entropy generation and exergetic sustainability index are affected mostly for Bose gas and power output and exergy output are affected mostly for the Fermi gas by x. At the high temperature conditions, work output and entropy generation have high values comparing with other degeneracy conditions.

  6. Brayton cycle for internal combustion engine exhaust gas waste heat recovery

    Directory of Open Access Journals (Sweden)

    J Galindo

    2015-06-01

    Full Text Available An average passenger car engine effectively uses about one-third of the fuel combustion energy, while the two-thirds are wasted through exhaust gases and engine cooling. It is of great interest to automotive industry to recover some of this wasted energy, thus increasing the engine efficiency and lowering fuel consumption and contamination. Waste heat recovery for internal combustion engine exhaust gases using Brayton cycle machine was investigated. The principle problems of application of such a system in a passenger car were considered: compressor and expander machine selection, machine size for packaging under the hood, efficiency of the cycle, and improvement of engine efficiency. Important parameters of machines design have been determined and analyzed. An average 2-L turbocharged gasoline engine’s New European Driving Cycle points were taken as inlet points for waste heat recovery system. It is theoretically estimated that the recuperated power of 1515 W can be achieved along with 5.7% improvement in engine efficiency, at the point where engine power is 26550 W.

  7. Evaluation of Active Working Fluids for Brayton Cycles in Space Applications

    Science.gov (United States)

    Conklin, J. C.; Courville, G. E.; Scott, J. H.

    2004-02-01

    The main parameter of interest for space thermal power conversion to electricity is specific power, defined as the total electric power output per unit of system mass, rather than the cycle thermal efficiency. For a closed Brayton cycle, performance with two active working fluids, nitrogen tetroxide and aluminum chloride, is compared to that with an inert mixture of helium and xenon having a molecular mass of 40. A chemically active working fluid is defined here as a chemical compound that has a relatively high molecular weight at temperatures appropriate for the compressor inlet and dissociates to a lighter molecular weight fluid at typical turbine inlet temperatures. The active working fluids may have the advantage of a higher net turbomachinery work output and an advantageous enhancement of the heat transfer coefficient in the heat exchangers. The fundamental theory of the active working fluid concept is presented to demonstrate these potential advantages. Scoping calculations of the heat exchanger mass for a selected spacecraft application of 36.4 kW of electrical power output show that the nitrogen tetroxide active working fluid has an advantageous 7% to 30% lower mass-to-power ratio than that for the inert noble gas mixture, depending on the allowable turbine inlet temperature. The calculations for the aluminum chloride system suggest only a slight improvement in performance relative to the inert noble gas mixture.

  8. High Temperature Fusion Reactor Cooling Using Brayton Cycle Based Partial Energy Conversion

    Science.gov (United States)

    Juhasz, Albert J.; Sawicki, Jerzy T.

    2003-01-01

    For some future space power systems using high temperature nuclear heat sources most of the output energy will be used in other than electrical form, and only a fraction of the total thermal energy generated will need to be converted to electrical work. The paper describes the conceptual design of such a partial energy conversion system, consisting of a high temperature fusion reactor operating in series with a high temperature radiator and in parallel with dual closed cycle gas turbine (CCGT) power systems, also referred to as closed Brayton cycle (CBC) systems, which are supplied with a fraction of the reactor thermal energy for conversion to electric power. Most of the fusion reactor's output is in the form of charged plasma which is expanded through a magnetic nozzle of the interplanetary propulsion system. Reactor heat energy is ducted to the high temperature series radiator utilizing the electric power generated to drive a helium gas circulation fan. In addition to discussing the thermodynamic aspects of the system design the authors include a brief overview of the gas turbine and fan rotor-dynamics and proposed bearing support technology along with performance characteristics of the three phase AC electric power generator and fan drive motor.

  9. Closed Brayton Cycle (CBC) Power Generation from an Electric Systems Perspective

    Science.gov (United States)

    Halsey, David G.; Fox, David A.

    2006-01-01

    Several forms of closed cycle heat engines exist to produce electrical energy suitable for space exploration or planetary surface applications. These engines include Stirling and Closed Brayton Cycle (CBC). Of these two, CBC has often been cited as providing the best balance of mass and efficiency for deep space or planetary power systems. Combined with an alternator on the same shaft, the hermetically sealed system provides the potential for long life and reliable operation. There is also a list of choices for the type of alternator. Choices include wound rotor machines, induction machines, switched reluctance machines, and permanent magnet generators (PMGs). In trades involving size, mass and efficiency the PMG is a favorable solution. This paper will discuss the consequences of using a CBC-PMG source for an electrical power system, and the system parameters that must be defined and controlled to provide a stable, useful power source. Considerations of voltage, frequency (including DC), and power quality will be discussed. Load interactions and constraints for various power types will also be addressed. Control of the CBC-PMG system during steady state operation and startup is also a factor.s

  10. A Mass Computation Model for Lightweight Brayton Cycle Regenerator Heat Exchangers

    Science.gov (United States)

    Juhasz, Albert J.

    2010-01-01

    Based on a theoretical analysis of convective heat transfer across large internal surface areas, this paper discusses the design implications for generating lightweight gas-gas heat exchanger designs by packaging such areas into compact three-dimensional shapes. Allowances are made for hot and cold inlet and outlet headers for assembly of completed regenerator (or recuperator) heat exchanger units into closed cycle gas turbine flow ducting. Surface area and resulting volume and mass requirements are computed for a range of heat exchanger effectiveness values and internal heat transfer coefficients. Benefit cost curves show the effect of increasing heat exchanger effectiveness on Brayton cycle thermodynamic efficiency on the plus side, while also illustrating the cost in heat exchanger required surface area, volume, and mass requirements as effectiveness is increased. The equations derived for counterflow and crossflow configurations show that as effectiveness values approach unity, or 100 percent, the required surface area, and hence heat exchanger volume and mass tend toward infinity, since the implication is that heat is transferred at a zero temperature difference. To verify the dimensional accuracy of the regenerator mass computational procedure, calculation of a regenerator specific mass, that is, heat exchanger weight per unit working fluid mass flow, is performed in both English and SI units. Identical numerical values for the specific mass parameter, whether expressed in lb/(lb/sec) or kg/ (kg/sec), show the dimensional consistency of overall results.

  11. Analysis of Superimposed Elementary Thermodynamic Cycles: from the Brayton-Joule to Advanced Mixed (Auto-Combined Cycles

    Directory of Open Access Journals (Sweden)

    Giovanni Manente

    2009-09-01

    Full Text Available

    The need for efficiency improvement in energy conversion systems leads to a stricter functional integration among system components. This results in structures of increasing complexity, the high performance of which are often difficult to be understood easily. To make the comprehension of these structures easier, a new approach is followed in this paper, consisting in their representation as partial or total superimposition of elementary thermodynamic cycles. Although system performance cannot, in general, be evaluated as the sum of the performance of the separate thermodynamic cycles, this kind of representation and analysis can be of great help in understanding directions of development followed in the literature for the construction of advanced energy systems, and could suggest new potential directions of work. The evolution from the simple Brayton-Joule cycle to the so called “mixed” cycles, in which heat at the turbine discharge is exploited using internal heat sinks only without using a separate bottoming section, is used to demonstrate the potentiality of the approach. Mixed cycles are named here "auto-combined cycles” to highlight the combination of different (gas and steam cycles within the same system components.

    • This paper is an updated version of a paper published in the ECOS'08 proceedings. 

  12. Dynamic neutronic and stability analysis of a burst mode, single cavity gas core reactor Brayton cycle space power system

    Science.gov (United States)

    Dugan, Edward T.; Kutikkad, Kiratadas

    The conceptual, burst-mode gaseous-core reactor (GCR) space nuclear power system presently subjected to reactor-dynamics and system stability studies operates on a closed Brayton cycle, via disk MHD generator for energy conversion. While the gaseous fuel density power coefficient of reactivity is found to be capable of rapidly stabilizing the GCR system, the power of this feedback renders standard external reactivity insertions inadequate for significant power-level changes during normal operation.

  13. Thermodynamic design of methane liquefaction system based on reversed-Brayton cycle

    Science.gov (United States)

    Chang, Ho-Myung; Chung, Myung Jin; Kim, Min Jee; Park, Seong Bum

    2009-06-01

    A thermodynamic design is performed for reversed-Brayton refrigeration cycle to liquefy methane separated from landfill gas (LFG) in distributed scale. Objective of the design is to find the most efficient operating conditions for a skid-mount type of liquefaction system that is capable of LNG production at 160 l/h. Special attention is paid on liquefying counterflow heat exchanger, because the temperature difference between cold refrigerant and methane is smallest at the middle of heat exchanger, which seriously limits the overall thermodynamic performance of the liquefaction system. Nitrogen is selected as refrigerant, as it is superior to helium in thermodynamic efficiency. In order to consider specifically the size effect of heat exchangers, the performance of plate-fin heat exchangers is estimated with rigorous numerical calculations by incorporating a commercial code for properties of methane and the refrigerant. Optimal conditions in operating pressure and heat exchanger size are presented and discussed for prototype construction under a governmental project in Korea.

  14. Use of RELAP5-3D for Dynamic Analysis of a Closed-Loop Brayton Cycle Coupled To a Nuclear Reactor

    Science.gov (United States)

    McCann, Larry D.

    2007-01-01

    This paper describes results of a dynamic system model for a pair of closed Brayton-cycle (CBC) loops running in parallel that are connected to a nuclear gas reactor. The model assumes direct coupling between the reactor and the Brayton-cycle loops. The RELAP5-3D (version 2.4.1) computer program was used to perform the analysis. Few reactors have ever been coupled to closed Brayton-cycle systems. As such their behavior under dynamically varying loads, startup and shut down conditions, and requirements for safe and autonomous operation are largely unknown. The model described in this paper represents the reactor, turbine, compressor, recuperator, heat rejection system and alternator. The initial results of the model indicate stable operation of the reactor-driven Brayton-cycle system. However, for analysts with mostly pressurized water reactor experience, the Brayton cycle loops coupled to a gas-cooled reactor also indicate some counter-intuitive behavior for the complete coupled system. This model has provided crucial information in evaluating the reactor design and would have been further developed for use in developing procedures for safe start up, shut down, safe-standby, and other autonomous operating modes had the plant development cycle been completed.

  15. Transient analysis of an FHR coupled to a helium Brayton power cycle

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Minghui [The Ohio State Univ., Columbus, OH (United States). Nuclear Engineering Program; Kim, In Hun [The Ohio State Univ., Columbus, OH (United States). Nuclear Engineering Program; Sun, Xiaodong [The Ohio State Univ., Columbus, OH (United States). Nuclear Engineering Program; Christensen, Richard [The Ohio State Univ., Columbus, OH (United States). Nuclear Engineering Program; Utgikar, Vivek [Univ. of Idaho, Idaho Falls, ID (United States); Sabharwall, Piyush [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-08-01

    The Fluoride salt-cooled High-temperature Reactor (FHR) features a passive decay heat removal system and a high-efficiency Brayton cycle for electricity generation. It typically employs an intermediate loop, consisting of an intermediate heat exchanger (IHX) and a secondary heat exchanger (SHX), to couple the primary system with the power conversion unit (PCU). In this study, a preliminary dynamic system model is developed to simulate transient characteristics of a prototypic 20-MWth Fluoride salt-cooled High-temperature Test Reactor (FHTR). The model consists of a series of differential conservation equations that are numerically solved using the MATLAB platform. For the reactor, a point neutron kinetics model is adopted. For the IHX and SHX, a fluted tube heat exchanger and an offset strip-fin heat exchanger are selected, respectively. Detailed geometric parameters of each component in the FHTR are determined based on the FHTR nominal steady-state operating conditions. Three initiating events are simulated in this study, including a positive reactivity insertion, a step increase in the mass flow rate of the PCU helium flow, and a step increase in the PCU helium inlet temperature to the SHX. The simulation results show that the reactor has inherent safety features for those three simulated scenarios. It is observed that the increase in the temperatures of the fuel pebbles and primary coolant is mitigated by the decrease in the reactor power due to negative temperature feedbacks. The results also indicate that the intermediate loop with the two heat exchangers plays a significant role in the transient progression of the integral reactor system.

  16. Modeling the small-scale dish-mounted solar thermal Brayton cycle

    Science.gov (United States)

    Le Roux, Willem G.; Meyer, Josua P.

    2016-05-01

    The small-scale dish-mounted solar thermal Brayton cycle (STBC) makes use of a sun-tracking dish reflector, solar receiver, recuperator and micro-turbine to generate power in the range of 1-20 kW. The modeling of such a system, using a turbocharger as micro-turbine, is required so that optimisation and further development of an experimental setup can be done. As a validation, an analytical model of the small-scale STBC in Matlab, where the net power output is determined from an exergy analysis, is compared with Flownex, an integrated systems CFD code. A 4.8 m diameter parabolic dish with open-cavity tubular receiver and plate-type counterflow recuperator is considered, based on previous work. A dish optical error of 10 mrad, a tracking error of 1° and a receiver aperture area of 0.25 m × 0.25 m are considered. Since the recuperator operates at a very high average temperature, the recuperator is modeled using an updated ɛ-NTU method which takes heat loss to the environment into consideration. Compressor and turbine maps from standard off-the-shelf Garrett turbochargers are used. The results show that for the calculation of the steady-state temperatures and pressures, there is good comparison between the Matlab and Flownex results (within 8%) except for the recuperator outlet temperature, which is due to the use of different ɛ-NTU methods. With the use of Matlab and Flownex, it is shown that the small-scale open STBC with an existing off-the-shelf turbocharger could generate a positive net power output with solar-to-mechanical efficiency of up to 12%, with much room for improvement.

  17. A review of test results on solar thermal power modules with dish-mounted Stirling and Brayton cycle engines

    Science.gov (United States)

    Jaffe, Leonard D.

    1988-01-01

    This paper presents results of development tests of various solar thermal parabolic dish modules and assemblies that used dish-mounted Brayton or Stirling cycle engines for production of electric power. These tests indicate that early modules achieve net efficiencies up to 29 percent in converting sunlight to electricity, as delivered to the grid. Various equipment deficiencies were observed and a number of malfunctions occurred. The performance measurements, as well as the malfunctions and other test experience, provided information that should be of value in developing systems with improved performance and reduced maintenance.

  18. Development of 0.5-5 W, 10K Reverse Brayton Cycle Cryocoolers - Phase II Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Doty, F. D.; Boman, A.; Arnold, S.; Spitzmesser, J. B.; Jones, D.; McCree, D.; Hacker, L. J.

    2001-10-15

    Miniature cryocoolers for the 8-30 K range are needed to provide 0.5-5 w of cooling to high sensitivity detectors (for long-wave-length IR, magnetism, mm-wave, X-ray, dark matter, and possibly y-ray detection) while maintaining low mass, ultra-low vibration, and good efficiency. This project presents a new approach to eliminating the problems normally encountered in efforts to build low-vibration, fieldable, miniature cryocoolers. Using the reverse Brayton Cycle (RBC), the approach applies and expands on existing spinner technology previously used only in Nuclear Magnetic Resonance (NMR) probes.

  19. Power density analysis and optimization of a regenerated closed variable-temperature heat reservoir Brayton cycle

    Energy Technology Data Exchange (ETDEWEB)

    Lingen Chen; Junlin Zheng; Fengrui Sun [Naval Univ. of Engineering, Faculty 306, Wuhan (China); Chih Wu [US Naval Academy, Mechanical Engineering Dept., Annapolis, MD (United States)

    2001-06-07

    In this paper, the power density, defined as the ratio of power output to the maximum specific volume in the cycle, is taken as the objective for performance analysis and optimisation of an irreversible regenerated closed Brayton cycle coupled to variable-temperature heat reservoirs from the viewpoint of finite time thermodynamics (FTT) or entropy generation minimisation (EGM). The analytical formulae about the relations between power density and pressure ratio are derived with the heat resistance losses in the hot- and cold-side heat exchangers and the regenerator, the irreversible compression and expansion losses in the compressor and turbine, the pressure drop losses at the heater, cooler and regenerator as well as in the piping, and the effect of the finite thermal capacity rate of the heat reservoirs. The obtained results are compared with those results obtained by using the maximum power criterion, and the advantages and disadvantages of maximum power density design are analysed. The maximum power density optimisation is performed in two stages. The first is to search the optimum heat conductance distribution corresponding to the optimum power density among the hot- and cold-side heat exchangers and the regenerator for a fixed total heat exchanger inventory. The second is to search the optimum thermal capacitance rate matching corresponding to the inventory. The second is to search the optimum thermal capacitance rate matching corresponding to the optimum power density between the working fluid and the high-temperature heat source for a fixed ratio of the thermal capacitance rates of two heat reservoirs. The influences of some design parameters, including the effectiveness of the regenerator, the inlet temperature ratio of the heat reservoirs, the effectiveness of the heat exchangers between the working fluid and the heat reservoirs, the efficiencies of the compressor and the turbine, and the pressure recovery coefficient, on the optimum heat conductance

  20. Power density analysis and optimization of a regenerated closed variable-temperature heat reservoir Brayton cycle

    Energy Technology Data Exchange (ETDEWEB)

    Lingen Chen; Junlin Zheng; Fengrui Sun [Naval University of Engineering, Wuhan (China). Faculty 306; Chih Wu [US Naval Academy, Annapolis, MD (United States). Mechanical Engineering Dept.

    2001-06-07

    In this paper, the power density, defined as the ratio of power output to the maximum specific volume in the cycle, is taken as the objective for performance analysis and optimization of an irreversible regenerated closed Brayton cycle coupled to variable-temperature heat reservoirs from the viewpoint of finite time thermodynamics (FTT) or entropy generation minimization (EGM). The analytical formulae about the relations between power density and pressure ratio are derived with the heat resistance losses in the hot- and cold-side heat exchangers and the regenerator, the irreversible compression and expansion losses in the compressor and turbine, the pressure drop losses at the heater, cooler and regenerator as well as in the piping, and the effect of the finite thermal capacity rate of the heat reservoirs. The obtained results are compared with those results obtained by using the maximum power criterion, and the advantages and disadvantages of maximum power density design are analysed. The maximum power density optimization is performed in two stages. The first is to search the optimum beat conductance distribution corresponding to the optimum power density among the hot- and cold-side heat exchangers and the regenerator for a fixed total heat exchanger inventory. The second is to search the optimum thermal capacitance rate matching corresponding to the optimum power density between the working fluid and the high-temperature heat source for a fixed ratio of the thermal capacitance rates of two heat reservoirs. The influences of some design parameters, including the effectiveness of the regenerator, the inlet temperature ratio of the heat reservoirs, the effectiveness of the heat exchangers between the working fluid and the heat reservoirs, the efficiencies of the compressor and the turbine, and the pressure recovery coefficient, on the optimum heat conductance distribution, the optimum thermal capacitance rate matching, and the maximum power density are provided by

  1. Performance Optimization of a Solar-Driven Multi-Step Irreversible Brayton Cycle Based on a Multi-Objective Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Ahmadi Mohammad Hosein

    2016-01-01

    Full Text Available An applicable approach for a multi-step regenerative irreversible Brayton cycle on the basis of thermodynamics and optimization of thermal efficiency and normalized output power is presented in this work. In the present study, thermodynamic analysis and a NSGA II algorithm are coupled to determine the optimum values of thermal efficiency and normalized power output for a Brayton cycle system. Moreover, three well-known decision-making methods are employed to indicate definite answers from the outputs gained from the aforementioned approach. Finally, with the aim of error analysis, the values of the average and maximum error of the results are also calculated.

  2. Optimized, Competitive Supercritical-CO2 Cycle GFR for Gen IV Service

    Energy Technology Data Exchange (ETDEWEB)

    M.J. Driscoll; P. Hejzlar; G. Apostolakis

    2008-09-08

    An overall plant design was developed for a gas-cooled fast reactor employing a direct supercritical Brayton power conversion system. The most important findings were that (1) the concept could be capital-cost competitive, but startup fuel cycle costs are penalized by the low core power density, specified in large part to satisfy the goal of significatn post-accident passive natural convection cooling; (2) active decay heat removal is preferable as the first line of defense, with passive performance in a backup role; (3) an innovative tube-in-duct fuel assembly, vented to the primpary coolant, appears to be practicable; and (4) use of the S-Co2 GFR to support hydrogen production is a synergistic application, since sufficient energy can be recuperated from the product H2 and 02 to allow the electrolysis cell to run 250 C hotter than the reactor coolant, and the water boilers can be used for reactor decay heat removal. Increasing core poer density is identified as the top priority for future work on GFRs of this type.

  3. Thermodynamic Analysis of a Supercritical Mercury Power Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, A.S. Jr.

    1969-04-15

    An heat engine is considered which employs supercritical mercury as the working fluid and a magnetohydrodynamic (MHD) generator for thermal to electrical energy conversion. The main thrust of the paper is power cycle thermodynamics, where constraints are imposed by utilizing a MHD generator operating between supercritical, electrically conducting states of the working fluid; and, pump work is accomplished with liquid mercury. The temperature range is approximately 300 to 2200 K and system pressure is > 1,500 atm. Equilibrium and transport properties are carefully considered since these are known to vary radically in the vicinity of the critical point, which is found near the supercritical states of interest. A maximum gross plant efficiency is 20% with a regenerator effectiveness of 90% and greater, a cycle pressure ratio of two, and with highly efficient pump and generator. Certain specified cycle irreversibilities and others such as heat losses and heat exchanger pressure drops, which are not accounted for explicitly, reduce the gross plant efficiency to a few per cent. Experimental efforts aimed at practical application of the power cycle are discouraged by the marginal thermodynamic performance predicted by this study, unless such applications are insensitive to gross cycle efficiency.

  4. Detailed analysis of the effect of the turbine and compressor isentropic efficiency on the thermal and exergy efficiency of a Brayton cycle

    Directory of Open Access Journals (Sweden)

    Živić Marija

    2014-01-01

    Full Text Available Energy and exergy analysis of a Brayton cycle with an ideal gas is given. The irreversibility of the adiabatic processes in turbine and compressor is taken into account through their isentropic efficiencies. The net work per cycle, the thermal efficiency and the two exergy efficiencies are expressed as functions of the four dimensionless variables: the isentropic efficiencies of turbine and compressor, the pressure ratio, and the temperature ratio. It is shown that the maximal values of the net work per cycle, the thermal and the exergy efficiency are achieved when the isentropic efficiencies and temperature ratio are as high as possible, while the different values of pressure ratio that maximize the net work per cycle, the thermal and the exergy efficiencies exist. These pressure ratios increase with the increase of the temperature ratio and the isentropic efficiency of compressor and turbine. The increase of the turbine isentropic efficiency has a greater impact on the increase of the net work per cycle and the thermal efficiency of a Brayton cycle than the same increase of compressor isentropic efficiency. Finally, two goal functions are proposed for thermodynamic optimization of a Brayton cycle for given values of the temperature ratio and the compressor and turbine isentropic efficiencies. The first maximizes the sum of the net work per cycle and thermal efficiency while the second the net work per cycle and exergy efficiency. In both cases the optimal pressure ratio is closer to the pressure ratio that maximizes the net work per cycle.

  5. The design and fabrication of a reverse Brayton cycle cryocooler system for the high temperature superconductivity cable cooling

    Science.gov (United States)

    Park, Jae Hong; Kwon, Yong Ha; Kim, Young Soo

    2005-01-01

    A high temperature superconductivity cable must be cooled below the nitrogen liquefaction temperature to apply the cable to power generation and transmission systems under superconducting state. To maintain the superconducting state, a reliable cryocooler system is also required. The design and fabrication of a cryocooler system have been performed with a reverse Brayton cycle using neon gas as a refrigerant. The system consists of a compressor, a recuperator, a cold-box, and control valves. The design of the system is made to have 1 kW cooling capacity. The heat loss through multilayer insulators is calculated. Conduction heat loss is about 7 W through valves and access ports and radiation heat loss is about 18 W on the surface of a cryocooler. The design factors are discussed in detail.

  6. Optimum performance of the small scale open and direct solar thermal Brayton cycle at various environmental conditions and constraints

    Energy Technology Data Exchange (ETDEWEB)

    Le Roux, W.G.; Bello-Ochende, T.; Meyer, J.P. [Department of Mechanical and Aeronautical Engineering, University of Pretoria, (South Africa)

    2011-07-01

    The energy of the sun can be transformed into mechanical power through the use of concentrated solar power systems. The use of the Brayton cycle with recuperator has significant advantages but also raises issues such as pressure loss and low net power output which are mainly due to irreversibilities of heat transfer and fluid friction. The aim of this study is to optimize the system to generate maximum net power output. Thermodynamic and dynamic trajectory optimizations were performed on a dish concentrator and an off-the-shelf micro-turbine and the effects of wind, solar irradiance and other environmental conditions and constraints on the power output were analyzed. Results showed that the maximum power output is increased when wind decreases and irradiance increases; solar irradiance was found to have a more significant impact than wind. This study highlighted the factors which impact the power generation of concentrated solar power systems so that designers can take them into account.

  7. An open reversed Brayton cycle with regeneration using moist air for deep freeze cooled by circulating water

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Shaobo [Guangdong Ocean University, College of Engineering, East Jiefang Rd. No. 40, Xiashan, Zhanjiang, Guangdong 524006 (China); Northwestern Polytechnical University, School of Aeroengine and Thermal Power Engineering, Xi' an, Shaanxi 710072 (China); Zhang, Hefei [Northwestern Polytechnical University, School of Aeroengine and Thermal Power Engineering, Xi' an, Shaanxi 710072 (China)

    2009-01-15

    This paper presents an open reversed Brayton cycle with regeneration using moist air for deep freeze cooled by circulating water, and proves its feasibility through performance simulation. Pinch technology is used to analyze the cooling of the wet air after compressor and the water used for cooling wet air after compressor. Its refrigeration depends mainly on the sensible heat of air and the latent heat of water vapor, its performance is more efficient than a conventional air-cycle, and the utilization of turbo-machinery makes it possible. The adoption of this cycle will make deep freeze easily and reduce initial cost because very low temperature, about -55 C, air is obtained. The sensitivity analysis of coefficient of performance to the efficiency of compressor and the efficiency of compressor, and the results of the cycle are also given. The simulation results show that the COP of this system depends on the temperature before turbine, the efficiency of compressor and the efficiency of compressor, and varies with the wet bulb temperature of the outdoor air. Humid air is a perfect working fluid for deep freeze with no cost to the user. (author)

  8. Design of Supercritical Carbon Dioxide Compressor Testing Loop

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Gu; Lee, Jeong Ik; Ahn, Yoon Han; Lee, Je Kyoung [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Yoon, Ho Joon; Addad, Yacine [KUSTAR, Abu Dhabi (United Arab Emirates)

    2012-05-15

    For small and medium-sized reactors and Generation IV reactors such as sodium-cooled fast reactor are recently under development actively. The supercritical CO{sub 2} Brayton cycle is considered as an attractive cycle for the above mentioned nuclear systems. This is because the supercritical CO{sub 2} Brayton cycle (S-CO{sub 2} cycle) is especially effective to reduce the volume of power generation system, which occupies 1.5{approx}2 times more space than the primary nuclear system in general. Comparing to traditional water-vapor cycle and helium cycle, the S-CO{sub 2} system has relatively much less volume and component size. Therefore, S-CO{sub 2} cycle can be used for many purposes such as nuclear ship propulsion where volume requirement is strict, or a small nuclear reactor when it is constructed on geographically limited area

  9. Supercritical Fluid Parameters in Organic Rankine Cycle Applications

    Directory of Open Access Journals (Sweden)

    Andreas Schuster

    2008-09-01

    Full Text Available Nowadays, the use of Organic Rankine Cycle (ORC in decentralised applications is linked with the fact that this process allows to use low temperature heat sources and offers an advantageous efficiency in small-scale applications. Many state of the art applications like geothermal and biomass fired power plants as well as new applications like solar desalination with reverse osmosis, waste heat recovery from biogas digestion plants or micro-Combined Heat and Power (micro-CHP systems can successfully use the ORC process. The investigation of supercritical parameters in ORC applications seems to bring promising results in decentralised energy production. This paper presents the results from the simulation of the ORC process in normal and supercritical fluid parameters and discusses the efficiency variation in various applications.

  10. A preliminary study of a D-T tokamak fusion reactor with advanced blanket using compact fusion advanced Brayton (CFAB) cycle

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, K.; Ohnishi, M.; Yamamoto, Y. [Kyoto Univ. (Japan)] [and others

    1994-12-31

    Key issues on a D-T Tokamak fusion reactor with advanced blanket concept using CFAB (Compact Fusion Advanced Brayton) cycle are presented. Although the previously proposed and studied compact fusion advanced Rankine cycle using mercury liquid metal has shown, in general, excellent performance characteristics in extracting energy and electricity with high efficiency by the {open_quotes}in-situ{close_quotes} nonequilibrium MHD disk generator, and in enhancing safety potential, there was a fear about uses of hazardous mercury as primary coolant as well as its limited natural resources. To overcome these disadvantages while retaining the advantage features of a ultra-high temperature coolant inherent in the synchrotron energy-enhanced D-T tokamak reactor, a compact fusion advanced Brayton cycle using helium was reexamined which was once considered relatively not superior in the CFAR study, at the expense of high, but acceptable circulation power, lower heat transfer characteristics, and probably of a little bit reduced safety.

  11. Performance Expectations of Closed-Brayton-Cycle Heat Exchangers in 100-kWe Nuclear Space Power Systems

    Science.gov (United States)

    Barrett, Michael J.

    2003-01-01

    Performance expectations of closed-Brayton-cycle heat exchangers to be used in 100-kWe nuclear space power systems were forecast. Proposed cycle state points for a system supporting a mission to three of Jupiter s moons required effectiveness values for the heat-source exchanger, recuperator and rejection exchanger (gas cooler) of 0.98,0.95 and 0.97, respectively. Performance parameters such as number of thermal units (Nm), equivalent thermal conductance (UA), and entropy generation numbers (Ns) varied from 11 to 19,23 to 39 kWK, and 0.019 to 0.023 for some standard heat exchanger configurations. Pressure-loss contributions to entropy generation were significant; the largest frictional contribution was 114% of the heat-transfer irreversibility. Using conventional recuperator designs, the 0.95 effectiveness proved difficult to achieve without exceeding other performance targets; a metallic, plate-fin counterflow solution called for 15% more mass and 33% higher pressure-loss than the target values. Two types of gas-coolers showed promise. Single-pass counterflow and multipass cross-counterflow arrangements both met the 0.97 effectiveness requirement. Potential reliability-related advantages of the cross-countefflow design were noted. Cycle modifications, enhanced heat transfer techniques and incorporation of advanced materials were suggested options to reduce system development risk. Carbon-carbon sheeting or foam proved an attractive option to improve overall performance.

  12. Waste heat recovery from adiabatic diesel engines by exhaust-driven Brayton cycles

    Energy Technology Data Exchange (ETDEWEB)

    Khalifa, H.E.

    1983-12-01

    This report presents an evaluation of Brayton Bottoming Systems (BBS) as waste heat recovery devices for future adiabatic diesel engines in heavy duty trucks. Parametric studies were performed to evaluate the influence of external and internal design parameters on BBS performance. Conceptual design and trade-off studies were undertaken to estimate the optimum configuration, size, and cost of major hardware components. The potential annual fuel savings of long-haul trucks equipped with BBS were estimated. The addition of a BBS to a turbocharged, nonaftercooled adiabatic engine would improve fuel economy by as much as 12%. In comparison with an aftercooled, turbocompound engine, the BBS-equipped turbocharged engine would offer a 4.4% fuel economy advantage. It is also shown that, if installed in tandem with an aftercooled turbocompound engine, the BBS could effect a 7.2% fuel economy improvement. The cost of a mass-produced 38 Bhp BBS is estimated at about $6460 or $170/Bhp. Technical and economic barriers that would hinder the commercial introduction of bottoming systems were identified.

  13. Selected aspects of operation of supercritical (transcritical organic Rankine cycle

    Directory of Open Access Journals (Sweden)

    Mocarsk Szymon

    2015-06-01

    Full Text Available The paper presents a literature review on the topic of vapour power plants working according to the two-phase thermodynamic cycle with supercritical parameters. The main attention was focused on a review of articles and papers on the vapour power plants working using organic circulation fluids powered with low- and medium-temperature heat sources. Power plants with water-steam cycle supplied with a high-temperature sources have also been shown, however, it has been done mainly to show fundamental differences in the efficiency of the power plant and applications of organic and water-steam cycles. Based on a review of available literature references a comparative analysis of the parameters generated by power plants was conducted, depending on the working fluid used, the type and parameters of the heat source, with particular attention to the needs of power plant internal load.

  14. Verification of a 2 kWe Closed-Brayton-Cycle Power Conversion System Mechanical Dynamics Model

    Science.gov (United States)

    Ludwiczak, Damian R.; Le, Dzu K.; McNelis, Anne M.; Yu, Albert C.; Samorezov, Sergey; Hervol, Dave S.

    2005-01-01

    Vibration test data from an operating 2 kWe closed-Brayton-cycle (CBC) power conversion system (PCS) located at the NASA Glenn Research Center was used for a comparison with a dynamic disturbance model of the same unit. This effort was performed to show that a dynamic disturbance model of a CBC PCS can be developed that can accurately predict the torque and vibration disturbance fields of such class of rotating machinery. The ability to accurately predict these disturbance fields is required before such hardware can be confidently integrated onto a spacecraft mission. Accurate predictions of CBC disturbance fields will be used for spacecraft control/structure interaction analyses and for understanding the vibration disturbances affecting the scientific instrumentation onboard. This paper discusses how test cell data measurements for the 2 kWe CBC PCS were obtained, the development of a dynamic disturbance model used to predict the transient torque and steady state vibration fields of the same unit, and a comparison of the two sets of data.

  15. Life cycle assessment analysis of supercritical coal power units

    Science.gov (United States)

    Ziębik, Andrzej; Hoinka, Krzysztof; Liszka, Marcin

    2010-09-01

    This paper presents the Life Cycle Assessment (LCA) analysis concerning the selected options of supercritical coal power units. The investigation covers a pulverized power unit without a CCS (Carbon Capture and Storage) installation, a pulverized unit with a "post-combustion" installation (MEA type) and a pulverized power unit working in the "oxy-combustion" mode. For each variant the net electric power amounts to 600 MW. The energy component of the LCA analysis has been determined. It describes the depletion of non-renewable natural resources. The energy component is determined by the coefficient of cumulative energy consumption in the life cycle. For the calculation of the ecological component of the LCA analysis the cumulative CO2 emission has been applied. At present it is the basic emission factor for the LCA analysis of power plants. The work also presents the sensitivity analysis of calculated energy and ecological factors.

  16. Systems Analyses of Advanced Brayton Cycles For High Efficiency Zero Emission Plants

    Energy Technology Data Exchange (ETDEWEB)

    A. D. Rao; J. Francuz; A. Verma; G. S. Samuelsen

    2006-10-30

    The ultimate goal of this program is to identify the power block cycle conditions and/or configurations which could increase the overall thermal efficiency of the Baseline IGCC by about 8% on a relative basis (i.e., 8% on a heat rate basis). This document presents the cycle conditions and/or the configurations for evaluation in an initial screening analysis. These cycle conditions and/or configurations for investigation in the screening analysis are identified by literature searches and brain storming sessions. The screening analysis in turn narrows down the number of promising cases for detailed analysis.

  17. High-Efficiency Low-Cost Solar Receiver for Use Ina a Supercritical CO2 Recompression Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, Shaun D. [Brayton Energy, LLC, Portsmouth, NH (United States); Kesseli, James [Brayton Energy, LLC, Portsmouth, NH (United States); Nash, James [Brayton Energy, LLC, Portsmouth, NH (United States); Farias, Jason [Brayton Energy, LLC, Portsmouth, NH (United States); Kesseli, Devon [Brayton Energy, LLC, Portsmouth, NH (United States); Caruso, William [Brayton Energy, LLC, Portsmouth, NH (United States)

    2016-04-06

    This project has performed solar receiver designs for two supercritical carbon dioxide (sCO2) power cycles. The first half of the program focused on a nominally 2 MWe power cycle, with a receiver designed for test at the Sandia Solar Thermal Test Facility. This led to an economical cavity-type receiver. The second half of the program focused on a 10 MWe power cycle, incorporating a surround open receiver. Rigorous component life and performance testing was performed in support of both receiver designs. The receiver performance objectives are set to conform to the US DOE goals of 6¢/kWh by 2020 . Key findings for both cavity-type and direct open receiver are highlighted below: A tube-based absorber design is impractical at specified temperatures, pressures and heat fluxes for the application; a plate-fin architecture however has been shown to meet performance and life targets; the $148/kWth cost of the design is significantly less than the SunShot cost target with a margin of 30%; the proposed receiver design is scalable, and may be applied to both modular cavity-type installations as well as large utility-scale open receiver installations; the design may be integrated with thermal storage systems, allowing for continuous high-efficiency electrical production during off-sun hours; costs associated with a direct sCO2 receiver for a sCO2 Brayton power cycle are comparable to those of a typical molten salt receiver; lifetimes in excess of the 90,000 hour goal are achievable with an optimal cell geometry; the thermal performance of the Brayton receiver is significantly higher than the industry standard, and enables at least a 30% efficiency improvement over the performance of the baseline steam-Rankine boiler/cycle system; brayton’s patent-pending quartz tube window provides a greater than five-percent efficiency benefit to the receiver by reducing both convection and radiation losses.

  18. Novel Supercritical Carbon Dioxide Power Cycle Utilizing Pressured Oxy-combustion in Conjunction with Cryogenic Compression

    Energy Technology Data Exchange (ETDEWEB)

    Brun, Klaus; McClung, Aaron; Davis, John

    2014-03-31

    The team of Southwest Research Institute® (SwRI) and Thar Energy LLC (Thar) applied technology engineering and economic analysis to evaluate two advanced oxy-combustion power cycles, the Cryogenic Pressurized Oxy-combustion Cycle (CPOC), and the Supercritical Oxy-combustion Cycle. This assessment evaluated the performance and economic cost of the two proposed cycles with carbon capture, and included a technology gap analysis of the proposed technologies to determine the technology readiness level of the cycle and the cycle components. The results of the engineering and economic analysis and the technology gap analysis were used to identify the next steps along the technology development roadmap for the selected cycle. The project objectives, as outlined in the FOA, were 90% CO{sub 2} removal at no more than a 35% increase in cost of electricity (COE) as compared to a Supercritical Pulverized Coal Plant without CO{sub 2} capture. The supercritical oxy-combustion power cycle with 99% carbon capture achieves a COE of $121/MWe. This revised COE represents a 21% reduction in cost as compared to supercritical steam with 90% carbon capture ($137/MWe). However, this represents a 49% increase in the COE over supercritical steam without carbon capture ($80.95/MWe), exceeding the 35% target. The supercritical oxy-combustion cycle with 99% carbon capture achieved a 37.9% HHV plant efficiency (39.3% LHV plant efficiency), when coupling a supercritical oxy-combustion thermal loop to an indirect supercritical CO{sub 2} (sCO{sub 2}) power block. In this configuration, the power block achieved 48% thermal efficiency for turbine inlet conditions of 650°C and 290 atm. Power block efficiencies near 60% are feasible with higher turbine inlet temperatures, however a design tradeoff to limit firing temperature to 650°C was made in order to use austenitic stainless steels for the high temperature pressure vessels and piping and to minimize the need for advanced turbomachinery features

  19. Performance of a Supercritical CO2 Bottoming Cycle for Aero Applications

    National Research Council Canada - National Science Library

    Florian Jacob; Andrew Martin Rolt; Joshua Marius Sebastiampillai; Vishal Sethi; Mathieu Belmonte; Pedro Cobas

    2017-01-01

    .... This could provide additional shaft power. Supercritical carbon dioxide closed-circuit power cycles are currently being investigated primarily for stationary power applications, but their high power density and efficiency, even for modest...

  20. Novel Supercritical Carbon Dioxide Power Cycle Utilizing Pressured Oxy-combustion in Conjunction with Cryogenic Compression

    Energy Technology Data Exchange (ETDEWEB)

    Brun, Klaus; McClung, Aaron; Davis, John

    2014-03-31

    The team of Southwest Research Institute® (SwRI) and Thar Energy LLC (Thar) applied technology engineering and economic analysis to evaluate two advanced oxy-combustion power cycles, the Cryogenic Pressurized Oxy-combustion Cycle (CPOC), and the Supercritical Oxy-combustion Cycle. This assessment evaluated the performance and economic cost of the two proposed cycles with carbon capture, and included a technology gap analysis of the proposed technologies to determine the technology readiness level of the cycle and the cycle components. The results of the engineering and economic analysis and the technology gap analysis were used to identify the next steps along the technology development roadmap for the selected cycle. The project objectives, as outlined in the FOA, were 90% CO{sub 2} removal at no more than a 35% increase in cost of electricity (COE) as compared to a Supercritical Pulverized Coal Plant without CO{sub 2} capture. The supercritical oxy-combustion power cycle with 99% carbon capture achieves a COE of $121/MWe. This revised COE represents a 21% reduction in cost as compared to supercritical steam with 90% carbon capture ($137/MWe). However, this represents a 49% increase in the COE over supercritical steam without carbon capture ($80.95/MWe), exceeding the 35% target. The supercritical oxy-combustion cycle with 99% carbon capture achieved a 37.9% HHV plant efficiency (39.3% LHV plant efficiency), when coupling a supercritical oxy-combustion thermal loop to an indirect supercritical CO{sub 2} (sCO{sub 2}) power block. In this configuration, the power block achieved 48% thermal efficiency for turbine inlet conditions of 650°C and 290 atm. Power block efficiencies near 60% are feasible with higher turbine inlet temperatures, however a design tradeoff to limit firing temperature to 650°C was made in order to use austenitic stainless steels for the high temperature pressure vessels and piping and to minimize the need for advanced turbomachinery features

  1. Computational Fluid Dynamics Analysis of Supercritical Carbon Dioxide Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae W.; Kim, Nam H.; Suh, Kune Y. [Seoul National University, Seoul (Korea, Republic of); Kim, Seung O. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2007-07-01

    The supercritical carbon dioxide (SCO{sub 2}) gas turbine Brayton cycle has been not only adopted in the secondary loop of the Generation IV nuclear energy systems but also planned to be installed in the high efficiency power conversion cycles of the nuclear fusion reactors. The potential beneficiaries include the Korea Advanced Liquid Metal Reactor (KALIMER), the Korea Superconducting Tokamak Advanced Research (KSTAR) as well as the International Thermonuclear Experimental Reactor (ITER). The reason for these welcomed applications is that the cycle can achieve the overall energy conversion efficiency as high as 45%. The SCO{sub 2} turbine efficiency is one of the major parameters affecting the overall Brayton cycle efficiency. Thus, optimal turbine design determines the economics of the Generation IV as well as the future nuclear fission and fusion energy industry. Seoul National University has recently been working on the SCO{sub 2} based Modular Optimized Brayton Integral System (MOBIS). MOBIS includes the Gas Advanced Turbine Operation Study (GATOS), the Loop Operating Brayton Optimization Study (LOBOS), the Nonsteady Operation Multidimensional Online Simulator (NOMOS), and the Turbine Advanced Compressor Operation Study (TACOS). This paper presents results from GATOS.

  2. Computational Fluid Dynamics Analysis of Supercritical Carbon Dioxide Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae W.; Kim, Nam H.; Suh, Kune Y. [Seoul National University, Seoul (Korea, Republic of); Kim, Seung O. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2006-07-01

    The supercritical carbon dioxide (SCO{sub 2}) gas turbine Brayton cycle has been not only adopted in the secondary loop of the Generation IV nuclear energy systems but also planned to be installed in the high efficiency power conversion cycles of the nuclear fusion reactors. The potential beneficiaries include the Korea Advanced Liquid Metal Reactor (KALIMER), Korea Superconducting Tokamak Advanced Research (KSTAR) and International Thermonuclear Experimental Reactor (ITER). The reason for these welcomed applications is that the cycle can achieve the overall energy conversion efficiency as high as 45%. The SCO{sub 2} turbine efficiency is one of the major parameters affecting the overall Brayton cycle efficiency. Thus, optimal turbine design determines the economics of the Generation IV as well as the future nuclear fission and fusion energy industry. Seoul National University has recently been working on the SCO{sub 2} based Modular Optimized Brayton Integral System (MOBIS). MOBIS includes the Gas Advanced Turbine Operation Study (GATOS), the Loop Operating Brayton Optimization Study (LOBOS), the Nonsteady Operation Multidimensional Online Simulator (NOMOS), and the Turbine Advanced Compressor Operation Study (TACOS). This paper presents first results from GATOS.

  3. Study on CO{sub 2} Recovery System Design in Supercritical CO{sub 2} Cycle for SFR Application

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Seok; Jung, Hwa-Young; Lee, Jeong Ik [KAIST, Daejeon (Korea, Republic of)

    2016-10-15

    As a part of Sodium-cooled Fast Reactor (SFR) development in Korea, the supercritical CO{sub 2} (S-CO{sub 2}) Brayton cycle is considered as an alternative power conversion system to eliminate sodium-water reaction (SWR) when the current conventional steam Rankine cycle is utilized with SFR. The parasitic loss caused by the leakage flow should be minimized since this greatly influences the cycle efficiency. Thus, a simple model for estimating the critical flow in a turbo-machinery seal was developed to predict the leakage flow rate and calculate the required total mass of working fluid in a S-CO{sub 2} power system to minimize the parasitic loss. In this work, study on CO{sub 2} recovery system design was conducted by finding the suitable recovery point with the developed simple CO{sub 2} critical flow model and sensitivity analysis was performed on the power system performance with respect to multiple CO{sub 2} recovery process options. The study of a CO{sub 2} recovery system design was conducted to minimize the thermal efficiency losses caused by CO{sub 2} inventory recovery system. For the first step, the configuration of a seal was selected. A labyrinth seal has suitable features for the S-CO{sub 2} power cycle application. Then, thermal efficiency losses with different CO{sub 2} leak rate and recovery point were evaluated. To calculate the leak rate in turbo-machinery by using the developed CO{sub 2} critical flow model, the conditions of storage tank is set to be closer to the recovery point. After modifying the critical flow model appropriately, total mass flow rate of leakage flow was calculated. Finally, the CO{sub 2} recovery system design work was performed to minimize the loss of thermal efficiency. The suggested system is not only simple and intuitive but also has relatively very low additional work loss from the compressor than other considered systems. When each leak rate is set to the conventional leakage rate of 1 kg/s per seal, the minimum and

  4. Multi-objective thermodynamic optimization of an irreversible regenerative Brayton cycle using evolutionary algorithm and decision making

    Directory of Open Access Journals (Sweden)

    Rajesh Kumar

    2016-06-01

    Full Text Available Brayton heat engine model is developed in MATLAB simulink environment and thermodynamic optimization based on finite time thermodynamic analysis along with multiple criteria is implemented. The proposed work investigates optimal values of various decision variables that simultaneously optimize power output, thermal efficiency and ecological function using evolutionary algorithm based on NSGA-II. Pareto optimal frontier between triple and dual objectives is obtained and best optimal value is selected using Fuzzy, TOPSIS, LINMAP and Shannon’s entropy decision making methods. Triple objective evolutionary approach applied to the proposed model gives power output, thermal efficiency, ecological function as (53.89 kW, 0.1611, −142 kW which are 29.78%, 25.86% and 21.13% lower in comparison with reversible system. Furthermore, the present study reflects the effect of various heat capacitance rates and component efficiencies on triple objectives in graphical custom. Finally, with the aim of error investigation, average and maximum errors of obtained results are computed.

  5. CFD Analysis of a supercritical carbon dioxide compressor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Gu; Lee, Jeong Ik; Ahn, Yoon Han; Lee, Jek Young; Cha, Jae Eun; Addad, Yacine [KAIST, Daejeon (Korea, Republic of)

    2012-10-15

    The supercritical carbon dioxide Brayton cycle is considered as an attractive cycle for the next generation nuclear systems. It was identified that the compressor can achieve very small compressing work as operating conditions become closer to the critical point. Smaller amount of input work contributes to the enhancement of overall net cycle efficiency. Comparing to traditional water vapor cycle and helium cycle, the S CO{sup 2} cycle has relatively much less volume and component size. Therefore, S CO{sup 2} cycle can be used for many purposes such as nuclear ship propulsion where volume requirement is strict, or a small nuclear reactor when it is constructed on geographically limited area One of the main factors for determining the supercritical Brayton cycle efficiency is the performance of turbomachineries. Many research organizations already obtained experimental data of S CO{sup 2} cycle turbomachineries, but the amount of data is still limited. Our research team is conducting a S CO{sup 2} compressor test to obtain fundamental data for advanced compressor design and measure the performance of the compressor near the critical point. The S CO{sup 2} compressor testing loop is specially designed to test main compressor of the loop. The S CO{sup 2} fluid shows the properties of gases and liquids at the same time, but its behavior is closer to the liquid rather than gas near the critical point. Therefore, we are performing compressor test with canned motor pump which is unique from other previous studies.

  6. 超临界二氧化碳在核反应堆系统中的应用%Applications of Supercritical Carbon Dioxide in Nuclear Reactor System

    Institute of Scientific and Technical Information of China (English)

    黄彦平; 王俊峰

    2012-01-01

    The applications of supercritical carbon dioxide Brayton cycle in nuclear reactor systems have attracted worldwide attention in recent years. In this paper, the advantages of employing supercritical carbon dioxide Brayton cycle in nuclear reactors were analyzed based on its fundamental conception. The investigations on supercritical carbon dioxide Brayton cycle were reviewed. The potential application area of supercritical carbon dioxide in Chinese advanced nuclear energy technology were analyzed and discussed, and some associated suggestions were proposed.%基于超临界二氧化碳布雷顿循环的基本原理,分析其应用于核反应堆系统的主要优势,介绍目前国际上超临界二氧化碳应用于核反应堆系统的相关研究进展,对超临界二氧化碳工质在我国未来先进核能技术研发中潜在的应用对象进行探讨,并提出相关建议.

  7. Selection of a closed Brayton cycle gas turbine for an intermediate-duty solar-electric power plant

    Science.gov (United States)

    Vieth, G. L.; Plummer, D. F.

    1980-03-01

    Subsystem and system analyses were performed to select the preferred working gas, performance characteristics and size of a closed cycle gas turbine for an intermediate-duty solar-electric power plant. Capital costs for all major subsystems were evaluated, but the principal selection criterion was the projected cost of electricity produced by the plant. Detailed analyses of the power conversion loop were conducted for both air and helium systems. Since the plant was intended for use on an intermediate-duty cycle, thermal storage was required. The coupling of the storage and power conversion loops in combination with the daily operating cycle influenced plant performance and energy costs in addition to the selection of the power conversion cycle.

  8. Performance comparison of different thermodynamic cycles for an innovative central receiver solar power plant

    Science.gov (United States)

    Reyes-Belmonte, Miguel A.; Sebastián, Andrés; González-Aguilar, José; Romero, Manuel

    2017-06-01

    The potential of using different thermodynamic cycles coupled to a solar tower central receiver that uses a novel heat transfer fluid is analyzed. The new fluid, named as DPS, is a dense suspension of solid particles aerated through a tubular receiver used to convert concentrated solar energy into thermal power. This novel fluid allows reaching high temperatures at the solar receiver what opens a wide range of possibilities for power cycle selection. This work has been focused into the assessment of power plant performance using conventional, but optimized cycles but also novel thermodynamic concepts. Cases studied are ranging from subcritical steam Rankine cycle; open regenerative Brayton air configurations at medium and high temperature; combined cycle; closed regenerative Brayton helium scheme and closed recompression supercritical carbon dioxide Brayton cycle. Power cycle diagrams and working conditions for design point are compared amongst the studied cases for a common reference thermal power of 57 MWth reaching the central cavity receiver. It has been found that Brayton air cycle working at high temperature or using supercritical carbon dioxide are the most promising solutions in terms of efficiency conversion for the power block of future generation by means of concentrated solar power plants.

  9. Exergy analysis of internal regeneration in supercritical cycles of ORC power plant

    Science.gov (United States)

    Borsukiewicz-Gozdur, Aleksandra

    2012-09-01

    In the paper presented is an idea of organic Rankine cycle (ORC) operating with supercritical parameters and so called dry fluids. Discussed is one of the methods of improving the effectiveness of operation of supercritical cycle by application of internal regeneration of heat through the use of additional heat exchanger. The main objective of internal regenerator is to recover heat from the vapour leaving the turbine and its transfer to the liquid phase of working fluid after the circulation pump. In effect of application of the regenerative heat exchanger it is possible to obtain improved effectiveness of operation of the power plant, however, only in the case when the ORC plant is supplied from the so called sealed heat source. In the present paper presented is the discussion of heat sources and on the base of the case study of two heat sources, namely the rate of heat of thermal oil from the boiler and the rate of heat of hot air from the cooler of the clinkier from the cement production line having the same initial temperature of 260 oC, presented is the influence of the heat source on the justification of application of internal regeneration. In the paper presented are the calculations for the supercritical ORC power plant with R365mfc as a working fluid, accomplished has been exergy changes and exergy efficiency analysis with the view to select the most appropriate parameters of operation of the power plant for given parameters of the heat source.

  10. Analysis of supercritical CO{sub 2} cycle control strategies and dynamic response for Generation IV Reactors.

    Energy Technology Data Exchange (ETDEWEB)

    Moisseytsev, A.; Sienicki, J. J. (Nuclear Engineering Division)

    2011-04-12

    The analysis of specific control strategies and dynamic behavior of the supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle has been extended to the two reactor types selected for continued development under the Generation IV Nuclear Energy Systems Initiative; namely, the Very High Temperature Reactor (VHTR) and the Sodium-Cooled Fast Reactor (SFR). Direct application of the standard S-CO{sub 2} recompression cycle to the VHTR was found to be challenging because of the mismatch in the temperature drop of the He gaseous reactor coolant through the He-to-CO{sub 2} reactor heat exchanger (RHX) versus the temperature rise of the CO{sub 2} through the RHX. The reference VHTR features a large temperature drop of 450 C between the assumed core outlet and inlet temperatures of 850 and 400 C, respectively. This large temperature difference is an essential feature of the VHTR enabling a lower He flow rate reducing the required core velocities and pressure drop. In contrast, the standard recompression S-CO{sub 2} cycle wants to operate with a temperature rise through the RHX of about 150 C reflecting the temperature drop as the CO{sub 2} expands from 20 MPa to 7.4 MPa in the turbine and the fact that the cycle is highly recuperated such that the CO{sub 2} entering the RHX is effectively preheated. Because of this mismatch, direct application of the standard recompression cycle results in a relatively poor cycle efficiency of 44.9%. However, two approaches have been identified by which the S-CO{sub 2} cycle can be successfully adapted to the VHTR and the benefits of the S-CO{sub 2} cycle, especially a significant gain in cycle efficiency, can be realized. The first approach involves the use of three separate cascaded S-CO{sub 2} cycles. Each S-CO{sub 2} cycle is coupled to the VHTR through its own He-to-CO{sub 2} RHX in which the He temperature is reduced by 150 C. The three respective cycles have efficiencies of 54, 50, and 44%, respectively, resulting in a net cycle

  11. Analysis of supercritical CO{sub 2} cycle control strategies and dynamic response for Generation IV Reactors.

    Energy Technology Data Exchange (ETDEWEB)

    Moisseytsev, A.; Sienicki, J. J. (Nuclear Engineering Division)

    2011-04-12

    The analysis of specific control strategies and dynamic behavior of the supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle has been extended to the two reactor types selected for continued development under the Generation IV Nuclear Energy Systems Initiative; namely, the Very High Temperature Reactor (VHTR) and the Sodium-Cooled Fast Reactor (SFR). Direct application of the standard S-CO{sub 2} recompression cycle to the VHTR was found to be challenging because of the mismatch in the temperature drop of the He gaseous reactor coolant through the He-to-CO{sub 2} reactor heat exchanger (RHX) versus the temperature rise of the CO{sub 2} through the RHX. The reference VHTR features a large temperature drop of 450 C between the assumed core outlet and inlet temperatures of 850 and 400 C, respectively. This large temperature difference is an essential feature of the VHTR enabling a lower He flow rate reducing the required core velocities and pressure drop. In contrast, the standard recompression S-CO{sub 2} cycle wants to operate with a temperature rise through the RHX of about 150 C reflecting the temperature drop as the CO{sub 2} expands from 20 MPa to 7.4 MPa in the turbine and the fact that the cycle is highly recuperated such that the CO{sub 2} entering the RHX is effectively preheated. Because of this mismatch, direct application of the standard recompression cycle results in a relatively poor cycle efficiency of 44.9%. However, two approaches have been identified by which the S-CO{sub 2} cycle can be successfully adapted to the VHTR and the benefits of the S-CO{sub 2} cycle, especially a significant gain in cycle efficiency, can be realized. The first approach involves the use of three separate cascaded S-CO{sub 2} cycles. Each S-CO{sub 2} cycle is coupled to the VHTR through its own He-to-CO{sub 2} RHX in which the He temperature is reduced by 150 C. The three respective cycles have efficiencies of 54, 50, and 44%, respectively, resulting in a net cycle

  12. Closed Brayton Cycle power system with a high temperature pellet bed reactor heat source for NEP applications

    Science.gov (United States)

    Juhasz, Albert J.; El-Genk, Mohamed S.; Harper, William B., Jr.

    1992-01-01

    Capitalizing on past and future development of high temperature gas reactor (HTGR) technology, a low mass 15 MWe closed gas turbine cycle power system using a pellet bed reactor heating helium working fluid is proposed for Nuclear Electric Propulsion (NEP) applications. Although the design of this directly coupled system architecture, comprising the reactor/power system/space radiator subsystems, is presented in conceptual form, sufficient detail is included to permit an assessment of overall system performance and mass. Furthermore, an attempt is made to show how tailoring of the main subsystem design characteristics can be utilized to achieve synergistic system level advantages that can lead to improved reliability and enhanced system life while reducing the number of parasitic load driven peripheral subsystems.

  13. Numerical analysis of air-foil shaped fin performance in printed circuit heat exchanger in a supercritical carbon dioxide power cycle

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Ho [Department of Mechanical Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Kwon, Jin Gyu [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Yoon, Sung Ho [Korea Institute of Nuclear Nonproliferation and Control, Daejeon 305-348 (Korea, Republic of); Park, Hyun Sun, E-mail: hejsunny@postech.ac.kr [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Kim, Moo Hwan [Korea Institute of Nuclear Safety, Daejeon 305-338 (Korea, Republic of); Cha, Jae Eun [Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of)

    2015-07-15

    Highlights: • Staggered arrangement affects the pressure drop but does not significantly affect to the heat transfer. • The total pressure drop is reduced, but the amount of acceleration pressure drop increases while that of frictional pressure drop decreases as the horizontal number increases. • For the vertical number, the total pressure drop decreases more largely than the horizontal number. • The objective function shows that the fully staggered arrangement shows best performance. - Abstract: One of the key issues of the PCHE technology in the supercritical CO{sub 2} Brayton cycle is to achieve an efficient and compact designs to be able to enhance heat transfer and reduce pressure drop. The issue is challenging due to the complex configuration of micro-channels in the PCHE. In this study, an innovative micro-channel equipped with an array of airfoil fins is analyzed to evaluate its performance. In so doing, sensitivity analysis with various design parameters is performed to configure the optimal arrangement of airfoil fins by using CFD analysis for Supercritical Carbon dioxide Integral Experimental Loop (SCIEL) in Korean Atomic Energy Research Institute (KAERI). Dominant geometric parameters of the fin arrangement that affects to the thermal and hydraulic performances are the horizontal, vertical and staggered pitches. ANSYS ICEM CFD and ANSYS CFX are used for the grid generation and the computational calculation. CO{sub 2} properties are used by using REFPROF software database. The inlet temperature of the hot side is 618 K and that of the cold side is 585 K. The reference mass flow rate is set as 1.2 g/s for the vertical number of 2.0, which is the Reynolds number of about 30,000. The mass flow rate changes from 0.4 to 4.8 g/s in order to investigate the Reynolds number effect. The k-ε model is selected as the turbulence model. In conclusions, the results show that the optimal arrangement of airfoil fins can be examined in terms of an objective

  14. Modeling and experimental results for condensing supercritical CO2 power cycles.

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Steven Alan; Conboy, Thomas M.; Radel, Ross F.; Rochau, Gary Eugene

    2011-01-01

    This Sandia supported research project evaluated the potential improvement that 'condensing' supercritical carbon dioxide (S-CO{sub 2}) power cycles can have on the efficiency of Light Water Reactors (LWR). The analytical portion of research project identified that a S-CO{sub 2} 'condensing' re-compression power cycle with multiple stages of reheat can increase LWR power conversion efficiency from 33-34% to 37-39%. The experimental portion of the project used Sandia's S-CO{sub 2} research loop to show that the as designed radial compressor could 'pump' liquid CO{sub 2} and that the gas-cooler's could 'condense' CO{sub 2} even though both of these S-CO{sub 2} components were designed to operate on vapor phase S-CO{sub 2} near the critical point. There is potentially very high value to this research as it opens the possibility of increasing LWR power cycle efficiency, above the 33-34% range, while lowering the capital cost of the power plant because of the small size of the S-CO{sub 2} power system. In addition it provides a way to incrementally build advanced LWRs that are optimally designed to couple to S-CO{sub 2} power conversion systems to increase the power cycle efficiency to near 40%.

  15. Coupling of Modular High-Temperature Gas-Cooled Reactor with Supercritical Rankine Cycle

    Directory of Open Access Journals (Sweden)

    Shutang Zhu

    2008-01-01

    Full Text Available This paper presents investigations on the possible combination of modular high-temperature gas-cooled reactor (MHTGR technology with the supercritical (SC steam turbine technology and the prospective deployments of the MHTGR SC power plant. Energy conversion efficiency of steam turbine cycle can be improved by increasing the main steam pressure and temperature. Investigations on SC water reactor (SCWR reveal that the development of SCWR power plants still needs further research and development. The MHTGR SC plant coupling the existing technologies of current MHTGR module design with operation experiences of SC FPP will achieve high cycle efficiency in addition to its inherent safety. The standard once-reheat SC steam turbine cycle and the once-reheat steam cycle with life-steam have been studied and corresponding parameters were computed. Efficiencies of thermodynamic processes of MHTGR SC plants were analyzed, while comparisons were made between an MHTGR SC plant and a designed advanced passive PWR - AP1000. It was shown that the net plant efficiency of an MHTGR SC plant can reach 45% or above, 30% higher than that of AP1000 (35% net efficiency. Furthermore, an MHTGR SC plant has higher environmental competitiveness without emission of greenhouse gases and other pollutants.

  16. Optimization of power-cycle arrangements for Supercritical Water cooled Reactors (SCWRs)

    Science.gov (United States)

    Lizon-A-Lugrin, Laure

    The world energy demand is continuously rising due to the increase of both the world population and the standard of life quality. Further, to assure both a healthy world economy as well as adequate social standards, in a relatively short term, new energy-conversion technologies are mandatory. Within this framework, a Generation IV International Forum (GIF) was established by the participation of 10 countries to collaborate for developing nuclear power reactors that will replace the present technology by 2030. The main goals of these nuclear-power reactors are: economic competitiveness, sustainability, safety, reliability and resistance to proliferation. As a member of the GIF, Canada has decided to orient its efforts towards the design of a CANDU-type Super Critical Water-cooled Reactor (SCWR). Such a system must run at a coolant outlet temperature of about 625°C and at a pressure of 25 MPa. It is obvious that at such conditions the overall efficiency of this kind of Nuclear Power Plant (NPP) will compete with actual supercritical water-power boilers. In addition, from a heat-transfer viewpoint, the use of a supercritical fluid allows the limitation imposed by Critical Heat Flux (CHF) conditions, which characterize actual technologies, to be removed. Furthermore, it will be also possible to use direct thermodynamic cycles where the supercritical fluid expands right away in a turbine without the necessity of using intermediate steam generators and/or separators. This work presents several thermodynamic cycles that could be appropriate to run SCWR power plants. Improving both thermal efficiency and mechanical power constitutes a multi-objective optimization problem and requires specific tools. To this aim, an efficient and robust evolutionary algorithm, based on genetic algorithm, is used and coupled to an appropriate power plant thermodynamic simulation model. The results provide numerous combinations to achieve a thermal efficiency higher than 50% with a

  17. Microbial potential for carbon and nutrient cycling in a geogenic supercritical carbon dioxide reservoir.

    Science.gov (United States)

    Freedman, Adam J E; Tan, BoonFei; Thompson, Janelle R

    2017-06-01

    Microorganisms catalyze carbon cycling and biogeochemical reactions in the deep subsurface and thus may be expected to influence the fate of injected supercritical (sc) CO2 following geological carbon sequestration (GCS). We hypothesized that natural subsurface scCO2 reservoirs, which serve as analogs for the long-term fate of sequestered scCO2 , harbor a 'deep carbonated biosphere' with carbon cycling potential. We sampled subsurface fluids from scCO2 -water separators at a natural scCO2 reservoir at McElmo Dome, Colorado for analysis of 16S rRNA gene diversity and metagenome content. Sequence annotations indicated dominance of Sulfurospirillum, Rhizobium, Desulfovibrio and four members of the Clostridiales family. Genomes extracted from metagenomes using homology and compositional approaches revealed diverse mechanisms for growth and nutrient cycling, including pathways for CO2 and N2 fixation, anaerobic respiration, sulfur oxidation, fermentation and potential for metabolic syntrophy. Differences in biogeochemical potential between two production well communities were consistent with differences in fluid chemical profiles, suggesting a potential link between microbial activity and geochemistry. The existence of a microbial ecosystem associated with the McElmo Dome scCO2 reservoir indicates that potential impacts of the deep biosphere on CO2 fate and transport should be taken into consideration as a component of GCS planning and modelling. © 2017 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  18. Life cycle analysis of geothermal power generation with supercritical carbon dioxide

    Science.gov (United States)

    Frank, Edward D.; Sullivan, John L.; Wang, Michael Q.

    2012-09-01

    Life cycle analysis methods were employed to model the greenhouse gas emissions and fossil energy consumption associated with geothermal power production when supercritical carbon dioxide (scCO2) is used instead of saline geofluids to recover heat from below ground. Since a significant amount of scCO2 is sequestered below ground in the process, a constant supply is required. We therefore combined the scCO2 geothermal power plant with an upstream coal power plant that captured a portion of its CO2 emissions, compressed it to scCO2, and transported the scCO2 by pipeline to the geothermal power plant. Emissions and energy consumption from all operations spanning coal mining and plant construction through power production were considered, including increases in coal use to meet steam demand for the carbon capture. The results indicated that the electricity produced by the geothermal plant more than balanced the increase in energy use resulting from carbon capture at the coal power plant. The effective heat rate (BTU coal per total kW h of electricity generated, coal plus geothermal) was comparable to that of traditional coal, but the ratio of life cycle emissions from the combined system to that of traditional coal was 15% when 90% carbon capture efficiency was assumed and when leakage from the surface was neglected. Contributions from surface leakage were estimated with a simple model for several hypothetical surface leakage rates.

  19. Buffer thermal energy storage for a solar Brayton engine

    Science.gov (United States)

    Strumpf, H. J.; Barr, K. P.

    1981-01-01

    A study has been completed on the application of latent-heat buffer thermal energy storage to a point-focusing solar receiver equipped with an air Brayton engine. To aid in the study, a computer program was written for complete transient/stead-state Brayton cycle performance. The results indicated that thermal storage can afford a significant decrease in the number of engine shutdowns as compared to operating without thermal storage. However, the number of shutdowns does not continuously decrease as the storage material weight increases. In fact, there appears to be an optimum weight for minimizing the number of shutdowns.

  20. Development of a 77K Reverse-Brayton Cryocooler with Multiple Coldheads Project

    Data.gov (United States)

    National Aeronautics and Space Administration — RTI will design and optimize an 80 W, 77K cryocooler based on the reverse turbo Brayton cycle (RTBC) with four identical coldheads for distributed cooling. Based on...

  1. Performance Optimization of a Solar-driven Irreversible Intercooled Regenerated Brayton Cycle%不可逆中冷回热太阳能布雷顿循环系统的优化分析

    Institute of Scientific and Technical Information of China (English)

    许益霖; 黄跃武

    2011-01-01

    建立了由太阳能集热器模型和不可逆中冷回热布雷顿循环模型组成的恒温热源条件下太阳能布雷顿循环系统,以系统总效率为目标函数,考虑了高低温侧换热器、回热器和中冷器的热阻损失以及压缩机和涡轮机的不可逆损失,借助数值计算对太阳能集热器的工作温度进行了优化,并分析了主要特征参数对总效率的影响.结果表明:太阳能布雷顿循环系统中存在一个最佳的太阳能集热器工作温度和相应的最大总效率及最大总输出功率;在此基础上,通过优化中间压比可使循环系统的总效率和相应的总输出功率达到双重最大值;系统总效率随着回热器传热有效度和光学效率的增加而提高;系统运行时存在一个最佳的总压比.%An irreversible solar-driven heat engine system with constant-temperature heat-reservoirs has been built up, which consists of the model of a solar collector and an intercooled regenerated Brayton cycle. Taking the overall efficiency as the objective function, and considering both the heat resistance in high/low temperature-side heat exchanger, regenerative heater and intercooler, and the irreversible loss in compressor and turbine, the operating temperature of solar collector has been optimized with the help of numerical simulation, while influence of the main parameters on its overall efficiency analyzed. Results show that for the solar-driven Brayton cycle, there exists an optimum collector operating temperature, a corresponding maximum overall efficiency and a maximum total output power; on this basis, both the overall efficiency and the total output power may reach their maximum value by optimizing the intermediate pressure ratio; the overall efficiency increases with the rise of thermal and optical efficiency of regenerative heater; there exists an optimum total pressure ratio for the system.

  2. Performance Analysis and Working Fluid Selection of a Supercritical Organic Rankine Cycle for Low Grade Waste Heat Recovery

    Directory of Open Access Journals (Sweden)

    Yourong Li

    2012-08-01

    Full Text Available The performance analysis of a supercritical organic Rankine cycle system driven by exhaust heat using 18 organic working fluids is presented. Several parameters, such as the net power output, exergy efficiency, expander size parameter (SP, and heat exchanger requirement of evaporator and the condenser, were used to evaluate the performance of this recovery cycle and screen the working fluids. The results reveal that in most cases, raising the expander inlet temperature is helpful to improve the net power output and the exergy efficiency. However, the effect of the expander inlet pressure on those parameters is related to the expander inlet temperature and working fluid used. Either lower expander inlet temperature and pressure, or higher expander inlet temperature and pressure, generally makes the net power output more. Lower expander inlet temperature results in larger total heat transfer requirement and expander size. According to the screening criteria of both the higher output and the lower investment, the following working fluids for the supercritical ORC system are recommended: R152a and R143a.

  3. Experimental and CFD Analysis of Printed Circuit Heat Exchanger for Supercritical CO{sub 2} Power Cycle Application

    Energy Technology Data Exchange (ETDEWEB)

    Baik, Seungjoon; Kim, Hyeon Tae; Kim, Seong Gu; Lee, Jekyoung; Lee, Jeong Ik [KAIST, Daejeon (Korea, Republic of)

    2015-10-15

    The supercritical carbon dioxide (S-CO{sub 2}) power cycle has been suggested as an alternative for the SFR power generation system. First of all, relatively mild sodium-CO{sub 2} interaction can reduce the accident probability. Also the S-CO{sub 2} power conversion cycle can achieve high efficiency with SFR core thermal condition. Moreover, the S-CO{sub 2} power cycle can reduce cycle footprint due to high density of the working fluid. Recently, various compact heat exchangers have been studied for developing an optimal heat exchanger. In this paper, the printed circuit heat exchanger was selected for S-CO{sub 2} power cycle applications and was closely investigated experimentally and analytically. Recently, design and performance prediction of PCHE received attention due to its importance in high pressure power systems such as S-CO{sub 2} cycle. To evaluate a PCHE performance with CO{sub 2} to water, KAIST research team designed and tested a lab-scale PCHE. From the experimental data and CFD analysis, pressure drop and heat transfer correlations are obtained. For the CFD analysis, Ansys-CFX commercial code was utilized with RGP table implementation. In near future, the turbulence model sensitivity study will be followed.

  4. Supercritical Combustion of Liquid Oxygen and Hydrocarbon for Staged-Combustion Cycle Engine Technology Development

    Science.gov (United States)

    2009-06-30

    Flows," J. Comput. Phys. 101, 104(1992). P.K. Kundu and I.M. Cohen, Fluid Mechanics , 2nd ed. (San Diego, California, 2001). S. Wang and V. Yang...various underlying mechanisms dictating the fluid atomization and energy-transfer behaviors; and 3) to identify and prioritize key injector design...present numerical analysis is able to capture many unique mechanisms dictating supercritical fluid injection and mixing dynamics, including thermodynamic

  5. Rankline-Brayton engine powered solar thermal aircraft

    Science.gov (United States)

    Bennett, Charles L [Livermore, CA

    2012-03-13

    A solar thermal powered aircraft powered by heat energy from the sun. A Rankine-Brayton hybrid cycle heat engine is carried by the aircraft body for producing power for a propulsion mechanism, such as a propeller or other mechanism for enabling sustained free flight. The Rankine-Brayton engine has a thermal battery, preferably containing a lithium-hydride and lithium mixture, operably connected to it so that heat is supplied from the thermal battery to a working fluid. A solar concentrator, such as reflective parabolic trough, is movably connected to an optically transparent section of the aircraft body for receiving and concentrating solar energy from within the aircraft. Concentrated solar energy is collected by a heat collection and transport conduit, and heat transported to the thermal battery. A solar tracker includes a heliostat for determining optimal alignment with the sun, and a drive motor actuating the solar concentrator into optimal alignment with the sun based on a determination by the heliostat.

  6. Rankine-Brayton engine powered solar thermal aircraft

    Science.gov (United States)

    Bennett, Charles L [Livermore, CA

    2009-12-29

    A solar thermal powered aircraft powered by heat energy from the sun. A Rankine-Brayton hybrid cycle heat engine is carried by the aircraft body for producing power for a propulsion mechanism, such as a propeller or other mechanism for enabling sustained free flight. The Rankine-Brayton engine has a thermal battery, preferably containing a lithium-hydride and lithium mixture, operably connected to it so that heat is supplied from the thermal battery to a working fluid. A solar concentrator, such as reflective parabolic trough, is movably connected to an optically transparent section of the aircraft body for receiving and concentrating solar energy from within the aircraft. Concentrated solar energy is collected by a heat collection and transport conduit, and heat transported to the thermal battery. A solar tracker includes a heliostat for determining optimal alignment with the sun, and a drive motor actuating the solar concentrator into optimal alignment with the sun based on a determination by the heliostat.

  7. Investigation of CO{sub 2} Recovery System Design in Supercritical Carbon Dioxide Power Cycle for Sodium-cooled Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Seok; Jung, Hwa-Young; Ahn, Yoonhan; Cho, Seong Kuk; Lee, Jeong Ik [KAIST, Daejeon (Korea, Republic of)

    2015-10-15

    These are mainly possible because the S-CO{sub 2} Brayton cycle has lower compressing work than other Brayton cycles due to its high density and low compressibility near the critical point. These attributes make easier to achieve higher turbine inlet temperature. Furthermore, the coolant chemistry control and component cooling systems are relatively simple for the S-CO{sub 2} cycle unlike the steam Rankine cycle, and therefore the total plant footprint can be greatly reduced further. However, certain amount of leakage flow is inevitable in the rotating turbo-machinery since the S-CO{sub 2} power cycle is a highly pressurized system. A computational model of critical flow in turbo-machinery seal is essential to predict the leakage flow and calculate the required total mass of working fluid in S-CO{sub 2} power system. Before designing a computational model of critical flow in turbo-machinery seal, this paper will identify what the issues are in predicting leakage flow and how these issues can be successfully addressed. Also, suitability of this solution in a large scale S-CO{sub 2} power cycle will be discussed, because this solution is for the small scale. S-CO{sub 2} power cycle has gained interest especially for the SFR application as an alternative to the conventional steam Rankine cycle, since S-CO{sub 2} power cycle can provide better performance and enhance safety. This paper discussed what the problem in leakage flow is and how to deal with this problem at present. High cavity pressure causing instability of gas foil bearing and large windage losses can be reduced by booster pump used to scavenge the gas in the rotor cavity. Also, labyrinth seals can be another good solution to decrease the rotor cavity pressure. Additionally, difference between large and small scale S-CO{sub 2} power cycle in turbo-machinery leakage is addressed. It is shown that optimization of CO{sub 2} recovery system design is more important to large scale S-CO{sub 2} power cycle. For

  8. Thermodynamic design of 10 kW Brayton cryocooler for HTS cable

    Science.gov (United States)

    Chang, Ho-Myung; Park, C. W.; Yang, H. S.; Sohn, Song Ho; Lim, Ji Hyun; Oh, S. R.; Hwang, Si Dole

    2012-06-01

    Thermodynamic design of Brayton cryocooler is presented as part of an ongoing governmental project in Korea, aiming at 1 km HTS power cable in the transmission grid. The refrigeration requirement is 10 kW for continuously sub-cooling liquid nitrogen from 72 K to 65 K. An ideal Brayton cycle for this application is first investigated to examine the fundamental features. Then a practical cycle for a Brayton cryocooler is designed, taking into account the performance of compressor, expander, and heat exchangers. Commercial software (Aspen HYSYS) is used for simulating the refrigeration cycle with real fluid properties of refrigerant. Helium is selected as a refrigerant, as it is superior to neon in thermodynamic efficiency. The operating pressure and flow rate of refrigerant are decided with a constraint to avoid the freezing of liquid nitrogen

  9. 逆布雷顿空气制冷机动态降温特性数值研究%Numerical study on dynamic cooling performance of reverse Brayton cycle air cryocooler

    Institute of Scientific and Technical Information of China (English)

    赵祥雄; 孙皖; 刘炅辉; 侯予

    2013-01-01

    建立了逆布雷顿空气制冷机系统时间相关数学模型,对系统动态降温过程进行了数值分析.详细阐述了系统主要部件板翅式换热器及透平膨胀机动态回热及降温数学模型.以该模型为基础,分析了逆布雷顿空气制冷系统不同入口压力、温度、流量及不同换热面积和膨胀机效率下的动态温降特性曲线,讨论了部分参数对系统动态降温性能的影响.结果表明:对于确定的入口流量,提高系统入口压力可以加快系统降温速度和最大温降;此外,系统设计时采用较大的回热换热器面积和提高膨胀机效率也是实现更大温降的有效手段.%In order to study the dynamic cooling process performance of a reverse Brayton cycle air cryocooler, a system time-dependent numerical model was set up and described, including the dynamic thermal performance model of a plate-fin heat exchanger and a turbo expander. The dynamic cooling process of the air cryocooler was discussed under different system inlet parameters, including pressure, temperature, volume flowrate, different heat exchange area and different turbo expander efficiency. The theoretical results shown that the higher the system inlet pressure the faster the system temperature decreases in case of low system inlet temperature and small system inlet flowrate, the increase of heat exchange area and turbo expander thermal efficiency can promote the system cooling performance.

  10. Supercritical water

    CERN Document Server

    Marcus, Yizhak

    2012-01-01

    Discover the many new and emerging applications of supercritical water as a green solvent Drawing from thousands of original research articles, this book reviews and summarizes what is currently known about the properties and uses of supercritical water. In particular, it focuses on new and emerging applications of supercritical water as a green solvent, including the catalytic conversion of biomass into fuels and the oxidation of hazardous materials. Supercritical Water begins with an introduction that defines supercritical fluids in general. It then defines supercritical wa

  11. Life and Reliability Characteristics of TurboBrayton Coolers

    Science.gov (United States)

    Breedlove, Jeff J.; Zagarola, Mark; Nellis, Greg; Dolan, Frank; Swift, Walt; Gibbon, Judith; Obenschain, Arthur F. (Technical Monitor)

    2000-01-01

    Wear and internal contaminants are two of the primary factors that influence reliable, long-life operation of turbo-Brayton cryocoolers. This paper describes tests that have been conducted and methods that have been developed for turbo-Brayton components and systems to assure reliable operation. The turbomachines used in these coolers employ self-acting gas bearings to support the miniature high-speed shafts, thus providing vibration-free operation. Because the bearings are self-acting, rubbing contact occurs during initial start-up and shutdown of the machines. Bearings and shafts are designed to endure multiple stop/start cycles without producing particles or surface features that would impair the proper operation of the machines. Test results are presented for a variety of turbomachines used in these systems. The tests document extended operating life and start/stop cycling behavior for machines over a range of time and temperature scales. Contaminants such as moisture and other residual gas impurities can be a source of degraded operation if they freeze out in sufficient quantities to block flow passages or if they mechanically affect the operation of the machines. A post-fabrication bakeout procedure has been successfully used to reduce residual internal contamination to acceptable levels in a closed cycle system. The process was developed during space qualification tests on the NICMOS cryocooler. Moisture levels were sampled over a six-month time interval confirming the effectiveness of the technique. A description of the bakeout procedure is presented.

  12. Operation Test of the Supercritical CO{sub 2} Compressor Supported with Active Magnetic Bearing

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jae Eun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Cho, Seong Kuk; Lee, Jeong IK [KAIST, Daejeon (Korea, Republic of)

    2016-10-15

    In this paper, the operation test status of the SCIEL sCO{sub 2} AMB Compressor is briefly described. The Supercritical CO{sub 2} Brayton Cycle Integral Experiment Loop (SCIEL) has been installed in Korea Atomic Energy Research Institute (KAERI) to develop the element technologies for the sCO{sub 2} cycle power generation system. The operation of the SCIEL has mainly focused on sCO{sub 2} compressor development and establishing sCO{sub 2} system control logic. The installation of the SCIEL low compression loop was finished in December 2014 and research team succeeded in generating electric power on the supercritical state of the CO{sub 2} in May 2015. The SCIEL has been built in KAERI to develop the element technologies and the system control logics for the sCO{sub 2} cycle power conversion unit of the next generation reactor. For the stable operation of the sCO{sub 2} compressor under high rotational speed, the AMB sCO{sub 2} compressor was developed and achieved the maximum 40,000 rpm.

  13. Design of an efficient space constrained diffuser for supercritical CO2 turbines

    Science.gov (United States)

    Keep, Joshua A.; Head, Adam J.; Jahn, Ingo H.

    2017-03-01

    Radial inflow turbines are an arguably relevant architecture for energy extraction from ORC and supercritical CO 2 power cycles. At small scale, design constraints can prescribe high exit velocities for such turbines, which lead to high kinetic energy in the turbine exhaust stream. The inclusion of a suitable diffuser in a radial turbine system allows some exhaust kinetic energy to be recovered as static pressure, thereby ensuring efficient operation of the overall turbine system. In supercritical CO 2 Brayton cycles, the high turbine inlet pressure can lead to a sealing challenge if the rotor is supported from the rotor rear side, due to the seal operating at rotor inlet pressure. An alternative to this is a cantilevered layout with the rotor exit facing the bearing system. While such a layout is attractive for the sealing system, it limits the axial space claim of any diffuser. Previous studies into conical diffuser geometries for supercritical CO 2 have shown that in order to achieve optimal static pressure recovery, longer geometries of a shallower cone angle are necessitated when compared to air. A diffuser with a combined annular-radial arrangement is investigated as a means to package the aforementioned geometric characteristics into a limited space claim for a 100kW radial inflow turbine. Simulation results show that a diffuser of this design can attain static pressure rise coefficients greater than 0.88. This confirms that annular-radial diffusers are a viable design solution for supercritical CO2 radial inflow turbines, thus enabling an alternative cantilevered rotor layout.

  14. Pore-scale Evolution of Supercritical CO2 within Bentheimer Sandstone during Multiple Drainage-Imbibition Cycles

    Science.gov (United States)

    Herring, A. L.; Andersson, L.; Wildenschild, D.

    2014-12-01

    Geologic CO2 sequestration has been proposed as a climate change mitigation strategy to limit emissions of CO2 to the atmosphere from large fossil-fuel burning CO2 point sources; however, there are concerns associated with the long-term stability of a mobile subsurface CO2 plume. The large-scale movement of subsurface supercritical CO2 (scCO2) can be prevented via capillary trapping, wherein scCO2 is immobilized in the subsurface by capillary interactions between the solid surface, resident brine, and scCO2. Capillary trapping occurs in two steps: first, the porous medium undergoes drainage as scCO2 is injected into the system; then, wetting fluid re-enters the medium in an imbibition process, isolating small bubbles of scCO2 in the pore bodies of the medium. There are many empirical models which predict capillary trapping for a single drainage-imbibition cycle; however, in an engineered CO2 sequestration project, it is possible to implement cyclic scCO2-water injections in a water-alternating-gas (WAG) injection scheme in which the system may undergo multiple CO2 injections to potentially increase the trapping efficiency of scCO2. We present experimental results of multiple drainage-imbibition cycles of scCO2 and 1:6 by mass potassium iodide (KI) brine within Bentheimer sandstone. Capillary (differential) pressure and absolute pressures for each phase were continuously measured throughout each flow process, which is a unique feature of our experimental system. Experiments were conducted at a working pressure of 8.3 MPa (1200 PSI) and 40oC, and synchrotron x-ray computed microtomography (x-ray CMT) images were collected of the drainage and imbibition process endpoints at a resolution of 3.19 μm at the Advanced Photon Source at Argonne National Laboratory. The evolution of the connectivity, topology, morphology, and capillary trapping of scCO2 phase is analyzed as a function of capillary pressure, scCO2 saturation, and sample history. Preliminary results suggest

  15. EXPLOIT STUDY OF NUCLEAR COMBINE CYCLE SYSTEM WITH TOPPING BRAYTON CYCLE%顶置燃气轮机核能联合循环系统开拓研究

    Institute of Scientific and Technical Information of China (English)

    林汝谋; 高林; 段立强

    2001-01-01

    本文探索研究核电站更新改造新技术。基于系统综合和能的梯级利用的思路,设计构筑压水堆核电站与燃气轮机相结合的核能联合循环系统流程超结构,通过对其综合优化,提出两种可供选用的顶置燃气轮机核能联合循环总体技术方案,还结合实例进行模拟分析,揭示了它们的热力学特性,从而提出核电站联合循环技术更新改造(NRCC-Repowering)的新途径与新方案及其设计分析方法。%Nuclear combine cycle systems with topping Braytoncycle for existing nuclear power stations have been exploited inthis paper. Based on the principle of energy cascadesutilization and system synthesis, the system flow superstructureof the combine cycle has been schemed out and have been syntheticallyoptimized, then two kind of system schemes havebeen put forward. At the same time, by setting up mathematicalmodel with four independent variables for this system, we have pointedout the relationship between system performanceand independent variables. These promising results obtained herewill be valuable for NRCC-Repowering of existing nuclear power stations.

  16. Corrosion in Supercritical carbon Dioxide: Materials, Environmental Purity, Surface Treatments, and Flow Issues

    Energy Technology Data Exchange (ETDEWEB)

    Sridharan, Kumar; Anderson, Mark

    2013-12-10

    The supercritical CO{sub 2} Brayton cycle is gaining importance for power conversion in the Generation IV fast reactor system because of its high conversion efficiencies. When used in conjunction with a sodium fast reactor, the supercritical CO{sub 2} cycle offers additional safety advantages by eliminating potential sodium-water interactions that may occur in a steam cycle. In power conversion systems for Generation IV fast reactors, supercritical CO{sub 2} temperatures could be in the range of 30°C to 650°C, depending on the specific component in the system. Materials corrosion primarily at high temperatures will be an important issue. Therefore, the corrosion performance limits for materials at various temperatures must be established. The proposed research will have four objectives centered on addressing corrosion issues in a high-temperature supercritical CO{sub 2} environment: Task 1: Evaluation of corrosion performance of candidate alloys in high-purity supercritical CO{sub 2}: The following alloys will be tested: Ferritic-martensitic Steels NF616 and HCM12A, austenitic alloys Incoloy 800H and 347 stainless steel, and two advanced concept alloys, AFA (alumina forming austenitic) steel and MA754. Supercritical CO{sub 2} testing will be performed at 450°C, 550°C, and 650°C at a pressure of 20 MPa, in a test facility that is already in place at the proposing university. High purity CO{sub 2} (99.9998%) will be used for these tests. Task 2: Investigation of the effects of CO, H{sub 2}O, and O{sub 2} impurities in supercritical CO{sub 2} on corrosion: Impurities that will inevitably present in the CO{sub 2} will play a critical role in dictating the extent of corrosion and corrosion mechanisms. These effects must be understood to identify the level of CO{sub 2} chemistry control needed to maintain sufficient levels of purity to manage corrosion. The individual effects of important impurities CO, H{sub 2}O, and O{sub 2} will be investigated by adding them

  17. On Brayton and Moser's missing stability theorem

    NARCIS (Netherlands)

    Jeltsema, D.; Scherpen, J. M. A.

    2005-01-01

    In the early 1960s, Brayton and Moser proved three theorems concerning the stability of nonlinear electrical circuits. The applicability of each theorem depends on three different conditions on the type of admissible nonlinearities in circuit. Roughly speaking, this means that the theorems apply to

  18. Brayton Isotope Power System (BIPS) facility specification

    Energy Technology Data Exchange (ETDEWEB)

    1976-05-31

    General requirements for the Brayton Isotope Power System (BIPS)/Ground Demonstration System (GDS) assembly and test facility are defined. The facility will include provisions for a complete test laboratory for GDS checkout, performance, and endurance testing, and a contamination-controlled area for assembly, fabrication, storage, and storage preparation of GDS components. Specifications, schedules, and drawings are included.

  19. Coupled optical/thermal/fluid analysis and design requirements for operation and testing of a supercritical CO2 solar receiver.

    Energy Technology Data Exchange (ETDEWEB)

    Khivsara, Sagar [Indian Institute of Science, Bangalor (India)

    2015-01-01

    Recent studies have evaluated closed-loop supercritical carbon dioxide (s-CO2) Brayton cycles to be a higher energy-density system in comparison to conventional superheated steam Rankine systems. At turbine inlet conditions of 923K and 25 MPa, high thermal efficiency (~50%) can be achieved. Achieving these high efficiencies will make concentrating solar power (CSP) technologies a competitive alternative to current power generation methods. To incorporate a s-CO2 Brayton power cycle in a solar power tower system, the development of a solar receiver capable of providing an outlet temperature of 923 K (at 25 MPa) is necessary. To satisfy the temperature requirements of a s-CO2 Brayton cycle with recuperation and recompression, it is required to heat s-CO2 by a temperature of ~200 K as it passes through the solar receiver. Our objective was to develop an optical-thermal-fluid model to design and evaluate a tubular receiver that will receive a heat input ~1 MWth from a heliostat field. We also undertook the documentation of design requirements for the development, testing and safe operation of a direct s-CO2 solar receiver. The main purpose of this document is to serve as a reference and guideline for design and testing requirements, as well as to address the technical challenges and provide initial parameters for the computational models that will be employed for the development of s-CO2 receivers.

  20. Conceptual System Design of a Supercritical CO2 cooled Micro Modular Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Gu; Oh, Bongseong; Baik, Seung Joon; Yu, Hwanyeal; Kim, Yonghee; Lee, Jeong Ik [KAIST, Daejeon (Korea, Republic of)

    2015-05-15

    The S-CO2 Brayton cycle has many advantages for SMR's power conversion system. The S-CO2 cycle can achieve small component size and simple cycle layout as shown in Fig. 1. Therefore, a concept of one module containing the S-CO2 cooled fast reactor core and power conversion system is realizable. Thanks to the compact heat exchanger technology such as Printed Circuit Heat Exchanger (PCHE), the supercritical fluid with mediocre heat transfer performance can be utilized to a thermal cycle. This concept of fully modularized reactor is named as KAIST Micro Modular Reactor (MMR). It can achieve large economic by production in series, and transported in the land way or sea way. Based on the design results and dimensions of the reactor core and cycle components, the authors propose a conceptual layout of KAIST MMR. Based on this concept of reactor core, power conversion system, and decay heat removal system, the seasonal operation and transient analysis will be performed in the further works.

  1. Preliminary design study of an alternate heat source assembly for a Brayton isotope power system

    Science.gov (United States)

    Strumpf, H. J.

    1978-01-01

    Results are presented for a study of the preliminary design of an alternate heat source assembly (HSA) intended for use in the Brayton isotope power system (BIPS). The BIPS converts thermal energy emitted by a radioactive heat source into electrical energy by means of a closed Brayton cycle. A heat source heat exchanger configuration was selected and optimized. The design consists of a 10 turn helically wound Hastelloy X tube. Thermal analyses were performed for various operating conditions to ensure that post impact containment shell (PICS) temperatures remain within specified limits. These limits are essentially satisfied for all modes of operation except for the emergency cooling system for which the PICS temperatures are too high. Neon was found to be the best choice for a fill gas for auxiliary cooling system operation. Low cycle fatigue life, natural frequency, and dynamic loading requirements can be met with minor modifications to the existing HSA.

  2. Design, fabrication, and performance of foil journal bearing for the brayton rotating unit

    Science.gov (United States)

    Licht, L.; Branger, M.

    1973-01-01

    Foil bearings were designed and manufactured to replace pivoted-shoe journal bearings in an existing Brayton Cycle turbo-alternator-compressor. The design of this unconventional rotor support was accomplished within the constraints and space limitations imposed by the present machine, and the substitution of foil bearings was effected without changes or modification other machine components. A housing and a test rig were constructed to incorporate the new foil-bearing support into a unified assemble with an air-driven rotor and the gimbal-mounted thrust bearing, seals, and shrouds of an actual Brayton Rotating Unit. The foil bearing required no external pressure source, and stable self-acting rotation was achieved at all speeds up to 43,200 rpm. Excellent wipe-wear characteristics of the foil bearing permitted well over 1000 start-stop cycles with no deterioriation of performance in the entire speed range.

  3. Materials, Turbomachinery and Heat Exchangers for Supercritical CO2 Systems

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Mark; Nellis, Greg; Corradini, Michael

    2012-10-19

    The objective of this project is to produce the necessary data to evaluate the performance of the supercritical carbon dioxide cycle. The activities include a study of materials compatibility of various alloys at high temperatures, the heat transfer and pressure drop in compact heat exchanger units, and turbomachinery issues, primarily leakage rates through dynamic seals. This experimental work will serve as a test bed for model development and design calculations, and will help define further tests necessary to develop high-efficiency power conversion cycles for use on a variety of reactor designs, including the sodium fast reactor (SFR) and very high-temperature gas reactor (VHTR). The research will be broken into three separate tasks. The first task deals with the analysis of materials related to the high-temperature S-CO{sub 2} Brayton cycle. The most taxing materials issues with regard to the cycle are associated with the high temperatures in the reactor side heat exchanger and in the high-temperature turbine. The system could experience pressures as high as 20MPa and temperatures as high as 650°C. The second task deals with optimization of the heat exchangers required by the S-CO{sub 2} cycle; the S-CO{sub 2} flow passages in these heat exchangers are required whether the cycle is coupled with a VHTR or an SFR. At least three heat exchangers will be required: the pre-cooler before compression, the recuperator, and the heat exchanger that interfaces with the reactor coolant. Each of these heat exchangers is unique and must be optimized separately. The most challenging heat exchanger is likely the pre-cooler, as there is only about a 40°C temperature change but it operates close to the CO{sub 2} critical point, therefore inducing substantial changes in properties. The proposed research will focus on this most challenging component. The third task examines seal leakage through various dynamic seal designs under the conditions expected in the S-CO{sub 2} cycle

  4. Numerical Comparison of NASA's Dual Brayton Power Generation System Performance Using CO2 or N2 as the Working Fluid

    Science.gov (United States)

    Ownens, Albert K.; Lavelle, Thomas M.; Hervol, David S.

    2010-01-01

    A Dual Brayton Power Conversion System (DBPCS) has been tested at the NASA Glenn Research Center using Nitrogen (N2) as the working fluid. This system uses two closed Brayton cycle systems that share a common heat source and working fluid but are otherwise independent. This system has been modeled using the Numerical Propulsion System Simulation (NPSS) environment. This paper presents the results of a numerical study that investigated system performance changes resulting when the working fluid is changed from gaseous (N2) to gaseous carbon dioxide (CO2).

  5. Comparison of Gas-Turbine Cycles for Space Applications

    Science.gov (United States)

    English, Robert E.; Slone, Henry O.

    1960-01-01

    On the basis of the radiator area required for rejecting cycle waste heat, Rankine vapor cycles are far superior to the basic Brayton gas cycle for space turbogenerating powerplants. The present analysis considers modifications of the basic Brayton cycle and compares the modified cycles to the basic cycle with radiator area as the criterion of merit. The results indicate that reductions in radiator area attainable by modifying the basic Brayton cycle are small, and thus the competitive position of gasturbine cycles relative to Rankine vapor cycles is unchanged.

  6. Super- and Transcritical Fluid Expansions for Next-Generation Energy Conversion Systems

    NARCIS (Netherlands)

    Harinck, J.

    2010-01-01

    The next generation of thermodynamic power cycles offers great potential as the conceptual basis for sustainable energy converters. Examples are the supercritical and superheated Organic Rankine cycle, the transcritical condensation cycle, the supercritical Brayton cycle, the Organic Stirling cycle

  7. Super- and Transcritical Fluid Expansions for Next-Generation Energy Conversion Systems

    NARCIS (Netherlands)

    Harinck, J.

    2010-01-01

    The next generation of thermodynamic power cycles offers great potential as the conceptual basis for sustainable energy converters. Examples are the supercritical and superheated Organic Rankine cycle, the transcritical condensation cycle, the supercritical Brayton cycle, the Organic Stirling cycle

  8. Thermodynamic Analysis of the Use a Chemical Heat Pump to Link a Supercritical Water-Cooled Nuclear Reactor and a Thermochemical Water-Splitting Cycle for Hydrogen Production

    Science.gov (United States)

    Granovskii, Mikhail; Dincer, Ibrahim; Rosen, Marc A.; Pioro, Igor

    Increases in the power generation efficiency of nuclear power plants (NPPs) are mainly limited by the permissible temperatures in nuclear reactors and the corresponding temperatures and pressures of the coolants in reactors. Coolant parameters are limited by the corrosion rates of materials and nuclear-reactor safety constraints. The advanced construction materials for the next generation of CANDU reactors, which employ supercritical water (SCW) as a coolant and heat carrier, permit improved “steam” parameters (outlet temperatures up to 625°C and pressures of about 25 MPa). An increase in the temperature of steam allows it to be utilized in thermochemical water splitting cycles to produce hydrogen. These methods are considered by many to be among the most efficient ways to produce hydrogen from water and to have advantages over traditional low-temperature water electrolysis. However, even lower temperature water splitting cycles (Cu-Cl, UT-3, etc.) require an intensive heat supply at temperatures higher than 550-600°C. A sufficient increase in the heat transfer from the nuclear reactor to a thermochemical water splitting cycle, without jeopardizing nuclear reactor safety, might be effectively achieved by application of a heat pump, which increases the temperature of the heat supplied by virtue of a cyclic process driven by mechanical or electrical work. Here, a high-temperature chemical heat pump, which employs the reversible catalytic methane conversion reaction, is proposed. The reaction shift from exothermic to endothermic and back is achieved by a change of the steam concentration in the reaction mixture. This heat pump, coupled with the second steam cycle of a SCW nuclear power generation plant on one side and a thermochemical water splitting cycle on the other, increases the temperature of the “nuclear” heat and, consequently, the intensity of heat transfer into the water splitting cycle. A comparative preliminary thermodynamic analysis is conducted

  9. Comparison between reverse Brayton and Kapitza based LNG boil-off gas reliquefaction system using exergy analysis

    Science.gov (United States)

    Kochunni, Sarun Kumar; Chowdhury, Kanchan

    2017-02-01

    LNG boil-off gas (BOG) reliquefaction systems in LNG carrier ships uses refrigeration devices which are based on reverse Brayton, Claude, Kapitza (modified Claude) or Cascade cycles. Some of these refrigeration devices use nitrogen as the refrigerants and hence nitrogen storage vessels or nitrogen generators needs to be installed in LNG carrier ships which consume space and add weight to the carrier. In the present work, a new configuration based on Kapitza liquefaction cycle which uses BOG itself as working fluid is proposed and has been compared with Reverse Brayton Cycle (RBC) on sizes of heat exchangers and compressor operating parameters. Exergy analysis is done after simulating at steady state with Aspen Hysys 8.6® and the comparison between RBC and Kapitza may help designers to choose reliquefaction system with appropriate process parameters and sizes of equipment. With comparable exergetic efficiency as that of an RBC, a Kaptiza system needs only BOG compressor without any need of nitrogen gas.

  10. Subcritical and supercritical water oxidation of organic, wet wastes for carbon cycling in regenerative life support systems

    Science.gov (United States)

    Ronsse, Frederik; Lasseur, Christophe; Rebeyre, Pierre; Clauwaert, Peter; Luther, Amanda; Rabaey, Korneel; Zhang, Dong Dong; López Barreiro, Diego; Prins, Wolter; Brilman, Wim

    2016-07-01

    For long-term human spaceflight missions, one of the major requirements is the regenerative life support system which has to be capable of recycling carbon, nutrients and water from both solid and liquid wastes generated by the crew and by the local production of food through living organisms (higher plants, fungi, algae, bacteria, …). The European Space Agency's Life Support System, envisioned by the MELiSSA project, consists of a 5 compartment artificial ecosystem, in which the waste receiving compartment (so-called compartment I or briefly 'CI') is based on thermophilic fermentation. However, as the waste generated by the crew compartment and food production compartment contain typical plant fibres (lignin, cellulose and hemicellulose), these recalcitrant fibres end up largely unaffected in the digestate (sludge) generated in the C-I compartment. Therefore, the C-I compartment has to be supplemented with a so-called fibre degradation unit (in short, FDU) for further oxidation or degradation of said plant fibres. A potential solution to degrading these plant fibres and other recalcitrant organics is their oxidation, by means of subcritical or supercritical water, into reusable CO2 while retaining the nutrients in an organic-free liquid effluent. By taking advantage of the altered physicochemical properties of water above or near its critical point (647 K, 22.1 MPa) - including increased solubility of non-polar compounds and oxygen, ion product and diffusivity - process conditions can be created for rapid oxidation of C into CO2. In this research, the oxidizer is provided as a hydrogen peroxide solution which, at elevated temperature, will dissociated into O2. The purpose of this study is to identify ideal process conditions which (a) ensure complete oxidation of carbon, (b) retaining the nutrients other than C in the liquid effluent and (c) require as little oxidizer as possible. Experiments were conducted on a continuous, tubular heated reactor and on batch

  11. Design and Off-Design Performance of 100 kWe-Class Brayton Power Conversion Systems

    Science.gov (United States)

    Johnson, Paul K.; Mason, Lee S.

    2005-02-01

    The NASA Glenn Research Center in-house computer model Closed Cycle Engine Program (CCEP) was used to explore the design trade space and off-design performance characteristics of 100 kWe-class recuperated Closed Brayton Cycle (CBC) power conversion systems. Input variables for a potential design point included the number of operating units (1, 2, 4), cycle peak pressure (0.5, 1, 2 MPa), and turbo-alternator shaft speed (30,45, 60 kRPM). The design point analysis assumed a fixed turbine inlet temperature (1150 K), compressor inlet temperature (400 K), helium-xenon working-fluid molecular weight (40 g/mol), compressor pressure ratio (2.0), recuperator effectiveness (0.95), and a Sodium-Potassium (NaK) pumped-loop radiator. The design point options were compared on the basis of thermal input power, radiator area, and mass. For a nominal design point with defined Brayton components and radiator area, off-design cases were examined by reducing turbine inlet temperature (as low as 900 K), reducing shaft speed (as low as 50% of nominal), and circulating a percentage (up to 20%) of the compressor exit flow back to the gas cooler. The off-design examination sought approaches to reduce thermal input power without freezing the radiator.

  12. Evaluation of High-Temperature Tensile Property of Diffusion Bond of Austenitic Alloys for S-CO{sub 2} Cycle Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sunghoon; Sah, Injin; Jang, Chanheui [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-12-15

    To improve the inherent safety of the sodium-cooled fast reactor (SFR), the supercritical CO{sub 2} (S-CO{sub 2}) Brayton cycle is being considered as an alternative power conversion system to steam the Rankine cycle. In the S-CO{sub 2} system, a PCHE (printed circuit heat exchanger) is being considered. In this type of heat exchangers, diffusion bonding is used for joining the thin plates. In this study, the diffusion bonding characteristics of various austenitic alloys were evaluated. The tensile properties were measured at temperatures starting from the room temperature up to 650℃. For the 316H and 347H types of stainless steel, the tensile ductility was well maintained up to 550℃. However, the Incoloy 800HT showed lower strength and ductility at all temperatures. The microstructure near the bond line was examined to understand the reason for the loss of ductility at high temperatures.

  13. Detonation Jet Engine. Part 1--Thermodynamic Cycle

    Science.gov (United States)

    Bulat, Pavel V.; Volkov, Konstantin N.

    2016-01-01

    We present the most relevant works on jet engine design that utilize thermodynamic cycle of detonative combustion. The efficiency advantages of thermodynamic detonative combustion cycle over Humphrey combustion cycle at constant volume and Brayton combustion cycle at constant pressure were demonstrated. An ideal Ficket-Jacobs detonation cycle, and…

  14. Plate-fin Heat-exchangers for a 10 kW Brayton Cryocooler and a 1 km HTS Cable

    Science.gov (United States)

    Chang, Ho-Myung; Gwak, Kyung Hyun; Jung, Seyong; Yang, Hyung Suk; Hwang, Si-Dole

    Plate-fin heat exchangers (PFHX) are designed and fabricated for a cryogenic cooling system, serving for a 10 kW Brayton cryocooler and a 1 km HTS transmission cable under development in Korea. To achieve compactness and thermal efficiency at the same time, a recuperative HX for Brayton cycle and a sub-cooling HX of liquid nitrogen for HTS cable are designed as integrated parts. A key design feature is focused on the coldest part of sub-cooling HX, where the streams of liquid nitrogen and refrigerant (helium gas) are arranged as two-pass cross-flow so that the risk of freeze-out of liquid nitrogen can be reduced. Details of hardware PFHX design are presented and discussed towards its immediate application to the HTS cable system.

  15. CFD analysis of supercritical CO2 used as HTF in a solar tower receiver

    Science.gov (United States)

    Roldán, M. I.; Fernández-Reche, J.

    2016-05-01

    The relative cost of a solar receiver can be minimized by the selection of an appropriate heat transfer fluid capable of achieving high receiver efficiencies. In a conventional central receiver system, the concentrated solar energy is transferred from the receiver tube walls to the heat transfer fluid (HTF), which passes through a heat exchanger to generate steam for a Rankine cycle. Thus, higher working fluid temperature is associated with greater efficiency in receiver and power cycle. Emerging receiver designs that can enable higher efficiencies using advanced power cycles, such as supercritical CO2 (s-CO2) closed-loop Brayton cycles, include direct heating of s-CO2 in tubular receiver designs capable of withstanding high internal fluid pressures (around 20 MPa) and temperatures (900 K). Due to the high pressures required and the presence of moving components installed in pipelines (ball-joints and/or flexible connections), the use of s-CO2 presents many technical challenges due to the compatibility of seal materials and fluid leakages of the moving connections. These problems are solved in solar tower systems because the receiver is fixed. In this regard, a preliminary analysis of a tubular receiver with s-CO2 as HTF has been developed using the design of a molten-salt receiver which was previously tested at Plataforma Solar de Almería (PSA). Therefore, a simplified CFD model has been carried out in this study in order to analyze the feasibility of s-CO2 as HTF in solar towers. Simulation results showed that the heat gained by s-CO2 was around 75% greater than the one captured by molten salts (fluid inlet temperature of 715 K), but at a pressure range of 7.5-9.7 MPa. Thus, the use of s-CO2 as HTF in solar tower receivers appears to be a promising alternative, taking into account both the operating conditions required and their maintenance cost.

  16. Pore-scale Simulations of Capillary Trapping of Supercritical CO2 after Multiple Drainage and Imbibition Cycles

    Science.gov (United States)

    Schaap, M. G.

    2015-12-01

    Carbon capture and storage (CCS) of carbon dioxide emissions generated by production or combustion of fossil fuels is a technologically viable means to reduce the build-up of CO2 in the atmosphere and oceans. On a fundamental level, capillary trapping of scCO2 is a pore-scale process that shares mechanisms that are relevant, for example in oil recovery and remediation of NAPL-contaminated aquifers. Capillary trapping of scCO2 differs rather significantly from trapping of oil recovery and NAPL remediation in that the goal is to maximize the amount of NWP storage, whereas the objective of the other applications is to minimize the amount of residual NWP. This difference makes research into capillary trapping of scCO2 unique, but also complex because scCO2 phase properties (e.g. viscosity, density, and interfacial tension) exhibit large shifts with pressure and temperature which can strongly alter the trapping potential and efficiency. In this presentation we compare direct pore-scale observations of the Brine-CO2 drainage and imbibition process with lattice Boltzmann model simulations. The observations were conducted with the synchrotron-based x-ray microtomography facility at the Advanced Photon Source (APS) at Argonne National Laboratory using a novel x-ray compatible, high-pressure, elevated temperature setup. The "large" volumes (~1200 mm3; 6.3 mm diameter and 40 mm in length) were segmented into solid phase (Bentheimer Sandstone), Brine (KI, 1140 kg/m3) and scCO2. We will present LB simulations of small (64^3 voxels) and large sections of the scanned cores with a simple Shan-Chen-type model and a more advanced Equation of State-type model and compare model results to pressure and CO2 saturation levels that were observed for the CO2 invasion and Brine re-imbibition process. We will present results for the smaller sections under multiple drainage and imbibition cycles to investigate whether this will lead to enhanced trapping of scCO2 as found in earlier research.

  17. Design and evaluation of a high temperature/pressure supercritical carbon dioxide direct tubular receiver for concentrating solar power applications

    Science.gov (United States)

    Ortega, Jesus Daniel

    This work focuses on the development of a solar power thermal receiver for a supercritical-carbon dioxide (sCO2), Brayton power-cycle to produce ~1 MWe. Closed-loop sCO2 Brayton cycles are being evaluated in combination with concentrating solar power to provide higher thermal-to-electric conversion efficiencies relative to conventional steam Rankine cycles. High temperatures (923--973 K) and pressures (20--25 MPa) are required in the solar receiver to achieve thermal efficiencies of ~50%, making concentrating solar power (CSP) technologies a competitive alternative to current power generation methods. In this study, the CSP receiver is required to achieve an outlet temperature of 923 K at 25 MPa or 973 K at 20 MPa to meet the operating needs. To obtain compatible receiver tube material, an extensive material review was performed based the ASME Boiler and Pressure Vessel Code, ASME B31.1 and ASME B313.3 codes respectively. Subsequently, a thermal-structural model was developed using a commercial computational fluid (CFD) dynamics and structural mechanics software for designing and analyzing the tubular receiver that could provide the heat input for a ~2 MWth plant. These results were used to perform an analytical cumulative damage creep-fatigue analysis to estimate the work-life of the tubes. In sequence, an optical-thermal-fluid model was developed to evaluate the resulting thermal efficiency of the tubular receiver from the NSTTF heliostat field. The ray-tracing tool SolTrace was used to obtain the heat-flux distribution on the surfaces of the receiver. The K-ω SST turbulence model and P-1 radiation model used in Fluent were coupled with SolTrace to provide the heat flux distribution on the receiver surface. The creep-fatigue analysis displays the damage accumulated due to the cycling and the permanent deformation of the tubes. Nonetheless, they are able to support the required lifetime. The receiver surface temperatures were found to be within the safe

  18. Supercritical boiler material selection using fuzzy analytic network process

    Directory of Open Access Journals (Sweden)

    Saikat Ranjan Maity

    2012-08-01

    Full Text Available The recent development of world is being adversely affected by the scarcity of power and energy. To survive in the next generation, it is thus necessary to explore the non-conventional energy sources and efficiently consume the available sources. For efficient exploitation of the existing energy sources, a great scope lies in the use of Rankin cycle-based thermal power plants. Today, the gross efficiency of Rankin cycle-based thermal power plants is less than 28% which has been increased up to 40% with reheating and regenerative cycles. But, it can be further improved up to 47% by using supercritical power plant technology. Supercritical power plants use supercritical boilers which are able to withstand a very high temperature (650-720˚C and pressure (22.1 MPa while producing superheated steam. The thermal efficiency of a supercritical boiler greatly depends on the material of its different components. The supercritical boiler material should possess high creep rupture strength, high thermal conductivity, low thermal expansion, high specific heat and very high temperature withstandability. This paper considers a list of seven supercritical boiler materials whose performance is evaluated based on seven pivotal criteria. Given the intricacy and difficulty of this supercritical boiler material selection problem having interactions and interdependencies between different criteria, this paper applies fuzzy analytic network process to select the most appropriate material for a supercritical boiler. Rene 41 is the best supercritical boiler material, whereas, Haynes 230 is the worst preferred choice.

  19. Brayton Isotope Power System (BIPS). Phase I. First annual technical report

    Energy Technology Data Exchange (ETDEWEB)

    1976-10-27

    The objective of the BIPS program is to develop a closed gas turbine dynamic conversion system for space application. The baseline system is a 7-year life, 450 lb, 1300 W(e) unit using Brayton cycle hardware developed for the NASA LeRC and two 2400 W(t) Multi-Hundred Watt isotope heat sources developed for the ERDA. Phase I of the three-phase BIPS program is the conceptual design of the flight system, the design, development, and testing of a prototype Ground Demonstration System (GDS). The Mini-Brayton Rotating Unit (Mini-BRU), Mini-BRU Recuperator (MBR), and Heat Source Assembly (HSA) will be integrated into the ground demonstrator loop, and the system will be tested under simulated space conditions at the AiResearch Space Power Laboratory. Successful completion of the Phase I effort in mid 1978 is expected to lead to the Phase II and Phase III follow-on efforts. Phase II is a 24-month effort for the development and qualification of a flight system. Qualification will include testing with an isotope heat source. Phase III is a 12-month effort to fabricate flight-qualified hardware for delivery in April 1981.

  20. An isothermal model of a hybrid Stirling/reverse-Brayton cryocooler

    Science.gov (United States)

    Nellis, G. F.; Maddocks, J. R.

    2003-01-01

    This paper presents a model of a cryogenic refrigerator that integrates a reverse-Brayton lower temperature stage with a 2-piston Stirling upper temperature stage using a rectification system of check valves and buffer volumes. The numerical model extends the isothermal Schmidt analysis of the Stirling cycle by deriving the additional dimensionless governing equations that characterize the recuperative system. Numerical errors are quantified and the results are verified against analytical solutions in the appropriate limits. The model is used to explore the effect of the rectification system's characteristics on the overall cycle's behavior. Finally, the model is used to optimize the hybrid system's design by varying the swept volume ratio and phase angle in order to maximize the refrigeration per unit of heat transfer in the recuperator and regenerator.

  1. Variations on the Zilch Cycle

    Science.gov (United States)

    Binder, P.-M.; Tanoue, C. K. S.

    2013-01-01

    Thermo dynamic cycles in introductory physics courses are usually made up from a small number of permutations of isothermal, adiabatic, and constant-pressure and volume quasistatic strokes, with the working fluid usually being an ideal gas. Among them we find the Carnot, Stirling, Otto, Diesel, and Joule-Brayton cycles; in more advanced courses,…

  2. Advanced Thermal Storage for Central Receivers with Supercritical Coolants

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Bruce D.

    2010-06-15

    The principal objective of the study is to determine if supercritical heat transport fluids in a central receiver power plant, in combination with ceramic thermocline storage systems, offer a reduction in levelized energy cost over a baseline nitrate salt concept. The baseline concept uses a nitrate salt receiver, two-tank (hot and cold) nitrate salt thermal storage, and a subcritical Rankine cycle. A total of 6 plant designs were analyzed, as follows: Plant Designation Receiver Fluid Thermal Storage Rankine Cycle Subcritical nitrate salt Nitrate salt Two tank nitrate salt Subcritical Supercritical nitrate salt Nitrate salt Two tank nitrate salt Supercritical Low temperature H2O Supercritical H2O Two tank nitrate salt Supercritical High temperature H2O Supercritical H2O Packed bed thermocline Supercritical Low temperature CO2 Supercritical CO2 Two tank nitrate salt Supercritical High temperature CO2 Supercritical CO2 Packed bed thermocline Supercritical Several conclusions have been drawn from the results of the study, as follows: 1) The use of supercritical H2O as the heat transport fluid in a packed bed thermocline is likely not a practical approach. The specific heat of the fluid is a strong function of the temperatures at values near 400 °C, and the temperature profile in the bed during a charging cycle is markedly different than the profile during a discharging cycle. 2) The use of supercritical CO2 as the heat transport fluid in a packed bed thermocline is judged to be technically feasible. Nonetheless, the high operating pressures for the supercritical fluid require the use of pressure vessels to contain the storage inventory. The unit cost of the two-tank nitrate salt system is approximately $24/kWht, while the unit cost of the high pressure thermocline system is nominally 10 times as high. 3) For the supercritical fluids, the outer crown temperatures of the receiver tubes are in the range of 700 to 800 °C. At temperatures of 700 °C and above

  3. Test Results From a Direct Drive Gas Reactor Simulator Coupled to a Brayton Power Conversion Unit

    Science.gov (United States)

    Hervol, David S.; Briggs, Maxwell H.; Owen, Albert K.; Bragg-Sitton, Shannon M.

    2009-01-01

    The Brayton Power Conversion Unit (BPCU) located at NASA Glenn Research Center (GRC) in Cleveland, OH is a closed cycle system incorporating a turboaltemator, recuperator, and gas cooler connected by gas ducts to an external gas heater. For this series of tests, the BPCU was modified by replacing the gas heater with the Direct Drive Gas heater or DOG. The DOG uses electric resistance heaters to simulate a fast spectrum nuclear reactor similar to those proposed for space power applications. The combined system thermal transient behavior was the focus of these tests. The BPCU was operated at various steady state points. At each point it was subjected to transient changes involving shaft rotational speed or DOG electrical input. This paper outlines the changes made to the test unit and describes the testing that took place along with the test results.

  4. Isotope Brayton ground demonstration testing and flight qualification. Volume 1. Technical program

    Energy Technology Data Exchange (ETDEWEB)

    1974-12-09

    A program is proposed for the ground demonstration, development, and flight qualification of a radioisotope nuclear heated dynamic power system for use on space missions beginning in the 1980's. This type of electrical power system is based upon and combines two aerospace technologies currently under intense development; namely, the MHW isotope heat source and the closed Brayton cycle gas turbine. This power system represents the next generation of reliable, efficient economic electrical power equipment for space, and will be capable of providing 0.5 to 2.0 kW of electric power to a wide variety of spacecraft for earth orbital and interplanetary missions. The immediate design will be based upon the requirements for the Air Force SURVSATCOM mission. The proposal is presented in three volumes plus an Executive Summary. This volume describes the tasks in the technical program.

  5. Preliminary performance of the Brayton 4.25 inch radial compressor operating in a helium xenon gas mixture

    Science.gov (United States)

    Asadourian, A. S.; Hecker, T. P.; Kruchowy, R.

    1971-01-01

    Compressor performance was mapped during the Brayton cycle power system testing. The range of testing included three shaft speeds: the design speed of 36,000 rpm, 10 percent overspeed (39,600 rpm), and 10 percent underspeed (32,400 rpm). A range of compressor inlet temperatures from 60 F to 120 F and discharge pressures from 20 to 45 psia were included. The effects of turbine inlet temperatures (from 1200 F to 1600 F) on the compressor were also studied. The data presented include plots of weight flow, compressor pressure ratio, efficiency, and temperature-rise ratio.

  6. Buffer thermal energy storage for an air Brayton solar engine

    Science.gov (United States)

    Strumpf, H. J.; Barr, K. P.

    1981-01-01

    The application of latent-heat buffer thermal energy storage to a point-focusing solar receiver equipped with an air Brayton engine was studied. To demonstrate the effect of buffer thermal energy storage on engine operation, a computer program was written which models the recuperator, receiver, and thermal storage device as finite-element thermal masses. Actual operating or predicted performance data are used for all components, including the rotating equipment. Based on insolation input and a specified control scheme, the program predicts the Brayton engine operation, including flows, temperatures, and pressures for the various components, along with the engine output power. An economic parametric study indicates that the economic viability of buffer thermal energy storage is largely a function of the achievable engine life.

  7. Selection of components for the IDEALHY preferred cycle for the large scale liquefaction of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Quack, H.; Seemann, I.; Klaus, M.; Haberstroh, Ch. [Technische Universitaet Dresden, Dresden (Germany); Berstad, D.; Walnum, H. T.; Neksa, P. [SINTEF Energy Research, Trondheim (Norway); Decker, L. [Linde Kryotechnik AG, Pfungen (Switzerland)

    2014-01-29

    In a future energy scenario, in which storage and transport of liquid hydrogen in large quantities will be used, the efficiency of the liquefaction of hydrogen will be of utmost importance. The goal of the IDEALHY working party is to identify the most promising process for a 50 t/d plant and to select the components, with which such a process can be realized. In the first stage the team has compared several processes, which have been proposed or realized in the past. Based on this information a process has been selected, which is thermodynamically most promising and for which it could be assumed that good components already exist or can be developed in the foreseeable future. Main features of the selected process are the compression of the feed stream to a relatively high pressure level, o-p conversion inside plate-fin heat exchangers and expansion turbines in the supercritical region. Precooling to a temperature between 150 and 100 K will be obtained from a mixed refrigerant cycle similar to the systems used successfully in natural gas liquefaction plants. The final cooling will be produced by two Brayton cycles, both having several expansion turbines in series. The selected overall process has still a number of parameters, which can be varied. The optimum, i.e. the final choice will depend mainly on the quality of the available components. Key components are the expansion turbines of the two Brayton cycles and the main recycle compressor, which may be common to both Brayton cycles. A six-stage turbo-compressor with intercooling between the stages is expected to be the optimum choice here. Each stage may consist of several wheels in series. To make such a high efficient and cost-effective compressor feasible, one has to choose a refrigerant, which has a higher molecular weight than helium. The present preferred choice is a mixture of helium and neon with a molecular weight of about 8 kg/kmol. Such an expensive refrigerant requires that the whole refrigeration loop

  8. Selection of components for the IDEALHY preferred cycle for the large scale liquefaction of hydrogen

    Science.gov (United States)

    Quack, H.; Seemann, I.; Klaus, M.; Haberstroh, Ch.; Berstad, D.; Walnum, H. T.; Neksa, P.; Decker, L.

    2014-01-01

    In a future energy scenario, in which storage and transport of liquid hydrogen in large quantities will be used, the efficiency of the liquefaction of hydrogen will be of utmost importance. The goal of the IDEALHY working party is to identify the most promising process for a 50 t/d plant and to select the components, with which such a process can be realized. In the first stage the team has compared several processes, which have been proposed or realized in the past. Based on this information a process has been selected, which is thermodynamically most promising and for which it could be assumed that good components already exist or can be developed in the foreseeable future. Main features of the selected process are the compression of the feed stream to a relatively high pressure level, o-p conversion inside plate-fin heat exchangers and expansion turbines in the supercritical region. Precooling to a temperature between 150 and 100 K will be obtained from a mixed refrigerant cycle similar to the systems used successfully in natural gas liquefaction plants. The final cooling will be produced by two Brayton cycles, both having several expansion turbines in series. The selected overall process has still a number of parameters, which can be varied. The optimum, i.e. the final choice will depend mainly on the quality of the available components. Key components are the expansion turbines of the two Brayton cycles and the main recycle compressor, which may be common to both Brayton cycles. A six-stage turbo-compressor with intercooling between the stages is expected to be the optimum choice here. Each stage may consist of several wheels in series. To make such a high efficient and cost-effective compressor feasible, one has to choose a refrigerant, which has a higher molecular weight than helium. The present preferred choice is a mixture of helium and neon with a molecular weight of about 8 kg/kmol. Such an expensive refrigerant requires that the whole refrigeration loop

  9. An Advanced Turbo-Brayton Converter for Radioisotope Power Systems

    Science.gov (United States)

    Zagarola, Mark V.; Izenson, Michael G.; Breedlove, Jeffrey J.; O'Connor, George M.; Ketchum, Andrew C.; Jetley, Richard L.; Simons, James K.

    2005-02-01

    Past work has shown that Brayton power converters are an attractive option for high power, long-duration space missions. More recently, Creare has shown that Brayton technology could be scaled with high efficiency and specific power to lower power levels suitable for radioisotope power conversion systems. Creare is currently leading the development of an advanced turbo-Brayton converter under NASA's Prometheus Program. The converter design is based on space-proven cryocooler technologies that have been shown to be safe; to provide long, maintenance-free lifetimes; and to have high reliability, negligible vibration emittance, and low EMI/EMC. The predicted performance of a converter at the beginning of life is greater than 20% (including electronic inefficiencies and overhead) with a converter specific power of greater than 8 We/kg for a test unit and greater than 15 We/kg for a flight unit. The degradation in performance over a 14-year mission lifetime is predicted to be negligible, and the primary life limiting factor is not expected to be an issue for greater than twice the mission duration. Work during the last year focused on the material and fabrication issues associated with a high temperature turbine and a lightweight recuperator, and the performance issues associated with the high-temperature insulation and power conversion electronics. The development of the converter is on schedule. Thermal vacuum testing to demonstrate a technology readiness level of 5 is currently planned for 2006.

  10. Offshore Rankine Cycles

    OpenAIRE

    Brandsar, Jo

    2012-01-01

    The title of the thesis - "Offshore Rankine Cycles" - is very general and cover a large range of engineering fields, e.g. thermodynamic cycles (Rankine, ORC, Brayton, Kalina, etc.), mechanical equipment (gas/steam turbine, heat exchangers and additional equipment) and safety concerns (flammable and/or toxic fluids, high temperature and pressures), to name the most important.The thesis try to give a brief overview of all critical points and alternatives, concerning employment of a wa...

  11. High Materials Performance in Supercritical CO2 in Comparison with Atmospheric Pressure CO2 and Supercritical Steam

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, Gordon [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Tylczak, Joseph [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Carney, Casey [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Dogan, Omer N. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

    2017-02-26

    This presentation covers environments (including advanced ultra-supercritical (A-USC) steam boiler/turbine and sCO2 indirect power cycle), effects of pressure, exposure tests, oxidation results, and mechanical behavior after exposure.

  12. Corrosion of Candidate High Temperature Alloys in Supercritical Carbon Dioxide

    Science.gov (United States)

    Parks, Curtis J.

    The corrosion resistance of three candidate alloys is tested in supercritical carbon dioxide (S-CO2) at different levels of temperature and pressure for up to 3000 hours. The purpose of the testing is to evaluate the compatibility of different engineering alloys in S-CO2 for use in a S-CO 2 Brayton cycle. The three alloys used are austenitic stainless steel 316, iron-nickel-base superalloy 718, and nickel-base superalloy 738. Each alloy is exposed to four combinations of temperature and pressure, consisting of either 550°C or 700°C at either 15 or 25 MPa for up to 1500 hours. At each temperature, an additional sample set is tested for 3000 hours and experienced an increase in pressure from 15 MPa to 25 MPa after 1500 hours of testing. All three alloys are successful in producing a protective oxide layer at the lower temperature of 550°C based on the logarithmic weight gain trends. At the higher temperature of 700°C, 316SS exhibits unfavourable linear weight gain trends at both pressures of 15 and 25 MPa. In comparison, IN-718 and IN-738 performs similarly in producing a protective oxide layer illustrated through a power weight gain relation. The effect of pressure is most pronounced at the operating temperature of 700°C, where the higher pressure of 25 MPa results in an increased rate of oxide formation. SEM analysis exposes a thin film oxide for both IN-718 and IN-738 but severe intergranular corrosion is exhibited by IN-738. Based on the testing conducted, both alloys show favourable characteristics for use in S-CO 2 conditions up to 700°C, but further testing is required to characterize the effect of the intergranular corrosion on the stability of oxide in IN-738. 316SS provided favourable results for use in temperatures of 550°C, but the protective oxide deteriorated at an operating temperature of 700°C.

  13. Supercritical fluid extraction

    Science.gov (United States)

    Wai, Chien M.; Laintz, Kenneth

    1994-01-01

    A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated or lipophilic crown ether or fluorinated dithiocarbamate. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process.

  14. Low-temperature Waste Heat Powered Supercritical Thermal Power Generation Cycle Using Low-boiling Point Fluids%低温余热驱动的低沸点工质超临界动力循环

    Institute of Scientific and Technical Information of China (English)

    王辉涛; 王华; 黄晓艳

    2009-01-01

    In order to improve the performance of the thermal power generation cycle driven by low-temperature waste heat, the system should be constructed to make the temnperature of the heated working fluid match the changing temperature of the fluid carrying waste heat, the supercritical Rankine cycle using organic fluid HFC125 as the working fluid is proved to be the best promising system driven by waste heat. The energy efficiency method should be used to evaluate the overall performance of the cyde.%低温余热动力回收热动循环应与余热流的变温特性很好地匹配才能获得较高的转化效率,采用低沸点有机工质HFC125实现超临界动力循环,能很好地逼近变温热源下的理想循环,从而获得较好的效果.采用效率来评价余热回收动力循环时,可以得到相对全面的结论.

  15. Mini-Brayton economic RTG study. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1974-01-01

    The objective of this study is to demonstrate the applicability of a radioisotope heated Mini-Brayton power system to the 1973 USAF/AEC requirements established for the SURVSATCOM Mission. The principal requiremenets of the power system, are: 400 We power level; maximum weight 205 lbs.; $1.2 to 2.0 million per unit cost; and 5y mission duration. A radioisotope heat source that meets the ACE Nuclear Safety Criteria is presented. The major aspects of the Reference Design MB-ERTG are summarized. The Reference Design, utilizes a flexible Brayton rotating unit (BRU), a /sup 244/Cm heat source with ceramic clad fuel cylinders and an aluminum radiator. The flexible BRU has a variable power output capability, from 400 We to 3000 We, and is an important factor in the formulation of a cost effective development plan. The system weight is 186 lb and unit cost, including the /sup 244/Cm fuel, acceptance testing and delivery is $748,000. The total development cost for the 5-yr program is estimated at $16.4M with an additional $6.5M required for /sup 244/Cm heat source development support, /sup 244/Cm fuel, heat source fabrication and capital equipment expenditures. (LCL)

  16. Electrochemistry in supercritical fluids

    Science.gov (United States)

    Branch, Jack A.; Bartlett, Philip N.

    2015-01-01

    A wide range of supercritical fluids (SCFs) have been studied as solvents for electrochemistry with carbon dioxide and hydrofluorocarbons (HFCs) being the most extensively studied. Recent advances have shown that it is possible to get well-resolved voltammetry in SCFs by suitable choice of the conditions and the electrolyte. In this review, we discuss the voltammetry obtained in these systems, studies of the double-layer capacitance, work on the electrodeposition of metals into high aspect ratio nanopores and the use of metallocenes as redox probes and standards in both supercritical carbon dioxide–acetonitrile and supercritical HFCs. PMID:26574527

  17. Electrochemistry in supercritical fluids.

    Science.gov (United States)

    Branch, Jack A; Bartlett, Philip N

    2015-12-28

    A wide range of supercritical fluids (SCFs) have been studied as solvents for electrochemistry with carbon dioxide and hydrofluorocarbons (HFCs) being the most extensively studied. Recent advances have shown that it is possible to get well-resolved voltammetry in SCFs by suitable choice of the conditions and the electrolyte. In this review, we discuss the voltammetry obtained in these systems, studies of the double-layer capacitance, work on the electrodeposition of metals into high aspect ratio nanopores and the use of metallocenes as redox probes and standards in both supercritical carbon dioxide-acetonitrile and supercritical HFCs.

  18. Some heat engine cycles in which liquids can work

    Science.gov (United States)

    Allen, P. C.; Paulson, D. N.; Wheatley, J. C.

    1981-01-01

    Liquids can work in heat engine cycles that employ regeneration. Four such cycles are discussed: Stirling, Malone, Stirling-Malone, and Brayton. Both regeneration and the role of the second thermodynamic medium are treated, and the principles are verified by quantitative measurements with propylene in a Stirling-Malone cycle. PMID:16592952

  19. Optimization of a Brayton cryocooler for ZBO liquid hydrogen storage in space

    Science.gov (United States)

    Deserranno, D.; Zagarola, M.; Li, X.; Mustafi, S.

    2014-11-01

    NASA is evaluating and developing technology for long-term storage of cryogenic propellant in space. A key technology is a cryogenic refrigerator which intercepts heat loads to the storage tank, resulting in a reduced- or zero-boil-off condition. Turbo-Brayton cryocoolers are particularly well suited for cryogen storage applications because the technology scales well to high capacities and low temperatures. In addition, the continuous-flow nature of the cycle allows direct cooling of the cryogen storage tank without mass and power penalties associated with a cryogenic heat transport system. To quantify the benefits and mature the cryocooler technology, Creare Inc. performed a design study and technology demonstration effort for NASA on a 20 W, 20 K cryocooler for liquid hydrogen storage. During the design study, we optimized these key components: three centrifugal compressors, a modular high-capacity plate-fin recuperator, and a single-stage turboalternator. The optimization of the compressors and turboalternator were supported by component testing. The optimized cryocooler has an overall flight mass of 88 kg and a specific power of 61 W/W. The coefficient of performance of the cryocooler is 23% of the Carnot cycle. This is significantly better performance than any 20 K space cryocooler existing or under development.

  20. Brayton power conversion system parametric design modelling for nuclear electric propulsion

    Science.gov (United States)

    Ashe, Thomas L.; Otting, William D.

    1993-11-01

    The parametrically based closed Brayton cycle (CBC) computer design model was developed for inclusion into the NASA LeRC overall Nuclear Electric Propulsion (NEP) end-to-end systems model. The code is intended to provide greater depth to the NEP system modeling which is required to more accurately predict the impact of specific technology on system performance. The CBC model is parametrically based to allow for conducting detailed optimization studies and to provide for easy integration into an overall optimizer driver routine. The power conversion model includes the modeling of the turbines, alternators, compressors, ducting, and heat exchangers (hot-side heat exchanger and recuperator). The code predicts performance to significant detail. The system characteristics determined include estimates of mass, efficiency, and the characteristic dimensions of the major power conversion system components. These characteristics are parametrically modeled as a function of input parameters such as the aerodynamic configuration (axial or radial), turbine inlet temperature, cycle temperature ratio, power level, lifetime, materials, and redundancy.

  1. Key Factors Influencing the Decision on the Number of Brayton Units for the Prometheus Space Reactor

    Science.gov (United States)

    Ashcroft, John; Belanger, Sean; Burdge, Wayne; Clementoni, Eric; Jensen, Krista; Proctor, N. Beth; Zemo-Fulkerson, Annie

    2007-01-01

    The Naval Reactors (NR) Program and its DOE Laboratories, KAPL and Bettis, were assigned responsibility to develop space reactor systems for the Prometheus Program. After investigating all of the potential reactor and energy conversion options, KAPL and Bettis selected a direct gas Brayton system as the reference approach for the nuclear electric propulsion missions, including the Jupiter Icy Moons Orbiter (JIMO). In order to determine the optimal plant architecture for the direct gas system, KAPL and Bettis investigated systems with one or two active Brayton units and up to two spare units. No final decision was made on the optimal system configuration for the NEP gas-Brayton system prior to closeout of the project. The two most promising options appear to be a single system without spares and a three Brayton system with two operating units, each producing half of the required load, with a single spare unit. The studies show that a single Brayton system, without spares, offers the lowest mass system, with potential for lower operating temperature, and a minimum of system and operational complexity. The lower required mass and increased system efficiency inherent in the single Brayton system may be exploited to satisfy other design objectives such as reduced reactor and radiator operating temperatures. While Brayton system lifetimes applicable to a JIMO or other nuclear electric propulsion (NEP) mission have not been demonstrated, there is no fundamental limit on the lifetime of the Brayton hardware. Use of additional Brayton units with installed spares will allow for continued operation in the event of a failure of an individual Brayton unit. However, preliminary system reliability evaluations do not point to any substantial reliability benefit provided by carrying spare Brayton units. If a spare unit is used, operating two of the units at full power with an unpowered spare proved more efficient than operating all three units at a reduced power and temperature

  2. Supercritical Airfoil Coordinates

    Data.gov (United States)

    National Aeronautics and Space Administration — Rectangular Supercritical Wing (Ricketts) - design and measured locations are provided in an Excel file RSW_airfoil_coordinates_ricketts.xls . One sheet is with Non...

  3. A Closed Brayton Power Conversion Unit Concept for Nuclear Electric Propulsion for Deep Space Missions

    Science.gov (United States)

    Joyner, Claude Russell; Fowler, Bruce; Matthews, John

    2003-01-01

    In space, whether in a stable satellite orbit around a planetary body or traveling as a deep space exploration craft, power is just as important as the propulsion. The need for power is especially important for in-space vehicles that use Electric Propulsion. Using nuclear power with electric propulsion has the potential to provide increased payload fractions and reduced mission times to the outer planets. One of the critical engineering and design aspects of nuclear electric propulsion at required mission optimized power levels is the mechanism that is used to convert the thermal energy of the reactor to electrical power. The use of closed Brayton cycles has been studied over the past 30 or years and shown to be the optimum approach for power requirements that range from ten to hundreds of kilowatts of power. It also has been found to be scalable to higher power levels. The Closed Brayton Cycle (CBC) engine power conversion unit (PCU) is the most flexible for a wide range of power conversion needs and uses state-of-the-art, demonstrated engineering approaches. It also is in use with many commercial power plants today. The long life requirements and need for uninterrupted operation for nuclear electric propulsion demands high reliability from a CBC engine. A CBC engine design for use with a Nuclear Electric Propulsion (NEP) system has been defined based on Pratt & Whitney's data from designing long-life turbo-machines such as the Space Shuttle turbopumps and military gas turbines and the use of proven integrated control/health management systems (EHMS). An integrated CBC and EHMS design that is focused on using low-risk and proven technologies will over come many of the life-related design issues. This paper will discuss the use of a CBC engine as the power conversion unit coupled to a gas-cooled nuclear reactor and the design trends relative to its use for powering electric thrusters in the 25 kWe to 100kWe power level.

  4. System design specification Brayton Isotope Power System (BIPS) Flight System (FS), and Ground Demonstration System (GDS)

    Energy Technology Data Exchange (ETDEWEB)

    1976-06-14

    The system design specification for ground demonstration, development, and flight qualification of a Brayton Isotope Power System (BIPS) is presented. The requirements for both a BIPS conceptual Flight System (FS) and a Ground Demonstration System (GDS) are defined.

  5. Phase I: controls preliminary design report for Brayton Isotope Power System (BIPS)

    Energy Technology Data Exchange (ETDEWEB)

    1976-08-20

    Background analyses of three control systems capable of controlling the speed, output voltage, and start rate of Brayton Isotope Power Systems (BIPS) are presented. Conclusions of all functions considered are summarized. (TFD)

  6. Advanced thermal-energy-storage concept-definition study for solar Brayton power plants. Final technical report, Volume I

    Energy Technology Data Exchange (ETDEWEB)

    1976-01-01

    The detailed results are presented of a technical and economic assessment of phase change and thermochemical energy storage systems in a solar power plant employing a high temperature Brayton cycle thermal engine with helium as the heat transport fluid. The assessment included an examination of the storage system operation, efficiency, power plant interaction, design, materials, safety, maintenance, environmental impact, system life, and economics. These considerations are implemented in the conceptual design of three baseline storage systems and their components for use in a solar power plant module of 50 megawatt electrical power output. Rationale is provided to support the configuration, operation and material choices. A preliminary assessment of the technology development and experimental test program requirements are also included. The report is contained in four separate volumes. This volume is the technical report.

  7. Drug delivery goes supercritical

    Directory of Open Access Journals (Sweden)

    Patrick J. Ginty

    2005-08-01

    Full Text Available In the field of drug delivery, the ability to control the size, morphology, and release of drug particles is fundamental to good targeting, but is often hampered by harsh processing conditions or inadequate methods; likewise for the processing of polymeric controlled-release systems. However, the use of supercritical fluids such as supercritical CO2 (scCO2 has provided a ‘clean’ and effective alternative to traditional methods of drug and polymer processing. In particular, scCO2 has a number of unique properties that make it possible to process both bioactive molecules and amorphous polymers without using toxic organic solvents or elevated temperatures. Here, we review the positive impact that supercritical fluids have had on the micronization, encapsulation, and impregnation of molecules of interest to both the pharmaceutical and biotechnology industries.

  8. Materials processing using supercritical fluids

    Directory of Open Access Journals (Sweden)

    Orlović Aleksandar M.

    2005-01-01

    Full Text Available One of the most interesting areas of supercritical fluids applications is the processing of novel materials. These new materials are designed to meet specific requirements and to make possible new applications in Pharmaceuticals design, heterogeneous catalysis, micro- and nano-particles with unique structures, special insulating materials, super capacitors and other special technical materials. Two distinct possibilities to apply supercritical fluids in processing of materials: synthesis of materials in supercritical fluid environment and/or further processing of already obtained materials with the help of supercritical fluids. By adjusting synthesis parameters the properties of supercritical fluids can be significantly altered which further results in the materials with different structures. Unique materials can be also obtained by conducting synthesis in quite specific environments like reversed micelles. This paper is mainly devoted to processing of previously synthesized materials which are further processed using supercritical fluids. Several new methods have been developed to produce micro- and nano-particles with the use of supercritical fluids. The following methods: rapid expansion of supercritical solutions (RESS supercritical anti-solvent (SAS, materials synthesis under supercritical conditions and encapsulation and coating using supercritical fluids were recently developed.

  9. Supercritical Synthesis of Biodiesel

    Directory of Open Access Journals (Sweden)

    Michel Vaultier

    2012-07-01

    Full Text Available The synthesis of biodiesel fuel from lipids (vegetable oils and animal fats has gained in importance as a possible source of renewable non-fossil energy in an attempt to reduce our dependence on petroleum-based fuels. The catalytic processes commonly used for the production of biodiesel fuel present a series of limitations and drawbacks, among them the high energy consumption required for complex purification operations and undesirable side reactions. Supercritical fluid (SCF technologies offer an interesting alternative to conventional processes for preparing biodiesel. This review highlights the advances, advantages, drawbacks and new tendencies involved in the use of supercritical fluids (SCFs for biodiesel synthesis.

  10. Development, application & assessment of improved condenser leak detection program at Brayton Point Station

    Energy Technology Data Exchange (ETDEWEB)

    Medina, C.A.; Bennett, B.A.; Thornton, M.W.

    1996-08-01

    The adverse impacts of air inleakage on condenser performance are well known and include elevated turbine back pressure, increased parasitic loads (to remove elevated levels of noncondensables from the condenser), and high dissolved oxygen levels in the feedwater cycle. Prolonged neglect of leakage leads to increased maintenance to feedwater and air removal systems as well as reduced cycle efficiency and the potential of a unit trip on high turbine back pressure. Leak detection performed on a scheduled basis, just prior to a scheduled outage, is an effective preventive maintenance activity for older stations and important for newer stations concerned with heat rate degradation and equipment performance. New England Power began a comprehensive air inleakage reduction program at its Brayton Point Generating Station (BPS) in 1990. The authors describe the development and application on Units 1 through 4, including its unique identification and documentation tools and its computerized leak source tracking and trending software program. Actual results gained from the programs use at BPS will be presented. To put the merits of the program in perspective, historically, many real and potentially large leak paths were not being tested, because helium leak detection crews normally inspected familiar and easy-to-reach areas around the condenser. Tracking and trending was practically non-existent, providing little documentation for root cause analysis when a large leak is suspect. Since the improved program was implemented at BPS, air in-leakage detection has increased by 300 percent, in-leakage rates have reduced 40% and turbine backpressure levels have improved. Station personnel now have a tool to diagnose condenser air in-leakage with test repeatability, whether it be a sudden incident of high in-leakage demanding immediate testing and repair or gradual increases which can be identified during pre-outage testing for repair during their scheduled outage. 3 figs., 2 tabs.

  11. US-UK Phase 3 Task 1 Oxidation in Supercritical Fluids

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, Gordon R. [National Energy Technology Lab. (NETL), Albany, OR (United States)

    2017-03-20

    A presentation of the US-UK Phase 3 Task 1 Oxidation in Supercritical Fluids. Includes slides on Supercritical Steam, sCO2 Power Cycles – Indirect, sCO2 Power Cycles – Direct, Experimental Exposures, Alloys, Why Si, Results—Ni-xCr Alloys (5-24Cr), Fatigue Crack Growth$-$Experiment, and Alloys and Samples, Fatigue Crack Growth—Results (H282).

  12. Structural Transition in Supercritical Fluids

    Directory of Open Access Journals (Sweden)

    Boris I. Sedunov

    2011-01-01

    Full Text Available The extension of the saturation curve ( on the PT diagram in the supercritical region for a number of monocomponent supercritical fluids by peak values for different thermophysical properties, such as heat capacities and and compressibility has been studied. These peaks signal about some sort of fluid structural transition in the supercritical region. Different methods give similar but progressively diverging curves st( for this transition. The zone of temperatures and pressures near these curves can be named as the zone of the fluid structural transition. The outstanding properties of supercritical fluids in this zone help to understand the physical sense of the fluid structural transition.

  13. THE UNIQUENESS OF BIFURCATION TO SEPARATRIX LOOPS IN SUPERCRITICAL CASES

    Institute of Scientific and Technical Information of China (English)

    SUNJIANHUA

    1994-01-01

    In paper[4] the existence of bifurcation to separatrix loops in supercritical cases on the plane is studied.This note is a continuation of [4].The author proves the uniqueness of limit cycles in a neighb-orhood of the separatrix loop,and the results strengthen the relevant conclusions in[1-6].

  14. Supercritical solvent coal extraction

    Science.gov (United States)

    Compton, L. E. (Inventor)

    1984-01-01

    Yields of soluble organic extract are increased up to about 50% by the supercritical extraction of particulate coal at a temperature below the polymerization temperature for coal extract fragments (450 C.) and a pressure from 500 psig to 5,000 psig by the conjoint use of a solvent mixture containing a low volatility, high critical temperature coal dissolution catalyst such as phenanthrene and a high volatility, low critical temperature solvent such as toluene.

  15. Thermodynamic behaviour of supercritical matter.

    Science.gov (United States)

    Bolmatov, Dima; Brazhkin, V V; Trachenko, K

    2013-01-01

    Since their discovery in 1822, supercritical fluids have been of enduring interest and have started to be deployed in many important applications. Theoretical understanding of the supercritical state is lacking and is seen to limit further industrial deployment. Here we study thermodynamic properties of the supercritical state and discover that specific heat shows a crossover between two different regimes, an unexpected result in view of currently perceived homogeneity of supercritical state in terms of physical properties. We subsequently formulate a theory of system thermodynamics above the crossover, and find good agreement between calculated and experimental specific heat with no free-fitting parameters. In this theory, energy and heat capacity are governed by the minimal length of the longitudinal mode in the system only, and do not explicitly depend on system-specific structure and interactions. We derive a power law and analyse supercritical scaling exponents in the system above the Frenkel line.

  16. Brayton-Moser Equations and New Passivity Properties for Nonlinear Electro-Mechanical Systems

    NARCIS (Netherlands)

    Jeltsema, Dimitri; Clemente-Gallardo, Jesus; Ortega, Romeo; Scherpen, Jacquelien M.A.; Klaassens, J. Ben

    2002-01-01

    This paper presents an alternative framework for a practically relevant class of nonlinear electro-mechanical systems. The formalism is based on a generalization of Brayton and Moser’s mixed-potential function. Instead of focusing on the usual energy-balance, the models are constructed using the pow

  17. Isotope Brayton ground demonstration testing and flight qualification program. Volume 1. Technical program

    Energy Technology Data Exchange (ETDEWEB)

    1974-12-09

    A proposal for the demonstration, development and production of the Isotope Brayton Flight System for space vehicles is presented with details on the technical requirements for designing and testing a ground demonstration system and on the program organization and personnel. (LCL)

  18. Specification requirements summary for the Brayton Isotope Power System (BIPS) Ground Demonstration System (GDS)

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, E.E.

    1976-02-10

    This document provides a summary of the required program specifications and procedures for the ERDA Phase I Brayton Isotope Power System (BIPS) Program. Also included are document definitions, descriptions, and formats, and a listing of commonly used abbreviations. This document is intended to be used as a guide in document preparation and control.

  19. From Brayton-Moser formulation to Port Hamiltonian representation : the CSTR case study.

    OpenAIRE

    Hoang, N.H.; Couenne, Françoise; Dochain, Denis; Le Gorrec, Yann

    2011-01-01

    International audience; This paper shows that any thermodynamic variable ful lling some stability criterion can be used as Hamiltonian for pseudo hamiltonian representation of a non isothermal Continuous Stirred Tank Reactor (CSTR) model. More precisely it is shown that from Brayton- Moser formulation is obtained some port hamiltonian representation with negative dissipation. This result is shown for reaction A !B.

  20. Cooling, freezing and heating with the air cycle: air as the ultimate green refrigerant

    NARCIS (Netherlands)

    Verschoor, M.J.E.

    2000-01-01

    Due to the recent concern about the damage that CFCs cause to the environment (ozone layer, global warming) and the absence of commonly acceptable alternative refrigerants, the search for alternative refrigeration concepts is going on. Air as refrigerant in the Joule-Brayton cycle (air cycle) is one

  1. Corrosion in supercritical fluids

    Energy Technology Data Exchange (ETDEWEB)

    Propp, W.A.; Carleson, T.E.; Wai, Chen M.; Taylor, P.R.; Daehling, K.W.; Huang, Shaoping; Abdel-Latif, M.

    1996-05-01

    Integrated studies were carried out in the areas of corrosion, thermodynamic modeling, and electrochemistry under pressure and temperature conditions appropriate for potential applications of supercritical fluid (SCF) extractive metallurgy. Carbon dioxide and water were the primary fluids studied. Modifiers were used in some tests; these consisted of 1 wt% water and 10 wt% methanol for carbon dioxide and of sulfuric acid, sodium sulfate, ammonium sulfate, and ammonium nitrate at concentrations ranging from 0.00517 to 0.010 M for the aqueous fluids. The materials studied were Types 304 and 316 (UNS S30400 and S31600) stainless steel, iron, and AISI-SAE 1080 (UNS G10800) carbon steel. The thermodynamic modeling consisted of development of a personal computer-based program for generating Pourbaix diagrams at supercritical conditions in aqueous systems. As part of the model, a general method for extrapolating entropies and related thermodynamic properties from ambient to SCF conditions was developed. The experimental work was used as a tool to evaluate the predictions of the model for these systems. The model predicted a general loss of passivation in iron-based alloys at SCF conditions that was consistent with experimentally measured corrosion rates and open circuit potentials. For carbon-dioxide-based SCFs, measured corrosion rates were low, indicating that carbon steel would be suitable for use with unmodified carbon dioxide, while Type 304 stainless steel would be suitable for use with water or methanol as modifiers.

  2. ENGINEERING BULLETIN: SUPERCRITICAL WATER OXIDATION

    Science.gov (United States)

    This engineering bulletin presents a description and status of supercritical water oxidation technology, a summary of recent performance tests, and the current applicability of this emerging technology. This information is provided to assist remedial project managers, contractors...

  3. Exergoeconomic performance optimization of an endoreversible intercooled regenerated Brayton cogeneration plant. Part 1: Thermodynamic model and parameter analyses

    Directory of Open Access Journals (Sweden)

    Lingen Chen, Bo Yang, Fengrui Sun

    2011-03-01

    Full Text Available A thermodynamic model of an endoreversible intercooled regenerative Brayton heat and power cogeneration plant coupled to constant-temperature heat reservoirs is established by using finite time thermodynamics in Part 1 of this paper. The heat resistance losses in the hot-, cold- and consumer-side heat exchangers, the intercooler and the regenerator are taken into account. The finite time exergoeconomic performance of the cogeneration plant is investigated. The analytical formulae about dimensionless profit rate and exergetic efficiency are derived. The numerical examples show that there exists an optimal value of intercooling pressure ratio which leads to an optimal value of dimensionless profit rate for the fixed total pressure ratio. There also exists an optimal total pressure ratio which leads to a maximum profit rate for the variable total pressure ratio. The effects of intercooling, regeneration and the ratio of the hot-side heat reservoir temperature to environment temperature on dimensionless profit rate and the corresponding exergetic efficiency are analyzed. At last, it is found that there exists an optimal consumer-side temperature which leads to a double-maximum dimensionless profit rate. The profit rate of the model cycle is optimized by optimal allocation of the heat conductance of the heat exchangers in Part 2 of this paper.

  4. Supercritical fluid technology

    Energy Technology Data Exchange (ETDEWEB)

    Penninger, J.M.L.; McHugh, M.A.; Radosz, M.; Krukonis, V.J.

    1985-01-01

    This book presents the state-of-the-art in the science and technology of supercritical fluid (scf) processing. Current research as described in the book, focuses on developments in equations of state for binary and multicomponent mixtures (including polymer solutions), solubility measurements at near-critical conditions, measurements of critical properties of binary mixtures and their correlation with equations of state. Progress in thermodynamics, coupled with advances in the design and construction of high pressure equipment, has opened up a wide avenue of commercial application (e.g. decaffeination of coffee beans, extractions of flavours and spices, purification of pharmaceutical products, separations of polymeric materials, deodorization and deacidification of vegetable oils, fractionation of fatty acids, coal liquefaction, wood delignitication, etc.)

  5. Nanotechnology and supercritical fluids | Hamidreza | Journal of ...

    African Journals Online (AJOL)

    Several techniques have been proposed to produce nanomaterials using ... of the supercritical based techniques applied to the production of nanoparticles materials. Keywords: Supercritical fluids; Nanoparticles; SCF technology; RESS; SAS.

  6. Systems Analyses of Advanced Brayton Cycles For High Efficiency Zero Emission Plants

    Energy Technology Data Exchange (ETDEWEB)

    A. D. Rao; J. Francuz; H. Liao; A. Verma; G. S. Samuelsen

    2006-11-01

    Table 1 shows that the systems efficiency, coal (HHV) to power, is 35%. Table 2 summarizes the auxiliary power consumption within the plant. Thermoflex was used to simulate the power block and Aspen Plus the balance of plant. The overall block flow diagram is presented in Figure A1.3-1 and the key unit process flow diagrams are shown in subsequent figures. Stream data are given in Table A1.3-1. Equipment function specifications are provided in Tables A1.3-2 through 17. The overall plant scheme consists of a cryogenic air separation unit supplying 95% purity O{sub 2} to GE type high pressure (HP) total quench gasifiers. The raw gas after scrubbing is treated in a sour shift unit to react the CO with H{sub 2}O to form H{sub 2} and CO{sub 2}. The gas is further treated to remove Hg in a sulfided activated carbon bed. The syngas is desulfurized and decarbonized in a Selexol acid gas removal unit and the decarbonized syngas after humidification and preheat is fired in GE 7H type steam cooled gas turbines. Intermediate pressure (IP) N{sub 2} from the ASU is also supplied to the combustors of the gas turbines as additional diluent for NOx control. A portion of the air required by the ASU is extracted from the gas turbines. The plant consists of the following major process units: (1) Air Separation Unit (ASU); (2) Gasification Unit; (3) CO Shift/Low Temperature Gas Cooling (LTGC) Unit; (4) Acid Gas Removal Unit (AGR) Unit; (5) Fuel Gas Humidification Unit; (6) Carbon Dioxide Compression/Dehydration Unit; (7) Claus Sulfur Recovery/Tail Gas Treating Unit (SRU/TGTU); and (8) Power Block.

  7. Reverse Brayton Cycle with Bladeless Turbo Compressor for Automotive Environmental Cooling

    Science.gov (United States)

    Cepeda-Rizo, Juan (Inventor); Ganapathi, Gani B. (Inventor)

    2016-01-01

    An automotive cabin cooling system uses a bladeless turbocompressor driven by automobile engine exhaust to compress incoming ambient air. The compressed air is directed to an intercooler where it is cooled and then to another bladeless turbine used as an expander where the air cools as it expands and is directed to the cabin interior. Excess energy may be captured by an alternator couple to the expander turbine. The system employs no chemical refrigerant and may be further modified to include another intercooler on the output of the expander turbine to isolate the cooled cabin environment.

  8. Waste heat recovery from adiabatic diesel engines by exhaust-driven Brayton cycles

    Science.gov (United States)

    Khalifa, H. E.

    1983-01-01

    An evaluation of Bryton Bottoming Systems (BBS) as waste heat recovery devices for future adiabatic diesel engines in heavy duty trucks is presented. Parametric studies were performed to evaluate the influence of external and internal design parameters on BBS performance. Conceptual design and trade-off studies were undertaken to estimate the optimum configuration, size, and cost of major hardware components. The potential annual fuel savings of long-haul trucks equipped with BBS were estimated. The addition of a BBS to a turbocharged, nonaftercooled adiabatic engine would improve fuel economy by as much as 12%. In comparison with an aftercooled, turbocompound engine, the BBS-equipped turbocharged engine would offer a 4.4% fuel economy advantage. If installed in tandem with an aftercooled turbocompound engine, the BBS could effect a 7.2% fuel economy improvement. The cost of a mass-produced 38 Bhp BBS is estimated at about $6460 or 170/Bhp. Technical and economic barriers that hinder the commercial introduction of bottoming systems were identified. Related studies in the area of waste heat recovery from adiabatic diesel engines and NASA-CR-168255 (Steam Rankine) and CR-168256 (Organic Rankine).

  9. Dynamic transition in supercritical iron.

    Science.gov (United States)

    Fomin, Yu D; Ryzhov, V N; Tsiok, E N; Brazhkin, V V; Trachenko, K

    2014-11-26

    Recent advance in understanding the supercritical state posits the existence of a new line above the critical point separating two physically distinct states of matter: rigid liquid and non-rigid gas-like fluid. The location of this line, the Frenkel line, remains unknown for important real systems. Here, we map the Frenkel line on the phase diagram of supercritical iron using molecular dynamics simulations. On the basis of our data, we propose a general recipe to locate the Frenkel line for any system, the recipe that importantly does not involve system-specific detailed calculations and relies on the knowledge of the melting line only. We further discuss the relationship between the Frenkel line and the metal-insulator transition in supercritical liquid metals. Our results enable predicting the state of supercritical iron in several conditions of interest. In particular, we predict that liquid iron in the Jupiter core is in the "rigid liquid" state and is highly conducting. We finally analyse the evolution of iron conductivity in the core of smaller planets such as Earth and Venus as well as exoplanets: as planets cool off, the supercritical core undergoes the transition to the rigid-liquid conducting state at the Frenkel line.

  10. Supercritical Fluid Reactions for Coal Processing

    Energy Technology Data Exchange (ETDEWEB)

    Charles A. Eckert

    1997-11-01

    Exciting opportunities exist for the application of supercritical fluid (SCF) reactions for the pre-treatment of coal. Utilizing reactants which resemble the organic nitrogen containing components of coal, we developed a method to tailor chemical reactions in supercritical fluid solvents for the specific application of coal denitrogenation. The tautomeric equilibrium of a Schiff base was chosen as one model system and was investigated in supercritical ethane and cosolvent modified supercritical ethane. The Diels-Alder reaction of anthracene and 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) was selected as a second model system, and it was investigated in supercritical carbon dioxide.

  11. Technology for Bayton-cycle powerplants using solar and nuclear energy

    Science.gov (United States)

    English, R. E.

    1986-01-01

    Brayton cycle gas turbines have the potential to use either solar heat or nuclear reactors for generating from tens of kilowatts to tens of megawatts of power in space, all this from a single technology for the power generating system. Their development for solar energy dynamic power generation for the space station could be the first step in an evolution of such powerplants for a very wide range of applications. At the low power level of only 10 kWe, a power generating system has already demonstrated overall efficiency of 0.29 and operated 38 000 hr. Tests of improved components show that these components would raise that efficiency to 0.32, a value twice that demonstrated by any alternate concept. Because of this high efficiency, solar Brayton cycle power generators offer the potential to increase power per unit of solar collector area to levels exceeding four times that from photovoltaic powerplants using present technology for silicon solar cells. The technologies for solar mirrors and heat receivers are reviewed and assessed. This Brayton technology for solar powerplants is equally suitable for use with the nuclear reactors. The available long time creep data on the tantalum alloy ASTAR-811C show that such Brayton cycles can evolve to cycle peak temperatures of 1500 K (2240 F). And this same technology can be extended to generate 10 to 100 MW in space by exploiting existing technology for terrestrial gas turbines in the fields of both aircraft propulsion and stationary power generation.

  12. Removing Solids From Supercritical Water

    Science.gov (United States)

    Hong, Glenn T.

    1992-01-01

    Apparatus removes precipitated inorganic salts and other solids in water-recycling process. Designed for use with oxidation in supercritical water which treats wastes and yields nearly pure water. Heating coils and insulation around vessel keep it hot. Locking bracket seals vessel but allows it to be easily opened for replacement of filled canisters.

  13. Supercritical multicomponent solvent coal extraction

    Science.gov (United States)

    Corcoran, W. H.; Fong, W. S.; Pichaichanarong, P.; Chan, P. C. F.; Lawson, D. D. (Inventor)

    1983-01-01

    The yield of organic extract from the supercritical extraction of coal with larger diameter organic solvents such as toluene is increased by use of a minor amount of from 0.1 to 10% by weight of a second solvent such as methanol having a molecular diameter significantly smaller than the average pore diameter of the coal.

  14. Ultra-Supercritical Pressure CFB Boiler Conceptual Design Study

    Energy Technology Data Exchange (ETDEWEB)

    Zhen Fan; Steve Goidich; Archie Robertson; Song Wu

    2006-06-30

    Electric utility interest in supercritical pressure steam cycles has revived in the United States after waning in the 1980s. Since supercritical cycles yield higher plant efficiencies than subcritical plants along with a proportional reduction in traditional stack gas pollutants and CO{sub 2} release rates, the interest is to pursue even more advanced steam conditions. The advantages of supercritical (SC) and ultra supercritical (USC) pressure steam conditions have been demonstrated in the high gas temperature, high heat flux environment of large pulverized coal-fired (PC) boilers. Interest in circulating fluidized bed (CFB) combustion, as an alternative to PC combustion, has been steadily increasing. Although CFB boilers as large as 300 MWe are now in operation, they are drum type, subcritical pressure units. With their sizes being much smaller than and their combustion temperatures much lower than those of PC boilers (300 MWe versus 1,000 MWe and 1600 F versus 3500 F), a conceptual design study was conducted herein to investigate the technical feasibility and economics of USC CFB boilers. The conceptual study was conducted at 400 MWe and 800 MWe nominal plant sizes with high sulfur Illinois No. 6 coal used as the fuel. The USC CFB plants had higher heating value efficiencies of 40.6 and 41.3 percent respectively and their CFB boilers, which reflect conventional design practices, can be built without the need for an R&D effort. Assuming construction at a generic Ohio River Valley site with union labor, total plant costs in January 2006 dollars were estimated to be $1,551/kW and $1,244/kW with costs of electricity of $52.21/MWhr and $44.08/MWhr, respectively. Based on the above, this study has shown that large USC CFB boilers are feasible and that they can operate with performance and costs that are competitive with comparable USC PC boilers.

  15. Universal scaling behavior of supercritical matter

    CERN Document Server

    Bolmatov, Dima; Trachenko, K

    2013-01-01

    Properties of supercritical fluids have been of enduring interest since the critical phenomena were discovered by Cagniard de la Tour in 1822, stimulating fundamental theoretical work and development of experimental techniques. Here, we study the thermodynamic properties of the supercritical state, and discover that specific heat shows a crossover between two different dynamic regimes of the low-temperature rigid liquid and high-temperature non-rigid supercritical fluid. We formulate a theory of heat capacity above the crossover, and find good agreement between calculated and experimental data for rare-gas supercritical liquids (Ne, Ar, Kr and Xe) with no free fitting parameters. We derive the relationship between scaling exponents of heat capacity and viscosity in the supercritical region, and show that these exponents exhibit universality. The universality is explained by the universal temperature behavior of the maximal length of the longitudinal phonons that can exist in the supercritical system and that ...

  16. Pulsed discharge plasmas in supercritical carbon dioxide

    OpenAIRE

    Kiyan, Tsuyoshi; Uemura, A.; Tanaka, K.; Zhang, C. H.; Namihira, Takao; Sakugawa, Takashi; Katsuki, Sunao; Akiyama, Hidenori; Roy, B.C.; Sasaki, M.; Goto, M.; キヤン, ツヨシ; ナミヒラ, タカオ; サクガワ, タカシ; カツキ, スナオ

    2005-01-01

    In recent years, several studies about electrical discharge plasma in supercritical carbon dioxide (CO2) have been carried out. One of the unique characteristics of supercritical fluid is a large density fluctuation near the critical point that can result in marked dramatic changes of thermal conductivity. Therefore, the electrical discharge plasma produced in supercritical fluid has unique features and reactions unlike those of normal plasma produced in gas phase. In our experiments, two typ...

  17. Dynamic simulation of 10 kW Brayton cryocooler for HTS cable

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Ho-Myung; Park, Chan Woo [Hong Ik University, Department of Mechanical Engineering, Seoul, 121-791 (Korea, Republic of); Yang, Hyung Suk; Hwang, Si Dole [KEPCO Research Institute, Daejeon, 305-760 (Korea, Republic of)

    2014-01-29

    Dynamic simulation of a Brayton cryocooler is presented as a partial effort of a Korean governmental project to develop 1∼3 km HTS cable systems at transmission level in Jeju Island. Thermodynamic design of a 10 kW Brayton cryocooler was completed, and a prototype construction is underway with a basis of steady-state operation. This study is the next step to investigate the transient behavior of cryocooler for two purposes. The first is to simulate and design the cool-down process after scheduled or unscheduled stoppage. The second is to predict the transient behavior following the variation of external conditions such as cryogenic load or outdoor temperature. The detailed specifications of key components, including plate-fin heat exchangers and cryogenic turbo-expanders are incorporated into a commercial software (Aspen HYSYS) to estimate the temporal change of temperature and flow rate over the cryocooler. An initial cool-down scenario and some examples on daily variation of cryocooler are presented and discussed, aiming at stable control schemes of a long cable system.

  18. Progress Towards a 6-10 K Turbo-Brayton Cryocooler

    Science.gov (United States)

    Zagarola, M. V.; Cragin, K. J.; Breedlove, J. J.; Davis, T. M.

    2006-04-01

    Turbomachine-based Brayton (turbo-Brayton) cryocoolers are an ideal option for long-duration space missions. Key attributes inherent to the technology are high reliability, extremely low vibration emittance, and flexible packaging and integration with instruments and spacecraft systems. The first space implementation of the technology was the NICMOS Cryocooler, which is a single-stage unit that was installed on the Hubble Space Telescope in March 2002. This cryocooler provides 7 W of cooling at 70 K and has been operating for 3.3 years (July 2005) without degradation in performance. New developments at Creare are focused on two-stage configurations with load temperatures as low as 6 K. The lower temperatures and loads have required advances in component technologies to meet aggressive targets for cryocooler mass, size and performance. The development of the electronics, compressors and intermediate turboalternator for a 6-10 K cryocooler are complete. This paper summarizes our accomplishments on the completed components, and reviews our progress towards the development of the remaining critical components, a lightweight recuperator and a high performance low temperature turboalternator.

  19. Preliminary studies on the heat exchanger option for S-CO{sub 2} power conversion cycle coupled to water cooled SMR

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Y.; Lee, J. [Dept. of Nuclear and Quantum Engineering, Korea Advanced Inst. of Science and Technology, 373-1 Guseong-dong Yuseong-gu, Daejeon, 305-701 (Korea, Republic of); Lee, J. I. [Dept. of Nuclear and Quantum Engineering, Korea Advanced Inst. of Science and Technology, 373-1 Guseong-dong Yuseong-gu, Daejeon, 305-701 (Korea, Republic of); Dept. of Nuclear Engineering, Khalifa Univ. of Science, Technology and Research (KUSTAR), P.O.Box 127788, Abu Dhabi (United Arab Emirates)

    2012-07-01

    For more than a half century, the steam Rankine cycle had been the major power conversion cycle for a nuclear power plant. However, as the interest on the next generation reactors grows, a variety of alternative power conversion systems have been studied. Among them, the S-CO{sub 2} cycle (Supercritical carbon dioxide Brayton cycle) is considered as a promising candidate due to several benefits such as 1) Relatively high thermal efficiency at relatively low turbine inlet temperature, 2) High efficiency with simple lay-out 3) Compactness of turbo-machineries. 4) Compactness of total cycle combined with PCHE (Printed Circuit Heat Exchanger). According to the conventional classification of heat exchangers (HE), there are three kind of HE, 1) Tubular HEs, 2) Plate-type HEs, 3) Extended surface HEs. So far, the researcher has mostly assumed PCHE type HE for the S-CO{sub 2} cycle due to its compactness with reasonably low pressure drop. However, PCHE is currently one of the most expensive components in the cycle, which can have a negative effect on the economics of the cycle. Therefore, an alternative for the HE should be seriously investigated. By comparing the operating condition (pressure and temperature) there are three kind of HE in the S-CO{sub 2} cycle, 1) IHX (Intermediate Heat exchanger) 2) Recuperator and 3) Pre-cooler. In each heat exchanger, hot side and cold side coolants are different, i.e. reactor coolant to S-CO{sub 2} (IHX), S-CO{sub 2} to S-CO{sub 2}(Recuperator), S-CO{sub 2} to water (Pre-cooler). By considering all the attributes mentioned above, all existing types of heat exchangers are compared to find a possible alternative to PCHE. The comparing factors are 1) Size(volume), 2) Cost. Plate fin type HEs are considered to be the most competitive heat exchanger regarding the size and the cost after some improvements on the design limit are made. (authors)

  20. Lipidomics by Supercritical Fluid Chromatography

    Directory of Open Access Journals (Sweden)

    Laurent Laboureur

    2015-06-01

    Full Text Available This review enlightens the role of supercritical fluid chromatography (SFC in the field of lipid analysis. SFC has been popular in the late 1980s and 1990s before almost disappearing due to the commercial success of liquid chromatography (LC. It is only 20 years later that a regain of interest appeared when new commercial instruments were introduced. As SFC is fully compatible with the injection of extracts in pure organic solvent, this technique is perfectly suitable for lipid analysis and can be coupled with either highly universal (UV or evaporative light scattering or highly specific (mass spectrometry detection methods. A short history of the use of supercritical fluids as mobile phase for the separation oflipids will be introduced first. Then, the advantages and drawbacks of SFC are discussed for each class of lipids (fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterols, prenols, polyketides defined by the LIPID MAPS consortium.

  1. Lipidomics by Supercritical Fluid Chromatography

    Science.gov (United States)

    Laboureur, Laurent; Ollero, Mario; Touboul, David

    2015-01-01

    This review enlightens the role of supercritical fluid chromatography (SFC) in the field of lipid analysis. SFC has been popular in the late 1980s and 1990s before almost disappearing due to the commercial success of liquid chromatography (LC). It is only 20 years later that a regain of interest appeared when new commercial instruments were introduced. As SFC is fully compatible with the injection of extracts in pure organic solvent, this technique is perfectly suitable for lipid analysis and can be coupled with either highly universal (UV or evaporative light scattering) or highly specific (mass spectrometry) detection methods. A short history of the use of supercritical fluids as mobile phase for the separation oflipids will be introduced first. Then, the advantages and drawbacks of SFC are discussed for each class of lipids (fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterols, prenols, polyketides) defined by the LIPID MAPS consortium. PMID:26090714

  2. Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 2: Advanced energy conversion systems. Part 1: Open-cycle gas turbines

    Science.gov (United States)

    Brown, D. H.; Corman, J. C.

    1976-01-01

    Ten energy conversion systems are defined and analyzed in terms of efficiency. These include: open-cycle gas turbine recuperative; open-cycle gas turbine; closed-cycle gas turbine; supercritical CO2 cycle; advanced steam cycle; liquid metal topping cycle; open-cycle MHD; closed-cycle inert gas MHD; closed-cycle liquid metal MHD; and fuel cells. Results are presented.

  3. Supercritical Fluid Chromatography, Pressurized Liquid Extraction and Supercritical Fluid Extraction

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Matthew C.; Yonker, Clement R.

    2006-06-15

    In this review we examine the related fields of supercritical fluid chromatography (SFC) and supercritical fluid extraction (SFE). We reviewed the published literature in the period from November 2003 to November 2005. Well over 300 papers were published in this period. This large body of work indicates continuing active growth of the field, but an exhaustive review is beyond the scope of this work. We have chosen to include a sampling of publications that best represent the continuing trends and new ideas in the field. In keeping with past reviews on this subject1, we have broadened our scope to include fluid systems operating at high temperature and pressure, but below the critical point. Various terms have been applied to this state: sub-critical fluid extraction, pressurized liquid extraction, and accelerated solvent extraction. The term accelerated solvent extraction has been used by instrument manufacturers to refer to this process, but we will use the more descriptive term pressurized liquid extraction (PLE) to refer to these systems. Most of the research in the field is of an “evolutionary” rather than “revolutionary” nature. As in the previous review period, applications papers make up a majority of the published work. Pharmaceutical applications continue to be a strong theme. Most of the pharmaceutical work has centered on preparative, rather than analytical, separations. Chiral separations are an exception, as analytical scale separations of chiral compounds are an area of intense interest. Food and natural products represent the next largest body of work. Major themes are the isolation and characterization of high-value added foodstuffs, fragrances, and flavor compounds from novel natural materials or agricultural by-products. The areas of food, natural products, and pharmaceutical separation science converge in the area of so-called nutraceuticals. These are typically high-value products, either sold alone or as part of a fortified food, that

  4. Supercritical Water Mixture (SCWM) Experiment

    Science.gov (United States)

    Hicks, Michael C.; Hegde, Uday G.

    2012-01-01

    The subject presentation, entitled, Supercritical Water Mixture (SCWM) Experiment, was presented at the International Space Station (ISS) Increment 33/34 Science Symposium. This presentation provides an overview of an international collaboration between NASA and CNES to study the behavior of a dilute aqueous solution of Na2SO4 (5% w) at near-critical conditions. The Supercritical Water Mixture (SCWM) investigation, serves as important precursor work for subsequent Supercritical Water Oxidation (SCWO) experiments. The SCWM investigation will be performed in DECLICs High Temperature Insert (HTI) for the purpose of studying critical fluid phenomena at high temperatures and pressures. The HTI includes a completely sealed and integrated test cell (i.e., Sample Cell Unit SCU) that will contain approximately 0.3 ml of the aqueous test solution. During the sequence of tests, scheduled to be performed in FY13, temperatures and pressures will be elevated to critical conditions (i.e., Tc = 374C and Pc = 22 MPa) in order to observe salt precipitation, precipitate agglomeration and precipitate transport in the presence of a temperature gradient without the influences of gravitational forces. This presentation provides an overview of the motivation for this work, a description of the DECLIC HTI hardware, the proposed test sequences, and a brief discussion of the scientific research objectives.

  5. Carbon dioxide-based supercritical fluids as IC manufacturing solvents

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, J.B.; Davenhall, L.B.; Taylor, C.M.V.; Sivils, L.D.; Pierce, T.; Tiefert, K.

    1999-05-11

    The production of integrated circuits (IC's) involves a number of discrete steps which utilize hazardous or regulated solvents and generate large waste streams. ES&H considerations associated with these chemicals have prompted a search for alternative, more environmentally benign solvent systems. An emerging technology for conventional solvent replacement is the use of supercritical fluids based on carbon dioxide (CO{sub 2}). Research work, conducted at Los Alamos in conjunction with the Hewlett-Packard Company, has lead to the development of a CO{sub 2}-based supercritical fluid treatment system for the stripping of hard-baked photoresists. This treatment system, known as Supercritical CO{sub 2} Resist Remover, or CORR, uses a two-component solvent composed of a nonhazardous, non-regulated compound, dissolved in supercritical CO{sub 2}. The solvent/treatment system has been successfully tested on metallized Si wafers coated with negative and positive photoresist, the latter both before and after ion-implantation. A description of the experimental data will be presented. Based on the initial laboratory results, the project has progressed to the design and construction of prototype, single-wafer photoresist-stripping equipment. The integrated system involves a closed-loop, recirculating cycle which continuously cleans and regenerates the CO{sub 2}, recycles the dissolved solvent, and separates and concentrates the spent resist. The status of the current design and implementation strategy of a treatment system to existing IC fabrication facilities will be discussed. Additional remarks will be made on the use of a SCORR-type system for the cleaning of wafers prior to processing.

  6. Incorporating supercritical steam turbines into molten-salt power tower plants :

    Energy Technology Data Exchange (ETDEWEB)

    Pacheco, James Edward; Wolf, Thorsten; Muley, Nishant

    2013-03-01

    Sandia National Laboratories and Siemens Energy, Inc., examined 14 different subcritical and supercritical steam cycles to determine if it is feasible to configure a molten-salt supercritical steam plant that has a capacity in the range of 150 to 200 MWe. The effects of main steam pressure and temperature, final feedwater temperature, and hot salt and cold salt return temperatures were determined on gross and half-net efficiencies. The main steam pressures ranged from 120 bar-a (subcritical) to 260 bar-a (supercritical). Hot salt temperatures of 566 and 600ÀC were evaluated, which resulted in main steam temperatures of 553 and 580ÀC, respectively. Also, the effects of final feedwater temperature (between 260 and 320ÀC) were evaluated, which impacted the cold salt return temperature. The annual energy production and levelized cost of energy (LCOE) were calculated using the System Advisory Model on 165 MWe subcritical plants (baseline and advanced) and the most promising supercritical plants. It was concluded that the supercritical steam plants produced more annual energy than the baseline subcritical steam plant for the same-size heliostat field, receiver, and thermal storage system. Two supercritical steam plants had the highest annual performance and had nearly the same LCOE. Both operated at 230 bar-a main steam pressure. One was designed for a hot salt temperature of 600ÀC and the other 565ÀC. The LCOEs for these plants were about 10% lower than the baseline subcritical plant operating at 120 bar-a main steam pressure and a hot salt temperature of 565ÀC. Based on the results of this study, it appears economically and technically feasible to incorporate supercritical steam turbines in molten-salt power tower plants.

  7. 10 MW Supercritical CO2 Turbine Test

    Energy Technology Data Exchange (ETDEWEB)

    Turchi, Craig

    2014-01-29

    The Supercritical CO2 Turbine Test project was to demonstrate the inherent efficiencies of a supercritical carbon dioxide (s-CO2) power turbine and associated turbomachinery under conditions and at a scale relevant to commercial concentrating solar power (CSP) projects, thereby accelerating the commercial deployment of this new power generation technology. The project involved eight partnering organizations: NREL, Sandia National Laboratories, Echogen Power Systems, Abengoa Solar, University of Wisconsin at Madison, Electric Power Research Institute, Barber-Nichols, and the CSP Program of the U.S. Department of Energy. The multi-year project planned to design, fabricate, and validate an s-CO2 power turbine of nominally 10 MWe that is capable of operation at up to 700°C and operates in a dry-cooled test loop. The project plan consisted of three phases: (1) system design and modeling, (2) fabrication, and (3) testing. The major accomplishments of Phase 1 included: Design of a multistage, axial-flow, s-CO2 power turbine; Design modifications to an existing turbocompressor to provide s-CO2 flow for the test system; Updated equipment and installation costs for the turbomachinery and associated support infrastructure; Development of simulation tools for the test loop itself and for more efficient cycle designs that are of greater commercial interest; Simulation of s-CO2 power cycle integration into molten-nitrate-salt CSP systems indicating a cost benefit of up to 8% in levelized cost of energy; Identification of recuperator cost as a key economic parameter; Corrosion data for multiple alloys at temperatures up to 650ºC in high-pressure CO2 and recommendations for materials-of-construction; and Revised test plan and preliminary operating conditions based on the ongoing tests of related equipment. Phase 1 established that the cost of the facility needed to test the power turbine at its full power and temperature would exceed the planned funding for Phases 2 and 3. Late

  8. INTEGRATED SUPERCRITICAL FLUID EXTRACTION AND BIOPROCESSING

    Directory of Open Access Journals (Sweden)

    Owen Catchpole

    2012-01-01

    Full Text Available Supercritical fluids are increasingly being used and promoted at a laboratory and pilot scale to produce high value, natural bioactives from biologically based raw materials. Supercritical CO2 is overwhelmingly the solvent of choice for these operations, but is largely limited to the processing of dry raw materials and the extraction of low polarity, low molecular weight compounds. The use of co-solvents and the use of alternative ‘near-critical’ extraction fluids such as dimethyl ether show potential to mitigate these limitations. Commercialisation of new supercritical extraction processes has arguably been limited because the supercritical extraction process has been developed in isolation of other processing steps necessary to achieve a successful product. This study reviews recent developments in integrated processing that incorporate the use of supercritical fluids for bioseparations and in particular process schemes that produce high value natural bioactives. Integrated processes include prior operation (fermentation, extraction, enzyme pre-treatment, physical fractionation or size reduction followed by supercritical extraction or fractionation and processes in which operations are carried out in situ in supercritical fluids (supercritical chromatography, enzymatic conversion, precipitation and coating of solutes. The use of co-solvents and alternative extraction solvents in these processes is discussed. Prospects for future developments are also discussed.

  9. Adsorption of ethyl acetate onto modified clays and its regeneration with supercritical CO2

    Directory of Open Access Journals (Sweden)

    A. M. Cavalcante

    2005-03-01

    Full Text Available Modified clays were used to remove ethyl acetate from aqueous solutions. These clays were regenerated using supercritical CO2. Structural changes in the montmorillonite clay after treatment with quaternary amines were studied. The surface properties of the modified clay changed from highly hydrophilic to highly organophilic. The clay was regenerated by percolation of a stream of CO2 through the porous montmorillonite matrix. Different pressures and temperatures were employed, resulting in different fluid conditions (gas, liquid, and supercritical. The experimental data was fitted with a simplified model. The best desorption result was found under supercritical conditions. A crossover effect was observed. The capacity of the modified clay as a pollutant attenuator remained almost unchanged after a regeneration cycle.

  10. Supercritical water oxidation - Microgravity solids separation

    Science.gov (United States)

    Killilea, William R.; Hong, Glenn T.; Swallow, Kathleen C.; Thomason, Terry B.

    1988-01-01

    This paper discusses the application of supercritical water oxidation (SCWO) waste treatment and water recycling technology to the problem of waste disposal in-long term manned space missions. As inorganic constituents present in the waste are not soluble in supercritical water, they must be removed from the organic-free supercritical fluid reactor effluent. Supercritical water reactor/solids separator designs capable of removing precipitated solids from the process' supercritical fluid in zero- and low- gravity environments are developed and evaluated. Preliminary experiments are then conducted to test the concepts. Feed materials for the experiments are urine, feces, and wipes with the addition of reverse osmosis brine, the rejected portion of processed hygiene water. The solid properties and their influence on the design of several oxidation-reactor/solids-separator configurations under study are presented.

  11. Carbon-Carbon Composites as Recuperator Material for Direct Gas Brayton Systems

    Energy Technology Data Exchange (ETDEWEB)

    RA Wolf

    2006-07-19

    Of the numerous energy conversion options available for a space nuclear power plant (SNPP), one that shows promise in attaining reliable operation and high efficiency is the direct gas Brayton (GB) system. In order to increase efficiency, the GB system incorporates a recuperator that accounts for nearly half the weight of the energy conversion system (ECS). Therefore, development of a recuperator that is lighter and provides better performance than current heat exchangers could prove to be advantageous. The feasibility of a carbon-carbon (C/C) composite recuperator core has been assessed and a mass savings of 60% and volume penalty of 20% were projected. The excellent thermal properties, high-temperature capabilities, and low density of carbon-carbon materials make them attractive in the GB system, but development issues such as material compatibility with other structural materials in the system, such as refractory metals and superalloys, permeability, corrosion, joining, and fabrication must be addressed.

  12. Degradation Characteristics of Wood Using Supercritical Alcohols

    Directory of Open Access Journals (Sweden)

    Jeeban Poudel

    2012-11-01

    Full Text Available In this work, the characteristics of wood degradation using supercritical alcohols have been studied. Supercritical ethanol and supercritical methanol were used as solvents. The kinetics of wood degradation were analyzed using the nonisothermal weight loss technique with heating rates of 3.1, 9.8, and 14.5 °C/min for ethanol and 5.2, 11.3, and 16.3 °C/min for methanol. Three different kinetic analysis methods were implemented to obtain the apparent activation energy and the overall reaction order for wood degradation using supercritical alcohols. These were used to compare with previous data for supercritical methanol. From this work, the activation energies of wood degradation in supercritical ethanol were obtained as 78.0–86.0, 40.1–48.1, and 114 kJ/mol for the different kinetic analysis methods used in this work. The activation energies of wood degradation in supercritical ethanol were obtained as 78.0–86.0, 40.1–48.1, and 114 kJ/mol. This paper also includes the analysis of the liquid products obtained from this work. The characteristic analysis of liquid products on increasing reaction temperature and time has been performed by GC-MS. The liquid products were categorized according to carbon numbers and aromatic/aliphatic components. It was found that higher conversion in supercritical ethanol occurs at a lower temperature than that of supercritical methanol. The product analysis shows that the majority of products fall in the 2 to 15 carbon number range.

  13. On the thermal efficiency of power cycles in finite time thermodynamics

    Science.gov (United States)

    Momeni, Farhang; Morad, Mohammad Reza; Mahmoudi, Ashkan

    2016-09-01

    The Carnot, Diesel, Otto, and Brayton power cycles are reconsidered endoreversibly in finite time thermodynamics (FTT). In particular, the thermal efficiency of these standard power cycles is compared to the well-known results in classical thermodynamics. The present analysis based on FTT modelling shows that a reduction in both the maximum and minimum temperatures of the cycle causes the thermal efficiency to increase. This is antithetical to the existing trend in the classical references. Under the assumption of endoreversibility, the relation between the efficiencies is also changed to {η }{{Carnot}}\\gt {η }{{Brayton}}\\gt {η }{{Diesel}}\\gt {η }{{Otto}}, which is again very different from the corresponding classical results. The present results benefit a better understanding of the important role of irreversibility on heat engines in classical thermodynamics.

  14. Using supercritical fluids to refine hydrocarbons

    Science.gov (United States)

    Yarbro, Stephen Lee

    2015-06-09

    A system and method for reactively refining hydrocarbons, such as heavy oils with API gravities of less than 20 degrees and bitumen-like hydrocarbons with viscosities greater than 1000 cp at standard temperature and pressure, using a selected fluid at supercritical conditions. A reaction portion of the system and method delivers lightweight, volatile hydrocarbons to an associated contacting unit which operates in mixed subcritical/supercritical or supercritical modes. Using thermal diffusion, multiphase contact, or a momentum generating pressure gradient, the contacting unit separates the reaction products into portions that are viable for use or sale without further conventional refining and hydro-processing techniques.

  15. Preliminary Study on the High Efficiency Supercritical Pressure Water-Cooled Reactor for Electricity Generation

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Yoon Yeong; Park, Jong Kyun; Cho, Bong Hyun and others

    2006-01-15

    This research has been performed to introduce a concept of supercritical pressure water cooled reactor(SCWR) in Korea The area of research includes core conceptual design, evaluation of candidate fuel, fluid systems conceptual design with mechanical consideration, preparation of safety analysis code, and construction of supercritical pressure heat transfer test facility, SPHINX, and preliminary test. As a result of the research, a set of tools for the reactor core design has been developed and the conceptual core design with solid moderator was proposed. The direct thermodynamic cycle has been studied to find a optimum design. The safety analysis code has also been adapted to supercritical pressure condition. A supercritical pressure CO2 heat transfer test facility has been constructed and preliminary test proved the facility works as expected. The result of this project will be good basis for the participation in the international collaboration under GIF GEN-IV program and next 5-year mid and long term nuclear research program of MOST. The heat transfer test loop, SPHINX, completed as a result of this project may be used for the power cycle study as well as further heat transfer study for the various geometries.

  16. The universal power and efficiency characteristics for irreversible reciprocating heat engine cycles

    CERN Document Server

    Qin Xiao Yong; Sun Feng Rui; Wu Chih

    2003-01-01

    The performance of irreversible reciprocating heat engine cycles with heat transfer loss and friction-like term loss is analysed using finite-time thermodynamics. The universal relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, and the optimal relation between power output and the efficiency of the cycles are derived. Moreover, analysis and optimization of the model were carried out in order to investigate the effect of cycle processes on the performance of the cycle using numerical examples. The results obtained herein include the performance characteristics of irreversible reciprocating Diesel, Otto, Atkinson and Brayton cycles.

  17. HTR-Based Power Plants’ Performance Analysis Applied on Conventional Combined Cycles

    Directory of Open Access Journals (Sweden)

    José Carbia Carril

    2015-01-01

    Full Text Available In high temperature reactors including gas cooled fast reactors and gas turbine modular helium reactors (GT-MHR specifically designed to operate as power plant heat sources, efficiency enhancement at effective cost under safe conditions can be achieved. Mentioned improvements concern the implementation of two cycle structures: (a, a stand alone Brayton operating with helium and a stand alone Rankine cycle (RC with regeneration, operating with carbon dioxide at ultrasupercritical pressure as working fluid (WF, where condensation is carried out at quasicritical conditions, and (b, a combined cycle (CC, in which the topping closed Brayton cycle (CBC operates with helium as WF, while the bottoming RC is operated with one of the following WFs: carbon dioxide, xenon, ethane, ammonia, or water. In both cases, an intermediate heat exchanger (IHE is proposed to provide thermal energy to the closed Brayton or to the Rankine cycles. The results of the case study show that the thermal efficiency, through the use of a CC, is slightly improved (from 45.79% for BC and from 50.17% for RC to 53.63 for the proposed CC with He-H2O operating under safety standards.

  18. Oxy-combustor operable with supercritical fluid

    Energy Technology Data Exchange (ETDEWEB)

    Brun, Klaus; McClung, Aaron M.; Owston, Rebecca A.

    2017-04-04

    An oxy-combustor is provided which comprises a combustion vessel including at least one solid fuel slurry inlet port, at least one oxygen inlet port and at least one supercritical fluid inlet port, wherein the combustion vessel is operable at an operating pressure of at least 1,100 psi; an interior of the combustion vessel comprises a combustion chamber and a supercritical fluid infusion chamber surrounding at least a part of the combustion chamber, the supercritical fluid infusion chamber and the combustion chamber are separated by a porous liner surrounding the combustion chamber, and the supercritical infusion chamber is located between the porous liner and an outer casing of the combustion vessel.

  19. Determination of solvation kinetics in supercritical fluids

    Energy Technology Data Exchange (ETDEWEB)

    Bright, F.V.

    1993-01-01

    Objective was to study solvation processes in pure and entrainer-modified supercritical fluids. Specific topics were: Kinetics for solvation in supercritical media, influence on entrainers on solvation, reversibility of solvation, effects of solvation on intramolecular solute-solute interaction kinetics, and impact of fluid density on these processes. Time-resolved fluorescence spectroscopy was used as the main analytical tool. A summary is given of the 2.5 years' research.

  20. Charting the landscape of supercritical string theory.

    Science.gov (United States)

    Hellerman, Simeon; Swanson, Ian

    2007-10-26

    Special solutions of string theory in supercritical dimensions can interpolate in time between theories with different numbers of spacetime dimensions and different amounts of world sheet supersymmetry. These solutions connect supercritical string theories to the more familiar string duality web in ten dimensions and provide a precise link between supersymmetric and purely bosonic string theories. Dimension quenching and c duality appear to be natural concepts in string theory, giving rise to large networks of interconnected theories.

  1. Water in supercritical carbon dioxide dyeing

    Directory of Open Access Journals (Sweden)

    Zheng Lai-Jiu

    2015-01-01

    Full Text Available This paper investigates the effect of water serving as entrainer on the dyeing of wool fabrics in supercritical carbon dioxide. Compared with previous supercritical dyeing methods, addition of water makes the dyeing process more effective under low temperature and low pressure. During dyeing process, dyestuff can be uniformly distributed on fabrics’s surface due to water interaction, as a result coloration is enhanced while color difference is decreased.

  2. Design of a Condenser-Boiler for a Binary Mercury-Organic Rankine Cycle Solar Dynamic Space Power System

    Science.gov (United States)

    1987-05-15

    support the power needs of the space station. Competitive cycles considered have been Brayton, Rankine, and Stirling cycles powered with either nuclear or...at 644 OK, radiator at 350 OK, and pump and turbine efficiencies at 0.54 and 8.72, respectively. There are pressure losses of 10.7% in the regenerator ...10.4% in the "boiler", and 19% drop from turbine outlet to pump (including regenerator and RFMD). These figures represent the preliminary results

  3. Supercritical fluid reverse micelle separation

    Science.gov (United States)

    Fulton, John L.; Smith, Richard D.

    1993-01-01

    A method of separating solute material from a polar fluid in a first polar fluid phase is provided. The method comprises combining a polar fluid, a second fluid that is a gas at standard temperature and pressure and has a critical density, and a surfactant. The solute material is dissolved in the polar fluid to define the first polar fluid phase. The combined polar and second fluids, surfactant, and solute material dissolved in the polar fluid is maintained under near critical or supercritical temperature and pressure conditions such that the density of the second fluid exceeds the critical density thereof. In this way, a reverse micelle system defining a reverse micelle solvent is formed which comprises a continuous phase in the second fluid and a plurality of reverse micelles dispersed in the continuous phase. The solute material is dissolved in the polar fluid and is in chemical equilibrium with the reverse micelles. The first polar fluid phase and the continuous phase are immiscible. The reverse micelles each comprise a dynamic aggregate of surfactant molecules surrounding a core of the polar fluid. The reverse micelle solvent has a polar fluid-to-surfactant molar ratio W, which can vary over a range having a maximum ratio W.sub.o that determines the maximum size of the reverse micelles. The maximum ratio W.sub.o of the reverse micelle solvent is then varied, and the solute material from the first polar fluid phase is transported into the reverse micelles in the continuous phase at an extraction efficiency determined by the critical or supercritical conditions.

  4. Supercritical fluid reverse micelle separation

    Science.gov (United States)

    Fulton, J.L.; Smith, R.D.

    1993-11-30

    A method of separating solute material from a polar fluid in a first polar fluid phase is provided. The method comprises combining a polar fluid, a second fluid that is a gas at standard temperature and pressure and has a critical density, and a surfactant. The solute material is dissolved in the polar fluid to define the first polar fluid phase. The combined polar and second fluids, surfactant, and solute material dissolved in the polar fluid is maintained under near critical or supercritical temperature and pressure conditions such that the density of the second fluid exceeds the critical density thereof. In this way, a reverse micelle system defining a reverse micelle solvent is formed which comprises a continuous phase in the second fluid and a plurality of reverse micelles dispersed in the continuous phase. The solute material is dissolved in the polar fluid and is in chemical equilibrium with the reverse micelles. The first polar fluid phase and the continuous phase are immiscible. The reverse micelles each comprise a dynamic aggregate of surfactant molecules surrounding a core of the polar fluid. The reverse micelle solvent has a polar fluid-to-surfactant molar ratio W, which can vary over a range having a maximum ratio W[sub o] that determines the maximum size of the reverse micelles. The maximum ratio W[sub o] of the reverse micelle solvent is then varied, and the solute material from the first polar fluid phase is transported into the reverse micelles in the continuous phase at an extraction efficiency determined by the critical or supercritical conditions. 27 figures.

  5. Design and optimization of a single stage centrifugal compressor for a solar dish-Brayton system

    Science.gov (United States)

    Wang, Yongsheng; Wang, Kai; Tong, Zhiting; Lin, Feng; Nie, Chaoqun; Engeda, Abraham

    2013-10-01

    According to the requirements of a solar dish-Brayton system, a centrifugal compressor stage with a minimum total pressure ratio of 5, an adiabatic efficiency above 75% and a surge margin more than 12% needs to be designed. A single stage, which consists of impeller, radial vaned diffuser, 90° crossover and two rows of axial stators, was chosen to satisfy this system. To achieve the stage performance, an impeller with a 6:1 total pressure ratio and an adiabatic efficiency of 90% was designed and its preliminary geometry came from an in-house one-dimensional program. Radial vaned diffuser was applied downstream of the impeller. Two rows of axial stators after 90° crossover were added to guide the flow into axial direction. Since jet-wake flow, shockwave and boundary layer separation coexisted in the impeller-diffuser region, optimization on the radius ratio of radial diffuser vane inlet to impeller exit, diffuser vane inlet blade angle and number of diffuser vanes was carried out at design point. Finally, an optimized centrifugal compressor stage fulfilled the high expectations and presented proper performance. Numerical simulation showed that at design point the stage adiabatic efficiency was 79.93% and the total pressure ratio was 5.6. The surge margin was 15%. The performance map including 80%, 90% and 100% design speed was also presented.

  6. Numerical simulations of LNG vapor dispersion in Brayton Fire Training Field tests with ANSYS CFX.

    Science.gov (United States)

    Qi, Ruifeng; Ng, Dedy; Cormier, Benjamin R; Mannan, M Sam

    2010-11-15

    Federal safety regulations require the use of validated consequence models to determine the vapor cloud dispersion exclusion zones for accidental liquefied natural gas (LNG) releases. One tool that is being developed in industry for exclusion zone determination and LNG vapor dispersion modeling is computational fluid dynamics (CFD). This paper uses the ANSYS CFX CFD code to model LNG vapor dispersion in the atmosphere. Discussed are important parameters that are essential inputs to the ANSYS CFX simulations, including the atmospheric conditions, LNG evaporation rate and pool area, turbulence in the source term, ground surface temperature and roughness height, and effects of obstacles. A sensitivity analysis was conducted to illustrate uncertainties in the simulation results arising from the mesh size and source term turbulence intensity. In addition, a set of medium-scale LNG spill tests were performed at the Brayton Fire Training Field to collect data for validating the ANSYS CFX prediction results. A comparison of test data with simulation results demonstrated that CFX was able to describe the dense gas behavior of LNG vapor cloud, and its prediction results of downwind gas concentrations close to ground level were in approximate agreement with the test data.

  7. Supercritical Fluid Facilitated Growth of Copper and Aluminum Oxide Nanoparticles

    Science.gov (United States)

    Williams, Geoffrey L.; Vohs, Jason K.; Brege, Jonathan J.; Fahlman, Bradley D.

    2005-01-01

    Supercritical fluids (SCFs) possess properties that are intermediate between liquids and gases. The combination of supercritical fluid technology with advanced characterization techniques such as electron microscopy provided a practical and rewarding undergraduate laboratory experiment.

  8. Microbial Inactivation by Ultrasound Assisted Supercritical Fluids

    Science.gov (United States)

    Benedito, Jose; Ortuño, Carmen; Castillo-Zamudio, Rosa Isela; Mulet, Antonio

    A method combining supercritical carbon dioxide (SC-CO2) and high power ultrasound (HPU) has been developed and tested for microbial/enzyme inactivation purposes, at different process conditions for both liquid and solid matrices. In culture media, using only SC-CO2, the inactivation rate of E. coli and S. cerevisiae increased with pressure and temperature; and the total inactivation (7-8 log-cycles) was attained after 25 and 140 min of SC-CO2 (350 bar, 36 °C) treatment, respectively. Using SC-CO2+HPU, the time for the total inactivation of both microorganisms was reduced to only 1-2 min, at any condition selected. The SC-CO2+HPU inactivation of both microorganisms was slower in juices (avg. 4.9 min) than in culture media (avg. 1.5 min). In solid samples (chicken, turkey ham and dry-cured pork cured ham) treated with SC-CO2 and SC-CO2+HPU, the inactivation rate of E. coli increased with temperature. The application of HPU to the SC-CO2 treatments accelerated the inactivation rate of E. coli and that effect was more pronounced in treatments with isotonic solution surrounding the solid food samples. The application of HPU enhanced the SC-CO2 inactivation mechanisms of microorganisms, generating a vigorous agitation that facilitated the CO2 solubilization and the mass transfer process. The cavitation generated by HPU could damage the cell walls accelerating the extraction of vital constituents and the microbial death. Thus, using the combined technique, reasonable industrial processing times and mild process conditions could be used which could result into a cost reduction and lead to the minimization in the food nutritional and organoleptic changes.

  9. Supercritical Extraction of Lycopene from Tomato Industrial Wastes with Ethane

    OpenAIRE

    Mendes, Rui L.; Cristino, Ana F.; Nobre, Beatriz P.; Luisa Gouveia; António F. Palavra; Patricia G. S. Matos

    2012-01-01

    Supercritical fluid extraction of all-E-lycopene from tomato industrial wastes (mixture of skins and seeds) was carried out in a semi-continuous flow apparatus using ethane as supercritical solvent. The effect of pressure, temperature, feed particle size, solvent superficial velocity and matrix initial composition was evaluated. Moreover, the yield of the extraction was compared with that obtained with other supercritical solvents (supercritical CO2...

  10. Supercritical Extraction of Lycopene from Tomato Industrial Waste with Ethane

    OpenAIRE

    Nobre, Beatriz P.; Gouveia, L.; Patricia G. S. Matos; Cristino, Ana F.; António F. Palavra; Mendes, Rui L.

    2012-01-01

    Supercritical fluid extraction of all-E-lycopene from tomato industrial wastes (mixture of skins and seeds) was carried out in a semi-continuous flow apparatus using ethane as supercritical solvent. The effect of pressure, temperature, feed particle size, solvent superficial velocity and matrix initial composition was evaluated. Moreover, the yield of the extraction was compared with that obtained with other supercritical solvents (supercritical CO2 and a near critical mixture of ethane and p...

  11. Feasibility Study of Supercritical Light Water Cooled Reactors for Electric Power Production

    Energy Technology Data Exchange (ETDEWEB)

    Philip MacDonald; Jacopo Buongiorno; James Sterbentz; Cliff Davis; Robert Witt; Gary Was; J. McKinley; S. Teysseyre; Luca Oriani; Vefa Kucukboyaci; Lawrence Conway; N. Jonsson: Bin Liu

    2005-02-13

    The supercritical water reactor (SCWR) has been the object of interest throughout the nuclear Generation IV community because of its high potential: a simple, direct cycle, compact configuration; elimination of many traditional LWR components, operation at coolant temperatures much higher than traditional LWRs and thus high thermal efficiency. It could be said that the SWR was viewed as the water counterpart to the high temperature gas reactor.

  12. Drying of supercritical carbon dioxide with membrane processes

    NARCIS (Netherlands)

    Lohaus, Theresa; Scholz, Marco; Koziara, Beata T.; Benes, N.E.; Wessling, Matthias

    2015-01-01

    In supercritical extraction processes regenerating the supercritical fluid represents the main cost constraint. Membrane technology has potential for cost efficient regeneration of water-loaded supercritical carbon dioxide. In this study we have designed membrane-based processes to dehydrate water-l

  13. Pharmaceutical applications of supercritical carbon dioxide.

    Science.gov (United States)

    Kaiser, C S; Römpp, H; Schmidt, P C

    2001-12-01

    The appearance of a supercritical state was already observed at the beginning of the 19th century. Nevertheless, the industrial extraction of plant and other natural materials started about twenty years ago with the decaffeination of coffee. Today carbon dioxide is the most common gas for supercritical fluid extraction in food and pharmaceutical industry. Since pure supercritical carbon dioxide is a lipophilic solvent, mixtures with organic solvents, especially alcohols, are used to increase the polarity of the extraction fluid; more polar compounds can be extracted in this way. The main fields of interest are the extraction of vegetable oils from plant material in analytical and preparative scale, the preparation of essential oils for food and cosmetic industry and the isolation of substances of pharmaceutical relevance. Progress in research was made by the precise measurement of phase equilibria data by means of different methods. Apart from extraction, supercritical fluid chromatography was introduced in the field of analytics, as well as micro- and nanoparticle formation using supercritical fluids as solvent or antisolvent. This review presents pharmaceutical relevant literature of the last twenty years with special emphasis on extraction of natural materials.

  14. Characteristics of compressible flow of supercritical kerosene

    Institute of Scientific and Technical Information of China (English)

    Feng-Quan Zhong; Xue-Jun Fan; Jing Wang; Gong Yu; Jian-Guo Li

    2012-01-01

    In this paper,compressible flow of aviation kerosene at supercritical conditions has been studied both numerically and experimentally.The thermophysical properties of supercritical kerosene are calculated using a 10-species surrogate based on the principle of extended corresponding states (ECS).Isentropic acceleration of supercritical kerosene to subsonic and supersonic speeds has been analyzed numerically.It has been found that the isentropic relationships of supercritical kerosene are significantly different from those of ideal gases.A two-stage fuel heating and delivery system is used to heat the kerosene up to a temperature of 820 K and pressure of 5.5 MPa with a maximum mass flow rate of 100 g/s.The characteristics of supercritical kerosene flows in a converging-diverging nozzle (Laval nozzle) have been studied experimentally.The results show that stable supersonic flows of kerosene could be established in the temperature range of 730 K-820 K and the measurements in the wall pressure agree with the numerical calculation.

  15. Driving Interconnected Networks to Supercriticality

    Directory of Open Access Journals (Sweden)

    Filippo Radicchi

    2014-04-01

    Full Text Available Networks in the real world do not exist as isolated entities, but they are often part of more complicated structures composed of many interconnected network layers. Recent studies have shown that such mutual dependence makes real networked systems potentially exposed to atypical structural and dynamical behaviors, and thus there is an urgent necessity to better understand the mechanisms at the basis of these anomalies. Previous research has mainly focused on the emergence of atypical properties in relation to the moments of the intra- and interlayer degree distributions. In this paper, we show that an additional ingredient plays a fundamental role for the possible scenario that an interconnected network can face: the correlation between intra- and interlayer degrees. For sufficiently high amounts of correlation, an interconnected network can be tuned, by varying the moments of the intra- and interlayer degree distributions, in distinct topological and dynamical regimes. When instead the correlation between intra- and interlayer degrees is lower than a critical value, the system enters in a supercritical regime where dynamical and topological phases are no longer distinguishable.

  16. Supercritical fluid extraction of hops

    Directory of Open Access Journals (Sweden)

    ZORAN ZEKOVIC

    2007-01-01

    Full Text Available Five cultivars of hop were extracted by the method of supercritical fluid extraction using carbon dioxide (SFE–CO2 as extractant. The extraction (50 g of hop sample using a CO2 flow rate of 97.725 L/h was done in the two steps: 1. extraction at 150 bar and 40°C for 2.5 h (sample of series A was obtained and, after that, the same sample of hop was extracted in the second step: 2. extraction at 300 bar and 40 °C for 2.5 h (sample of series B was obtained. The Magnum cultivar was chosen for the investigation of the extraction kinetics. For the qualitative and quantitative analysis of the obtained hop extracts, the GC-MS method was used. Two of four themost common compounds of hop aroma (a-humulene and b-caryophyllene were detected in samples of series A. In addition, isomerized a-acids and a high content of b-acids were detected. The a-acids content in the samples of series B was the highest in the extract of the Magnum cultivar (it is a bitter variety of hop. The low contents of a-acids in all the other hop samples resulted in extracts with low a-acids content, i.e., that contents were under the prescribed a-acids content.

  17. Supercritical carbon dioxide hop extraction

    Directory of Open Access Journals (Sweden)

    Pfaf-Šovljanski Ivana I.

    2005-01-01

    Full Text Available The hop of Magnum cultivar was extracted using supercritical carbon dioxide (SFE-as extractant. Extraction was carried out in the two steps: the first one being carried out at 150 bar and 40°C for 2.5 h (Extract A, and the second was the extraction of the same hop sample at 300 bar and 40°C for 2.5 h (Extract B. Extraction kinetics of the system hop-SFE-CO2 was investigated. Two of four most common compounds of hop aroma (α-humulene and β-caryophyllene were detected in Extract A. Isomerised α-acids and β-acids were detected too. a-Acid content in Extract B was high (that means it is a bitter variety of hop. Mathematical modeling using empirical model characteristic time model and simple single sphere model has been performed on Magnum cultivar extraction experimental results. Characteristic time model equations, best fitted experimental results. Empirical model equation, fitted results well, while simple single sphere model equation poorly approximated the results.

  18. Supercritical waste oxidation pump investigation

    Energy Technology Data Exchange (ETDEWEB)

    Thurston, G.; Garcia, K.

    1993-02-01

    This report investigates the pumping techniques and pumping equipment that would be appropriate for a 5,000 gallon per day supercritical water oxidation waste disposal facility. The pumps must boost water, waste, and additives from atmospheric pressure to approximately 27.6 MPa (4,000 psia). The required flow ranges from 10 gpm to less than 0.1 gpm. For the higher flows, many commercial piston pumps are available. These pumps have packing and check-valves that will require periodic maintenance; probably at 2 to 6 month intervals. Several commercial diaphragm pumps were also discovered that could pump the higher flow rates. Diaphragm pumps have the advantage of not requiring dynamic seals. For the lower flows associated with the waste and additive materials, commercial diaphragm pumps. are available. Difficult to pump materials that are sticky, radioactive, or contain solids, could be injected with an accumulator using an inert gas as the driving mechanism. The information presented in this report serves as a spring board for trade studies and the development of equipment specifications.

  19. A thermodynamic review of cryogenic refrigeration cycles for liquefaction of natural gas

    Science.gov (United States)

    Chang, Ho-Myung

    2015-12-01

    A thermodynamic review is presented on cryogenic refrigeration cycles for the liquefaction process of natural gas. The main purpose of this review is to examine the thermodynamic structure of various cycles and provide a theoretical basis for selecting a cycle in accordance with different needs and design criteria. Based on existing or proposed liquefaction processes, sixteen ideal cycles are selected and the optimal conditions to achieve their best thermodynamic performance are investigated. The selected cycles include standard and modified versions of Joule-Thomson (JT) cycle, Brayton cycle, and their combined cycle with pure refrigerants (PR) or mixed refrigerants (MR). Full details of the cycles are presented and discussed in terms of FOM (figure of merit) and thermodynamic irreversibility. In addition, a new method of nomenclature is proposed to clearly identify the structure of cycles by abbreviation.

  20. Hydrodynamics and Mass Transfer Performance in Supercritical Fluid Extraction Columns

    Institute of Scientific and Technical Information of China (English)

    石冰洁; 张泽廷; 等

    2002-01-01

    New models for describing hydrodynamics and mass transfer performance in supercritical fluid extraction columns were proposed.Those models were proved by experimental data,which were obtained in supercritical fluid extraction packed column,spray column and sieve tray column respectively.The inner diameter of those columns areΦ25mm,These experimental systems include supercritical carbon dioxideisopropanol-water and supercritical carbon dioxide-ethanol-water,in which supercritical carbon dioxide was dispersed phase,and another was continuous phase.The extraction processes were operated with continuous countercurrent flow.The predicted values are agreed well with experimental data.

  1. DNS of High Pressure Supercritical Combustion

    Science.gov (United States)

    Chong, Shao Teng; Raman, Venkatramanan

    2016-11-01

    Supercritical flows have always been important to rocket motors, and more recently to aircraft engines and stationary gas turbines. The purpose of the present study is to understand effects of differential diffusion on reacting scalars using supercritical isotropic turbulence. Focus is on fuel and oxidant reacting in the transcritical region where density, heat capacity and transport properties are highly sensitive to variations in temperature and pressure. Reynolds and Damkohler number vary as a result and although it is common to neglect differential diffusion effects if Re is sufficiently large, this large variation in temperature with heat release can accentuate molecular transport differences. Direct numerical simulations (DNS) for one step chemistry reaction between fuel and oxidizer are used to examine the differential diffusion effects. A key issue investigated in this paper is if the flamelet progress variable approach, where the Lewis number is usually assumed to be unity and constant for all species, can be accurately applied to simulate supercritical combustion.

  2. Supercritical fluid thermodynamics for coal processing

    Energy Technology Data Exchange (ETDEWEB)

    van Swol, F. (Illinois Univ., Urbana, IL (United States). Dept. of Chemical Engineering); Eckert, C.A. (Georgia Inst. of Tech., Atlanta, GA (United States). School of Chemical Engineering)

    1988-09-15

    The main objective of this research is to develop an equation of state that can be used to predict solubilities and tailor supercritical fluid solvents for the extraction and processing of coal. To meet this objective we have implemented a two-sided. approach. First, we expanded the database of model coal compound solubilities in higher temperature fluids, polar fluids, and fluid mixtures systems. Second, the unique solute/solute, solute/cosolvent and solute/solvent intermolecular interactions in supercritical fluid solutions were investigated using spectroscopic techniques. These results increased our understanding of the molecular phenomena that affect solubility in supercritical fluids and were significant in the development of an equation of state that accurately reflects the true molecular makeup of the solution. (VC)

  3. Supercritical fluid mixing in Diesel Engine Applications

    Science.gov (United States)

    Bravo, Luis; Ma, Peter; Kurman, Matthew; Tess, Michael; Ihme, Matthias; Kweon, Chol-Bum

    2014-11-01

    A numerical framework for simulating supercritical fluids mixing with large density ratios is presented in the context of diesel sprays. Accurate modeling of real fluid effects on the fuel air mixture formation process is critical in characterizing engine combustion. Recent work (Dahms, 2013) has suggested that liquid fuel enters the chamber in a transcritical state and rapidly evolves to supercritical regime where the interface transitions from a distinct liquid/gas interface into a continuous turbulent mixing layer. In this work, the Peng Robinson EoS is invoked as the real fluid model due to an acceptable compromise between accuracy and computational tractability. Measurements at supercritical conditions are reported from the Constant Pressure Flow (CPF) chamber facility at the Army Research Laboratory. Mie and Schlieren optical spray diagnostics are utilized to provide time resolved liquid and vapor penetration length measurement. The quantitative comparison presented is discussed. Oak Ridge Associated Universities (ORAU).

  4. Heat Transfer Phenomena of Supercritical Fluids

    Energy Technology Data Exchange (ETDEWEB)

    Krau, Carmen Isabella; Kuhn, Dietmar; Schulenberg, Thomas [Forschungszentrum Karlsruhe, Institute for Nuclear and Energy Technologies, 76021 Karlsruhe (Germany)

    2008-07-01

    In concepts for supercritical water cooled reactors, the reactor core is cooled and moderated by water at supercritical pressures. The significant temperature dependence of the fluid properties of water requires an exact knowledge of the heat transfer mechanism to avoid fuel pin damages. Near the pseudo-critical point a deterioration of heat transfer might happen. Processes, that take place in this case, are not fully understood and are due to be examined systematically. In this paper a general overview on the properties of supercritical water is given, experimental observations of different authors will be reviewed in order to identify heat transfer phenomena and onset of occurrence. The conceptional design of a test rig to investigate heat transfer in the boundary layer will be discussed. Both, water and carbon dioxide, may serve as operating fluids. The loop, including instrumentation and safety devices, is shown and suitable measuring methods are described. (authors)

  5. Analysis, design, fabrication and testing of the mini-Brayton rotating unit (Mini-BRU). Volume 1: Text and tables

    Science.gov (United States)

    Dobler, F. X.

    1978-01-01

    A 500 to 2100 watt power output Mini-Brayton Rotating Unit (Mini-BRU)was analyzed, designed, fabricated and tested. Performance and test data for the various components is included. Components tested include the 2.12 in. diameter compressor, the 2.86 in. diameter turbine, the Rice alternator and the cantilevered foil-type journal and thrust bearings. Also included are results on the fabrication of a C-103 turbine plenum/nozzle assembly and on offgassing of the organic materials in the alternator stator.

  6. Renormalization group analysis of graphene with a supercritical Coulomb impurity

    CERN Document Server

    Nishida, Yusuke

    2016-01-01

    We develop a field theoretical approach to massless Dirac fermions in a supercritical Coulomb potential. By introducing an Aharonov-Bohm solenoid at the potential center, the critical Coulomb charge can be made arbitrarily small for one partial wave sector, where a perturbative renormalization group analysis becomes possible. We show that a scattering amplitude for reflection of particle at the potential center exhibits the renormalization group limit cycle, i.e., log-periodic revolutions as a function of the scattering energy, revealing the emergence of discrete scale invariance. This outcome is further incorporated in computing the induced charge and current densities, which turn out to have power law tails with coefficients log-periodic with respect to the distance from the potential center. Our findings are consistent with the previous prediction obtained by directly solving the Dirac equation and can in principle be realized by graphene experiments with charged impurities.

  7. Renormalization group analysis of graphene with a supercritical Coulomb impurity

    Science.gov (United States)

    Nishida, Yusuke

    2016-08-01

    We develop a field-theoretic approach to massless Dirac fermions in a supercritical Coulomb potential. By introducing an Aharonov-Bohm solenoid at the potential center, the critical Coulomb charge can be made arbitrarily small for one partial-wave sector, where a perturbative renormalization group analysis becomes possible. We show that a scattering amplitude for reflection of particle at the potential center exhibits the renormalization group limit cycle, i.e., log-periodic revolutions as a function of the scattering energy, revealing the emergence of discrete scale invariance. This outcome is further incorporated in computing the induced charge and current densities, which turn out to have power-law tails with coefficients log-periodic with respect to the distance from the potential center. Our findings are consistent with the previous prediction obtained by directly solving the Dirac equation and can in principle be realized by graphene experiments with charged impurities.

  8. Performance Analysis of Supercritical Binary Geothermal Power Plants

    Directory of Open Access Journals (Sweden)

    Ahmet Dagdas

    2015-01-01

    Full Text Available It is possible to generate electricity by utilizing medium-temperature geothermal sources in various closed cycles. These geothermal power plants are very important and valuable as they utilize the sources which have low exergy. In recent years, medium-temperature sources that are around 150°C are used widely for electricity generation. In this study, performance of a supercritical binary power plant, that uses such a geothermal source, is analyzed to find the optimum turbine inlet pressure that maximizes power generation. In this power plant different working fluids are analyzed to find the appropriate fluid that maximizes power generation and efficiency. The observed working fluids are R134a, isobutane, R404a, n-Butane, and R152a. The performance of the plant is calculated with these fluids separately and it is found that the best fluid for performance is R152a for pure fluid and R404a for mixture fluid.

  9. Optimizing the CSP Tower Air Brayton Cycle System to Meet the SunShot Objectives - Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Bryner, Elliott [Soutwest Research Inst., San Antonio, TX (United States); Brun, Klaus [Soutwest Research Inst., San Antonio, TX (United States); Coogan, Shane [Soutwest Research Inst., San Antonio, TX (United States); Cunningham, C. Seth [Soutwest Research Inst., San Antonio, TX (United States); Poerner, Nathan [Soutwest Research Inst., San Antonio, TX (United States)

    2016-02-26

    The objective of this project is to increase Concentrated Solar Power (CSP) tower air receiver and gas turbine temperature capabilities to 1,000ºC by the development of a novel gas turbine combustor, which can be integrated on a megawatt-scale gas turbine, such as the Solar Turbines Mercury 50™. No combustor technology currently available is compatible with the CSP application target inlet air temperature of 1,000°C. Autoignition and flashback at this temperature prevent the use of conventional lean pre-mix injectors that are currently employed to manage NOx emissions. Additional challenges are introduced by the variability of the high-temperature heat source provided by the field of solar collectors, the heliostat in CSP plants. For optimum energy generation from the power turbine, the turbine rotor inlet temperature (TRIT) should remain constant. As a result of changing heat load provided to the solar collector from the heliostat, the amount of energy input required from the combustion system must be adjusted to compensate. A novel multi-bank lean micro-mix injector has been designed and built to address the challenges of high-temperature combustion found in CSP applications. The multi-bank arrangement of the micro-mix injector selectively injects fuel to meet the heat addition requirements to maintain constant TRIT with changing solar load. To validate the design, operation, and performance of the multi-bank lean micro-mix injector, a novel combustion test facility has been designed and built at Southwest Research Institute® (SwRI®) in San Antonio, TX. This facility, located in the Turbomachinery Research Facility, provides in excess of two kilograms per second of compressed air at nearly eight bar pressure. A two-megawatt electric heater raises the inlet temperature to 800°C while a secondary gas-fired heater extends the operational temperature range of the facility to 1,000°C. A combustor test rig connected to the heater has been designed and built to test the multi-bank lean micro-mix injector over the range of CSP operating conditions. The fuel is controlled and selectively delivered to the banks of the injector based on combustor inlet conditions that correspond to turbine operating points. The combustor rig is equipped with a data acquisition system and a suite of instrumentation for measuring temperature, pressure, and species concentration. This unique test facility has been built and commissioned and a prototype of the multi-bank lean micro-mix injector design has been tested. Operation of the combustor and injector has been demonstrated over the full range of CSP inlet conditions and for the range of turbine load conditions specified. The multi-bank operation of the injector has been proven to be an effective design for managing the variable flow rates of air and fuel due to changing inlet conditions from the solar field and turbine loads.

  10. Dynamic Modeling and Control of Nuclear Reactors Coupled to Closed-Loop Brayton Cycle Systems using SIMULINK™

    Science.gov (United States)

    Wright, Steven A.; Sanchez, Travis

    2005-02-01

    The operation of space reactors for both in-space and planetary operations will require unprecedented levels of autonomy and control. Development of these autonomous control systems will require dynamic system models, effective control methodologies, and autonomous control logic. This paper briefly describes the results of reactor, power-conversion, and control models that are implemented in SIMULINK™ (Simulink, 2004). SIMULINK™ is a development environment packaged with MatLab™ (MatLab, 2004) that allows the creation of dynamic state flow models. Simulation modules for liquid metal, gas cooled reactors, and electrically heated systems have been developed, as have modules for dynamic power-conversion components such as, ducting, heat exchangers, turbines, compressors, permanent magnet alternators, and load resistors. Various control modules for the reactor and the power-conversion shaft speed have also been developed and simulated. The modules are compiled into libraries and can be easily connected in different ways to explore the operational space of a number of potential reactor, power-conversion system configurations, and control approaches. The modularity and variability of these SIMULINK™ models provides a way to simulate a variety of complete power generation systems. To date, both Liquid Metal Reactors (LMR), Gas Cooled Reactors (GCR), and electric heaters that are coupled to gas-dynamics systems and thermoelectric systems have been simulated and are used to understand the behavior of these systems. Current efforts are focused on improving the fidelity of the existing SIMULINK™ modules, extending them to include isotopic heaters, heat pipes, Stirling engines, and on developing state flow logic to provide intelligent autonomy. The simulation code is called RPC-SIM (Reactor Power and Control-Simulator).

  11. Adsorption from Experimental Isotherms of Supercritical Gases

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A mathematical method was proposed for the determination of absolute adsorption from experimental isotherms. The method is based on the numerical equality of the absolute and the excess adsorption when either the gas phase density or the amount adsorbed is not quite considerable. The initial part of the experimental isotherms, which represents the absolute adsorption, became linear with some mathematical manipulations. The linear isotherms were reliably formulated. As consequence, either the volume or the density of the supercritical adsorbate could be determined by a non-empirical way. This method was illustrated by the adsorption data of supercritical hydrogen and methane on a superactivated carbon in large ranges of temperature and pressure.

  12. Charting the landscape of supercritical string theory

    CERN Document Server

    Hellerman, Simeon

    2007-01-01

    Special solutions of string theory in supercritical dimensions can interpolate in time between theories with different numbers of spacetime dimensions (via dimension quenching) and different amounts of worldsheet supersymmetry (via c-duality). These solutions connect supercritical string theories to the more familiar string duality web in ten dimensions, and provide a precise link between supersymmetric and purely bosonic string theories. Dimension quenching and c-duality appear to be natural concepts in string theory, giving rise to large networks of interconnected theories. We describe some of these networks in detail and discuss general consistency constraints on the types of transitions that arise in this framework.

  13. Supercritical carbondioxide extraction of cypermethrin in different ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-04-12

    Apr 12, 2010 ... century coincided with the development of industrial methods of cultivation ... though supercritical CO2 is a good solvent only for the extraction of non-polar to ..... 101-111. Lange's Handbook of Chemistry (1985) . ed. Dean JA ...

  14. Destruction of Energetic Materials in Supercritical Water

    Science.gov (United States)

    2002-06-25

    THERMOCHEMISTRY OF ENERGETIC MATERIALS IN SUPERCRITICAL WATER...fringe spacing is 13.5 µm and the acoustic signal period is 28.3 ns. 138 SECTION VI THERMOCHEMISTRY OF ENERGETIC MATERIALS IN...validation calculation studied the solvation free energies of alkali–chloride ion pairs in liquid water. Such information can teach us about the

  15. Supercritical fluid extraction and processing of foods

    Science.gov (United States)

    Consumers are aware of the processing techniques used to manufacture food and health supplements and are concerned about the impact of those processes on their health and the environment. Processes that use supercritical fluids as an alternative to solvents that are used to extract nutrients and bio...

  16. Supercritical-Multiple-Solvent Extraction From Coal

    Science.gov (United States)

    Corcoran, W.; Fong, W.; Pichaichanarong, P.; Chan, P.; Lawson, D.

    1983-01-01

    Large and small molecules dissolve different constituents. Experimental apparatus used to test supercritical extraction of hydrogen rich compounds from coal in various organic solvents. In decreasing order of importance, relevant process parameters were found to be temperature, solvent type, pressure, and residence time.

  17. Improved Supercritical-Solvent Extraction of Coal

    Science.gov (United States)

    Compton, L.

    1982-01-01

    Raw coal upgraded by supercritical-solvent extraction system that uses two materials instead of one. System achieved extraction yields of 20 to 49 weight percent. Single-solvent yields are about 25 weight percent. Experimental results show extraction yields may be timedependent. Observed decreases in weight of coal agreed well with increases in ash content of residue.

  18. Diiodination of Alkynes in supercritical Carbon dioxide

    Institute of Scientific and Technical Information of China (English)

    李金恒; 谢叶香; 尹笃林; 江焕峰

    2003-01-01

    A general,green and efficient method for the synthesis of transdiiodoalkenes in CO2(sc) has been developed.Trans-diiodoalkenes were obtained stereospecifically in quantitative yields via diiodination of both electron-rich and electron-deficient alkynes in the presence of KI,Ce(SO4)2 and water in supercritical carbon dioxide [CO2(sc)]at 40℃.

  19. Petrophysical core characterization at supercritical geothermal conditions

    Science.gov (United States)

    Kummerow, Juliane; Raab, Siegfried

    2015-04-01

    There is a growing scientific interest in the exploitation of supercritical geothermal reservoirs to increase the efficiency of geothermal power plants. The utilisation of geothermal energy requires in any case the detailed knowledge of the reservoir. In reservoir engineering, the characterisation of the geothermal system by electrical resistivity tomography (ERT) is a common geophysical exploration and monitoring strategy. For a realistic interpretation of the field measurements it is necessary to know both, the physical properties of the rock and those of the interacting fluid at defined temperature and pressure conditions. While there have been made great effort in determine the physical and chemical properties of water above its critical point (Tcritical = 374.21° C and pcritical = 221.2 bar), the influence of fluid-rock interactions on petrophysical properties in supercritical aqueous systems is nearly unknown. At supercritical conditions the viscosity of the fluid is low, which enhances the mass transfer and diffusion-controlled chemical reactions. This may have considerable effects on the porosity and hydraulic properties of a rock. To investigate high-enthalpy fluid-rock systems, in the framework of the EU-funded project IMAGE we have built a new percolation set-up, which allows for the measurement of electrical resistivity and permeability of rock samples at controlled supercritical conditions of aqueous fluids (pore pressure = 400 bar and a temperature = 400° C). First results will be presented.

  20. Advanced power cycles and configurations for solar towers: Modeling and optimization of the decoupled solar combined cycle concept

    Science.gov (United States)

    García-Barberena, Javier; Olcoz, Asier; Sorbet, Fco. Javier

    2017-06-01

    CSP technologies are essential to allow large shares of renewables into the grid due to their unique ability to cope with the large variability of the energy resource by means of technically and economically feasible thermal energy storage (TES) systems. However, there is still the need and sought to achieve technological breakthroughs towards cost reductions and increased efficiencies. For this, research on advanced power cycles, like the Decoupled Solar Combined Cycle (DSCC) is, are regarded as a key objective. The DSCC concept is, basically, a Combined Brayton-Rankine cycle in which the bottoming cycle is decoupled from the operation of the topping cycle by means of an intermediate storage system. According to this concept, one or several solar towers driving a solar air receiver and a Gas Turbine (Brayton cycle) feed through their exhaust gasses a single storage system and bottoming cycle. This general concept benefits from a large flexibility in its design. On the one hand, different possible schemes related to number and configuration of solar towers, storage systems media and configuration, bottoming cycles, etc. are possible. On the other, within a specific scheme a large number of design parameters can be optimized, including the solar field size, the operating temperatures and pressures of the receiver, the power of the Brayton and Rankine cycles, the storage capacity and others. Heretofore, DSCC plants have been analyzed by means of simple steady-state models with pre-stablished operating parameters in the power cycles. In this work, a detailed transient simulation model for DSCC plants has been developed and is used to analyze different DSCC plant schemes. For each of the analyzed plant schemes, a sensitivity analysis and selection of the main design parameters is carried out. Results show that an increase in annual solar to electric efficiency of 30% (from 12.91 to 16.78) can be achieved by using two bottoming Rankine cycles at two different

  1. Proposal for an advanced heat source assembly for the Isotope Brayton Power System. Volume 1. Technical program and statement of work

    Energy Technology Data Exchange (ETDEWEB)

    1974-12-09

    The technical program plan for evaluating the performance and safety of a radioisotope-fueled Brayton power system for space vehicles is presented with schedules for evaluating heat source design and safety, for specifying power system requirements, and for the development and operation of a ground demonstration system. (LCL)

  2. Recovery of Minerals in Martian Soils Via Supercritical Fluid Extraction

    Science.gov (United States)

    Debelak, Kenneth A.; Roth, John A.

    2001-03-01

    We are investigating the use of supercritical fluids to extract mineral and/or carbonaceous material from Martian surface soils and its igneous crust. Two candidate supercritical fluids are carbon dioxide and water. The Martian atmosphere is composed mostly of carbon dioxide (approx. 95.3%) and could therefore provide an in-situ source of carbon dioxide. Water, although present in the Martian atmosphere at only approx. 0.03%, is also a candidate supercritical solvent. Previous work done with supercritical fluids has focused primarily on their solvating properties with organic compounds. Interestingly, the first work reported by Hannay and Hogarth at a meeting of the Royal Society of London in 1879 observed that increasing or decreasing the pressure caused several inorganic salts e.g., cobalt chloride, potassium iodide, and potassium bromide, to dissolve or precipitate in supercritical ethanol. In high-pressure boilers, silica, present in most boiler feed waters, is dissolved in supercritical steam and transported as dissolved silica to the turbine blades. As the pressure is reduced the silica precipitates onto the turbine blades eventually requiring the shutdown of the generator. In supercritical water oxidation processes for waste treatment, dissolved salts present a similar problem. The solubility of silicon dioxide (SiO2) in supercritical water is shown. The solubility curve has a shape characteristic of supercritical systems. At a high pressure (greater than 1750 atmospheres) increasing the temperature results in an increase in solubility of silica, while at low pressures, less than 400 atm., the solubility decreases as temperature increases. There are only a few studies in the literature where supercritical fluids are used in extractive metallurgy. Bolt modified the Mond process in which supercritical carbon monoxide was used to produce nickel carbonyl (Ni(CO)4). Tolley and Tester studied the solubility of titanium tetrachloride (TiCl4) in supercritical CO2

  3. Simulation and parametric optimisation of thermal power plant cycles

    Directory of Open Access Journals (Sweden)

    P. Ravindra Kumar

    2016-09-01

    Full Text Available The objective of the paper is to analyse parametric studies and optimum steam extraction pressures of three different (subcritical, supercritical and ultra-supercritical coal fired power plant cycles at a particular main steam temperature of 600 °C by keeping the reheat temperature at 537 °C and condenser pressure at 0.09 bar as constant. In order to maximize the heat rate gain possible with supercritical and ultra-supercritical steam conditions, eight stages of feed water heater arrangement with single reheater is considered. The system is optimized in such a way that the percentage exergetic losses are reduced for the increase of the exergetic efficiency and higher fuel utilization. The plant cycles are simulated and optimized by using Cycle Tempo 5.0 simulation software tool. From the simulation study, it is observed that the thermal efficiency of the three different power plant cycles obtained as 41.40, 42.48 and 43.03%, respectively. The specific coal consumption for three different power plant cycles are 0.56, 0.55 and 0.54 Tonnes/MWh. The improvement in feed water temperatures at the inlet of steam generator of respective cycles are 291, 305 and 316 °C.

  4. Bio-oil production from biomass via supercritical fluid extraction

    Energy Technology Data Exchange (ETDEWEB)

    Durak, Halil, E-mail: halildurak@yyu.edu.tr [Yuzuncu Yıl University, Vocational School of Health Services, 65080, Van (Turkey)

    2016-04-18

    Supercritical fluid extraction is used for producing bio-fuel from biomass. Supercritical fluid extraction process under supercritical conditions is the thermally disruption process of the lignocellulose or other organic materials at 250-400 °C temperature range under high pressure (4-5 MPa). Supercritical fluid extraction trials were performed in a cylindrical reactor (75 mL) in organic solvents (acetone, ethanol) under supercritical conditions with (calcium hydroxide, sodium carbonate) and without catalyst at the temperatures of 250, 275 and 300 °C. The produced liquids at 300 °C in supercritical liquefaction were analyzed and characterized by elemental, GC-MS and FT-IR. 36 and 37 different types of compounds were identified by GC-MS obtained in acetone and ethanol respectively.

  5. Supercritical Fluids Processing of Biomass to Chemicals and Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Olson, Norman K. [Iowa State Univ., Ames, IA (United States)

    2011-09-28

    The main objective of this project is to develop and/or enhance cost-effective methodologies for converting biomass into a wide variety of chemicals, fuels, and products using supercritical fluids. Supercritical fluids will be used both to perform reactions of biomass to chemicals and products as well as to perform extractions/separations of bio-based chemicals from non-homogeneous mixtures. This work supports the Biomass Program’s Thermochemical Platform Goals. Supercritical fluids are a thermochemical approach to processing biomass that, while aligned with the Biomass Program’s interests in gasification and pyrolysis, offer the potential for more precise and controllable reactions. Indeed, the literature with respect to the use of water as a supercritical fluid frequently refers to “supercritical water gasification” or “supercritical water pyrolysis.”

  6. Bio-oil production from biomass via supercritical fluid extraction

    Science.gov (United States)

    Durak, Halil

    2016-04-01

    Supercritical fluid extraction is used for producing bio-fuel from biomass. Supercritical fluid extraction process under supercritical conditions is the thermally disruption process of the lignocellulose or other organic materials at 250-400 °C temperature range under high pressure (4-5 MPa). Supercritical fluid extraction trials were performed in a cylindrical reactor (75 mL) in organic solvents (acetone, ethanol) under supercritical conditions with (calcium hydroxide, sodium carbonate) and without catalyst at the temperatures of 250, 275 and 300 °C. The produced liquids at 300 °C in supercritical liquefaction were analyzed and characterized by elemental, GC-MS and FT-IR. 36 and 37 different types of compounds were identified by GC-MS obtained in acetone and ethanol respectively.

  7. Design Study of Supercritical CO{sub 2} Integral Experiment Loop (SCIEL)

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Yoonhan; Lee, Jaekyoung; Lee, Jeong Ik [Korea Adavanced Institute of Science and Technology, Daejeon (Korea, Republic of); Cha, Jae Eun [Korean Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    As the global warming becomes more substantial, the development of highly efficient power conversion system gains a lot of interests to reduce CO{sub 2} emission. Supercritical CO{sub 2} (S-CO{sub 2}) cycle is considered as one of the promising candidates due to the competitive efficiency in the mild turbine inlet temperature range, and the compact footprint with compact turbomachinery and heat exchangers. With these advantages, S-CO{sub 2} cycle can be utilized as the power conversion system of fossil power, advanced nuclear reactor, renewable energy system and a bottoming cycle for gas turbine or high temperature fuel cell, as well. In addition, the S-CO{sub 2} cycle is considered as the alternative power conversion system of a Sodium-cooled Fast Reactor (SFR) as the violent Sodium-Water Reaction (SWR) can be replaced with the mild Sodium-CO{sub 2} Reaction (SCR). To demonstrate the S-CO{sub 2} cycle performance, the integral test facilities were constructed and the operational results were reported by several countries. The development of S-CO{sub 2} cycle can be utilized as the power conversion system including the fossil power, next generation nuclear reactor, and concentrated solar power systems as the cycle efficiency is high in the mild turbine inlet temperature range (450-650 .deg. C) and the layout is simple with the physically compact system size. To demonstrate the S-CO{sub 2} cycle performance, Supercritical CO{sub 2} Integral Experiment Loop (SCIEL) has been under development by the joint research team of KAERI, KAIST and POSTECH. The final layout of SCIEL is recuperated cycle with a double stage of compression and expansion to achieve 2.57 pressure ratio. Considering the temperature difference limit of PCHE, a series of recuperation process is utilized.

  8. Industrial applications and current trends in supercritical fluid technologies

    OpenAIRE

    Gamse Thomas

    2005-01-01

    Supercritical fluids have a great potential for wide fields of processes Although CO2 is still one of the most used supercritical gases, for special purposes propane or even fluorinated-chlorinated fluids have also been tested. The specific characteristics of supercritical fluids behaviour were analyzed such as for example the solubilities of different components and the phase equilibria between the solute and solvent. The application at industrial scale (decaffeinating of tea and coffee, hop...

  9. Solvent adsorption in SFC : Adsorption of methanol under supercritical conditions

    OpenAIRE

    Edström, Emelie

    2015-01-01

    Chromatography is a widely used separation technique including many different modes, for example supercritical fluid chromatography (SFC) which uses a supercritical fluid as mobile phase. A supercritical fluid is achieved when a substance is subjected to a temperature and pressure above the critical point and the boundary between the liquid phase and gas phase is erased. The interest for SFC has increased in recent years, mainly for separation of chiral molecules in the pharmaceutical industr...

  10. Supercritical water oxidation of products of human metabolism

    Science.gov (United States)

    Tester, Jefferson W.; Orge A. achelling, Richard K. ADTHOMASSON; Orge A. achelling, Richard K. ADTHOMASSON

    1986-01-01

    Although the efficient destruction of organic material was demonstrated in the supercritical water oxidation process, the reaction kinetics and mechanisms are unknown. The kinetics and mechanisms of carbon monoxide and ammonia oxidation in and reaction with supercritical water were studied experimentally. Experimental oxidation of urine and feces in a microprocessor controlled system was performed. A minaturized supercritical water oxidation process for space applications was design, including preliminary mass and energy balances, power, space and weight requirements.

  11. Solubility and Phase Behavior of CL20 in Supercritical Fluids

    Science.gov (United States)

    2006-09-01

    supercritical state. The fugacity of the solute in the supercritical fluid can be evaluated using a cubic equation of state such as the Redlich - Kwong ...pro- gram was validated using available literature data for the solubility of naphthalene and of biphenyl in supercritical CO2. The applicability of...promising process using environmentally benign compressed gases as either solvents or anti-solvents is being investi- gated for applications in

  12. Comparative evaluation of three alternative power cycles for waste heat recovery from the exhaust of adiabatic diesel engines

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, M.M.

    1985-07-01

    Three alternative power cycles were compared in application as an exhaust-gas heat-recovery system for use with advanced ''adiabatic'' diesel engines. The power cycle alternatives considered were steam Rankine, organic Rankine with RC-1 as the working fluid, and variations of an air Brayton cycle. The comparison was made in terms of fuel economy and economic payback potential for heavy-duty trucks operating in line-haul service. The results indicate that, in terms of engine rated specific fuel consumption, a diesel/alternative-power-cycle engine offers a significant improvement over the turbocompound diesel used as the baseline for comparison. The maximum improvement resulted from the use of a Rankine cycle heat-recovery system in series with turbocompounding. The air Brayton cycle alternatives studied, which included both simple-cycle and compression-intercooled configurations, were less effective and provided about half the fuel consumption improvement of the Rankine cycle alternatives under the same conditions. Capital and maintenance cost estimates were also developed for each of the heat-recovery power cycle systems. These costs were integrated with the fuel savings to identify the time required for net annual savings to pay back the initial capital investment. The sensitivity of capital payback time to arbitrary increases in fuel price, not accompanied by corresponding hardware cost inflation, was also examined. The results indicate that a fuel price increase is required for the alternative power cycles to pay back capital within an acceptable time period.

  13. Comparative evaluation of three alternative power cycles for waste heat recovery from the exhaust of adiabatic diesel engines

    Science.gov (United States)

    Bailey, M. M.

    1985-01-01

    Three alternative power cycles were compared in application as an exhaust-gas heat-recovery system for use with advanced adiabatic diesel engines. The power cycle alternatives considered were steam Rankine, organic Rankine with RC-1 as the working fluid, and variations of an air Brayton cycle. The comparison was made in terms of fuel economy and economic payback potential for heavy-duty trucks operating in line-haul service. The results indicate that, in terms of engine rated specific fuel consumption, a diesel/alternative-power-cycle engine offers a significant improvement over the turbocompound diesel used as the baseline for comparison. The maximum imporvement resulted from the use of a Rankine cycle heat-recovery system in series with turbocompounding. The air Brayton cycle alternatives studied, which included both simple-cycle and compression-intercooled configurations, were less effective and provided about half the fuel consumption improvement of the Rankine cycle alternatives under the same conditions. Capital and maintenance cost estimates were also developed for each of the heat-recovery power cycle systems. These costs were integrated with the fuel savings to identify the time required for net annual savings to pay back the initial capital investment. The sensitivity of capital payback time to arbitrary increases in fuel price, not accompanied by corresponding hardware cost inflation, was also examined. The results indicate that a fuel price increase is required for the alternative power cycles to pay back capital within an acceptable time period.

  14. Air bottoming cycle, an alternative to combined cycles. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kaikko, J. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Energy Technology

    2002-02-01

    In this work, the idea of Air Bottoming Cycle (ABC) has been studied. The objectives for the work have been to establish an understanding of the concept for power and heat generation as well as to find - if possible - feasible concepts for future use in the Swedish energy system. Combined cycle in power generation is an established technology. In the conventional combined cycle, a gas turbine works as a topping cycle together with the steam (Rankine) bottoming cycle. In the ABC the steam bottoming cycle is replaced with a gas turbine (Brayton) bottoming cycle having air as a working fluid. The two gas turbines are thermally connected over a gas-to-gas heat exchanger. This concept promises savings in weight and cost, as well as operating benefits, compared to the Rankine bottoming technology. The ABC has been modelled using a heat balance program, and a parametric study for the concept optimisation as well as for off-design analysis has been performed. Performance of the ABC has been compared to other, established technologies. A preliminary economic evaluation has been made. As a result of the study, it is clarified that the Rankine bottoming cycle with steam remains superior to the ABC as regards electrical efficiency in the medium and large power scale. For small-scale applications (<10 MW{sub e}) where the thermodynamic advantage of the Rankine cycle is not dominating any longer and its economy is burdened by the heavy investment structure, the ABC becomes the better alternative for energy utilisation. A preliminary economic evaluation shows that (at energy prices autumn 2000) the ABC is at the same level as the comparable small-scale cogeneration installations. Due to high power-to-heat ratio however, higher electricity prices will favour the ABC. One interesting feature of the ABC is that about 50% of the dissipated low-value heat from the cycle is carried by clean (sterile) air at the temperature around 200 deg C. This air can be utilised for space heating or

  15. Air bottoming cycle, an alternative to combined cycles. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kaikko, J. [Royal Inst. of Techn., Stockholm (Sweden). Dept. of Energy Technology

    2001-10-01

    In this work, the idea of Air Bottoming Cycle (ABC) has been studied. The objectives for the work have been to establish an understanding of the concept for power and heat generation as well as to find - if possible - feasible concepts for future use in the Swedish energy system. Combined cycle in power generation is an established technology. In the conventional combined cycle, a gas turbine works as a topping cycle together with the steam (Rankine) bottoming cycle. In the ABC the steam bottoming cycle is replaced with a gas turbine (Brayton) bottoming cycle having air as a working fluid. The two gas turbines are thermally connected over a gas-to-gas heat exchanger. This concept promises savings in weight and cost, as well as operating benefits, compared to the Rankine bottoming technology. The ABC has been modelled using a heat balance program, and a parametric study for the concept optimisation as well as for off-design analysis has been performed. Performance of the ABC has been compared to other, established technologies. A preliminary economic evaluation has been made. As a result of the study, it is clarified that the Rankine bottoming cycle with steam remains superior to the ABC as regards electrical efficiency in the medium and large power scale. For small-scale applications (<10 MW{sub e}) where the thermodynamic advantage of the Rankine cycle is not dominating any longer and its economy is burdened by the heavy investment structure, the ABC becomes the better alternative for energy utilisation. A preliminary economic evaluation shows that (at energy prices autumn 2000) the ABC is at the same level as the comparable small-scale cogeneration installations. Due to high power-to-heat ratio however, higher electricity prices will favour the ABC. One interesting feature of the ABC is that about 50% of the dissipated low-value heat from the cycle is carried by clean (sterile) air at the temperature around 200 deg C. This air can be utilised for space heating or

  16. Supercritical Water Process for the Chemical Recycling of Waste Plastics

    Science.gov (United States)

    Goto, Motonobu

    2010-11-01

    The development of chemical recycling of waste plastics by decomposition reactions in sub- and supercritical water is reviewed. Decomposition reactions proceed rapidly and selectively using supercritical fluids compared to conventional processes. Condensation polymerization plastics such as PET, nylon, and polyurethane, are relatively easily depolymerized to their monomers in supercritical water. The monomer components are recovered in high yield. Addition polymerization plastics such as phenol resin, epoxy resin, and polyethylene, are also decomposed to monomer components with or without catalysts. Recycling process of fiber reinforced plastics has been studied. Pilot scale or commercial scale plants have been developed and are operating with sub- and supercritical fluids.

  17. Supercritical Water Liquefaction of Coal and Waste Tires

    National Research Council Canada - National Science Library

    Prapan KUCHONTHARA; Yukihiko MATSUMURA

    2001-01-01

      Supercritical water liquefaction of scrap tire rubber and Ishikari coal, separately and in mixtures was investigated to study the possible synergetic effects of coliquefaction between the feedstocks...

  18. Dependence of Reaction Rate Constants on Density in Supercritical Fluids

    Institute of Scientific and Technical Information of China (English)

    WANGTao; SHENZhongyao

    2002-01-01

    A new method,which correlates rate constants of chemical reactions and density or pressure in supercritical fluids,was developed.Based on the transition state theory and thermodynamic principles, the rate constant can be reasonably correlated with the density of the supercritical fluid,and a correlation equation was obtained. Coupled with the equation of state (EOS) of a supercritical solvent,the effect of pressure on reaction rate constant could be represented.Two typical systems were used to test this method.The result indicates that this method is suitable for dilute supercritical fluid solutions.

  19. Reaction Behavior of Unsaturated Compounds in Sub- and Supercritical Water

    Institute of Scientific and Technical Information of China (English)

    K. Kobiro

    2005-01-01

    @@ 1Introduction Much attention has been paid on the chemistry of sub- and supercritical water, because of their unique prosperities such as low viscosity, low polarity, and high solubility to organic compounds[1]. Recently, the unique sub- and supercritical water is applied as reaction media and reaction catalysts for organic reactions[2,3].We herein disclose the unique reaction of unsaturated compounds in sub- and supercritical water with specific interaction between unsaturated bond(s) and high-density and high-energy water molecule(s) in sub- and supercritical water.

  20. Supercritical CO{sub 2} fluid for chip resistor cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.W.; Chang, R.T.; Lin, W.K.; Lin, R.D.; Liang, M.T.; Yang, J.F.; Wang, J.B.

    1999-09-01

    The cleaning ability of supercritical CO{sub 2} was examined on chip resistors. Extraction analyses were made by atomic absorption spectroscopy and the extent of surface cleaning observed by scanning electron microscopy. Experimental results showed that the flow-cleaning process of supercritical CO{sub 2} possessed the advantages of having a superior cleaning ability and permitting a nondrying step. These characteristics strongly suggest that supercritical CO{sub 2} is a superior alternative to the traditional deionized water used in rinsing chip resistors. Moreover, a higher pressure and temperature can benefit the cleaning ability of this novel supercritical CO{sub 2} cleaning technique.

  1. The pseudocritical regions for supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Imre, A.R., E-mail: imre.attila@energia.mta.hu [HAS Centre for Energy Research, Thermohydraulics Department, P.O. Box 49, H-1525 Budapest (Hungary); University Cologne, Institute for Physical Chemistry, Luxemburger Str. 116, D-50939 Koeln (Germany); Deiters, U.K.; Kraska, T. [University Cologne, Institute for Physical Chemistry, Luxemburger Str. 116, D-50939 Koeln (Germany); Tiselj, I. [Jozef Stefan Institute, Reactor Engineering Division, Jamova 39, 1000 Ljubljana (Slovenia)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Supercritical water behaves anomalously around the Widom lines. Black-Right-Pointing-Pointer We calculated the location of the Widom lines for several thermodynamic functions. Black-Right-Pointing-Pointer Simple quadratic fitting equations are given to describe these lines. - Abstract: Vapour pressure curves and stability lines can be extended beyond the critical points into the supercritical domain by so-called Widom lines, along which some thermodynamic property undergoes a rapid change and liquid-like behaviour turns to vapour-like one. Knowledge about such lines is therefore important for thermohydraulic calculations and design. There are several properties that can be chosen as defining property of a Widom line. In this short note we calculate and compare several kinds of Widom lines for water.

  2. Depolymerization of polyethylene terephthalate in supercritical methanol

    Science.gov (United States)

    Goto, Motonobu; Koyamoto, Hiroshi; Kodama, Akio; Hirose, Tsutomu; Nagaoka, Shoji

    2002-11-01

    The degradation of polyethylene terephthalate (PET) in supercritical methanol was investigated with the aim of developing a process for chemical recycling of waste plastics. A batch reactor was used at temperatures of 573-623 K under an estimated pressure of 20 MPa for a reaction time of 2-120 min. PET was decomposed to its monomers, dimethyl terephthalate and ethylene glycol, by methanolysis in supercritical methanol. The reaction products were analysed using size-exclusion chromatography, gas chromatography-mass spectrometry, and reversed-phase liquid chromatography. The molecular weight distribution of the products was obtained as a function of reaction time. The yields of monomer components of the decomposition products including by-products were measured. Continuous kinetics analysis was performed on the experimental data.

  3. Supercritical separation process for complex organic mixtures

    Science.gov (United States)

    Chum, Helena L.; Filardo, Giuseppe

    1990-01-01

    A process is disclosed for separating low molecular weight components from complex aqueous organic mixtures. The process includes preparing a separation solution of supercritical carbon dioxide with an effective amount of an entrainer to modify the solvation power of the supercritical carbon dioxide and extract preselected low molecular weight components. The separation solution is maintained at a temperature of at least about 70.degree. C. and a pressure of at least about 1,500 psi. The separation solution is then contacted with the organic mixtures while maintaining the temperature and pressure as above until the mixtures and solution reach equilibrium to extract the preselected low molecular weight components from the organic mixtures. Finally, the entrainer/extracted components portion of the equilibrium mixture is isolated from the separation solution.

  4. Supercritical Fluid Extraction of Flavonoids from Dandelion

    Directory of Open Access Journals (Sweden)

    Wu Jun

    2014-01-01

    Full Text Available In this study, the total flavonoids from dandelion was extracted by supercritical CO2 and the total flavonoids content in the extract was investigated by the sodium nitrite-aluminum nitrate method with Rutin as a standard product. Single-factor experiments were carried out to map the effects of extraction pressure, temperature, time and entrainer amount on the yield of flavonoids. The orthogonal experiments on the optimum technology parameters demonstrated that the influence of the experimental conditions over the yield from high to low was: (a pressure, (b temperature, (c entrainer amount, (d time. The optimization result showed that under the conditions of 50°C, 35 MPa, 80 min and 4.0 mL/g entrainer amount, the yield of the preparative supercritical fluid extraction was 4.974%.

  5. Stochastic simulation of supercritical fluid extraction processes

    Directory of Open Access Journals (Sweden)

    Mizutani F. T.

    2000-01-01

    Full Text Available Process simulation involves the evaluation of output variables by the specification of input variables and process parameters. However, in a real process, input data and parameters cannot be known without uncertainty. This fact may limit the utilization of simulation results to predict plant behavior. In order to achieve a more realistic analysis, the procedure of stochastic simulation can be conducted. This technique is based on a large set of simulation runs where input variables and parameters are randomly selected according to adequate probability density functions. The objective of this work is to illustrate the application of a stochastic simulation procedure to the process of fractionation of orange essential oil, using supercritical carbon dioxide in a multistage extraction column. Analysis of the proposed example demonstrates the importance of the stochastic simulation to develop more reliable designs and operating conditions for a supercritical fluid extraction process.

  6. Using supercritical fluids to refine hydrocarbons

    Science.gov (United States)

    Yarbro, Stephen Lee

    2014-11-25

    This is a method to reactively refine hydrocarbons, such as heavy oils with API gravities of less than 20.degree. and bitumen-like hydrocarbons with viscosities greater than 1000 cp at standard temperature and pressure using a selected fluid at supercritical conditions. The reaction portion of the method delivers lighter weight, more volatile hydrocarbons to an attached contacting device that operates in mixed subcritical or supercritical modes. This separates the reaction products into portions that are viable for use or sale without further conventional refining and hydro-processing techniques. This method produces valuable products with fewer processing steps, lower costs, increased worker safety due to less processing and handling, allow greater opportunity for new oil field development and subsequent positive economic impact, reduce related carbon dioxide, and wastes typical with conventional refineries.

  7. Supercritical CO{sub 2} mediated synthesis and catalytic activity of graphene/Pd nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Lulu [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeoungbuk 712-749 (Korea, Republic of); Nguyen, Van Hoa [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeoungbuk 712-749 (Korea, Republic of); Department of Chemistry, Nha Trang University, 2 Nguyen Dinh Chieu, Nha Trang (Viet Nam); Shim, Jae-Jin, E-mail: jjshim@yu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeoungbuk 712-749 (Korea, Republic of)

    2015-11-15

    Highlights: • RGO/Pd composite was efficiently prepared via a facile method in supercritical CO{sub 2}. • Graphene sheets were coated uniformly with Pd nanoparticles with a size of ∼8 nm. • Composites exhibited excellent catalytic activity in the Suzuki reaction even after 10 cycles. - Abstract: Graphene sheets were decorated with palladium nanoparticles using a facile and efficient method in supercritical CO{sub 2}. The nanoparticles were formed on the graphene sheets by the simple hydrogen reduction of palladium(II) hexafluoroacetylacetonate precursor in supercritical CO{sub 2}. The product was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Highly dispersed nanoparticles with various sizes and shapes adhered well to the graphene sheets. The composites showed high catalytic activities for the Suzuki reaction under aqueous and aerobic conditions within 5 min. The effects of the different Pd precursor loadings on the catalytic activities of the composites were also examined.

  8. Effect of supercritical fluid density on nanoencapsulated drug particle size using the supercritical antisolvent method.

    Science.gov (United States)

    Kalani, Mahshid; Yunus, Robiah

    2012-01-01

    The reported work demonstrates and discusses the effect of supercritical fluid density (pressure and temperature of supercritical fluid carbon dioxide) on particle size and distribution using the supercritical antisolvent (SAS) method in the purpose of drug encapsulation. In this study, paracetamol was encapsulated inside L-polylactic acid, a semicrystalline polymer, with different process parameters, including pressure and temperature, using the SAS process. The morphology and particle size of the prepared nanoparticles were determined by scanning electron microscopy and transmission electron microscopy. The results revealed that increasing temperature enhanced mean particle size due to the plasticizing effect. Furthermore, increasing pressure enhanced molecular interaction and solubility; thus, particle size was reduced. Transmission electron microscopy images defined the internal structure of nanoparticles. Thermal characteristics of nanoparticles were also investigated via differential scanning calorimetry. Furthermore, X-ray diffraction pattern revealed the changes in crystallinity structure during the SAS process. In vitro drug release analysis determined the sustained release of paracetamol in over 4 weeks.

  9. Dye solubility in supercritical carbon dioxide fluid

    Directory of Open Access Journals (Sweden)

    Yan Jun

    2015-01-01

    Full Text Available Supercritical carbon dioxide fluid is an alternative solvent for the water of the traditional dyeing. The solubility of dyestuff affects greatly the dyeing process. A theoretical model for predicting the dye solubility is proposed and verified experimentally. The paper concludes that the pressure has a greater impact on the dyestuff solubility than temperature, and an optimal dyeing condition is suggested for the highest distribution coefficient of dyestuff.

  10. Computational Modeling of Supercritical and Transcritical Flows

    Science.gov (United States)

    2017-01-09

    reasonably accurate for supercritical and transcritical combustion. 15. SUBJECT TERMS N/A 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...pr Reduced pressure (p/pc) Tc Critical temperature Tr Reduced temperature (T/Tc) Vm Molar volume Xi Mole fraction of species i Z Compressibility ω...pressure states. A 5.5mm by 0.4064mm domain uses a uniform 256 × 512 Cartesian grid. The code is fifth order accurate in space and a third order

  11. Supercritical fluid extraction of mercury species.

    Science.gov (United States)

    Foy, G P; Pacey, G E

    2003-12-23

    Supercritical fluid extraction was used to recover organic and inorganic mercury species. Variations in pressure, water, methanol, and chelator create methods that allowed separation of inorganic from organic mercury species. When extracted using a compromised set of extraction conditions, the order of extraction was methyl, phenyl and inorganic mercury. For the individually optimized conditions, quantitative recoveries were observed. Level as low as 20 ppb were extracted and then determined using ICP.

  12. Supercritical CO2 Extraction of Ethanol

    OpenAIRE

    GÜVENÇ, A.; MEHMETOĞLU, Ü.; ÇALIMLI, A.

    1999-01-01

    Extraction of ethanol was studied from both synthetic ethanol solution and fermentation broth using supercritical CO2 in an extraction apparatus in ranges of 313 to 333 K and 80 to 160 atmospheres, for varying extraction times. The experimental system consists mainly of four parts: a CO2 storage system, a high-pressure liquid pump, an extractor and a product collection unit. Samples were analyzed by gas chromatography. Effects of temperature, pressure, extraction time, initial ethan...

  13. Use of supercritical carbon dioxide extraction

    Energy Technology Data Exchange (ETDEWEB)

    Taniguchi, Masayuki (Niigata Univ., Faculty of Engineering, Niigata, (Japan))

    1989-09-25

    Supercritical fluid extraction is a novel diffusion and separation technique which exploits simultaneously the increase of vapor pressure and the difference of chemical affinities of fluids near the critical point. A solvent which is used as the supercritical fluid has the following features: the critical point exists in the position of relatively ease of handling, the solvent is applicable to the extraction of a physiological active substance of thermal instability. Carbon dioxide as the solvent is non-flammable, non-corrosive, non-toxic, cheap, and readily available of high purity. The results of studies on the use of supercritical carbon dioxide (SC-CO{sub 2}) as a solvent for natural products in the fermentation and food industries, were collected. SC-CO{sub 2} extraction are used in many fields, examples for the application are as follows: removal of organic solvents from antibiotics; extraction of vegetable oils contained in wheat germ oil, high quality mustard seeds, rice bran and so on; brewing of sake using rice and rice-koji; use as a non-aqueous medium for the synthesis of precursors of the Aspartame; and use in sterilization. 66 refs., 17 figs., 21 tabs.

  14. Determination of binary diffusion coefficients in supercritical carbon dioxide with supercritical fluid chromatography (SFC)

    Energy Technology Data Exchange (ETDEWEB)

    Dahmen, N.; Duelberg, A.; Schneider, G.M. (Bochum Univ. (Germany, F.R.). Lehrstuhl fuer Physikalische Chemie 2)

    1990-03-01

    Binary diffusion coefficient D{sub 12} in supercritical carbon dioxide were determined in a Supercritical Fluid Chromatography (SFC) apparatus by the peak broadening method (PBM). Some cyclic and linear ketones were investigated as a function of pressure between 9.5 and 18 MPa at about 314 K corresponding to densities form 513 to 820 kg m{sup -3}. The resulting D{sub 12} values are of the order of 10{sup -8} m{sup 2} s{sup -1} and lnD{sub 12} decreases about linearly with increasing density {rho} of the CO{sub 2}. (orig.).

  15. Thermodynamic Analysis of Supplementary-Fired Gas Turbine Cycles

    DEFF Research Database (Denmark)

    Elmegaard, Brian; Henriksen, Ulrik Birk; Qvale, Einar Bjørn

    2002-01-01

    This paper presents an analysis of the possibilities for improving the efficiency of an indirectly biomass-fired gas turbine (IBFGT) by supplementary direct gas-firing. The supplementary firing may be based on natural gas, biogas, or pyrolysis gas. {The interest in this cycle arise from a recent...... demonstration of a two-stage gasification process through construction of several plants.} A preliminary analysis of the ideal recuperated Brayton cycle shows that for this cycle any supplementary firing will have a marginal efficiency of unity per extra unit of fuel. The same result is obtained...... for the indirectly fired gas turbine (IFGT) and for the supplementary-fired IFGT. Both results show that the combination of external firing and internal firing have the potential of reducing or solving some problems with the use of biomass both in the recuperated and the indirectly fired gas turbine: The former...

  16. Thermodynamic Analysis of Supplementary-Fired Gas Turbine Cycles

    DEFF Research Database (Denmark)

    Elmegaard, Brian; Henriksen, Ulrik Birk; Qvale, Einar Bjørn

    2003-01-01

    This paper presents an analysis of the possibilities for improving the efficiency of an indi-rectly biomass-fired gas turbine (IBFGT) by supplementary direct gas-firing. The supple-mentary firing may be based on natural gas, biogas or pyrolysis gas. Intuitively, sup-plementary firing is expected...... to result in a high marginal efficiency. The paper shows that depending on the application, this is not always the case. The interest in this cycle arises from a recent demonstration of the feasibility of a two-stage gasification process through construction of several plants. The gas from this process...... could be divided into two streams, one for primary and one for supplementary firing. A preliminary analysis of the ideal, recuperated Brayton cycle shows that for this cycle any supplementary firing will have a marginal efficiency of unity per extra unit of fuel. The same result is obtained...

  17. Bistable switching in supercritical n+-n-n+GaAs transferred electron devices

    DEFF Research Database (Denmark)

    Jøndrup, Peter; Jeppesen, Palle; Jeppson, Bert

    1976-01-01

    Bistable switching in supercritically doped n+-n-n+GaAs transferred electron devices (TED's) is investigated experimentally and interpreted in computer simulations, for which details of the computer program are given. Three switching modes all leading to stable anode domains are discussed, namely......: 1) cathode-triggered traveling domain; 2) cathode-triggered accumulation layer; 3) anode-triggered domain. Relative current drops up to 40 percent, and switching times down to 60 ps are obtained in low-duty-cycle pulsed experiments with threshold currents around 400 mA. Optimum device parameters...

  18. Numerical thermodynamic optimization of supercritical coal fired power plant with support of IPSEpro software

    Science.gov (United States)

    Elsner, Witold; Kowalczyk, Łukasz; Marek, Maciej

    2012-09-01

    The paper presents a thermodynamic optimization of supercritical coal fired power plant. The aim of the study was to optimize part of the thermal cycle consisted of high-pressure turbine and two chosen highpressure feed water heaters. Calculations were carried out using IPSEpro software combined with MATLAB, where thermal efficiency and gross power generation efficiency were chosen as objective functions. It was shown that the optimization with newly developed framework is sufficiently precise and its main advantage is the reduction of computation time on comparison to the classical method. The calculations have shown the tendency of the increase in efficiency, with the rise of a number of function variables.

  19. Feasibility Study of Supercritical Light Water Cooled Fast Reactors for Actinide Burning and Electric Power Production

    Energy Technology Data Exchange (ETDEWEB)

    Mac Donald, Philip Elsworth; Buongiorno, Jacopo; Davis, Cliff Bybee; Weaver, Kevan Dean

    2002-01-01

    The use of supercritical temperature and pressure light water as the coolant in a direct-cycle nuclear reactor offers potential for considerable plant simplification and consequent capital and O&M cost reduction compared with current light water reactor (LWR) designs. Also, given the thermodynamic conditions of the coolant at the core outlet (i.e. temperature and pressure beyond the water critical point), very high thermal efficiencies of the power conversion cycle are possible (i.e. up to 46%). Because no change of phase occurs in the core, the need for steam separators and dryers as well as for BWR-type recirculation pumps is eliminated, which, for a given reactor power, results in a substantially shorter reactor vessel than the current BWRs. Furthermore, in a direct cycle the steam generators are not needed. If a tight fuel rod lattice is adopted, it is possible to significantly reduce the neutron moderation and attain fast neutron energy spectrum conditions. In this project a supercritical water reactor concept with a simple, blanket-free, pancake-shaped core will be developed. This type of core can make use of either fertile or fertile-free fuel and retain the hard spectrum to effectively burn plutonium and minor actinides from LWR spent fuel while efficiently generating electricity.

  20. Introduction to supercritical fluids a spreadsheet-based approach

    CERN Document Server

    Smith, Richard; Peters, Cor

    2013-01-01

    This text provides an introduction to supercritical fluids with easy-to-use Excel spreadsheets suitable for both specialized-discipline (chemistry or chemical engineering student) and mixed-discipline (engineering/economic student) classes. Each chapter contains worked examples, tip boxes and end-of-the-chapter problems and projects. Part I covers web-based chemical information resources, applications and simplified theory presented in a way that allows students of all disciplines to delve into the properties of supercritical fluids and to design energy, extraction and materials formation systems for real-world processes that use supercritical water or supercritical carbon dioxide. Part II takes a practical approach and addresses the thermodynamic framework, equations of state, fluid phase equilibria, heat and mass transfer, chemical equilibria and reaction kinetics of supercritical fluids. Spreadsheets are arranged as Visual Basic for Applications (VBA) functions and macros that are completely (source code) ...

  1. Metal Nanoparticles Preparation In Supercritical Carbon Dioxide Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Harry W. Rollins

    2004-04-01

    The novel optical, electronic, and/or magnetic properties of metal and semiconductor nanoparticles have resulted in extensive research on new methods for their preparation. An ideal preparation method would allow the particle size, size distribution, crystallinity, and particle shape to be easily controlled, and would be applicable to a wide variety of material systems. Numerous preparation methods have been reported, each with its inherent advantages and disadvantages; however, an ideal method has yet to emerge. The most widely applied methods for nanoparticle preparation include the sonochemical reduction of organometallic reagents,(1&2) the solvothermal method of Alivisatos,(3) reactions in microemulsions,(4-6) the polyol method (reduction by alcohols),(7-9) and the use of polymer and solgel materials as hosts.(10-13) In addition to these methods, there are a variety of methods that take advantage of the unique properties of a supercritical fluid.(14&15) Through simple variations of temperature and pressure, the properties of a supercritical fluid can be continuously tuned from gas-like to liquid-like without undergoing a phase change. Nanoparticle preparation methods that utilize supercritical fluids are briefly reviewed below using the following categories: Rapid Expansion of Supercritical Solutions (RESS), Reactive Supercritical Fluid Processing, and Supercritical Fluid Microemulsions. Because of its easily accessible critical temperature and pressure and environmentally benign nature, carbon dioxide is the most widely used supercritical solvent. Supercritical CO2 is unfortunately a poor solvent for many polar or ionic species, which has impeded its use in the preparation of metal and semiconductor nanoparticles. We have developed a reactive supercritical fluid processing method using supercritical carbon dioxide for the preparation of metal and metal sulfide particles and used it to prepare narrowly distributed nanoparticles of silver (Ag) and silver sulfide

  2. Design Construction and Operation of a Supercritical Carbon Dioxide (sCO2) Loop for Investigation of Dry Cooling and Natural Circulation Potential for Use in Advanced Small Modular Reactors Utilizing sCO2 Power Conversion Cycles.

    Energy Technology Data Exchange (ETDEWEB)

    Middleton, Bobby D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rodriguez, Salvador B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Carlson, Matthew David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-11-01

    This report outlines the work completed for a Laboratory Directed Research and Development project at Sandia National Laboratories from October 2012 through September 2015. An experimental supercritical carbon dioxide (sCO 2 ) loop was designed, built, and o perated. The experimental work demonstrated that sCO 2 can be uti lized as the working fluid in an air - cooled, natural circulation configuration to transfer heat from a source to the ultimate heat sink, which is the surrounding ambient environment in most ca ses. The loop was also operated in an induction - heated, water - cooled configuration that allows for measurements of physical parameters that are difficult to isolate in the air - cooled configuration. Analysis included the development of two computational flu id dynamics models. Future work is anticipated to answer questions that were not covered in this project.

  3. Development of cooling system for 66/6.9kV-20MVA REBCO superconducting transformers with Ne turbo-Brayton refrigerator and subcooled liquid nitrogen

    Science.gov (United States)

    Iwakuma, M.; Adachi, K.; Yun, K.; Yoshida, K.; Sato, S.; Suzuki, Y.; Umeno, T.; Konno, M.; Hayashi, H.; Eguchi, T.; Izumi, T.; Shiohara, Y.

    2015-12-01

    We developed a turbo-Brayton refrigerator with Ne gas as a working fluid for a 3 ϕ- 66/6.9kV-2MVA superconducting transformer with coated conductors which was bath-cooled with subcooled LN2. The two-stage compressor and expansion turbine had non-contact magnetic bearings for a long maintenance interval. In the future, we intend to directly install a heat exchanger into the Glass-Fiber-Reinforced-Plastics cryostat of a transformer and make a heat exchange between the working fluid gas and subcooled LN2. In this paper we investigate the behaviour of subcooled LN2 in a test cryostat, in which heater coils were arranged side by side with a flat plate finned-tube heat exchanger. Here a He turbo-Brayton refrigerator was used as a substitute for a Ne turbo-Brayton one. The pressure at the surface of LN2 in the cryostat was one atmosphere. Just under the LN2 surface, a stationary layer of LN2 was created over the depth of 20 cm and temperature dropped from 77 K to 65 K with depth while, in the lower level than that, a natural convection flow of LN2 was formed and temperature was almost uniform over 1 m depth. The boundary plane between the stationary layer and the natural convection region was visible.

  4. Thermodynamic cycles of nuclear power plants; Les cycles thermodynamiques des centrales nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Normand, T.; Andreani, J.; Tejedor, V.

    2010-07-01

    Above all a nuclear power plant is a thermal system whose efficiency relies on the thermodynamic cycle that turns the heat produced by the fission of uranium nuclei into electricity. The thermodynamic yield is an essential parameter to dimension a power plant. This book is dedicated to the presentation of the thermodynamic cycles that have been chosen in the different types of French PWR: CP0, P4, N4 and EPR. These cycles are classical steam cycles that have been used and optimized for 40 years, but they are physically limited and do not respond to the expectations of future generations of reactors. The last part deals with the thermodynamic cycles that might be involved in the fourth generation of nuclear reactors: cycles with super-critical steam, direct cycles for high temperature gas, indirect gas cycles, and cycles with super-critical CO{sub 2}. The first part of the book gives an account of the situation of nuclear power in France. (A.C.)

  5. Supercritical fluids: Reactions, materials and applications

    Energy Technology Data Exchange (ETDEWEB)

    Tumas, W.; Jacobson, G.B.; Josephsohn, N.S.; Brown, G.H.

    1999-04-09

    A number of important processes utilizing supercritical fluids have been either implemented or are emerging for extractions, separations and a wide range of cleaning applications. Supercritical fluids can be reasonable solvents yet share many of the advantages of gases including miscibility with other gases (i.e. hydrogen and oxygen), low viscosities and high diffusivities. Carbon dioxide has the further advantages of being nontoxic, nonflammable, inexpensive and currently unregulated. The use of compressed gases, either as liquids or supercritical fluids, as reaction media offers the opportunity to replace conventional hazardous solvents and also to optimize and potentially control the effect of solvent on chemical and material processing. The last several years has seen a significant growth in advances in chemical synthesis, catalytic transformations and materials synthesis and processing. The authors report on results from an exploratory program at Los Alamos National Laboratory aimed at investigating the use of dense phase fluids, particularly carbon dioxide, as reaction media for homogeneous, heterogeneous and phase-separable catalytic reactions in an effort to develop new, environmentally-friendly methods for chemical synthesis and processing. This approach offers the possibility of opening up substantially different chemical pathways, increasing selectivity at higher reaction rates, facilitating downstream separations and mitigating the need for hazardous solvents. Developing and understanding chemical and catalytic transformations in carbon dioxide could lead to greener chemistry at three levels: (1) Solvent replacement; (2) Better chemistry (e.g. higher reactivity, selectivity, less energy consumption); and (3) New chemistry (e.g. novel separations, use of COP{sub 2} as a C-1 source).

  6. Supercritical Water Oxidation Data Acquisition Testing

    Energy Technology Data Exchange (ETDEWEB)

    K. M. Garcia

    1996-08-01

    Supercritical Water Oxidation (SCWO) is a high pressure oxidation process that blends air, water, and organic waste material in an oxidizer in which where the temperature and pressure in the oxidizer are maintained above the critical point of water. Supercritical water mixed with hydrocarbons, which would be insoluble at subcritical conditions, forms a homogeneous phase which possesses properties associated with both a gas and a liquid. Hydrocarbons in contact with oxygen and SCW are readily oxidized. These properties of SCW make it an attractive means for the destruction of waste streams containing organic materials. SCWO technology holds great promise for treating mixed wastes in an environmentally safe and efficient manner. In the spring of 1994 the U.S. Department of Energy (DOE) initiated a Supercritical Water Oxidation Data Acquisition Testing (SCWODAT) program. The SCWODAT program provided further information and operational data on the effectiveness of treating both simulated mixed waste and typical Navy hazardous waste using the SCWO technology. The program concentrated on the acquisition of data through pilot plant testing. The Phase I DOE testing used a simulated waste stream that contained a complex machine cutting oil and metals, that acted as surrogates for radionuclides. The Phase II Navy testing included pilot testing using hazardous waste materials to demonstrate the effectiveness of the SCWO technology. The SCWODAT program demonstrated that the SCWO process oxidized the simulated waste stream containing complex machine cutting oil, selected by DOE as representative of one of the most difficult of the organic waste streams for which SCWO had been applied. The simulated waste stream with surrogate metals in solution was oxidized, with a high destruction efficiency, on the order of 99.97%, in both the neutralized and unneutralized modes of operation.

  7. Supercritical fluid thermodynamics from equations of state

    Science.gov (United States)

    Giovangigli, Vincent; Matuszewski, Lionel

    2012-03-01

    Supercritical multicomponent fluid thermodynamics are often built from equations of state. We investigate mathematically such a construction of a Gibbsian thermodynamics compatible at low density with that of ideal gas mixtures starting from a pressure law. We further study the structure of chemical production rates obtained from nonequilibrium statistical thermodynamics. As a typical application, we consider the Soave-Redlich-Kwong cubic equation of state and investigate mathematically the corresponding thermodynamics. This thermodynamics is then used to study the stability of H2-O2-N2 mixtures at high pressure and low temperature as well as to illustrate the role of nonidealities in a transcritical H2-O2-N2 flame.

  8. Supercritical-pressure light water cooled reactors

    CERN Document Server

    Oka, Yoshiaki

    2014-01-01

    This book focuses on the latest reactor concepts, single pass core and experimental findings in thermal hydraulics, materials, corrosion, and water chemistry. It highlights research on supercritical-pressure light water cooled reactors (SCWRs), one of the Generation IV reactors that are studied around the world. This book includes cladding material development and experimental findings on heat transfer, corrosion and water chemistry. The work presented here will help readers to understand the fundamental elements of reactor design and analysis methods, thermal hydraulics, materials and water

  9. A Simplified Supercritical Fast Reactor with Thorium Fuel

    Directory of Open Access Journals (Sweden)

    Peng Zhang

    2014-01-01

    Full Text Available Super-Critical water-cooled Fast Reactor (SCFR is a feasible option for the Gen-IV SCWR designs, in which much less moderator and thus coolant are needed for transferring the fission heat from the core compared with the traditional LWRs. The fast spectrum of SCFR is useful for fuel breeding and thorium utilization, which is then beneficial for enhancing the sustainability of the nuclear fuel cycle. A SCFR core is constructed in this work, with the aim of simplifying the mechanical structure and keeping negative coolant void reactivity during the whole core life. A core burnup simulation scheme based on Monte Carlo lattice homogenization is adopted in this study, and the reactor physics analysis has been performed with DU-MOX and Th-MOX fuel. The main issues discussed include the fuel conversion ratio and the coolant void reactivity. The analysis shows that thorium-based fuel can provide inherent safety for SCFR without use of blanket, which is favorable for the mechanical design of SCFR.

  10. Topping PCFB combustion plant with supercritical steam pressure

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, A. [Foster Wheeler Development Corp., Livingston, NJ (United States); White, J. [Parsons Power Group Inc., Reading, PA (United States)

    1997-11-01

    Research is being conducted to develop a new type of coal fired plant for electric power generation. This new type of plant, called a second generation or topping pressurized circulating fluidized bed combustion (topping PCFB) plant, offers the promise of efficiencies greater than 46 percent (HHV), with both emissions and a cost of electricity that are significantly lower than conventional pulverized coal fired plants with scrubbers. The topping PCFB plant incorporates the partial gasification of coal in a carbonizer, the combustion of carbonizer char in a pressurized circulating fluidized bed combustor (PCFB), and the combustion of carbonizer fuel gas in a topping combustor to achieve gas turbine inlet temperatures of 2,300 F and higher. After completing pilot plant tests of a carbonizer, a PCFB, and a gas turbine topping combustor, all being developed for this new plant, the authors calculated a higher heating value efficiency of 46.2 percent for the plant. In that analysis, the plant operated with a conventional 2,400 psig steam cycle with 1,000 F superheat and reheat steam and a 2.5 inch mercury condenser back pressure. This paper identifies the efficiency gains that this plant will achieve by using supercritical pressure steam conditions.

  11. Effects of supercritical environment on hydrocarbon-fuel injection

    Science.gov (United States)

    Shin, Bongchul; Kim, Dohun; Son, Min; Koo, Jaye

    2017-04-01

    In this study, the effects of environment conditions on decane were investigated. Decane was injected in subcritical and supercritical ambient conditions. The visualization chamber was pressurized to 1.68 MPa by using nitrogen gas at a temperature of 653 K for subcritical ambient conditions. For supercritical ambient conditions, the visualization chamber was pressurized to 2.52 MPa by using helium at a temperature of 653 K. The decane injection in the pressurized chamber was visualized via a shadowgraph technique and gradient images were obtained by a post processing method. A large variation in density gradient was observed at jet interface in the case of subcritical injection in subcritical ambient conditions. Conversely, for supercritical injection in supercritical ambient conditions, a small density gradient was observed at the jet interface. In a manner similar to that observed in other cases, supercritical injection in subcritical ambient conditions differed from supercritical ambient conditions such as sphere shape liquid. Additionally, there were changes in the interface, and the supercritical injection core width was thicker than that in the subcritical injection. Furthermore, in cases with the same injection conditions, the change in the supercritical ambient normalized core width was smaller than the change in the subcritical ambient normalized core width owing to high specific heat at the supercritical injection and small phase change at the interface. Therefore, the interface was affected by the changing ambient condition. Given that the effect of changing the thermodynamic properties of propellants could be essential for a variable thrust rocket engine, the effects of the ambient conditions were investigated experimentally.

  12. Chapter 11: Concentrating Solar Power

    Energy Technology Data Exchange (ETDEWEB)

    Turchi, Craig S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Stekli, J. [U.S. Department of Energy; Bueno, P. C. [Southwest Research Institute

    2017-01-02

    This chapter summarizes the applications of the supercritical CO2 (sCO2) Brayton cycle in concentrating solar power (CSP) plants. The design and operation of CSP plants are reviewed to highlight the requirements for the power cycle and attributes that are advantageous for the solar-thermal application. The sCO2 Brayton cycle offers the potential of higher cycle efficiency versus superheated or supercritical steam cycles at temperatures relevant for CSP applications. In addition, Brayton cycle systems using sCO2 are anticipated to have smaller weight and volume, lower thermal mass, and less complex power blocks compared with Rankine cycles due to the higher density of the fluid and simpler cycle design. The simpler machinery and compact size of the sCO2 process may also reduce the installation, maintenance, and operation cost of the system. Power cycle capacities in the range of 10-150 MWe are anticipated for the CSP application. In this chapter, we explore sCO2 Brayton cycle configurations that have attributes that are desirable from the perspective of a CSP application, such as the ability to accommodate dry cooling and daily cycling, as well as integration with thermal energy storage.

  13. Supercritical Fluid Extraction: Present Status and Prospects

    Energy Technology Data Exchange (ETDEWEB)

    King, J. W.

    2002-07-01

    Supercritical extraction (SFE), using primarily environmentally-benign carbon dioxide (CO{sub 2}) as the extraction agent, is reviewed with respect to its present status and future use. SFE was developed for analytical application in the mid 1980's in response to the desire to reduce the use of organic solvents in the laboratory environment and is becoming a standard method for the preparation and analysis of lipid-containing sample matrices. Currently, analytical SFE is predominately practiced in the off-line mode, using both sequential and parallel extraction modes. Depending on the instrumental configuration, the preparation of up to 24 samples can be accomplished on one instrument on a daily basis. Several other benefits can be achieved using SFE, such as the processing of thermally-sensitive analytes and rapid analyte extraction kinetics relative to extraction with liquid solvents. Examples are provided not only of the analytical SFE of oils and fats, but of volatile solutes from an array of sample types. Finally, the relevance of analytical SFE to processing with supercritical fluids (SFs) is documented using examples from our own research involving a combinatorial approach to optimising processing conditions. (Author) 70 refs.

  14. Performance of supercritical methanol in polyurethane degradation

    Directory of Open Access Journals (Sweden)

    Liu Lu

    2016-01-01

    Full Text Available Polyurethane is a group of block copolymer which is composed of diisocyanate, chain extender, and polyol, including polyurethane foam, polyurethane elastomer, waterborne polyurethane, etc. This research focused on thermoplastic polyurethane elastomer (TPU which is formed with 4,4’-diphenylmethane diisocyanate (MDI, poly(1,4-butanediol-hexanedioic acid diolpolyester(PBA and extended with 1,4-butanediol(BDO.The degradation of TPU was carried out with the help of methanol as the supercritical solvent. The SEM of the reaction residues revealed the process of the depolymerisation. The products were measured by GC-MS and found out to be PBA, BDO and 4,4’-methylene diphenyl carbamate(MDC which is themethylate of MDI.GC-FID, HPLC-UV and GPC were used to further analysis. The experimental results showed that supercritical methanol performed outstandingly in TPU recycling, it needed lower temperature and shorter time than regular methods. At 230°C/70min, over 90% raw materials of TPU could be recovered.

  15. Supercritical extraction of oleaginous: parametric sensitivity analysis

    Directory of Open Access Journals (Sweden)

    Santos M.M.

    2000-01-01

    Full Text Available The economy has become universal and competitive, thus the industries of vegetable oil extraction must advance in the sense of minimising production costs and, at the same time, generating products that obey more rigorous patterns of quality, including solutions that do not damage the environment. The conventional oilseed processing uses hexane as solvent. However, this solvent is toxic and highly flammable. Thus the search of substitutes for hexane in oleaginous extraction process has increased in the last years. The supercritical carbon dioxide is a potential substitute for hexane, but it is necessary more detailed studies to understand the phenomena taking place in such process. Thus, in this work a diffusive model for semi-continuous (batch for the solids and continuous for the solvent isothermal and isobaric extraction process using supercritical carbon dioxide is presented and submitted to a parametric sensitivity analysis by means of a factorial design in two levels. The model parameters were disturbed and their main effects analysed, so that it is possible to propose strategies for high performance operation.

  16. Supercritical fluid chromatography (SFC). Pt. 3. Applications

    Energy Technology Data Exchange (ETDEWEB)

    Leyendecker, D.; Hoefler, F.

    1989-05-01

    During the last few years, Supercritical Fluid Chromatography (SFC) has been emerged from an academic object of research to an important tool for the analytical chemist. Persuasive SFC-applications have been reported analyzing substrates with low volatilities, either due to high molecular weights or to high polarities, thermally or solvatolytically labile molecules, or analytes without chromophores or electroactive groups. Examples are oligomers and polymers up to a molecular weight of 10,000 g/mol, e.g., polysiloxanes, polyethers (nonionic surfactants), polyesters, polystyrenes and other vinyl polymers, polyenes etc. In addition, SFC is applicable to the analysis of several monomers. In the petroleum and coal industries, SFC was employed for the characterization of high boiling hydrocarbon mixtures as well as for group separations of alkanes, olefins, and aromatics. Due to the high solvent strength of supercritical fluids, several pesticides, herbicides, and fungicides can be determined either separately or in combination with polar metabolites. Physiologically active substances often are thermally labile and polar at the same time. SFC has been successfully applied to the analysis of steroids, prostaglandins, cannabinoids and other drugs, flavours, and medicines. It is also well suited for analyzing natural or synthetic mono-, di-, and triglycerides. (orig.).

  17. Toward Better Modeling of Supercritical Turbulent Mixing

    Science.gov (United States)

    Selle, Laurent; Okongo'o, Nora; Bellan, Josette; Harstad, Kenneth

    2008-01-01

    study was done as part of an effort to develop computational models representing turbulent mixing under thermodynamic supercritical (here, high pressure) conditions. The question was whether the large-eddy simulation (LES) approach, developed previously for atmospheric-pressure compressible-perfect-gas and incompressible flows, can be extended to real-gas non-ideal (including supercritical) fluid mixtures. [In LES, the governing equations are approximated such that the flow field is spatially filtered and subgrid-scale (SGS) phenomena are represented by models.] The study included analyses of results from direct numerical simulation (DNS) of several such mixing layers based on the Navier-Stokes, total-energy, and conservation- of-chemical-species governing equations. Comparison of LES and DNS results revealed the need to augment the atmospheric- pressure LES equations with additional SGS momentum and energy terms. These new terms are the direct result of high-density-gradient-magnitude regions found in the DNS and observed experimentally under fully turbulent flow conditions. A model has been derived for the new term in the momentum equation and was found to perform well at small filter size but to deteriorate with increasing filter size. Several alternative models were derived for the new SGS term in the energy equation that would need further investigations to determine if they are too computationally intensive in LES.

  18. Supercritical water oxidation treatment of textile sludge.

    Science.gov (United States)

    Zhang, Jie; Wang, Shuzhong; Li, Yanhui; Lu, Jinling; Chen, Senlin; Luo, XingQi

    2016-10-17

    In this work, we studied the supercritical water oxidation (SCWO) of the textile sludge, the hydrothermal conversion of typical textile compounds and the corrosion properties of stainless steel 316. Moreover, the influence mechanisms of NaOH during these related processes were explored. The results show that decomposition efficiency for organic matter in liquid phase of the textile sludge was improved with the increment of reaction temperature or oxidation coefficient. However, the organic substance in solid phase can be oxidized completely in supercritical water. Serious coking occurred during the high pressure water at 250-450°C for the Reactive Orange 7, while at 300 and 350°C for the polyvinyl alcohol. The addition of NaOH not only accelerated the destruction of organic contaminants in the SCWO reactor, but effectively inhibited the dehydration conversion of textile compounds during the preheating process, which was favorable for the treatment system of textile sludge. The corrosion experiment results indicate that the stainless steel 316 could be competent for the body materials of the reactor and the heat exchangers. Furthermore, there was prominent enhancement of sodium hydroxide for the corrosion resistance of 316 in subcritical water. On the contrary the effect was almost none during SCWO.

  19. Supercritical Fluid Extraction of Palm Carotenoids

    Directory of Open Access Journals (Sweden)

    Puah C. Wei

    2005-01-01

    Full Text Available The extraction of carotenoids from crude palm oil was carried out in a dynamic (flow- through supercritical fluid extraction system. The carotenoids obtained were quantified using off-line UV-visible spectrophotometry. The effects of operating pressure and temperature, flow rate of the supercritical carbon dioxide (SC-CO2, sample size of feed used on the solubility of palm carotenoids were investigated. The results showed that the extraction of carotenoids was governed by its solubility in the SC-CO2 and can be enhanced by increasing pressure at a constant temperature or decreasing temperature at a constant pressure. Increasing the flow rate and decreasing the sample size can reduce the extraction time but do not enhance the solubility. Palm carotenoids have very low solubility in SC-CO2 in the range of 1.31 x 10-4 g kg-1 to 1.58 x 10-3 g kg-1 for the conditions investigated in this study. The experimental data obtained were compared with those published by other workers and correlated by a density-based equation as proposed by Chrastil.

  20. Supercritical fluid extraction of Beauvericin from maize.

    Science.gov (United States)

    Ambrosino, P; Galvano, F; Fogliano, V; Logrieco, A; Fresa, R; Ritieni, A

    2004-02-27

    Beauvericin (BEA), a supercritical fluid extraction with supercritical carbon dioxide from maize was investigated. Extraction efficiencies under several different extraction conditions were examined. Pressure, temperature, extraction time, organic modifier and water matrix content (10%) were investigated. The best extraction conditions were at a temperature of 60 degrees C, 3200psi, for 30min static extraction time and methanol as modifier solvent. Extraction recovery of 36% without modifier by adding water to the matrix in the extraction vessel (reproducibility relative standard deviations (R.S.D.)=3-5%) were recorded. Extraction recovery of 76.9% with methanol as co-solvent (reproducibility R.S.D.=3-5%) was obtained. Data shows that SFE gives a lower BEA recovery compared to conventional extraction protocol with organic solvents while SFE with modifier and conventional extraction yields are comparable. BEA extract contents were determined by high pressure liquid chromatography (HPLC) with a diode array detector (DAD) at 205nm and BEA peak confirmed by LC-MS. Acetonitrile-water as mobile phase and column C-18 were both tested. Instrumental and analytical parameters were optimized in the range linear interval from 1 to 500mgkg(-1) and reached a detection limit of 2ng.

  1. Desorption of toluene from modified clays using supercritical carbon dioxide

    Directory of Open Access Journals (Sweden)

    Carneiro D. G. P.

    2004-01-01

    Full Text Available The main objective of this work is to study the regeneration capacity of modified clays using supercritical fluid. These modified clays are used as organic compound adsorvents. The experimental step was done using a packed column with the clay contaminated by toluene. The results obtained showed the influence of the density of the supercritical CO2 and of the organic modifier in the desorption process. These data were modeled with first- and second-order models. Better results were obtained using the second-order model. This study makes possible the scale-up of the desorption process for regeneration of solid matrices using supercritical fluids.

  2. High Density Thermal Energy Storage with Supercritical Fluids

    Science.gov (United States)

    Ganapathi, Gani B.; Wirz, Richard

    2012-01-01

    A novel approach to storing thermal energy with supercritical fluids is being investigated, which if successful, promises to transform the way thermal energy is captured and utilized. The use of supercritical fluids allows cost-affordable high-density storage with a combination of latent heat and sensible heat in the two-phase as well as the supercritical state. This technology will enhance penetration of several thermal power generation applications and high temperature water for commercial use if the overall cost of the technology can be demonstrated to be lower than the current state-of-the-art molten salt using sodium nitrate and potassium nitrate eutectic mixtures.

  3. Exergoeconomic performance optimization of an endoreversible intercooled regenerated Brayton cogeneration plant. Part 2: Heat conductance allocation and pressure ratio optimization

    Directory of Open Access Journals (Sweden)

    Bo Yang, Lingen Chen, Fengrui Sun

    2011-03-01

    Full Text Available Finite time exergoeconomic performance of an endoreversible intercooled regenerative Brayton cogeneration plant is optimized based on the model which is established using finite time thermodynamic in Part 1 of this paper. It is found that the optimal heat conductance allocation of the regenerator is zero. When the total pressure ratio and the heat conductance allocation of the regenerator are fixed, it is shown that there exist an optimal intercooling pressure ratio, and a group of optimal heat conductance allocations among the hot-, cold- and consumer-side heat exchangers and the intercooler, which correspond to a maximum dimensionless profit rate. When the total pressure ratio is variable, there exists an optimal total pressure ratio which corresponds to a double-maximum dimensionless profit rate, and the corresponding exergetic efficiency is obtained. The effects of the total heat exchanger conductance, price ratios and the consumer-side temperature on the double-maximum dimensionless profit rate and the corresponding exergetic efficiency are discussed. It is found that there exists an optimal consumer-side temperature which corresponds to a thrice-maximum dimensionless profit rate.

  4. Thermodynamic properties of supercritical carbon dioxide: Widom and Frenkel lines

    Science.gov (United States)

    Fomin, Yu. D.; Ryzhov, V. N.; Tsiok, E. N.; Brazhkin, V. V.

    2015-02-01

    Supercritical fluids are widely used in a number of important technological applications, yet the theoretical progress in the field has been rather moderate. Fairly recently, a new understanding of the liquidlike and gaslike properties of supercritical fluids has come to the fore, particularly with the advent of the Widom and Frenkel lines that aim to demarcate different physical properties on the phase diagram. Here, we report the results of a computational study of supercritical carbon dioxide, one of the most important fluids in the chemical industry. We study the response functions of CO2 in the supercritical state and calculate the locations of their maxima (Widom lines). We also report the preliminary calculations of the Frenkel line, the line of crossover of microscopic dynamics of particles. Our insights are relevant to physical processes in the atmosphere of Venus and its evolution.

  5. Supercritical Fluid Extraction of Aflatoxin B 1 from Soil

    Science.gov (United States)

    This research describes the development of a Supercritical Fluid Extraction (SFE) method to recover aflatoxin B1 from fortified soil. The effects of temperature, pressure, modifier (identity and percentage), and extraction type were assessed. Using the optimized SFE conditions, ...

  6. Measurement of Orotic Acid in Urine by Supercritical Fluid Chromatography

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This work presents a simple, rapid and reliable supercritical fluid chromatography (SFC) method for a sensitive measurement of orotic acid in human urine. The samples were diluted with deionized water and analyzed directly without any pretreatment.

  7. Finite connections for supercritical Bernoulli bond percolation in 2D

    CERN Document Server

    Campanino, Massimo; Louidor, Oren

    2009-01-01

    Two vertices are said to be finitely connected if they belong to the same cluster and this cluster is finite. We derive sharp asymptotics for finite connection probabilities for supercritical Bernoulli bond percolation on Z^2.

  8. Supercritical fluid technology for energy and environmental applications

    CERN Document Server

    Anikeev, Vladimir

    2014-01-01

    Supercritical Fluid Technology for Energy and Environmental Applications covers the fundamental principles involved in the preparation and characterization of supercritical fluids (SCFs) used in the energy production and other environmental applications. Energy production from diversified resources - including renewable materials - using clean processes can be accomplished using technologies like SCFs. This book is focused on critical issues scientists and engineers face in applying SCFs to energy production and environmental protection, the innovative solutions they have found, and the challenges they need to overcome. The book also covers the basics of sub- and supercritical fluids, like the thermodynamics of phase and chemical equilibria, mathematical modeling, and process calculations. A supercritical fluid is any substance at a temperature and pressure above its critical point where distinct liquid and gas phases do not exist. At this state the compound demonstrates unique properties, which can be "fine...

  9. Simultaneous Graphite Exfoliation and N Doping in Supercritical Ammonia.

    Science.gov (United States)

    Sasikala, Suchithra Padmajan; Huang, Kai; Giroire, Baptiste; Prabhakaran, Prem; Henry, Lucile; Penicaud, Alain; Poulin, Philippe; Aymonier, Cyril

    2016-11-16

    We report the exfoliation of graphite and simultaneous N doping of graphene by two methods: supercritical ammonia treatment and liquid-phase exfoliation with NH4OH. While the supercritical ammonia allowed N doping at a level of 6.4 atom % in 2 h, the liquid-phase exfoliation with NH4OH allowed N doping at a level of 2.7 atom % in 6 h. The N doped graphene obtained via the supercritical ammonia route had few layers (supercritical ammonia as an exfoliation agent and N doping precursor for graphene. Notably, the N doped graphene showed electrocatalytic activity toward oxygen reduction reaction with high durability and good methanol tolerance compared to those of commercial Pt/C catalyst.

  10. Supercritical Fluid Extraction of Aflatoxin B 1 from Soil

    Science.gov (United States)

    This research describes the development of a Supercritical Fluid Extraction (SFE) method to recover aflatoxin B1 from fortified soil. The effects of temperature, pressure, modifier (identity and percentage), and extraction type were assessed. Using the optimized SFE conditions, ...

  11. Physical properties of the benchmark models program supercritical wing

    Science.gov (United States)

    Dansberry, Bryan E.; Durham, Michael H.; Bennett, Robert M.; Turnock, David L.; Silva, Walter A.; Rivera, Jose A., Jr.

    1993-01-01

    The goal of the Benchmark Models Program is to provide data useful in the development and evaluation of aeroelastic computational fluid dynamics (CFD) codes. To that end, a series of three similar wing models are being flutter tested in the Langley Transonic Dynamics Tunnel. These models are designed to simultaneously acquire model response data and unsteady surface pressure data during wing flutter conditions. The supercritical wing is the second model of this series. It is a rigid semispan model with a rectangular planform and a NASA SC(2)-0414 supercritical airfoil shape. The supercritical wing model was flutter tested on a flexible mount, called the Pitch and Plunge Apparatus, that provides a well-defined, two-degree-of-freedom dynamic system. The supercritical wing model and associated flutter test apparatus is described and experimentally determined wind-off structural dynamic characteristics of the combined rigid model and flexible mount system are included.

  12. Plasticisation and complexation of certain polymers in supercritical CO2

    CSIR Research Space (South Africa)

    Labuschagne, Philip W

    2004-09-01

    Full Text Available A polymer system (polyvinylpyrrolidone + polyvinyl acetate-co-crotonic acid) was successfully identified for use as encapsulation material for sensitive actives using supercritical CO2 as plasticisation medium, having the following properties: 1...

  13. Helium liquefier cycles with saturated vapor compression

    Science.gov (United States)

    Minta, M.; Smith, J. L., Jr.

    The three refrigeration stages of the conventional helium liquefaction cycle are related to liquid nitrogen precooling, the use of expansion engines, and a J-T expansion. For an operation of helium refrigerators at temperatures below 4.2 K reduced pressure levels are required. Such an operation makes it necessary to enhance the compressor size and the heat exchanger surface area. In the case of 1.8 K refrigerators, practical cycles with three pressure levels are employed. It is pointed out that the saturated-vapor-compression (SVC) helium cycle provides an alternative solution to these problems. The present investigation is concerned with the design study of a SVC helium liquifier operating at elevated pressures. The study was conducted to demonstrate the potential of the SVC cycle on the basis of a direct comparison with a conventional cycle using the same precooling expanders and a supercritical wet expander instead of a J-T valve.

  14. Determination of solvation kinetics in supercritical fluids. Summary report

    Energy Technology Data Exchange (ETDEWEB)

    Bright, F.V.

    1993-01-01

    Objective was to study solvation processes in pure and entrainer-modified supercritical fluids. Specific topics were: Kinetics for solvation in supercritical media, influence on entrainers on solvation, reversibility of solvation, effects of solvation on intramolecular solute-solute interaction kinetics, and impact of fluid density on these processes. Time-resolved fluorescence spectroscopy was used as the main analytical tool. A summary is given of the 2.5 years` research.

  15. Supercritical hydrogenation and acid-catalysed reactions "without gases".

    Science.gov (United States)

    Hyde, Jason R; Poliakoff, Martyn

    2004-07-07

    The high temperature catalytic decomposition of HCO2H and HCO2Et are used to generate the high pressure H2 and the supercritical fluids needed for micro-scale hydrogenation of organic compounds; our approach overcomes the problems and limitations of handling high pressure gases on a small-scale and opens the way to the widespread use of continuous supercritical reactions in the laboratory.

  16. Research in Supercritical Fuel Properties and Combustion Modeling

    Science.gov (United States)

    2015-09-18

    any significant impact on the normal hydrocarbon oxidation kinetics . These are ethanol, dimethyl ether( DME ), and methyl formate (C2H5OH, CH3OCH3...research are to develop stimulated scattering as a diagnostic for supercritical fluids, and to evaluate reaction kinetics inputs involving 2-4...measurements for refractive index measurements, and tested our supercritical cell. On the reaction kinetics task, review and evaluation of reactions, rate

  17. Fischer-Tropsch synthesis in supercritical fluids. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Akgerman, A.; Bukur, D.B.

    1998-12-31

    The objective of this study was to investigate Fischer-Tropsch Synthesis (FTS) in the supercritical phase employing a commercial precipitated iron catalysts. As the supercritical fluid the authors used propane and n-hexane. The catalyst had a nominal composition of 100 Fe/5 Cu/4.2 K/25 SiO{sub 2} on mass basis and was used in a fixed bed reactor under both normal (conventional) and supercritical conditions. Experimental data were obtained at different temperatures (235 C, 250 C, and 260 C) and synthesis gas feed compositions (H{sub 2}/CO molar feed ratio of 0.67, 1.0 and 2.0) in both modes of operation under steady state conditions. The authors compared the performance of the precipitated iron catalyst in the supercritical phase, with the data obtained in gas phase (fixed bed reactor) and slurry phase (STS reactor). Comparisons were made in terms of bulk catalyst activity and various aspects of product selectivity (e.g. lumped hydrocarbon distribution and olefin content as a function of carbon number). In order to gain better understanding of the role of intraparticle mass transfer during FTS under conventional or supercritical conditions, the authors have measured diffusivities of representative hydrocarbon products in supercritical fluids, as well as their effective diffusion rates into the pores of catalyst at the reaction conditions. They constructed a Taylor dispersion apparatus to measure diffusion coefficients of hydrocarbon products of FTS in sub and supercritical ethane, propane, and hexane. In addition, they developed a tracer response technique to measure the effective diffusivities in the catalyst pores at the same conditions. Based on these results they have developed an equation for prediction of diffusion in supercritical fluids, which is based on the rough hard sphere theory.

  18. Electrochemistry in Near-Critical and Supercritical Fluids. I. Ammonia.

    Science.gov (United States)

    1984-07-18

    in a supercritical fluid containing an electrolyte. We show j here that electrocheical techniques, such as cyclic voltametry and .’ chronocoulametrY...8217,_- Electrochemistry, supercritical, ammonia S&. ASSTRACT. (CGWIU&UI VOWO *fo of Rea@ d 8~ US F &I-*I 81116 Cyclic voltanmetric and chronocoulometric studies of N...Bard 4 Department of Chemi stry, The University of Texas Austin, TX 78712 (Abstract) Cyclic voittuuntric and chronocoulometric studies of NH3

  19. Independent Research and Design of 600-MW Supercritical CFB Boiler

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In order to further develop and improve the technologies for large-capacity supercritical CFB boiler, the key technologies for large CFB boiler were systematically studied, based on the development of first domestically-made 210-MW and 330-MW CFB boilers. The scheme of 600-MW supercritical CFB boiler was designed, including the furnace structure, key components, steam-water system and auxiliary systems, which laid a technical foundation for the engineering applications.

  20. Isolation of Organochlorine Pesticide from Ginseng with Supercritical CO2

    Institute of Scientific and Technical Information of China (English)

    李淑芬; 王幼君; 全灿; 田松江

    2005-01-01

    The feasibility of removal of the organochlorine pesticides residues of hexachlorocyclohexane(BHC) from radix ginseng with supercritical CO2 was explored. Some factors, such as extraction pressure, extraction temperature, and kinds of co-solvents were investigated. The experimental results indicate that it is possible to reduce BHC residues in radix ginseng to the level of 0.1 × 10-6 with supercritical CO2 in the presence of suitable amount of co-solvent, such as water.

  1. Extraction of olive oil with supercritical carbon dioxide / Ilana Geerdts

    OpenAIRE

    Geerdts, Ilana

    2005-01-01

    The principal objective of this study was to extract olive oil from the fruit of Olea europaea by means of supercritical carbon dioxide (sc-C02) as an alternative to traditional methods. Extractions were performed on a laboratory scale supercritical fluid extractor of the latest design, featuring three mutually independent flow systems and extremely high flow rates. A number of extraction runs based on a statistical design was performed to establish the conditions (time, pressu...

  2. Hydrogenation of diesel aromatic compounds in supercritical solvent environment

    Directory of Open Access Journals (Sweden)

    E.P. Martins

    2000-09-01

    Full Text Available Reactions under supercritical conditions have been employed in many processes. Furthermore, an increasing number of commercial reactions have been conducted under supercritical or near critical conditions. These reaction conditions offer several advantages when compared to conditions in conventional catalytic processes in liquid-phase, gas-liquid interface, or even some gas-phase reactions. Basically, a supercritical solvent can diminish the reactant’s transport resistance from the bulk region to the catalyst surface due to enhancement of liquid diffusivity values and better solubility than those in different phases. Another advantage is that supercritical solvents permit prompt and easy changes in intermolecular properties in order to modify reaction parameters, such as conversion or selectivity, or even proceed with the separation of reaction products. Diesel fractions from petroleum frequently have larger than desirable quantities of aromatic compounds. Diesel hydrogenation is intended to decrease these quantities, i.e., to increase the quantity of paraffin present in this petroleum fraction. In this work, the hydrogenation of tetralin was studied as a model reaction for the aromatic hydrogenation process. A conventional gas-liquid-solid catalytic process was compared with that of supercritical carbon dioxide substrate under similar conditions. Additionally, an equilibrium conversion diagram was calculated for this reaction in a wide range of temperature and reactant ratios, so as to optimize the operational conditions and improve the results of subsequent experiments. An increase in the rate of reaction at 493 K in supercritical fluid, as compared to that in the conventional process, was observed.

  3. Effects of Gravity on Supercritical Water Oxidation (SCWO) Processes

    Science.gov (United States)

    Hegde, Uday; Hicks, Michael

    2013-01-01

    The effects of gravity on the fluid mechanics of supercritical water jets are being studied at NASA to develop a better understanding of flow behaviors for purposes of advancing supercritical water oxidation (SCWO) technologies for applications in reduced gravity environments. These studies provide guidance for the development of future SCWO experiments in new experimental platforms that will extend the current operational range of the DECLIC (Device for the Study of Critical Liquids and Crystallization) Facility on board the International Space Station (ISS). The hydrodynamics of supercritical fluid jets is one of the basic unit processes of a SCWO reactor. These hydrodynamics are often complicated by significant changes in the thermo-physical properties that govern flow behavior (e.g., viscosity, thermal conductivity, specific heat, compressibility, etc), particularly when fluids transition from sub-critical to supercritical conditions. Experiments were conducted in a 150 ml reactor cell under constant pressure with water injections at various flow rates. Flow configurations included supercritical jets injected into either sub-critical or supercritical water. Profound gravitational influences were observed, particularly in the transition to turbulence, for the flow conditions under study. These results will be presented and the parameters of the flow that control jet behavior will be examined and discussed.

  4. Hydrogenation of diesel aromatic compounds in supercritical solvent environment

    Energy Technology Data Exchange (ETDEWEB)

    Martins, E.P.; Aranda, D.A.G.; Pessoa, F.L.P. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Escola de Quimica. Dept. de Engenharia Quimica. E-mail: donato@h2o.eq.ufrj.br; pessoa@h2o.eq.ufrj.br; Zotin, J.L. [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas. E-mail: zotin@cenpes.petrobras.com.br

    2000-09-01

    Reactions under supercritical conditions have been employed in many processes. Furthermore, an increasing number of commercial reactions have been conducted under supercritical or near critical conditions. These reaction conditions offer several advantages when compared to conditions in conventional catalytic processes in liquid-phase, gas-liquid interface., or even some gas-phase reactions. basically, a supercritical solvent can diminish the reactant's transport resistance from the bulk region to the catalyst surface due to enhancement of liquid diffusivity values and better solubility than those in different phases. Another advantage is that supercritical solvents permit prompt and easy changes in intermolecular properties in order to modify reaction parameters, such as conversion or selectivity, or even proceed with the separation of reaction products. Diesel fractions from petroleum frequently have larger than desirable quantities of aromatic compounds. Diesel hydrogenation is intended to decrease these quantities, to increase the quantity of paraffin present in this petroleum fraction. In this work, the hydrogenation of tetralin was studied as a model reaction for the aromatic hydrogenation process. A conventional gas-liquid-solid catalytic process was compared with that of supercritical carbon dioxide substrate under similar conditions. Additionally, an equilibrium conversion diagram was calculated for this reaction in a wide range of temperature and reactant ratios, so as to optimize the operational conditions and improve the results of subsequent experiments. An increase in the rate of reaction at 493 K in supercritical fluid, as compared to that in the conventional process, was observed. (author)

  5. Supercritical extraction of lycopene from tomato industrial wastes with ethane.

    Science.gov (United States)

    Nobre, Beatriz P; Gouveia, Luisa; Matos, Patricia G S; Cristino, Ana F; Palavra, António F; Mendes, Rui L

    2012-07-11

    Supercritical fluid extraction of all-E-lycopene from tomato industrial wastes (mixture of skins and seeds) was carried out in a semi-continuous flow apparatus using ethane as supercritical solvent. The effect of pressure, temperature, feed particle size, solvent superficial velocity and matrix initial composition was evaluated. Moreover, the yield of the extraction was compared with that obtained with other supercritical solvents (supercritical CO₂ and a near critical mixture of ethane and propane). The recovery of all-E-lycopene increased with pressure, decreased with the increase of the particle size in the initial stages of the extraction and was not practically affected by the solvent superficial velocity. The effect of the temperature was more complex. When the temperature increased from 40 to 60 °C the recovery of all-E-lycopene increased from 80 to 90%. However, for a further increase to 80 °C, the recovery remained almost the same, indicating that some E-Z isomerization could have occurred, as well as some degradation of lycopene. The recovery of all-E-lycopene was almost the same for feed samples with different all-E-lycopene content. Furthermore, when a batch with a higher all-E-lycopene content was used, supercritical ethane and a near critical mixture of ethane and propane showed to be better solvents than supercritical CO₂ leading to a faster extraction with a higher recovery of the carotenoid.

  6. Reactions of supercritical water and supercritical methanol with benzaldehyde; Chorinkaisui oyobi chorinkai methanol to benzaldehyde tono hanno

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, C.; Yasuda, T.; Nishi, K.; Takahashi, S. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science

    1996-11-01

    The reactions of supercritical water and supercritical methanol with benzaldehyde have been examined in the temperature range from 553 to 693 K, and the reaction pathways have been examined from the temporal variations of the reaction products. For the reaction of benzaldehyde with supercritical water, the major product was benzene, which was formed from the pyrolysis of benzaldehyde. The benzoic acid and benzyl alcohol were the by-products, produced from the Cannizzaro-type disproportionation reaction of benzaldehyde with the hydrate formed from the reaction with water and benzaldehyde. The major product for the reaction of benzaldehyde with supercritical methanol was benzyl alcohol, and the by-product were dimethylacetal, benzene, and methyl benzoic acid. Under the reaction conditions of this study, a significant amount of acetal was produced from benzaldehyde and methanol. The pyrolysis of acetal yielded benzyl alcohol. 29 refs., 6 figs., 4 tabs.

  7. Formation of energetic materials using supercritical fluids

    Energy Technology Data Exchange (ETDEWEB)

    Teipel, U.; Kroeber, H.; Krause, H.H. [Fraunhofer-Institut fuer Chemische Technologie (ICT), Pfinztal (Germany)

    2001-10-01

    A new field of applications of compressed gases is the formation of solid particles with well-defined properties, e.g. the particle size, the particle size distribution, the particle shape, the specific surface area and free of solvent inclusions. It is possible to process moderately solids like energetic materials which are difficult to comminute due to their sensitivity to mechanical or thermal stress. The characteristics of compressed gases allow to vary the morphology of solid particles in a wide range. A pilot plant is presented, which has been built to prepare fine particles by the rapid expansion of supercritical solutions (RESS process) and precipitation by a compressed fluid antisolvent (PCA process). In this contribution the micronization of different energetic materials by the RESS and PCA processes will be under investigation. (orig.)

  8. Thermodynamic properties of superheated and supercritical steam

    Energy Technology Data Exchange (ETDEWEB)

    Malhotra, A. [Indian Inst. of Technology, New Delhi (India). Dept. of Mechanical Engineering; Panda, D.M.R. [Dadri Gas Power Station, NTPC, Gautam Buddha Nagar (India)

    2001-07-01

    An existing formulation for steam properties is due to Irvine and Liley. Their equations are convenient to program and do not require excessive computational time to produce results. The properties computed from these equations compare favourably with standard data. An additional advantage of these equations is that they follow prescribed theoretical trends by reducing to perfect-gas behaviour away from the saturation dome. However, a difficulty with these equations is that, at pressures above 10 MPa and close to the saturation dome, unacceptably large errors (above 10%) are produced. These equations are examined in the present work with a view towards enhancing their range of application through the use of additional functions. It is shown that the errors may be reduced to within 1% over the entire range of pressures (both sub-critical and super-critical pressures) required in steam-plant calculations. (author)

  9. Electromagnetic Whistler Precursors at Supercritical Interplanetary Shocks

    Science.gov (United States)

    Wilson, L. B., III

    2012-01-01

    We present observations of electromagnetic precursor waves, identified as whistler mode waves, at supercritical interplanetary shocks using the Wind search coil magnetometer. The precursors propagate obliquely with respect to the local magnetic field, shock normal vector, solar wind velocity, and they are not phase standing structures. All are right-hand polarized with respect to the magnetic field (spacecraft frame), and all but one are right-hand polarized with respect to the shock normal vector in the normal incidence frame. Particle distributions show signatures of specularly reflected gyrating ions, which may be a source of free energy for the observed modes. In one event, we simultaneously observe perpendicular ion heating and parallel electron acceleration, consistent with wave heating/acceleration due to these waves.

  10. Gasification of cyanobacterial in supercritical water.

    Science.gov (United States)

    Zhang, Huiwen; Zhu, Wei; Xu, Zhirong; Gong, Miao

    2014-01-01

    Cyanobacterial collected from eutrophic freshwater lakes constituted intractable waste with a rich algae biomass content. Supercritical water gasification (SCWG) was proposed to treat the cyanobacterial and to produce hydrogen for energy. The H 2 yield reached 2.92 mol/kg at reaction conditions of 500 °C, 30 min and 22 MPa; this yield accounted for 26% of the total gaseous products. Abundant ammonia and dissolved reactive phosphorous were concentrated in the liquid product, which could be recovered and used as a liquid fertilizer. Solid residue, which accounted only for about 1% of the wet weight, was mainly composed of coke and ash. The efficiency of H 2 production was better than that from other biomass, because of the abundant organic matter in cyanobacterial. Thus, cyanobacterial are an ideal biomass feedstock for H 2 production from SCWG.

  11. Supercritical droplet combustion and related transport phenomena

    Science.gov (United States)

    Yang, Vigor; Hsieh, K. C.; Shuen, J. S.

    1993-01-01

    An overview of recent advances in theoretical analyses of supercritical droplet vaporization and combustion is conducted. Both hydrocarbon and cryogenic liquid droplets over a wide range of thermodynamic states are considered. Various important high-pressure effects on droplet behavior, such as thermodynamic non-ideality, transport anomaly, and property variation, are reviewed. Results indicate that the ambient gas pressure exerts significant control of droplet gasification and burning processes through its influence on fluid transport, gas-liquid interfacial thermodynamics, and chemical reactions. The droplet gasification rate increases progressively with pressure. However, the data for the overall burnout time exhibit a considerable change in the combustion mechanism at the criticl pressure, mainly as a result of reduced mass diffusivity and latent heat of vaporization with increased pressure. The influence of droplet size on the burning characteristics is also noted.

  12. Supercritical Antisolvent Precipitation of Microparticles of Quercetin

    Institute of Scientific and Technical Information of China (English)

    刘学武; 李志义; 韩冰; 苑塔亮

    2005-01-01

    Supercritical antisolvent (SAS) process is a recently developed technology to produce micro- and nanoparticles. This paper presents a continuous apparatus to conduct experiment of SAS process. With the apparatus,the effects of pressure, temperature and flow ratio of CO2 to the solution on the shape and size of particles are studied for the quercetin-ethanol-CO2 system. Spherical quercetin microparticles with diameters ranging form i μm to 6μm can be obtained while ethanol is used as organic solvent. The most effective fact on the shape and size of particles is pressure, the next is temperature and the last is the flow ratio of CO2 to solution.

  13. Etching of glass microchips with supercritical water.

    Science.gov (United States)

    Karásek, Pavel; Grym, Jakub; Roth, Michal; Planeta, Josef; Foret, František

    2015-01-07

    A novel method of etching channels in glass microchips with the most tunable solvent, water, was tested as an alternative to common hydrogen fluoride-containing etchants. The etching properties of water strongly depend on temperature and pressure, especially in the vicinity of the water critical point. The chips were etched at the subcritical, supercritical and critical temperature of water, and the resulting channel shape, width, depth and surface morphology were studied by scanning electron microscopy and 3D laser profilometry. Channels etched with the hot water were compared with the chips etched with standard hydrogen fluoride-containing solution. Depending on the water pressure and temperature, the silicate dissolved from the glass could be re-deposited on the channel surface. This interesting phenomenon is described together with the conditions necessary for its utilization. The results illustrate the versatility of pure water as a glass etching and surface morphing agent.

  14. Heat transfer in a vertical 7-element bundle cooled with supercritical Freon-12

    Energy Technology Data Exchange (ETDEWEB)

    Richards, G.; Milner, A.; Pascoe, C.; Patel, H.; Peiman, W.; Saltanov, Eu. [Univ. of Ontario Inst. of Tech., Faculty of Energy Systems and Nuclear Science, Oshawa, Ontario (Canada); Pometko, R.S.; Opanasenko, A.N. [Inst. of Physics and Power Engineering, Obninsk (Russian Federation); Shelegov, A.S. [IATE, Obninsk (Russian Federation); Kirillov, P.L. [Inst. of Physics and Power Engineering, Obninsk (Russian Federation); Pioro, I. [Univ. of Ontario Inst. of Tech., Faculty of Energy Systems and Nuclear Science, Oshawa, Ontario (Canada)

    2010-07-01

    Currently, SuperCritical Water-cooled nuclear Reactor (SCWR) concepts are being developed worldwide with an objective to increase thermal efficiencies of future Nuclear Power Plants (NPPs) on 10 -15% compared to those of current water-cooled NPPs. With such an increase in the thermal efficiencies, SCW NPPs will be at the current level of the most advanced thermal power plants: coal-fired SCW NPPs and combined-cycle gas-fired NPPs. However, to be able to develop SCWRs at least several key technical problems should be resolved. One of these problems is limited amount of experimental data on heat transfer in fuel bundles and based on that SCW heat-transfer correlations. Experiments in SCW are very complicated and expensive due to high critical parameters of water (pressure 22.064 MPa and temperature 374.95°C). Moreover, there are only few SCW test rigs, which capable to perform experiments in full-scale bundles. As a preliminary approach supercritical-pressure heat-transfer experiments in bundles can be performed in modeling fluids such as Freons or carbon dioxide. Therefore, a set of experimental data was obtained in Freon-12-cooled bundle simulator at the Institute of Physics and Power Engineering (IPPE, Obninsk, Russia). A vertical 7-element bundle was installed in a hexagonal flow channel. The test section consisted of elements that were 9.5 mm in diameter with the total heated length of 1 m. Bulk-fluid and wall temperature profiles were recorded using thermocouples. Several heat-transfer regimes were tested. Also, this paper references thermophysical properties of supercritical Freon-12 at the critical pressure (4.1361 MPa) and test pressure of 4.65 MPa. (author)

  15. Supercritical water oxidation of landfill leachate.

    Science.gov (United States)

    Wang, Shuzhong; Guo, Yang; Chen, Chongming; Zhang, Jie; Gong, Yanmeng; Wang, Yuzhen

    2011-01-01

    In this paper, ammonia as an important ingredient in landfill leachate was mainly studied. Based on Peng-Robinson formulations and Gibbs free energy minimization method, the estimation of equilibrium composition and thermodynamic analysis for supercritical water oxidation of ammonia (SCWO) was made. As equilibrium is reached, ammonia could be totally oxidized in SCW. N(2) is the main product, and the formation of NO(2) and NO could be neglected. The investigation on SCWO of landfill leachate was conducted in a batch reactor at temperature of 380-500 °C, reaction time of 50-300s and pressure of 25 MPa. The effect of reaction parameters such as oxidant equivalent ratio, reaction time and temperature were investigated. The results showed that COD and NH(3) conversion improved as temperature, reaction time and oxygen excess increased. Compared to organics, NH(3) is a refractory compound in supercritical water. The conversion of COD and NH(3) were higher in the presence of MnO(2) than that without catalyst. The interaction between reaction temperature and time was analyzed by using response surface method (RSM) and the results showed that its influence on the NH(3) conversion was relatively insignificant in the case without catalyst. A global power-law rate expression was regressed from experimental data to estimate the reaction rate of NH(3). The activation energy with and without catalyst for NH(3) oxidation were 107.07 ± 8.57 kJ/mol and 83.22 ± 15.62 kJ/mol, respectively.

  16. Selective Extraction of Uranium from Liquid or Supercritical Carbon Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Farawila, Anne F.; O' Hara, Matthew J.; Wai, Chien M.; Taylor, Harry Z.; Liao, Yu-Jung

    2012-07-31

    Current liquid-liquid extraction processes used in recycling irradiated nuclear fuel rely on (1) strong nitric acid to dissolve uranium oxide fuel, and (2) the use of aliphatic hydrocarbons as a diluent in formulating the solvent used to extract uranium. The nitric acid dissolution process is not selective. It dissolves virtually the entire fuel meat which complicates the uranium extraction process. In addition, a solvent washing process is used to remove TBP degradation products, which adds complexity to the recycling plant and increases the overall plant footprint and cost. A liquid or supercritical carbon dioxide (l/sc -CO2) system was designed to mitigate these problems. Indeed, TBP nitric acid complexes are highly soluble in l/sc -CO2 and are capable of extracting uranium directly from UO2, UO3 and U3O8 powders. This eliminates the need for total acid dissolution of the irradiated fuel. Furthermore, since CO2 is easily recycled by evaporation at room temperature and pressure, it eliminates the complex solvent washing process. In this report, we demonstrate: (1) A reprocessing scheme starting with the selective extraction of uranium from solid uranium oxides into a TBP-HNO3 loaded Sc-CO2 phase, (2) Back extraction of uranium into an aqueous phase, and (3) Conversion of recovered purified uranium into uranium oxide. The purified uranium product from step 3 can be disposed of as low level waste, or mixed with enriched uranium for use in a reactor for another fuel cycle. After an introduction on the concept and properties of supercritical fluids, we first report the characterization of the different oxides used for this project. Our extraction system and our online monitoring capability using UV-Vis absorbance spectroscopy directly in sc-CO2 is then presented. Next, the uranium extraction efficiencies and kinetics is demonstrated for different oxides and under different physical and chemical conditions: l/sc -CO2 pressure and temperature, TBP/HNO3 complex used

  17. Universal Expression of Efficiency at Maximum Power: A Quantum-Mechanical Brayton Engine Working with a Single Particle Confined in a Power-Law Trap

    Science.gov (United States)

    Ye, Zhuo-Lin; Li, Wei-Sheng; Lai, Yi-Ming; He, Ji-Zhou; Wang, Jian-Hui

    2015-12-01

    We propose a quantum-mechanical Brayton engine model that works between two superposed states, employing a single particle confined in an arbitrary power-law trap as the working substance. Applying the superposition principle, we obtain the explicit expressions of the power and efficiency, and find that the efficiency at maximum power is bounded from above by the function: η+ = θ/(θ + 1), with θ being a potential-dependent exponent. Supported by the National Natural Science Foundation of China under Grant Nos. 11505091, 11265010, and 11365015, and the Jiangxi Provincial Natural Science Foundation under Grant No. 20132BAB212009

  18. Supercritical CO2 assisted process for the production of high-purity and sterile nano-hydroxyapatite/chitosan hybrid scaffolds.

    Science.gov (United States)

    Ruphuy, G; Souto-Lopes, M; Paiva, D; Costa, P; Rodrigues, A E; Monteiro, F J; Salgado, C L; Fernandes, M H; Lopes, J C; Dias, M M; Barreiro, M F

    2017-05-04

    Hybrid scaffolds composed of hydroxyapatite (HAp), in particular in its nanometric form (n-HAp), and chitosan (CS) are promising materials for non-load-bearing bone graft applications. The main constraints of their production concern the successful implementation of the final purification/neutralization and sterilization steps. Often, the used purification strategies can compromise scaffold structural features, and conventional sterilization techniques can result in material's thermal degradation and/or contamination with toxic residues. In this context, this work presents a process to produce n-HAp/CS scaffolds mimicking bone composition and structure, where an innovative single step based on supercritical CO2 extraction was used for both purification and sterilization. A removal of 80% of the residual acetic acid was obtained (T = 75°C, p = 8.0 MPa, 2 extraction cycles of 2 h) giving rise to scaffolds exhibiting adequate interconnected porous structure, fast swelling and storage modulus compatible with non-load-bearing applications. Moreover, the obtained scaffolds showed cytocompatibility and osteoconductivity without further need of disinfection/sterilization procedures. Among the main advantages, the proposed process comprises only three steps (n-HAp/CS dispersion preparation; freeze-drying; and supercritical CO2 extraction), and the supercritical CO2 extraction show clear advantages over currently used procedures based on neutralization steps. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

  19. Preliminary Design of In-Pile Supercritical Pressurized Water Test Loop

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Based on two proven technologies, current light water reactors (LWRs) and the supercritical coal-fired power plants, the supercritical water-cooled reactor (SCWR) is one of the six Generation-Ⅳ

  20. SUPERCRITICAL FLUID EXTRACTION OF POLYCYCLIC AROMATIC HYDROCARBON MIXTURES FROM CONTAMINATED SOILS

    Science.gov (United States)

    Highly contaminated (with PAHs) topsoils were extracted with supercritical CO2 to determine the feasibility and mechanism of supercritical fluid extraction (SFE). Effect of SCF density, temperature, cosolvent type and amount, and of slurrying the soil with water were ...

  1. Steam-Reheat Option for Supercritical-Water-Cooled Reactors

    Science.gov (United States)

    Saltanov, Eugene

    SuperCritical-Water-cooled Reactors (SCWRs) are being developed as one of the Generation-IV nuclear-reactor concepts. Main objectives of the development are to increase thermal efficiency of a Nuclear Power Plant (NPP) and to decrease capital and operational costs. The first objective can be achieved by introducing nuclear steam reheat inside a reactor and utilizing regenerative feedwater heaters. The second objective can be achieved by designing a steam cycle that closely matches that of the mature supercritical fossil-fuelled power plants. The feasibility of these objectives is discussed. As a part of this discussion, heat-transfer calculations have been performed and analyzed for SuperCritical-Water (SCW) and SuperHeated-Steam (SHS) channels of the proposed reactor concept. In the calculations a uniform and three non-uniform Axial Heat Flux Profiles (AHFPs) were considered for six different fuels (UO2, ThO 2, MOX, UC2, UC, and UN) and at average and maximum channel power. Bulk-fluid, sheath, and fuel centerline temperatures as well as the Heat Transfer Coefficient (HTC) profiles were obtained along the fuel-channel length. The HTC values are within a range of 4.7--20 kW/m2·K and 9.7--10 kW/m2·K for the SCW and SHS channels respectively. The main conclusion is that while all the mentioned fuels may be used for the SHS channel, only UC2, UC, or UN are suitable for a SCW channel, because their fuel centerline temperatures are at least 1000°C below melting point, while that of UO2, ThO2 , and MOX may reach melting point.

  2. Coating properties of a novel water stationary phase in capillary supercritical fluid chromatography.

    Science.gov (United States)

    Murakami, Jillian N; Thurbide, Kevin B

    2015-05-01

    The coating properties of a novel water stationary phase used in capillary supercritical fluid chromatography were investigated. The findings confirm that increasing the length or internal diameter of the type 316 stainless-steel column used provides a linear increase in the volume of stationary phase present. Under normal operating conditions, results indicate that about 4.9 ± 0.5 μL/m of water phase is deposited uniformly inside of a typical 250 μm internal diameter 316 stainless-steel column, which translates to an area coverage of about 6.3 ± 0.5 nL/mm(2) regardless of dimension. Efforts to increase the stationary phase volume present showed that etching the stainless-steel capillary wall using hydrofluoric acid was very effective for this. For instance, after five etching cycles, this volume doubled inside of both the type 304 and the type 316 stainless-steel columns examined. This in turn doubled analyte retention, while maintaining good peak shape and column efficiency. Overall, 316 stainless-steel columns were more resistant to etching than 304 stainless-steel columns. Results indicate that this approach could be useful to employ as a means of controlling the volume of water stationary phase that can be established inside of the stainless-steel columns used with this supercritical fluid chromatography technique.

  3. Heat Load Estimator for Smoothing Pulsed Heat Loads on Supercritical Helium Loops

    Science.gov (United States)

    Hoa, C.; Lagier, B.; Rousset, B.; Bonnay, P.; Michel, F.

    Superconducting magnets for fusion are subjected to large variations of heat loads due to cycling operation of tokamaks. The cryogenic system shall operate smoothly to extract the pulsed heat loads by circulating supercritical helium into the coils and structures. However the value of the total heat loads and its temporal variation are not known before the plasma scenario starts. A real-time heat load estimator is of interest for the process control of the cryogenic system in order to anticipate the arrival of pulsed heat loads to the refrigerator and finally to optimize the operation of the cryogenic system. The large variation of the thermal loads affects the physical parameters of the supercritical helium loop (pressure, temperature, mass flow) so those signals can be used for calculating instantaneously the loads deposited into the loop. The methodology and algorithm are addressed in the article for estimating the heat load deposition before it reaches the refrigerator. The CEA patented process control has been implemented in a Programmable Logic Controller (PLC) and has been successfully validated on the HELIOS test facility at CEA Grenoble. This heat load estimator is complementary to pulsed load smoothing strategies providing an estimation of the optimized refrigeration power. It can also effectively improve the process control during the transient between different operating modes by adjusting the refrigeration power to the need. This way, the heat load estimator participates to the safe operation of the cryogenic system.

  4. Industrial applications and current trends in supercritical fluid technologies

    Directory of Open Access Journals (Sweden)

    Gamse Thomas

    2005-01-01

    Full Text Available Supercritical fluids have a great potential for wide fields of processes Although CO2 is still one of the most used supercritical gases, for special purposes propane or even fluorinated-chlorinated fluids have also been tested. The specific characteristics of supercritical fluids behaviour were analyzed such as for example the solubilities of different components and the phase equilibria between the solute and solvent. The application at industrial scale (decaffeinating of tea and coffee, hop extraction or removal of pesticides from rice, activity in supercritical extraction producing total extract from the raw material or different fractions by using the fractionated separation of beverages (rum, cognac, whisky, wine, beer cider, of citrus oils and of lipids (fish oils, tall oil were also discussed. The main interest is still for the extraction of natural raw materials producing food ingredients, nutraceuticals and phytopharmaceuticals but also cleaning purposes were tested such as the decontamination of soils the removal of residual solvents from pharmaceutical products, the extraction of flame retardants from electronic waste or precision degreasing and cleaning of mechanical and electronic parts. An increasing interest obviously exists for impregnation purposes based on supercritical fluids behaviour, as well as for the dying of fibres and textiles. The production of fine particles in the micron and submicron range, mainly for pharmaceutical products is another important application of supercritical fluids. Completely new products can be produced which is not possible under normal conditions. Supercritical fluid technology has always had to compete with the widespread opinion that these processes are very expensive due to very high investment costs in comparison with classical low-pressure equipment. Thus the opinion is that these processes should be restricted to high-added value products. A cost estimation for different plant sizes and

  5. Supercritical fluid reactions for coal processing. Quarterly progress report, April 1, 1996--June 30, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Eckert, C.A.

    1996-11-01

    Exciting opportunities exist for the application of supercritical fluid (SCF) reactions for the pre-treatment of coal. Utilizing reactants which resemble the organic nitrogen containing components of coal, we propose to develop a method to tailor chemical reactions in supercritical fluid solvents for the specific application of coal denitrogenation. The tautomeric equilibrium of a Schiff base was chosen as the model system and was investigated in supercritical ethane and cosolvent modified supercritical ethane.

  6. Supercritical fluid reactions for coal processing. Quarterly report, January 1, 1996--March 31, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Eckert, C.A.

    1996-10-01

    Exciting opportunities exist for the application of supercritical fluid (SCF) reactions for the pre-treatment of coal. Utilizing reactants which resemble the organic nitrogen containing components of coal, we propose to develop a method to tailor chemical reactions in supercritical fluid solvents for the specific application of coal denitrogenation. The tautomeric equilibrium of a Schiff base was chosen as the model system and was investigated in supercritical ethane and cosolvent modified supercritical ethane.

  7. Supercritical Carbon Dioxide Power Generation System Definition: Concept Definition and Capital Cost Estimate

    Energy Technology Data Exchange (ETDEWEB)

    Stoddard, Larry [Black & Veatch, Kansas City, MO (United States); Galluzzo, Geoff [Black & Veatch, Kansas City, MO (United States); Andrew, Daniel [Black & Veatch, Kansas City, MO (United States); Adams, Shannon [Black & Veatch, Kansas City, MO (United States)

    2016-06-30

    The Department of Energy’s (DOE’s) Office of Renewable Power (ORP) has been tasked to provide effective program management and strategic direction for all of the DOE’s Energy Efficiency & Renewable Energy’s (EERE’s) renewable power programs. The ORP’s efforts to accomplish this mission are aligned with national energy policies, DOE strategic planning, EERE’s strategic planning, Congressional appropriation, and stakeholder advice. ORP is supported by three renewable energy offices, of which one is the Solar Energy Technology Office (SETO) whose SunShot Initiative has a mission to accelerate research, development and large scale deployment of solar technologies in the United States. SETO has a goal of reducing the cost of Concentrating Solar Power (CSP) by 75 percent of 2010 costs by 2020 to reach parity with base-load energy rates, and 30 percent further reductions by 2030. The SunShot Initiative is promoting the implementation of high temperature CSP with thermal energy storage allowing generation during high demand hours. The SunShot Initiative has funded significant research and development work on component testing, with attention to high temperature molten salts, heliostats, receiver designs, and high efficiency high temperature supercritical CO2 (sCO2) cycles. DOE retained Black & Veatch to support SETO’s SunShot Initiative for CSP solar power tower technology in the following areas: 1. Concept definition, including costs and schedule, of a flexible test facility to be used to test and prove components in part to support financing. 2. Concept definition, including costs and schedule, of an integrated high temperature molten salt (MS) facility with thermal energy storage and with a supercritical CO2 cycle generating approximately 10MWe. 3. Concept definition, including costs and schedule, of an integrated high temperature falling particle facility with thermal energy storage and with a supercritical CO2 cycle

  8. Topics in Chemical Instrumentation--An Introduction to Supercritical Fluid Chromatography: Part 1: Principles and Instrumentation.

    Science.gov (United States)

    Palmieri, Margo D.

    1988-01-01

    Identifies the properties and characteristics of supercritical fluids. Discusses the methodology for supercritical fluid chromatography including flow rate, plate height, column efficiency, viscosity, and other factors. Reviews instruments, column types, and elution conditions. Lists supercritical fluid data for 22 compounds, mostly organic. (MVL)

  9. Reaction kinetics of cellulose hydrolysis in subcritical and supercritical water

    Science.gov (United States)

    Olanrewaju, Kazeem Bode

    The uncertainties in the continuous supply of fossil fuels from the crisis-ridden oil-rich region of the world is fast shifting focus on the need to utilize cellulosic biomass and develop more efficient technologies for its conversion to fuels and chemicals. One such technology is the rapid degradation of cellulose in supercritical water without the need for an enzyme or inorganic catalyst such as acid. This project focused on the study of reaction kinetics of cellulose hydrolysis in subcritical and supercritical water. Cellulose reactions at hydrothermal conditions can proceed via the homogeneous route involving dissolution and hydrolysis or the heterogeneous path of surface hydrolysis. The work is divided into three main parts. First, the detailed kinetic analysis of cellulose reactions in micro- and tubular reactors was conducted. Reaction kinetics models were applied, and kinetics parameters at both subcritical and supercritical conditions were evaluated. The second major task was the evaluation of yields of water soluble hydrolysates obtained from the hydrolysis of cellulose and starch in hydrothermal reactors. Lastly, changes in molecular weight distribution due to hydrothermolytic degradation of cellulose were investigated. These changes were also simulated based on different modes of scission, and the pattern generated from simulation was compared with the distribution pattern from experiments. For a better understanding of the reaction kinetics of cellulose in subcritical and supercritical water, a series of reactions was conducted in the microreactor. Hydrolysis of cellulose was performed at subcritical temperatures ranging from 270 to 340 °C (tau = 0.40--0.88 s). For the dissolution of cellulose, the reaction was conducted at supercritical temperatures ranging from 375 to 395 °C (tau = 0.27--0.44 s). The operating pressure for the reactions at both subcritical and supercritical conditions was 5000 psig. The results show that the rate-limiting step in

  10. Menstrual Cycle

    Science.gov (United States)

    ... Luteal (after egg release) Changes During the Menstrual Cycle The menstrual cycle is regulated by the complex interaction of ... egg release) Luteal (after egg release) The menstrual cycle begins with menstrual bleeding (menstruation), which marks the first day of ...

  11. Supercritical fluid processing: opportunities for new resist materials and processes

    Science.gov (United States)

    Gallagher-Wetmore, Paula M.; Ober, Christopher K.; Gabor, Allen H.; Allen, Robert D.

    1996-05-01

    Over the past two decades supercritical fluids have been utilized as solvents for carrying out separations of materials as diverse as foods, polymers, pharmaceuticals, petrochemicals, natural products, and explosives. More recently they have been used for non-extractive applications such as recrystallization, deposition, impregnation, surface modification, and as a solvent alternative for precision parts cleaning. Today, supercritical fluid extraction is being practiced in the foods and beverage industries; there are commercial plants for decaffeinating coffee and tea, extracting beer flavoring agents from hops, and separating oils and oleoresins from spices. Interest in supercritical fluid processing of polymers has grown over the last ten years, and many new purification, fractionation, and even polymerization techniques have emerged. One of the most significant motivations for applying this technology to polymers has been increased performance demands. More recently, with increasing scrutiny of traditional solvents, supercritical fluids, and in particular carbon dioxide, are receiving widespread attention as 'environmentally conscious' solvents. This paper describes several examples of polymers applications, including a few involving photoresists, which demonstrate that as next- generation advanced polymer systems emerge, supercritical fluids are certain to offer advantages as cutting edge processing tools.

  12. Experimental study of elliptical jet from sub to supercritical conditions

    Science.gov (United States)

    Muthukumaran, C. K.; Vaidyanathan, Aravind

    2014-04-01

    The jet mixing at supercritical conditions involves fluid dynamics as well as thermodynamic phenomena. All the jet mixing studies at critical conditions to the present date have focused only on axisymmetric jets. When the liquid jet is injected into supercritical environment, the thermodynamic transition could be well understood by considering one of the important fluid properties such as surface tension since it decides the existence of distinct boundary between the liquid and gaseous phase. It is well known that an elliptical liquid jet undergoes axis-switching phenomena under atmospheric conditions due to the presence of surface tension. The experimental investigations were carried out with low speed elliptical jet under supercritical condition. Investigation of the binary component system with fluoroketone jet and N2 gas as environment shows that the surface tension force dominates for a large downstream distance, indicating delayed thermodynamic transition. The increase in pressure to critical state at supercritical temperature is found to expedite the thermodynamic transition. The ligament like structures has been observed rather than droplets for supercritical pressures. However, for the single component system with fluoroketone jet and fluoroketone environment shows that the jet disintegrates into droplets as it is subjected to the chamber conditions even for the subcritical pressures and no axis switching phenomenon is observed. For a single component system, as the pressure is increased to critical state, the liquid jet exhibits gas-gas like mixing behavior and that too without exhibiting axis-switching behavior.

  13. Experimental study of elliptical jet from sub to supercritical conditions

    Energy Technology Data Exchange (ETDEWEB)

    Muthukumaran, C. K.; Vaidyanathan, Aravind, E-mail: aravind7@iist.ac.in [Department of Aerospace Engineering, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India)

    2014-04-15

    The jet mixing at supercritical conditions involves fluid dynamics as well as thermodynamic phenomena. All the jet mixing studies at critical conditions to the present date have focused only on axisymmetric jets. When the liquid jet is injected into supercritical environment, the thermodynamic transition could be well understood by considering one of the important fluid properties such as surface tension since it decides the existence of distinct boundary between the liquid and gaseous phase. It is well known that an elliptical liquid jet undergoes axis-switching phenomena under atmospheric conditions due to the presence of surface tension. The experimental investigations were carried out with low speed elliptical jet under supercritical condition. Investigation of the binary component system with fluoroketone jet and N{sub 2} gas as environment shows that the surface tension force dominates for a large downstream distance, indicating delayed thermodynamic transition. The increase in pressure to critical state at supercritical temperature is found to expedite the thermodynamic transition. The ligament like structures has been observed rather than droplets for supercritical pressures. However, for the single component system with fluoroketone jet and fluoroketone environment shows that the jet disintegrates into droplets as it is subjected to the chamber conditions even for the subcritical pressures and no axis switching phenomenon is observed. For a single component system, as the pressure is increased to critical state, the liquid jet exhibits gas-gas like mixing behavior and that too without exhibiting axis-switching behavior.

  14. Extraction of metals using supercritical fluid and chelate forming legand

    Science.gov (United States)

    Wai, Chien M.; Laintz, Kenneth E.

    1998-01-01

    A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent is described. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated .beta.-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated .beta.-diketone and a trialkyl phosphate, or a fluorinated .beta.-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated .beta.-diketone and a trialkyl phosphate or a trialkylphosphine oxide tends to enhance the extraction efficiencies for actinides and lanthanides. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The method is particularly useful for extracting actinides and lanthanides from acidic solutions. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process.

  15. Extraction of metals using supercritical fluid and chelate forming ligand

    Science.gov (United States)

    Wai, C.M.; Laintz, K.E.

    1998-03-24

    A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent is described. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated {beta}-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated {beta}-diketone and a trialkyl phosphate, or a fluorinated {beta}-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated {beta}-diketone and a trialkyl phosphate or a trialkylphosphine oxide tends to enhance the extraction efficiencies for actinides and lanthanides. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The method is particularly useful for extracting actinides and lanthanides from acidic solutions. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process. 7 figs.

  16. Supercritical fluid extraction: Application in the food industry

    Directory of Open Access Journals (Sweden)

    Skala Dejan U.

    2002-01-01

    Full Text Available Supercritical fluid extraction is an extraction process realized with supercritical fluids, which are at a temperature and pressure above their critical temperature and critical pressure. This process has shown to be very efficient one for the isolation of different substances of medium molecular weights and molecules of relatively low polarity. The solubility of more polar substances in supercritical fluids can be improved by the addition of small amounts of other polar solvents (cosolvent to the supercritical fluids, which is the main solvent in extraction process. The advantage of supercritical extraction compared to other extraction procedures (the application of classical organic solvents hydrodistillation, distillation with steam is that SFE is usually performed at moderate temperature (e.g. with SF CO2 at 40-70°C so it can be applied for the separation of different substances which are thermally unstable and have a larger vapour pressure. All of these facts indicate that SFE is of special interest for the food and pharmaceutical industry.

  17. Oxidation behavior of Incoloy 800 under simulated supercritical water conditions

    Energy Technology Data Exchange (ETDEWEB)

    Fulger, M. [Institute for Nuclear Research Pitesti, POB 78, Campului Street, No. 1, 115400 Mioveni (Romania)], E-mail: manuela.fulger@nuclear.ro; Ohai, D.; Mihalache, M.; Pantiru, M. [Institute for Nuclear Research Pitesti, POB 78, Campului Street, No. 1, 115400 Mioveni (Romania); Malinovschi, V. [University of Pitesti, Research Center for Advanced Materials, Targul din Vale Street, No. 1, 110040 Pitesti (Romania)

    2009-03-31

    For a correct design of supercritical water-cooled reactor (SCWR) components, data regarding the behavior of candidate materials in supercritical water are necessary. Corrosion has been identified as a critical problem because the high temperature and the oxidative nature of supercritical water may accelerate the corrosion kinetics. The goal of this paper is to investigate the oxidation behavior of Incoloy 800 exposed in autoclaves under supercritical water conditions for up to 1440 h. The exposure conditions (thermal deaerated water, temperatures of 723, 773, 823 and 873 K and a pressure of 25 MPa) have been selected as relevant for a supercritical power plant concept. To investigate the structural changes of the oxide films, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX) and electrochemical impedance spectroscopy (EIS) analyses were used. Results show changes in the oxides chemical composition, microstructure and thickness versus testing conditions (pressure, temperature and time). The oxide films are composed of two layers: an outer layer enriched in Fe oxide and an inner layer enriched in Cr and Ni oxides corresponding to small cavities supposedly due to internal oxidation.

  18. Conceptual design of a thermalhydraulic loop for multiple test geometries at supercritical conditions named Supercritical Phenomena Experimental Test Apparatus (SPETA)

    Science.gov (United States)

    Adenariwo, Adepoju

    The efficiency of nuclear reactors can be improved by increasing the operating pressure of current nuclear reactors. Current CANDU-type nuclear reactors use heavy water as coolant at an outlet pressure of up to 11.5 MPa. Conceptual SuperCritical Water Reactors (SCWRs) will operate at a higher coolant outlet pressure of 25 MPa. Supercritical water technology has been used in advanced coal plants and its application proves promising to be employed in nuclear reactors. To better understand how supercritical water technology can be applied in nuclear power plants, supercritical water loops are used to study the heat transfer phenomena as it applies to CANDU-type reactors. A conceptual design of a loop known as the Supercritical Phenomena Experimental Apparatus (SPETA) has been done. This loop has been designed to fit in a 9 m by 2 m by 2.8 m enclosure that will be installed at the University of Ontario Institute of Technology Energy Research Laboratory. The loop include components to safely start up and shut down various test sections, produce a heat source to the test section, and to remove reject heat. It is expected that loop will be able to investigate the behaviour of supercritical water in various geometries including bare tubes, annulus tubes, and multi-element-type bundles. The experimental geometries are designed to match the fluid properties of Canadian SCWR fuel channel designs so that they are representative of a practical application of supercritical water technology in nuclear plants. This loop will investigate various test section orientations which are the horizontal, vertical, and inclined to investigate buoyancy effects. Frictional pressure drop effects and satisfactory methods of estimating hydraulic resistances in supercritical fluid shall also be estimated with the loop. Operating limits for SPETA have been established to be able to capture the important heat transfer phenomena at supercritical conditions. Heat balance and flow calculations have

  19. Chemistry and catalysis in supercritical media

    Energy Technology Data Exchange (ETDEWEB)

    Tumas, W.; Morgenstern, D.; Feng, S. [and others

    1997-07-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The aim of this research is to explore the potential of supercritical fluids as reaction media for stoichiometric and catalytic chemical transformations in an effort to develop new, environmentally-friendly methods for chemical synthesis or processing. This approach offers the possibility of opening up substantially different chemical pathways, increasing selectivity while enhancing reaction rates, facilitating downstream separations and mitigating the need for hazardous solvents. The authors describe investigations into a number of catalytic processes for which carbon dioxide represents a viable solvent replacement. In several cases they have observed significant enhancements in selectivity and/or reactivity relative to conventional organic solvents. They have investigated the following catalytic processes: (a) selective oxidation including dihydroxylation and epoxidation, (b) asymmetric hydrogenation and hydrogen transfer reduction, (c) Lewis acid catalyzed acylation and alkylation, and (c) coupling of amines with carbon dioxide to make isocyanates.

  20. Coal gasification with water under supercritical conditions

    Energy Technology Data Exchange (ETDEWEB)

    A.A. Vostrikov; S.A. Psarov; D.Yu. Dubov; O.N. Fedyaeva; M.Ya. Sokol [Russian Academy of Sciences, Novosibirsk (Russian Federastion). Kutateladze Institute of Thermophysics, Siberian Division

    2007-08-15

    The conversion of an array of coal particles in supercritical water (SCW) was studied in a semibatch reactor at a pressure of 30 MPa, 500-750{sup o}C, and a reaction time of 1-12 min. The bulk conversion, surface conversion, and random pore models were used to describe the conversion. The quantitative composition of reaction products was determined, and the dependence of the rate of reaction on the degree of coal conversion, reaction time, and reaction temperature was obtained on the assumption of a first-order reaction and the Arrhenius function. It was found that the gasification of coal under SCW conditions without the addition of oxidizing agents is a weakly endothermic process. The addition of CO{sub 2} to SCW decreased the rate of conversion and increased the yield of CO. It was found that, at a 90% conversion of the organic matter of coal (OMC) in a flow of SCW in a time of 2 min, the process power was 26 W/g per gram of OMC.

  1. Kinetics of coal conversion in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Anatoli A. Vostrikov; Sergey A. Psarov; Dmitri Yu. Dubov; Oxana N. Fedyaeva; Mikhail Ya. Sokol [Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation). Institute of Thermophysics

    2007-09-15

    Conversion of the coal particle pack in supercritical water (SCW) was studied in the semibatch reactor under the pressure of P = 30 MPa, in the temperature range of T = 500-750{sup o}C, and in the reaction time of t = 60-720 s. The experimental results were analyzed within the framework of homogeneous, nonreacted core, and random pore models. The quantitative composition of conversion products was determined. Dependences of the conversion rate on the degree of coal conversion, reaction time, and temperature were described in an assumption of the first-order reaction and Arrhenius dependence. It was found that activation energy of conversion is E = 103 kJ/mol and the pre-exponential factor is A{sub 0} = 1.3 x 10{sup 3.1} s{sup -1}. It was revealed that coal gasification in SCW without oxidants is the weakly endothermic process. The addition of CO{sub 2} into SCW decreases the conversion rate and increases the CO yield. 20 refs., 8 figs.

  2. Supercritical fluids technology for clean biofuel production

    Institute of Scientific and Technical Information of China (English)

    Dongsheng Wen; H.Jiang; Kai Zhang

    2009-01-01

    Biofuels are liquid or gaseous fuels that are predominantly produced from biomass for transport sector applications.As biofuels are renewable,sustainable,carbon neutral and environmentally benign,they have been proposed as promising alternative fuels for gasoline and diesel engines.This paper reviews state-of-the-art application of the supercritical fluid(SCF)technique in biofuels production that includes biodiesel from vegetable oils via the transesterification process,bio-hydrogen from the gasification and bio-oil from the lique-faction of biomass,with biodiesel production as the main focus. The global biofuel situation and biofuel economics are also reviewed.The SCF has been shown to be a promising technique for future large-scale biofuel production,especially for biodiesel production from waster oil and fat.Compared with conventional biofuel production methods,the SCF technology possesses a number of advantages that includes fast inetics,high fuel production rate,ease of continuous operation and elimination of the necessity of catalysts.The harsh operation environment,i.e. the high temperature and high pressure,and its request on the materials and associated cost are the main concerns for its wide application.

  3. Some Organic Reactions in Supercritical Carbon Dioxide

    Institute of Scientific and Technical Information of China (English)

    JIANG Huan-feng; YANG Xiao-yue; LI Guo-ping; ZOU Gang

    2004-01-01

    Organic reactions in supercritical carbon dioxide (scCO2) have facilitated great progress in recent years 1. ScCO2, as an environmentally friendly reaction medium, may be a substitute for volatile and toxic organic solvents and show some special advantages. Firstly, CO2 is inexpensive,nonflammable, nontoxic and chemical inert under many conditions. Secondly, scCO2 possesses hybrid properties of both liquid and gas, to the advantage of some reactions involving gaseous reagents. Control of the solvent density by variation of the temperature and pressure enables the solvent properties to be "tuned" to reactants. Finally, separating of CO2 from the reaction mixture is energy-efficient and simple. Here we disclose our new work on some organic reactions involving small molecules in scCO2.The results showed that the upper reactions in scCO2 could be carried out smoothly and thepressure of CO2 had a remarkable effect on the conversion and selectivity.

  4. Towards Overhauser DNP in supercritical CO2

    Science.gov (United States)

    van Meerten, S. G. J.; Tayler, M. C. D.; Kentgens, A. P. M.; van Bentum, P. J. M.

    2016-06-01

    Overhauser Dynamic Nuclear Polarization (ODNP) is a well known technique to improve NMR sensitivity in the liquid state, where the large polarization of an electron spin is transferred to a nucleus of interest by cross-relaxation. The efficiency of the Overhauser mechanism for dipolar interactions depends critically on fast local translational dynamics at the timescale of the inverse electron Larmor frequency. The maximum polarization enhancement that can be achieved for 1H at high magnetic fields benefits from a low viscosity solvent. In this paper we investigate the option to use supercritical CO2 as a solvent for Overhauser DNP. We have investigated the diffusion constants and longitudinal nuclear relaxation rates of toluene in high pressure CO2. The change in 1H T1 by addition of TEMPO radical was analyzed to determine the Overhauser cross-relaxation in such a mixture, and is compared with calculations based on the Force Free Hard Sphere (FFHS) model. By analyzing the relaxation data within this model we find translational correlation times in the range of 2-4 ps, depending on temperature, pressure and toluene concentration. Such short correlation times may be instrumental for future Overhauser DNP applications at high magnetic fields, as are commonly used in NMR. Preliminary DNP experiments have been performed at 3.4 T on high pressure superheated water and model systems such as toluene in high pressure CO2.

  5. The Supercritical Pile Model for GRBs

    Science.gov (United States)

    Kazanas, Demos

    2006-01-01

    We present the spectral and temporal radiative signatures expected within the Supercritical Pile model of Gamma Ray Bursts (GRB). This model is motivated by the need for a process that provides the dissipation necessary in GRB and presents a well defined scheme for converting the energy stored in the relativistic protons of the Relativistic Blast Waves (RBW) associated with GRB into radiation; at the same time it leads to spectra which exhibit a peak in the burst nuF(sub nu) distribution at an energy E(sub p) approximately equal to 1 MeV in the observer s frame, in agreement with observation and largely independent of the Lorentz factor GAMMA of the associated relativistic outflow. Furthermore, this scheme does not require (but does not preclude) acceleration of particles at the shock other than that provided by the isotropization of the flow bulk kinetic energy on the RBW frame. In the present paper we model in detail the evolution of protons, electrons and photons from a RBW to produce detailed spectra of the prompt GRB phase as a function of time from across a very broad range spanning roughly 4 log10 GAMMA decades in frequency. The model spectra are in general agreement with observations and provide a means for the delineating of the model parameters through direct comparison with trends observed in GRB properties.

  6. Towards Overhauser DNP in supercritical CO2.

    Science.gov (United States)

    van Meerten, S G J; Tayler, M C D; Kentgens, A P M; van Bentum, P J M

    2016-06-01

    Overhauser Dynamic Nuclear Polarization (ODNP) is a well known technique to improve NMR sensitivity in the liquid state, where the large polarization of an electron spin is transferred to a nucleus of interest by cross-relaxation. The efficiency of the Overhauser mechanism for dipolar interactions depends critically on fast local translational dynamics at the timescale of the inverse electron Larmor frequency. The maximum polarization enhancement that can be achieved for (1)H at high magnetic fields benefits from a low viscosity solvent. In this paper we investigate the option to use supercritical CO2 as a solvent for Overhauser DNP. We have investigated the diffusion constants and longitudinal nuclear relaxation rates of toluene in high pressure CO2. The change in (1)H T1 by addition of TEMPO radical was analyzed to determine the Overhauser cross-relaxation in such a mixture, and is compared with calculations based on the Force Free Hard Sphere (FFHS) model. By analyzing the relaxation data within this model we find translational correlation times in the range of 2-4ps, depending on temperature, pressure and toluene concentration. Such short correlation times may be instrumental for future Overhauser DNP applications at high magnetic fields, as are commonly used in NMR. Preliminary DNP experiments have been performed at 3.4T on high pressure superheated water and model systems such as toluene in high pressure CO2.

  7. Digested sewage sludge gasification in supercritical water.

    Science.gov (United States)

    Zhai, Yunbo; Wang, Chang; Chen, Hongmei; Li, Caiting; Zeng, Guangming; Pang, Daoxiong; Lu, Pei

    2013-04-01

    Digested sewage sludge gasification in supercritical water was studied. Influences of main reaction parameters, including temperature (623-698 K), pressure (25-35 Mpa), residence time (10-15 min) and dry matter content (5-25 wt%), were investigated to optimize the gasification process. The main gas products were methane, carbon monoxide, carbon dioxide and traces of ethene, etc. Results showed that 10 wt% dry matter content digested sewage sludge at a temperature of 698 K and residence time of 50 min, with a pressure of 25 MPa, were the most favorable conditions for the sewage sludge gasification and carbon gasification efficiencies. In addition, potassium carbonate (K2CO3) was also employed as the catalyst to make a comparison between gasification with and without catalyst. When 2.6 g K2CO3 was added, a gasification efficiency of 25.26% and a carbon gasification efficiency of 20.02% were achieved, which were almost four times as much as the efficiencies without catalyst. K2CO3 has been proved to be effective in sewage sludge gasification.

  8. Welding immiscible polymers with a supercritical fluid.

    Science.gov (United States)

    Wang, Xiaochu; Sanchez, Isaac C

    2007-11-20

    Polymer adhesion between two immiscible polymers is usually poor because there is little interpenetration of one polymer into the other at the interface. Increasing the width of the interfacial zone can enhance adhesion and mechanical properties. In principle, this can be accomplished by exposing heterogeneous polymer materials to a high-pressure fluid. The fluid can act as a common solvent and promote interpenetration. It also increases chain mobility at the interface, which helps to promote "welding" of the two polymers. A combination of the gradient theory of inhomogeneous systems and the Sanchez-Lacombe equation of state was used to investigate this phenomenon, especially the effect of the high compressibility of supercritical (SC) fluid on the compatibilization of two incompatible polymers. We calculate the interfacial density profile, interfacial thickness, and interfacial tension between the two polymers with and without the SC fluid. We find that the interfacial tension is decreased and the interfacial thickness is increased with high-pressure SC fluid for the ternary systems we have investigated. As the critical point is approached and the SC compressibility becomes large, no enhancement or deleterious effects on compatibilization were observed.

  9. Supercritical carbon dioxide extraction of electrolyte from spent lithium ion batteries and its characterization by gas chromatography with chemical ionization

    Science.gov (United States)

    Mönnighoff, Xaver; Friesen, Alex; Konersmann, Benedikt; Horsthemke, Fabian; Grützke, Martin; Winter, Martin; Nowak, Sascha

    2017-06-01

    The aging products of the electrolyte from a commercially available state-of-the-art 18650-type cell were investigated. During long term cycling a huge difference in their performance and lifetime at different temperatures was observed. By interpretation of a strong capacity fading of cells cycled at 20 °C compared to cells cycled at 45 °C a temperature depending aging mechanism was determined. To investigate the influence of the electrolyte on this fading, the electrolyte was extracted by supercritical fluid extraction (SFE) and then analyzed by gas chromatography (GC) with electron impact (EI) ionization and mass selective detection. To obtain more information with regard to the identification of unknown decomposition products further analysis with positive chemical ionization (PCI) and negative chemical ionization (NCI) was performed. 17 different volatile organic aging products were detected and identified. So far, seven of them were not yet known in literature and several formation pathways were postulated taking previously published literature into account.

  10. Synthesis of biodiesel from edible and non-edible oils in supercritical alcohols and enzymatic synthesis in supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Vivek Rathore; Giridhar Madras [Indian Institute of Science, Bangalore (India). Department of Chemical Engineering

    2007-12-15

    Biodiesel is an attractive alternative fuel because it is environmentally friendly and can be synthesized from edible and non-edible oils. The synthesis of biodiesel from edible oils like palm oil and groundnut oil and from crude non-edible oils like Pongamia pinnata and Jatropha curcas was investigated in supercritical methanol and ethanol without using any catalyst from 200 to 400{sup o}C at 200 bar. The variables affecting the conversion during transesterification, such as molar ratio of alcohol to oil, temperature and time were investigated in supercritical methanol and ethanol. Biodiesel was also synthesized enzymatically with Novozym-435 lipase in presence of supercritical carbon dioxide. The effect of reaction variables such as temperature, molar ratio, enzyme loading and kinetics of the reaction was investigated for enzymatic synthesis in supercritical carbon dioxide. Very high conversions (>80%) were obtained within 10 min and nearly complete conversions were obtained at within 40 min for the synthesis of biodiesel in supercritical alcohols. However, conversions of only 60-70% were obtained in the enzymatic synthesis even after 8 h. 48 refs., 8 figs., 1 tab.

  11. A high-efficiency power cycle in which hydrogen is compressed by absorption in metal hydrides.

    Science.gov (United States)

    Powell, J R; Salzano, F J; Yu, W S; Milau, J S

    1976-07-23

    A high-efficiency power cycle is proposed in which molecular hydrogen gas is used as a working fluid in a regenerative closed Brayton cycle. The hydrogen gas is compressed by an absorption-desorption cycle on metal hydride (FeTiH(x)) beds. Low-temperature solar or geothermal heat (temperature about 100 degrees C) is used for the compression process, and high-temperature fossil fuel or nuclear heat (temperature about 700 degrees C) supplies the expansion work in the turbine. Typically, about 90 percent of the high-temperature heat input is converted to electricity, while about 3 kilowatts of low-temperature heat is required per kilowatt of electrical output.

  12. Producing Polymer Fibers by Electrospinning in Supercritical Fluids

    Directory of Open Access Journals (Sweden)

    Lu Li

    2013-01-01

    Full Text Available Nanofibers have a wide range of applications, including filtration and biomedical engineering. Porous or hollow fibers with large surface-to-volume ratios are more popular in some fields than the common nanofibers. Porous nanofibers can be obtained through electrospinning with highly volatile solvents or through special treatment following electrospinning. A new process where electrospinning is conducted in supercritical or near-critical CO2 to produce porous or hollow nanofibers has been summarized. In addition, a process entailing compressed N2-assisted electrospinning was attempted to produce PVP nanofibers in this work, but it was proved to be unsuccessful. Since the fiber morphologies are dependent on the phase behavior of organic solvents in supercritical fluids, ASPEN PLUS 2006 was used to simulate the phase equilibrium of the solvent-supercritical fluid system to explain why porous or hollow fibers can be obtained in compressed CO2, but not in compressed N2.

  13. Research Progress on Preparation of Graphene by Supercritical Fluid Exfoliation

    Directory of Open Access Journals (Sweden)

    HU Sheng-fei

    2017-03-01

    Full Text Available As a new type of two-dimensional carbonaceous material, graphene has excellent physical properties and great application potential. The key problem to realize graphene industrialization is to find a large-scale preparing method of graphene with high quality and low cost. In this paper, the advantages and disadvantages of preparation methods for graphene were first reviewed, and then the mechanism, research status and characterization methods of supercritical fluids exfoliated method were introduced in details. And the features of supercritical fluids exfoliated method with the assistance of ultrasonication and pyrene-polymers were summarized. The advantages of supercritical fluids exfoliated method are simple equipment, processing conditions easy to achieve and products with high quality, and a new way of thinking for the industrial production of graphene is provided.

  14. Biodiesel fuel from rapeseed oil as prepared in supercritical methanol

    Energy Technology Data Exchange (ETDEWEB)

    Saka, S.; Kusdiana, D. [Kyoto University, Kyoto (Japan). Dept. of Socio-Environmental Energy Science, Graduate School of Energy Science

    2001-01-01

    Transesterification reaction of rapeseed oil in supercritical methanol was investigated without using any catalyst. An experiment has been carried out in the batch-type reaction vessel preheated at 350 and 400{degree}C and at a pressure of 45-65 MPa, and with a molar ratio of 1:42 of the rapeseed oil to methanol. It was consequently demonstrated that, in a preheating temperature of 350{degree}C, 240 s of supercritical treatment of methanol was sufficient to convert the rapeseed oil to methyl esters and that, although the prepared methyl esters were basically the same as those of the common method with a basic catalyst, the yield of methyl esters by the former was found to be higher than that by the latter. In addition, it was found that this supercritical methanol process requires the shorter reaction time and simpler purification procedure because of the unused catalyst. 16 refs., 9 figs., 2 tabs.

  15. Preparation of drug delivery systems using supercritical fluid technology.

    Science.gov (United States)

    Kompella, U B; Koushik, K

    2001-01-01

    Small changes in temperature and pressure near the critical region induce dramatic changes in the density and solubility of supercritical fluids, thereby facilitating the use of environmentally benign agents such as CO2 for their solvent and antisolvent properties in processing a wide variety of materials. While supercritical fluid technologies have been in commercial use in the food and chromatography industries for several years, only recently has this technology made inroads in the formulation of drug delivery systems. This review summarizes some of the recent applications of supercritical fluid technology in the preparation of drug delivery systems. Drugs containing polymeric particles, plain drug particles, solute-containing liposomes, and inclusion complexes of drug and carrier have been formulated using this technology. Also, polymer separation using this technology is enabling the selection of a pure fraction of a polymer, thereby allowing a more precise control of drug release from polymeric delivery systems.

  16. Application of Neutron Radiography to Flow Visualization in Supercritical Water

    Science.gov (United States)

    Takenaka, N.; Sugimoto, K.; Takami, S.; Sugioka, K.; Tsukada, T.; Adschiri, T.; Saito, Y.

    Supercritical water is used in various chemical reaction processes including hydrothermal synthesis of metal oxide nano-particles, oxidation, chemical conversion of biomass and plastics. Density of the super critical water is much less than that of the sub-critical water. By using neutron radiography, Peterson et al. have studied salt precipitation processes in supercritical water and the flow pattern in a reverse-flow vessel for salt precipitation, and Balasko et al. have revealed the behaviour of supercritical water in a container. The nano-particles were made by mixing the super critical flow and the sub critical water solution. In the present study, neutron radiography was applied to the flow visualization of the super and sub critical water mixture in a T-junction made of stainless steel pipes for high pressure and temperature conditions to investigate their mixing process. Still images by a CCD camera were obtained by using the neutron radiography system at B4 port in KUR.

  17. Application of supercritical antisolvent method in drug encapsulation: a review

    Directory of Open Access Journals (Sweden)

    Kalani M

    2011-07-01

    Full Text Available Mahshid Kalani, Robiah YunusChemical and Environmental Engineering, Faculty of Engineering, University Putra Malaysia, Selangor Darul Ehsan, MalaysiaAbstract: The review focuses on the application of supercritical fluids as antisolvents in the pharmaceutical field and demonstrates the supercritical antisolvent method in the use of drug encapsulation. The main factors for choosing the solvent and biodegradable polymer to produce fine particles to ensure effective drug delivery are emphasized and the effect of polymer structure on drug encapsulation is illustrated. The review also demonstrates the drug release mechanism and polymeric controlled release system, and discusses the effects of the various conditions in the process, such as pressure, temperature, concentration, chemical compositions (organic solvents, drug, and biodegradable polymer, nozzle geometry, CO2 flow rate, and the liquid phase flow rate on particle size and its distribution.Keywords: supercritical antisolvent method, drug encapsulation, particle size, drug release mechanisms, drug delivery

  18. Molecular Dynamics Investigation of Benzene in Supercritical Water

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Microscopic structure and diffusion properties of benzene in ambient water (298 K, 0.1 MPa) and super critical water (673-773 K, 25-35 MPa) are investigated by molecular dynamics simulation with site-site models. It is found that at the ambient condition, the water molecules surrounding a benzene molecule form a hydrogen bond network. The hydrogen bond interaction between supercritical water molecules decreases dramatically under supercritical conditions. The diffusion coefficients of both the solute molecule and solvent molecule at supercritical conditions increase by 30-180 times than those at the ambient condition. With the temperature approaching the critical temperature, the change of diffusion coefficient with pressure becomes pronounced.

  19. A note on the total domination supercritical graphs

    Directory of Open Access Journals (Sweden)

    Abdollah Alimadadi

    2012-09-01

    Full Text Available Let $G$ be a connected spanning subgraph of $K_{s,s}$ and let $H$ be the complement of $G$ relative to $K_{s,s}$. The graph $G$ is {it $k$-supercritical} relative to $K_{s,s}$ if $gamma_t(G=k$ and $gamma_t(G+e=k-2$ for all $ein E(H$. The 2002 paper by T.W. Haynes, M.A. Henning and L.C. van der Merwe, "Total domination supercritical graphs with respect to relative complements" that appeared in Discrete Mathematics, 258 (2002, 361-371, presents a theorem (Theorem 11 to produce $(2k + 2$-supercritical graphs relative to $K_{2k+1, 2k+1}$ of diameter $5$, for each $kgeq 2$. However, the families of graphs in their proof are not the case. We present a correction of this theorem.

  20. The latent heat of vaporization of supercritical fluids

    Science.gov (United States)

    Banuti, Daniel; Raju, Muralikrishna; Hickey, Jean-Pierre; Ihme, Matthias

    2016-11-01

    The enthalpy of vaporization is the energy required to overcome intermolecular attractive forces and to expand the fluid volume against the ambient pressure when transforming a liquid into a gas. It diminishes for rising pressure until it vanishes at the critical point. Counterintuitively, we show that a latent heat is in fact also required to heat a supercritical fluid from a liquid to a gaseous state. Unlike its subcritical counterpart, the supercritical pseudoboiling transition is spread over a finite temperature range. Thus, in addition to overcoming intermolecular attractive forces, added energy simultaneously heats the fluid. Then, considering a transition from a liquid to an ideal gas state, we demonstrate that the required enthalpy is invariant to changes in pressure for 0 intermolecular forces in the real fluid vapor during heating. At supercritical pressures, all of the transition occurs at non-equilibrium; for p -> 0 , all of the transition occurs at equilibrium.

  1. Supercritical power plant 600 MW with cryogenic oxygen plant and CCS installation

    Science.gov (United States)

    Kotowicz, Janusz; Dryjańska, Aleksandra

    2013-09-01

    This article describes a thermodynamic analysis of an oxy type power plant. The analyzed power plant consists of: 1) steam turbine for supercritical steam parameters of 600 °C/29 MPa with a capacity of 600 MW; 2) circulating fluidized bed boiler, in which brown coal with high moisture content (42.5%) is burned in the atmosphere enriched in oxygen; 3) air separation unit (ASU); 4) CO2 capture installation, where flue gases obtained in the combustion process are compressed to the pressure of 150 MPa. The circulated fluidized bed (CFB) boiler is integrated with a fuel dryer and a cryogenic air separation unit. Waste nitrogen from ASU is heated in the boiler, and then is used as a coal drying medium. In this study, the thermal efficiency of the boiler, steam cycle thermal efficiency and power demand were determined. These quantities made possible to determine the net efficiency of the test power plant.

  2. Surfactant/Supercritical Fluid Cleaning of Contaminated Substrates

    Science.gov (United States)

    White, Gary L.

    1997-01-01

    CFC's and halogenated hydrocarbon solvents have been the solvents of choice to degrease and otherwise clean precision metal parts to allow proper function. Recent regulations have, however, rendered most of these solvents unacceptable for these purposes. New processes which are being used or which have been proposed to replace these solvents usually either fail to remove water soluble contaminants or produce significant aqueous wastes which must then be disposed of. In this work, a new method for cleaning surfaces will be investigated. Solubility of typical contaminants such as lubricating greases and phosphatizing bath residues will be studied in several surfactant/supercritical fluid solutions. The effect of temperature, pressure, and the composition of the cleaning mixture on the solubility of oily, polar, and ionic contaminants will be investigated. A reverse micellar solution in a supercritical light hydrocarbon solvent will be used to clean samples of industrial wastes. A reverse micellar solution is one where water is dissolved into a non-polar solvent with the aid of a surfactant. The solution will be capable of dissolving both water-soluble contaminants and oil soluble contaminants. Once the contaminants have been dissolved into the solution they will be separated from the light hydrocarbon and precipitated by a relatively small pressure drop and the supercritical solvent will be available for recycle for reuse. The process will be compared to the efficacy of supercritical CO2 cleaning by attempting to clean the same types of substrates and machining wastes with the same contaminants using supercritical CO2. It is anticipated that the supercritical CO2 process will not be capable of removing ionic residues.

  3. Precipitation of fluticasone propionate microparticles using supercritical antisolvent

    Directory of Open Access Journals (Sweden)

    A Vatanara

    2009-03-01

    Full Text Available ABSTRACT Background: The ability of supercritical fluids (SCFs, such as carbon dioxide, to dissolve and expand or extract organic solvents and as result lower their solvation power, makes it possible the use of SCFs for the precipitation of solids from organic solutions. The process could be the injection of a solution of the substrate in an organic solvent into a vessel which is swept by a supercritical fluid. The aim of this study was to ascertain the feasibility of supercritical processing to prepare different particulate forms of fluticasone propionate (FP, and to evaluate the influence of different liquid solvents and precipitation temperatures on the morphology, size and crystal habit of particles. Method: The solution of FP in organic solvents, was precipitated by supercritical carbon dioxide (SCCO2 at two pressure and temperature levels. Effects of process parameters on the physicochemical characteristics of harvested microparticles were evaluated. Results: Particle formation was observed only at the lower selected pressure, whilst at the higher pressure, no precipitation of particles was occurred due to dissolution of FP in supercritical antisolvent. The micrographs of the produced particles showed different morphologies for FP obtained from different conditions. The results of thermal analysis of the resulted particles showed that changes in the processing conditions didn't influence thermal behavior of the precipitated particles. Evaluation of the effect of temperature on the size distribution of particles showed that increase in the temperature from 40 oC to 50 oC, resulted in reduction of the mean particle size from about 30 µm to about 12 μm. ‍Conclusion: From the results of this study it may be concluded that, processing of FP by supercritical antisolvent could be an approach for production of diverse forms of the drug and drastic changes in the physical characteristics of microparticles could be achieved by changing the

  4. Supercritical Extraction of Lycopene from Tomato Industrial Wastes with Ethane

    Directory of Open Access Journals (Sweden)

    Rui L. Mendes

    2012-07-01

    Full Text Available Supercritical fluid extraction of all-E-lycopene from tomato industrial wastes (mixture of skins and seeds was carried out in a semi-continuous flow apparatus using ethane as supercritical solvent. The effect of pressure, temperature, feed particle size, solvent superficial velocity and matrix initial composition was evaluated. Moreover, the yield of the extraction was compared with that obtained with other supercritical solvents (supercritical CO2 and a near critical mixture of ethane and propane. The recovery of all-E-lycopene increased with pressure, decreased with the increase of the particle size in the initial stages of the extraction and was not practically affected by the solvent superficial velocity. The effect of the temperature was more complex. When the temperature increased from 40 to 60 °C the recovery of all-E-lycopene increased from 80 to 90%. However, for a further increase to 80 °C, the recovery remained almost the same, indicating that some E-Z isomerization could have occurred, as well as some degradation of lycopene. The recovery of all-E-lycopene was almost the same for feed samples with different all-E-lycopene content. Furthermore, when a batch with a higher all-E-lycopene content was used, supercritical ethane and a near critical mixture of ethane and propane showed to be better solvents than supercritical CO2 leading to a faster extraction with a higher recovery of the carotenoid.

  5. Destruction of energetic materials by supercritical water oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Beulow, S.J.; Dyer, R.B.; Harradine, D.M.; Robinson, J.M.; Oldenborg, R.C.; Funk, K.A.; McInroy, R.E.; Sanchez, J.A.; Spontarelli, T.

    1993-10-01

    Supercritical water oxidation is a relatively low-temperature process that can give high destruction efficiencies for a variety of hazardous chemical wastes. Results are presented examining the destruction of high explosives and propellants in supercritical water and the use of low temperature, low pressure hydrolysis as a pretreatment process. Reactions of cyclotrimethylene trinitramine (RDX), cyclotetramethylene tetranitramine (HMX), nitroguanidine (NQ), pentaerythritol tetranitrate (PETN), and 2,4,6-trinitrotoluene (TNT) are examined in a flow reactor operated at temperatures between 400{degrees}C and 650{degrees}C. Explosives are introduced into the reactor at concentrations below the solubility limits. For each of the compounds, over 99.9% is destroyed in less than 30 seconds at temperatures above 600{degrees}C. The reactions produce primarily N{sub 2}, N{sub 2}O,CO{sub 2}, and some nitrate and nitrite ions. The distribution of reaction products depends on reactor pressure, temperature, and oxidizer concentration. Kinetics studies of the reactions of nitrate and nitrite ions with various reducing reagents in supercritical water show that they can be rapidly and completely destroyed at temperatures above 525{degrees}C. The use of slurries and hydrolysis to introduce high concentrations of explosives into a supercritical water reactor is examined. For some compounds the rate of reaction depends on particle size. The hydrolysis of explosives at low temperatures (<100{degrees}C) and low pressures (<1 atm) under basic conditions produces water soluble, non-explosive products which are easily destroyed by supercritical water oxidation. Large pieces of explosives (13 cm diameter) have been successfully hydrolyzed. The rate, extent, and products of the hydrolysis depend on the type and concentration of base. Results from the base hydrolysis of triple base propellant M31A1E1 and the subsequent supercritical water oxidation of the hydrolysis products are presented.

  6. Supercritical Water Reactor (SCWR) - Survey of Materials Research and Development Needs to Assess Viability

    Energy Technology Data Exchange (ETDEWEB)

    Philip E. MacDonald

    2003-09-01

    Supercritical water-cooled reactors (SCWRs) are among the most promising advanced nuclear systems because of their high thermal efficiency [i.e., about 45% vs. 33% of current light water reactors (LWRs)] and considerable plant simplification. SCWRs achieve this with superior thermodynamic conditions (i.e., high operating pressure and temperature), and by reducing the containment volume and eliminating the need for recirculation and jet pumps, pressurizer, steam generators, steam separators and dryers. The reference SCWR design in the U.S. is a direct cycle, thermal spectrum, light-water-cooled and moderated reactor with an operating pressure of 25 MPa and inlet/outlet coolant temperature of 280/500 °C. The inlet flow splits, partly to a down-comer and partly to a plenum at the top of the reactor pressure vessel to flow downward through the core in special water rods to the inlet plenum. This strategy is employed to provide good moderation at the top of the core, where the coolant density is only about 15-20% that of liquid water. The SCWR uses a power conversion cycle similar to that used in supercritical fossil-fired plants: high- intermediate- and low-pressure turbines are employed with one moisture-separator re-heater and up to eight feedwater heaters. The reference power is 3575 MWt, the net electric power is 1600 MWe and the thermal efficiency is 44.8%. The fuel is low-enriched uranium oxide fuel and the plant is designed primarily for base load operation. The purpose of this report is to survey existing materials for fossil, fission and fusion applications and identify the materials research and development needed to establish the SCWR viabilitya with regard to possible materials of construction. The two most significant materials related factors in going from the current LWR designs to the SCWR are the increase in outlet coolant temperature from 300 to 500 °C and the possible compatibility issues associated with the supercritical water environment.

  7. Exp6-polar thermodynamics of dense supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Bastea, S; Fried, L E

    2007-12-13

    We introduce a simple polar fluid model for the thermodynamics of dense supercritical water based on a Buckingham (exp-6) core and point dipole representation of the water molecule. The proposed exp6-polar thermodynamics, based on ideas originally applied to dipolar hard spheres, performs very well when tested against molecular dynamics simulations. Comparisons of the model predictions with experimental data available for supercritical water yield excellent agreement for the shock Hugoniot, isotherms and sound speeds, and are also quite good for the self-diffusion constant and relative dielectric constant. We expect the present approach to be also useful for other small polar molecules and their mixtures.

  8. Measurement of flow in supercritical flow regime using cutthroat flumes

    Indian Academy of Sciences (India)

    Shrikant A Tekade; Avinash D Vasudeo; Aniruddha D Ghare; Ramesh N Ingle

    2016-02-01

    Cutthroat flume is commonly used for measurement of subcritical flow in open channel because of its simplicity and ease of construction. No experimental data is available in literature for measurement of flow in supercritical regime using cutthroat flume. The present paper finds the feasibility of cutthroat flume as a measurement device for flow in supercritical regime. Experimental data are generated to develop the relation between discharge and observed head at a specified location on upstream of throat section. Regression analysis for discharge and head indicated a good correlation. Based on all the experimental data generated, a relationship between discharge and head is proposed.

  9. Supercritical CO2 extraction of essential oils from Thymus vulgaris

    Directory of Open Access Journals (Sweden)

    S.A.B. Vieira de Melo

    2000-09-01

    Full Text Available Supercritical CO2 extraction of essential oil from Thymus vulgaris leaves was studied using experimental data recently obtained in the Florys S.p.A. laboratory. Mass transfer coefficients in the supercritical and solid phases from extraction curves at 40°C and 20 MPa were evaluated using a mathematical model based on the local adsorption equilibrium of essential oil on lipid in leaves. The adsorption equilibrium constant was fitted to these experimental data, and internal and external mass transfer resistances were calculated, allowing identification of the mechanism controlling the extraction process.

  10. AN INTERIM THERMODYNAMIC PROPERTY FORMULATION FOR SUPERCRITICAL n-HEXANE

    Directory of Open Access Journals (Sweden)

    Azzedine Abbaci

    2010-07-01

    Full Text Available Accurate information on the thermodynamic properties of supercritical fluids is highly sought for the chemical technology, especially, supercritical extraction technology. The thermodynamic properties of fluids near the critical region are strongly affected by the presence of fluctuations and therefore, can not be described by conventional equation. We have investigated an interim formulation for the behavior of the thermodynamic properties of n-hexane in the vicinity of the critical region. For this reason we have used the so-called “crossover model” to describe the thermodynamic properties of n-hexane in a wide range of temperatures and densities around the critical point.

  11. Supercritical carbon dioxide-based sterilization of decellularized heart valves.

    Science.gov (United States)

    Hennessy, Ryan S; Jana, Soumen; Tefft, Brandon J; Helder, Meghana R; Young, Melissa D; Hennessy, Rebecca R; Stoyles, Nicholas J; Lerman, Amir

    2017-02-01

    The goal of this research project encompasses finding the most efficient and effective method of decellularized tissue sterilization. Aortic tissue grafts have been utilized to repair damaged or diseased valves. Although, the tissues for grafting are collected aseptically, it does not eradicate the risk of contamination nor disease transfer. Thus, sterilization of grafts is mandatory. Several techniques have been applied to sterilize grafts; however, each technique shows drawbacks. In this study, we compared several sterilization techniques: supercritical carbon dioxide, electrolyzed water, gamma radiation, ethanol-peracetic acid, and hydrogen peroxide for impact on the sterility and mechanical integrity of porcine decellularized aortic valves. Valve sterility was characterized by histology, microbe culture, and electron microscopy. Uniaxial tensile testing was conducted on the valve cusps along their circumferential orientation to study these sterilization techniques on their integrity. Ethanol-peracetic acid and supercritical carbon dioxide treated valves were found to be sterile. The tensile strength of supercritical carbon dioxide treated valves (4.28 ± 0.22 MPa) was higher to those valves treated with electrolyzed water, gamma radiation, ethanol-peracetic acid and hydrogen peroxide (1.02 ± 0.15, 1.25 ± 0.25, 3.53 ± 0.41 and 0.37 ± 0.04 MPa, respectively). Superior sterility and integrity were found in the decellularized porcine aortic valves with supercritical carbon dioxide sterilization. This sterilization technique may hold promise for other decellularized soft tissues. Sterilization of grafts is essential. Supercritical carbon dioxide, electrolyzed water, gamma radiation, ethanol-peracetic acid, and hydrogen peroxide techniques were compared for impact on sterility and mechanical integrity of porcine decellularized aortic valves. Ethanol-peracetic acid and supercritical carbon dioxide treated valves were found to be sterile using histology, microbe

  12. Solubilities of triolein in supercritical CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, M.A.; Bernardo-Gil, M.G. [Instituto Superior Tecnico, Lisboa (Portugal). Dept. de Engenharia Quimica

    1995-11-01

    A vegetable oil typically consists of a range of triglycerides, approximately 10% diglycerides, and a small fraction of free fatty acids and other minor constituents. The use of supercritical carbon dioxide for solvent extraction is currently the subject of numerous investigations. The solubilities of triolein in supercritical carbon dioxide were measured over a temperature range of 308--328 K and at pressures between 8 and 20 MPa by the static method. The data were correlated by the model proposed by Chrastil and the modification proposed by Adachi and Lu and Del Valle and Aguilera.

  13. SOLID PHASE TRANSITION OF SYNDIOTACTIC POLYSTYRENE IN SUPERCRITICAL CO2

    Institute of Scientific and Technical Information of China (English)

    Yu-ying Li; Jia-song He

    2002-01-01

    Solid phase transition of the a form crystals to the β form crystals in syndiotactic polystyrene (sPS) samples has occurred in supercritical CO2. This transformation is different from those detected under other conditions. The effects of some factors (e.g. time, temperature, and pressure) on the solid phase transformation of sPS in supercritical CO2 were analyzed in detail. Experimental results show that longer time, higher temperature or higher pressure favors the transformation of the α form crystals to the β form crystals.

  14. Supercritical water oxidation - Concept analysis for evolutionary Space Station application

    Science.gov (United States)

    Hall, John B., Jr.; Brewer, Dana A.

    1986-01-01

    The ability of a supercritical water oxidation (SCWO) concept to reduce the number of processes needed in an evolutionary Space Station design's Environmental Control and Life Support System (ECLSS), while reducing resupply requirements and enhancing the integration of separate ECLSS functions into a single Supercritical Water Oxidation process, is evaluated. While not feasible for an initial operational capability Space Station, the SCWO's application to the evolutionary Space Station configuration would aid the integration of eight ECLSS functions into a single one, thereby significantly reducing program costs.

  15. Neural networks for predicting mass transfer parameters in supercritical extraction

    Directory of Open Access Journals (Sweden)

    A.P. Fonseca

    2000-12-01

    Full Text Available Neural networks have been investigated for predicting mass transfer coefficients from supercritical Carbon Dioxide/Ethanol/Water system. To avoid the difficulties associated with reduce experimental data set available for supercritical extraction in question, it was chosen to use a technique to generate new semi-empirical data. It combines experimental mass transfer coefficient with those obtained from correlation available in literature, producing an extended data set enough for efficient neural network identification. With respect to available experimental data, the results obtained to benefit neural networks in comparing with empirical correlations for predicting mass transfer parameters.

  16. Extraction of oil from wheat germ by supercritical CO2.

    Science.gov (United States)

    Piras, Alessandra; Rosa, Antonella; Falconieri, Danilo; Porcedda, Silvia; Dessì, Maria A; Marongiu, Bruno

    2009-07-15

    This study examined the supercritical fluid extraction of wheat germ oil. The effects of pressure (200-300 bar at 40 degrees C) and extraction time on the oil quality/quantity were studied. A comparison was also made between the relative qualities of material obtained by SFE and by organic solvent extraction. The extracts were analyzed for alpha-tocopherol and polyunsaturated fatty acid content. The maximum wheat germ oil yield at about 9% was obtained with supercritical carbon dioxide extraction at 300 bar, while fatty acid and alpha-tocopherol composition of the extracts was not remarkable affected by either pressure or the extraction method.

  17. [Chemical constituents from supercritical CO2 extraction of Schisandra chinensis].

    Science.gov (United States)

    Zhu, Hong-yan; Lin, Hai-cheng; Wang, Guo-li; Zhang, Lian-xue

    2014-11-01

    To study the chemical constituents from the supercritical CO2 extraction of Schisandra chinensis. The compounds were separated and purified by conventional column chromatography and their structures were identified by spectroscopic methods. Nine compounds were isolated from the supercritical CO2 extraction of Schisandra chinensis, and their structures were identified as chrysophanol(1),schisandrin B(2), β-sitosterol(3), schisandrin C(4),schisandrol A(5), angeloylgomisin H(6), daucosterol(7) 1, 5-dimethyl citrate (8), and shikimic acid (9). Compounds 1, 8 and 9 are isolated from Schisandra chinensis for the first time,and compound 1 as an anthraquinone is isolated from this genus for the first time.

  18. Processing of polyolefin blends in supercritical propane solution

    Science.gov (United States)

    Han, Suh Joon

    New polymer blending methods are developed and studied by processing polyolefins in supercritical propane in this research. Polypropylene and ethylene copolymers were dissolved in supercritical propane, and processed via various paths and reactions, i.e., RESS (rapid expansion of supercritical solution), ICSS (isobaric crystallization from supercritical solution), and thermoplastic vulcanizate (TPV) formation. Each process resulted in a unique morphology of polyolefin blends. The effect of polyolefin microstructure on the solution behavior in supercritical propane was investigated, and the relationship between the morphology of the polyolefin blends and processing paths in supercritical propane solutions was established. To understand the thermodynamic properties of polyolefins in bulk and solutions, the solubility parameter was estimated by measurement of the internal pressure from the experimental P-V-T data for polyolefins in the melt state. As the short chain branch content in the ethylene copolymers increased, the internal pressure decreased. The cloud-point pressures of binary polymer solutions in propane decreased as the extent of short chain branching increased in the ethylene copolymers. At the same degree of branching, the cloud-point pressure decreased slightly with increasing branch length. The cloud-point pressures of a ternary polymer solution in the pressure-temperature phase diagrams were higher than those of binary polymer solutions at the same composition (indicating poorer solubility). Microfibers and microparticles (10 ˜ 50 mum diameter) were precipitated from the RESS process while microcellular foams were obtained from the ICSS process. The phase domains of the ethylene-butene (EB) copolymer in the polypropylene from the RESS process were smaller for highly branched EB copolymer. The surface morphology of ethylene copolymers in the microcelluar foams was also changed by increasing the branch content from microparticles to a viscous layer. New

  19. Generic supercritical water technology; Generic technology to shite no chorinkaisui riyo gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Arai, K.; Ajiri, M.; Inomata, H.; Smith, R.; Hakuta, Y. [Tohoku University, Sendai (Japan). Faculty of Engineering; Yokoyama, C. [Tohoku University, Sendai (Japan). The Institute forChemical Reaction Science; Chin, L. [New Energy and Industrial Technology Development Organization, Tokyo, (Japan)

    1997-02-01

    This paper describes the measurement and analysis for clarifying solution structure of supercritical water and exhibition mechanism of solvent functions. It also describes the development of new processes using supercritical water as reaction solvent. The PVT measurements were conducted in the supercritical region using pure water and NaCl aqueous solution, to confirm the reduction of molar volume of the electrolyte solution. The hydration structure was examined in the supercritical aqueous solution by the molecular dynamic simulation. As a result, presence of hydrogen bond structure, where the contribution of two branching hydrogen bond can not be ignored, was suggested under the supercritical condition. Characteristics of supercritical aqueous solutions are analyzed through in-situ Raman and scattered X-ray spectral measurements. Moreover, this paper introduces developments of some processes in the supercritical water, such as decomposition of wasted polymers, recovery of chemical materials, reforming of heavy hydrocarbons by contact hydrogenation, and synthesis of fine powders of metal oxide by reaction crystallization.

  20. Molecular dynamics simulation of the key characteristics of the supercritical CO2-pentaerythritol tetraacetate system

    Science.gov (United States)

    Lei, Peiyu; Jin, Zunlong; Liu, Hong; Wang, Dingbiao; Liu, Donglai

    2016-12-01

    Supercritical CO2 is widely used in many fields of industry. Investigation of statistical mechanics of CO2 fluid under quasi critical and supercritical state has great significance. Equilibrium molecular dynamics (EMD) simulations are carried out to investigate the statistical mechanics and macroscopic performance of CO2 fluid under the quasi critical and supercritical state. The results show that the bond length and bond angle distributions for supercritical CO2 are Gaussian distribution basically. The dimers' proportion of supercritical CO2 system changes with pressure increasing. T-type dimer has high share within the system when pressure is higher than 9MPa. It can be inferred that T-type dimer leads to CO2 physical properties changing tempestuously under supercritical state. The effect that lubricating oil has on microstructure and heat transfer of supercritical CO2 is also investigated in the present work. The results show the lubricating oil produces significant effect on the dimers' structure under low pressure.

  1. Treatment of sewage sludge in supercritical water and evaluation of the combined process of supercritical water gasification and oxidation.

    Science.gov (United States)

    Qian, Lili; Wang, Shuzhong; Xu, Donghai; Guo, Yang; Tang, Xingying; Wang, Longfei

    2015-01-01

    Influences of temperature and oxidation coefficient (n) on sewage sludge treatment in supercritical water and its corresponding reaction mechanism were studied. Moreover, the combined process of supercritical water gasification (SCWG) and supercritical water oxidation (SCWO) was also investigated. The results show that ammonia nitrogen, phenols and pyridines are main refractory intermediates. The weight of solid products at 873K and n=4 is only 3.5wt.% of the initial weight, which is lower than that after combustion. Volatile organics in solid phase have almost released at 723K and n=0. Highest yield of combustible gases was obtained at n=0, and H2 yield can reach 11.81mol/kg at 873K. Furthermore, the combination of SCWG at 723K and SCWO at 873K with a total n=1 is feasible for its good effluent quality and low operation costs.

  2. Review of the coal-fired, over-supercritical and ultra-supercritical steam power plants

    Science.gov (United States)

    Tumanovskii, A. G.; Shvarts, A. L.; Somova, E. V.; Verbovetskii, E. Kh.; Avrutskii, G. D.; Ermakova, S. V.; Kalugin, R. N.; Lazarev, M. V.

    2017-02-01

    The article presents a review of developments of modern high-capacity coal-fired over-supercritical (OSC) and ultra-supercritical (USC) steam power plants and their implementation. The basic engineering solutions are reported that ensure the reliability, economic performance, and low atmospheric pollution levels. The net efficiency of the power plants is increased by optimizing the heat balance, improving the primary and auxiliary equipment, and, which is the main thing, by increasing the throttle conditions. As a result of the enhanced efficiency, emissions of hazardous substances into the atmosphere, including carbon dioxide, the "greenhouse" gas, are reduced. To date, the exhaust steam conditions in the world power industry are p 0 ≈ 30 MPa and t 0 = 610/620°C. The efficiency of such power plants reaches 47%. The OSC plants are being operated in Germany, Denmark, Japan, China, and Korea; pilot plants are being developed in Russia. Currently, a project of a power plant for the ultra-supercritical steam conditions p 0 ≈ 35 MPa and t 0 = 700/720°C with efficiency of approximately 50% is being studied in the EU within the framework of the Thermie AD700 program, project AD 700PF. Investigations in this field have also been launched in the United States, Japan, and China. Engineering solutions are also being sought in Russia by the All-Russia Thermal Engineering Research Institute (VTI) and the Moscow Power Engineering Institute. The stated steam parameter level necessitates application of new materials, namely, nickel-base alloys. Taking into consideration high costs of nickel-base alloys and the absence in Russia of technologies for their production and manufacture of products from these materials for steam-turbine power plants, the development of power plants for steam parameters of 32 MPa and 650/650°C should be considered to be the first stage in creating the USC plants as, to achieve the above parameters, no expensive alloys are require. To develop and

  3. Supercritical fluid extraction: Present status and prospects

    Directory of Open Access Journals (Sweden)

    King, Jerry W.

    2002-03-01

    Full Text Available Supercritical extraction (SFE, using primarily environmentally-benign carbon dioxide (CO2 as the extracting agent, is reviewed with respect to its present status and future use. SFE was developed for analytical application in the mid 1980’s in response to the desire to reduce the use of organic solvents in the laboratory environment and is becoming a standard method for the preparation and analysis of lipid-containing sample matrices. Currently, analytical SFE is predominately practiced in the off-line mode, using both sequential and parallel extraction modes. Depending on the instrumental configuration, the preparation of up to 24 samples can be accomplished on one instrument on a daily basis. Several other benefits can be achieved using SFE, such as the processing of thermally-sensitive analytes and rapid analyte extraction kinetics relative to extraction with liquid solvents. Examples are provided not only of the analytical SFE of oils and fats, but of volatile solutes from an array of sample types. Finally, the relevance of analytical SFE to processing with supercritical fluids (SFs is documented using examples from our own research involving a combinatorial approach to optimising processing conditions.Este artículo revisa el presente y el uso futuro de la extracción con fluidos supercríticos (SFE, principalmente dióxido de carbono (CO2 benigno para el ambiente. La extracción con fluidos supercríticos se desarrolló como aplicación analítica a mediados de los años 80 como respuesta al deseo de reducir el uso de disolventes orgánicos en el ambiente del laboratorio, y se está convirtiendo en un método estándar con respecto a la preparación y análisis de muestras conteniendo lípidos. Actualmente, la analítica de SFE es predominantemente aplicada en modo “off-line”, usando modos de extracción secuenciales y paralelos. Dependiendo de la configuración de la instrumentación, se pueden llegar a preparar diariamente

  4. Supercritical water pyrolysis of sewage sludge.

    Science.gov (United States)

    Ma, Wenchao; Du, Guiyue; Li, Jian; Fang, Yuanhao; Hou, Li'an; Chen, Guanyi; Ma, Degang

    2017-01-01

    Municipal sewage sludge (SS) from wastewater treatment plant containing high water content (>85wt.%), lead to the difficulty of co-combustion with MSW or coal due to the high cost of drying. This study explores an alternative method by supercritical water (SCW) pyrolysis of sewage sludge (SS) in a high pressure reaction vessel. The effects of temperature and moisture content of SS on yield and composition of the products (bio-oil, bio char and non-condensable gas) were studied. A temperature of 385°C and moisture content of 85wt.% were found to be the optimum conditions for the maximum bio-oil production of 37.23wt.%, with a higher heating value of 31.08MJ/kg. In the optimum condition, the yields of aliphatic hydrocarbon and phenols were about 29.23wt.% and 12.51wt.%, respectively. The physical and chemical properties of bio-char were analyzed by using XRF and BET. Results of GC analyses of NCG showed that it has the maximum HHV of 13.39MJ/m(3) at 445°C and moisture content of 85wt.%. The reaction path from SS to bio-oil through SCW pyrolysis was given. Moreover, carbon balance was calculated for the optimal condition, and finding out that 64.27wt.% of the carbon content was transferred from SS to bio-oil. Finally, this work demonstrates that the SCW pyrolysis is a promising disposal method for SS. Copyright © 2016. Published by Elsevier Ltd.

  5. Fast Cycled Superconducting Magnet - Connecting hydraulically the Fast Cycled magnet to the cryogenic feed box.

    CERN Multimedia

    Maximilien Brice

    2012-01-01

    Photo 1 : Connecting hydraulically the Fast Cycled magnet to the cryogenic feed box. Patrck Viret and Guy Deferne technicians of TE-MSC-TF in SM18. - Photo 2 : Installation of the Fast Cycled Superconducting Magnet (FCM) to the new cold feed box in Sm18. - Photo 3 : Connecting the powering cables of the FCM to the feed box. - Photo 5/6 : The connections of the Fast Cycled Magnet. Intermediate pieces. - Photo 7 : Hydraulic connections of the Fast Cycle Magnet cable to allow the cooling of the magnet’s conductor ( Cable in conduit type) with supercritical helium. - Photo 8 : Verification of the connection: design versus reality. Guy Deferne and Frederick Rougemont, technicians of TE-MSC-TE in SM18.

  6. Feasibility Study of Supercritical Light Water Cooled Reactors for Electric Power Production, Progress Report for Work Through September 2003, 2nd Annual/8th Quarterly Report

    Energy Technology Data Exchange (ETDEWEB)

    Philip E. MacDonald

    2003-09-01

    The supercritical water-cooled reactor (SCWR) is one of the six reactor technologies selected for research and development under the Generation-IV program. SCWRs are promising advanced nuclear systems because of their high thermal efficiency (i.e., about 45% vs. about 33% efficiency for current Light Water Reactors, LWRs) and considerable plant simplification. SCWRs are basically LWRs operating at higher pressure and temperatures with a direct once-through cycle. Operation above the critical pressure eliminates coolant boiling, so the coolant remains single-phase throughout the system. Thus the need for recirculation and jet pumps, a pressurizer, steam generators, steam separators and dryers is eliminated. The main mission of the SCWR is generation of low-cost electricity. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and supercritical fossil-fired boilers, a large number of which is also in use around the world.

  7. Survival Time of a Censored Supercritical Galton-Watson Process

    CERN Document Server

    Couronné, Olivier

    2011-01-01

    We study the asymptotic behavior of the survival time of a supercritical Galton-Watson process censored at a certain level. As a byproduct we obtain the asymptotics for the speed of a particular case of a particle system with branching and selection introduced by B\\'erard and Gou\\'er\\'e (2010).

  8. Research activities on supercritical fluid science in food biotechnology.

    Science.gov (United States)

    Khosravi-Darani, Kianoush

    2010-06-01

    This article serves as an overview, introducing the currently popular area of supercritical fluids and their uses in food biotechnology. Within each application, and wherever possible, the basic principles of the technique, as well as a description of the history, instrumentation, methodology, uses, problems encountered, and advantages over the traditional, non-supercritical methods are given. Most current commercial application of the supercritical extraction involve biologically-produced materials; the technique may be particularly relevant to the extraction of biological compounds in cases where there is a requirement for low-temperature processing, high mass-transfer rates, and negligible carrying over of the solvent into the final product. Special applications to food processing include the decaffeination of green coffee beans, the production of hops extracts, the recovery of aromas and flavors from herbs and spices, the extraction and fractionation of edible oils, and the removal of contaminants, among others. New advances, in which the extraction is combined with reaction or crystallization steps, may further increase the attractiveness of supercritical fluids in the bioprocess industries. To develop and establish a novel and effective alternative to heating treatment, the lethal action of high hydrostatic pressure CO(2) on microorganisms, with none or only a minimal heating process, has recently received a great deal of attention.

  9. Solubilities of sub- and supercritical carbon dioxide in polyester resins

    NARCIS (Netherlands)

    Nalawade, SP; Picchioni, F; Janssen, LPBM; Patil, VE; Keurentjes, JTF; Staudt, R; Nalawade, Sameer P.; Patil, Vishal E.; Keurentjes, Jos T.F.

    In supercritical carbon dioxide (CO2) assisted polymer processes the solubility of CO2 in a polymer plays a vital role. The higher the amount of CO2 dissolved in a polymer the higher is the viscosity reduction of the polymer. Solubilities Of CO2 in polyester resins based on propoxylated bisphenol

  10. Reforming of methanol and glycerol in supercritical water

    NARCIS (Netherlands)

    van Bennekom, J. G.; Venderbosch, R. H.; Assink, D.; Heeres, H. J.

    2011-01-01

    Reforming of pure glycerol, crude glycerin, and methanol (pure and in the presence of Na(2)CO(3)) in supercritical water was investigated. Continuous experiments were carried out at temperatures between 450 and 650 degrees C, residence times between 6 and 173 s, and feed concentrations of 3-20 wt%.

  11. Large Deviation for Supercritical Branching Processes with Immigration

    Institute of Scientific and Technical Information of China (English)

    Jing Ning LIU; Mei ZHANG

    2016-01-01

    In this paper, we study the large deviation for a supercritical branching process with immigration controlled by a sequence of non-negative integer-valued independently identical distributed random variables, improving the previous results for non immigration processes. We rely heavily on the detail description and limit property of the generating function of immigration processes.

  12. Stability of wheat germ oil obtained by supercritical carbon dioxide ...

    African Journals Online (AJOL)

    심정은

    with 1,3-regiospecific lipase at different temperatures (40 to 70°C) to produce diglycerides and ... Key words: Supercritical carbon dioxide, wheat germ oil, ethanolysis, .... Methanol (1 mL), replacing the extract, was used as the blank. The.

  13. Supercritical carbon dioxide process for pasteurization of fruit juices

    Science.gov (United States)

    Supercritical carbon dioxide (SCCO2) nonthermal processing inactivates microorganisms in juices using non-toxic and non-reactive CO2. However, data is lacking on the inactivation of E. coli K12 and L. plantarum in apple cider using pilot plant scale SCCO2 equipment. For this study, pasteurized pres...

  14. Supercritical Fluid Chromatography- A Hybrid of GC and LC

    Directory of Open Access Journals (Sweden)

    Kaushal K Chandrul

    2010-03-01

    Full Text Available

    High performance specifications and unique functionality of chromatographic techniques is a demand of pharmaceutical industry and research. This leads to the origin of Supercritical Fluid Chromatography (SFC. It is a rapidly expanding analytical technique. The main feature that differentiates SFC from other chromatographic techniques is the replacement of either the liquid or gas mobile phase with a supercritical fluid mobile phase. It is considered a hybrid of GC and LC technique. High diffusion coefficient and low viscosity of supercritical fluids is responsible for high speed analysis, high efficiency and high sensitivity. Low mobile-phase flow rate, density programming and compatability with GC and LC detectors make SFC a versatile chromatographic technique in analytical research and development. It has a unique characteristic of analyzing thermo labile or non-volatile substances. This review highlights the role of supercritical fluid chromatography in the separation of polymers, thermally labile pesticides, fatty acids, metal chelates and organometallic compounds, chiral and achiral molecules, identification and analysis of polar samples, explosives, drugs of abuse and application of SFC in forensic science (fingerprinting. 

  15. Supercritical fluid chromatography-A Hybrid of GC and LC

    Directory of Open Access Journals (Sweden)

    Neha Sethi

    2010-01-01

    Full Text Available High performance specifications and unique functionality of chromatographic techniques is a demand of pharmaceutical industry and research. This leads to the origin of Supercritical Fluid Chromatography (SFC. It is a rapidly expanding analytical technique. The main feature that differentiates SFC from other chromatographic techniques is the replacement of either the liquid or gas mobile phase with a supercritical fluid mobile phase. It is considered a hybrid of GC and LC technique. High diffusion coefficient and low viscosity of supercritical fluids is responsible for high speed analysis, high efficiency and high sensitivity. Low mobile-phase flow rate, density programming and compatability with GC and LC detectors make SFC a versatile chromatographic technique in analytical re-search and development. It has a unique characteristic of analyzing thermo labile or non-volatile substances. This review highlights the role of supercritical fluid chromatography in the separation of polymers, thermally labile pesticides, fatty acids, metal chelates and organometallic compounds, chiral and achiral molecules, identification and analysis of polar samples, explosives, drugs of abuse and application of SFC in forensic science (fingerprint-ing.

  16. Preparation of PMMA Foam by Supercritical CO2 with Ethanol

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Supercritical CO2 with ethanol as blowing agent foamed poly(methylmethacrylate) (PMMA) fiber at 308.15K and in the pressure range from 12-15MPa. The foam structure was detected using scanning electron microscope. It was found that the concentration of ethanol in the fluid is a major parameter to affect the foam structure.

  17. WaiGao Qiao: taking supercritical technology to new heights

    Energy Technology Data Exchange (ETDEWEB)

    Kessel, W.; Weiss, G.; Kawa, P. [Alstom, Stuttgart (Germany)

    2006-06-15

    In their first two years of commercial life the two supercritical boilers of Wai Gao Qiao Phase II, at 900 MWe each the largest operating coal fired units in China and the largest tangentially fired bituminous coal fired boilers in the world have performed reliably and efficiently. 11 figs., 1 tab.

  18. Extraction of heavy oil by supercritical carbon dioxide

    DEFF Research Database (Denmark)

    Rudyk, Svetlana Nikolayevna; Spirov, Pavel; Søgaard, Erik Gydesen

    2010-01-01

    The present study deals with the extraction of heavy oil by supercritical carbon dioxide at the pressure values changing from 16 to 56 MPa at the fixed value of temperature: 60oC. The amount of the recovered liquid phase of oil was calculated as a percentage of the extracted amount to the initial...

  19. Solubilities of ferrocene and acetylferrocene in supercritical carbon dioxide

    DEFF Research Database (Denmark)

    Kazemi, Somayeh; Belandria, Veronica; Janssen, Nico

    2012-01-01

    In this work, the solubilities of ferrocene and acetylferrocene in supercritical carbon dioxide (scCO2) were measured using an analytical method in a quasi-flow apparatus. High-performance liquid chromatography was applied through an online sampling procedure to determine the concentration...

  20. Capillary supercritical fluid chromatography-mass spectrometry (SFC-MS)

    Energy Technology Data Exchange (ETDEWEB)

    Kalinoski, H.T.; Udseth, H.R.; Chess, E.K.; Smith, R.D.

    1986-10-01

    The physical and chemical characteristics of supercritical fluids have prompted the development of supercritical fluid chromatography (SFC) for the analysis of labile and less volatile compounds. High resolution chromatographic separations with efficiencies approaching those of gas chromatography and high speed analyses are possible in capillary SFC using pressure programming methods and narrow bore columns. Further refinement of the SFC-mass spectrometry interface (SFC-MS) provides the basis for extension to more polar fluid systems with greater solvating power and the selectivity and sensitivity of mass spectrometric detection. The use of polar modified fluids has been facilitated by advances in understanding of supercritical fluid phase behavior. Fluid mixtures have been prepared for analysis of more polar, higher molecular weight analytes, that allow mild chromatographic temperatures and allow full exploitation of selectivity offered through control of fluid pressure (i.e., density). Continuing development of the SFC-MS interface has led to designs which can be near routinely applied with fluids such as CO/sub 2/, and providing enhanced transport of truly nonvolatile compounds to the mass spectrometer ionization regions. These advances also include an SFC interface to a high resolution, dual electric magnetic sector instrument, allowing supercritical fluid solvents to be explited for on-line extraction-mass spectrometry for characterization of complex, often otherwise intractable, materials. 26 refs., 5 figs., 1 tab.

  1. Manometric determination of supercritical gas sorption in coal

    NARCIS (Netherlands)

    Van Hemert, P.

    2009-01-01

    The characteristics of the manometric method are investigated so that it can be used to obtain accurate data of sorption of supercritical gas in coal. Furthermore, data of the sorption of carbon dioxide, methane and nitrogen in coal at in situ conditions have been determined. Accurate data are req

  2. Statistical mechanical description of supercritical fluid extraction and retrograde condensation

    Science.gov (United States)

    Park, S. J.; Kwak, T. Y.; Mansoori, G. A.

    1987-07-01

    The phenomena of supercritical fluid extraction (SFE) and its reverse effect, which is known as retrograde condensation (RC), have found new and important applications in industrial separation of chemical compounds and recovery and processing of natural products and fossil fuels. Full-scale industrial utilization of SFE/RC processes requires knowledge about thermodynamic and transport characteristics of the asymmetric mixtures involved and the development of predictive modeling and correlation techniques for performance of the SFE/RC system under consideration. In this report, through the application of statistical mechanical techniques, the reasons for the lack of accuracy of existing predictive approaches are described and they are improved. It is demonstrated that these techniques also allow us to study the effect of mixed supercritical solvents on the solubility of heavy solutes (solids) at different compositions of the solvents, pressures, and temperatures. Fluid phase equilibrium algorithms based on the conformal solution van der Waals mixing rules and different equations of state are presented for the prediction of solubilities of heavy liquid in supercritical gases. It is shown that the Peng-Robinson equation of state based on conformal solution theory can predict solubilites of heavy liquid in supercritical gases more accurately than the van der Waals and Redlich-Kwong equations of state.

  3. Promising flame retardant textile in supercritical carbon dioxide

    Science.gov (United States)

    Since carbon dioxide is non-toxic, non-flammable and cost-effective, supercritical carbon dioxide (scCO2) is widely used in textile dyeing applications. Due to its environmentally benign character, scCO2 is considered in green chemistry as a substitute for organic solvents in chemical reactions. O...

  4. Supercritical fluid chromatography for lipid analysis in foodstuffs.

    Science.gov (United States)

    Donato, Paola; Inferrera, Veronica; Sciarrone, Danilo; Mondello, Luigi

    2017-01-01

    The task of lipid analysis has always challenged separation scientists, and new techniques in chromatography were often developed for the separation of lipids; however, no single technique or methodology is yet capable of affording a comprehensive screening of all lipid species and classes. This review acquaints the role of supercritical fluid chromatography within the field of lipid analysis, from the early developed capillary separations based on pure CO2 , to the most recent techniques employing packed columns under subcritical conditions, including the niche multidimensional techniques using supercritical fluids in at least one of the separation dimensions. A short history of supercritical fluid chromatography will be introduced first, from its early popularity in the late 1980s, to the sudden fall and oblivion until the last decade, experiencing a regain of interest within the chromatographic community. Afterwards, the subject of lipid nomenclature and classification will be briefly dealt with, before discussing the main applications of supercritical fluid chromatography for food analysis, according to the specific class of lipids.

  5. Supercritical fluid extraction and bioactivity of cedarwood oil

    Science.gov (United States)

    Supercritical carbon dioxide (70°C, 4,000 psi) was used to extract cedarwood oil from Eastern redcedar, Juniperus virginiana L. The CO2-derived oil was tested for biological activity against several species of arthropods, including mosquitoes, ticks, houseflies, and ants. The cedarwood oil was found...

  6. SUPERCRITICAL WATER OXIDATION MODEL DEVELOPMENT FOR SELECTED EPA PRIORITY POLLUTANTS

    Science.gov (United States)

    Supercritical Water Oxidation (SCWO) evaluated for five compounds: acetic acid, 2,4-dichlorophenol, pentachlorophenol, pyridine, 2,4-dichlorophenoxyacetic acid (methyl ester). inetic models were developed for acetic acid, 2,4-dichlorophenol, and pyridine. he test compounds were e...

  7. Up-Scaled Supercritical Flow Synthesis of Hybrid Materials

    DEFF Research Database (Denmark)

    Hellstern, Henrik Christian; Becker, Jacob; Hald, Peter

    A new, up-scaled supercritical flow synthesis apparatus is currently under construction in Aarhus. A module based system allows for a range of parameter studies with improved parameter control. The dual-reactor setup enables both single phase and core-shell nanoparticle synthesis, and the large...

  8. Treatment of municipal sewage sludge in supercritical water: A review.

    Science.gov (United States)

    Qian, Lili; Wang, Shuzhong; Xu, Donghai; Guo, Yang; Tang, Xingying; Wang, Laisheng

    2016-02-01

    With increasing construction of wastewater treatment plants and stricter policies, municipal sewage sludge (MSS) disposal has become a serious problem. Treatment of MSS in supercritical water (SCW) can avoid the pre-drying procedure and secondary pollution of conventional methods. SCW treatment methods can be divided into supercritical water gasification (SCWG), supercritical water partial oxidation (SCWPO) and supercritical water oxidation (SCWO) technologies with increasing amounts of oxidants. Hydrogen-rich gases can be generated from MSS by SCWG or SCWPO technology using oxidants less than stoichiometric ratio while organic compounds can be completely degraded by SCWO technology with using an oxidant excess. For SCWG and SCWPO technologies, this paper reviews the influences of different process variables (MSS properties, moisture content, temperature, oxidant amount and catalysts) on the production of gases. For SCWO technology, this paper reviews research regarding the removal of organics with or without hydrothermal flames and the changes in heavy metal speciation and risk. Finally, typical systems for handling MSS are summarized and research needs and challenges are proposed.

  9. The solubilities of phosphate and sulfate salts in supercritical water

    NARCIS (Netherlands)

    Leusbrock, Ingo; Metz, Sybrand J.; Rexwinkel, Glenn; Versteeg, Geert F.

    2010-01-01

    Inorganic compounds are regularly present in aqueous streams. To understand their influence and behavior on these streams at supercritical conditions, little to no property data is available, which can be used as starting point for further research or application design. Since inorganic compounds te

  10. Supercritical Water Gasification of Biomass: A Literature and Technology Overview

    NARCIS (Netherlands)

    Yakaboylu, O.; Harinck, J.; Smit, K.G.; De Jong, W.

    2014-01-01

    The supercritical water gasification process is an alternative to both conventional gasification as well as anaerobic digestion as it does not require drying and the process takes place at much shorter residence times; a few minutes at most. The drastic changes in the thermo-physical properties of w

  11. Cobalt carbonyl catalyzed olefin hydroformylation in supercritical carbon dioxide

    Science.gov (United States)

    Rathke, Jerome W.; Klingler, Robert J.

    1993-01-01

    A method of olefin hydroformylation is provided wherein an olefin reacts with a carbonyl catalyst and with reaction gases such as hydrogen and carbon monoxide in the presence of a supercritical reaction solvent, such as carbon dioxide. The invention provides higher yields of n-isomer product without the gas-liquid mixing rate limitation seen in conventional Oxo processes using liquid media.

  12. Green dyeing of cotton fabrics by supercritical carbon dioxide

    Directory of Open Access Journals (Sweden)

    Zhang Juan

    2015-01-01

    Full Text Available Green dyeing process with zero waste water emission is a hot topic recently. This paper reveals that supercritical carbon dioxide is the best candidate for this purpose. Effects of thermodynamic parameters, such as enthalpy and entropy of activation, on dyeing process are studied experimentally.

  13. Supercritical water oxidation data acquisition testing. Final report, Volume I

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-11-01

    This report discusses the phase one testing of a data acquisition system for a supercritical water waste oxidation system. The system is designed to destroy a wide range of organic materials in mixed wastes. The design and testing of the MODAR Oxidizer is discussed. An analysis of the optimized runs is included.

  14. Solubilities of sub- and supercritical carbon dioxide in polyester resins

    NARCIS (Netherlands)

    Nalawade, SP; Picchioni, F; Janssen, LPBM; Patil, VE; Keurentjes, JTF; Staudt, R; Nalawade, Sameer P.; Patil, Vishal E.; Keurentjes, Jos T.F.

    2006-01-01

    In supercritical carbon dioxide (CO2) assisted polymer processes the solubility of CO2 in a polymer plays a vital role. The higher the amount of CO2 dissolved in a polymer the higher is the viscosity reduction of the polymer. Solubilities Of CO2 in polyester resins based on propoxylated bisphenol (P

  15. Aerobic Oxidation of Methyl Vinyl Ketone in Supercritical Carbon Dioxide

    Institute of Scientific and Technical Information of China (English)

    OUYANG,Xiao-Yue(欧阳小月); JIANG,Huan-Feng(江焕峰); CHENG,Jin-Sheng(程金生); ZHANG,Qun-Jian(张群健)

    2002-01-01

    Aerobic oxidation of methyl vinyl ketone to acetal in supercritical carbon dioxide are achieved in high conversion and high selectivity when oxygen pressure reaches 0.5MPa. The effects of cocatalysts,additive, pressure and temperature of the reaction are studied in detail.

  16. Preparation of Aromatic Polycarbonate Nanoparticles using Supercritical Carbon Dioxide

    Science.gov (United States)

    Lee, Jun-Young; Song, Cheong-Hun; Kim, Joong-In; Kim, Jung-Hyun

    2002-04-01

    A novel synthetic process for producing aromatic polycarbonate (PC) nanoparticles using supercritical CO2 was developed. The objective of the present research work was to synthesize high molecular weight PC nanoparticles using transesterification between bisphenol-A (BPA) and diphenyl carbonate (DPC) in supercritical CO2 which is an excellent plasticizing agent and a good solvent for phenol, a by-product of the reaction. Poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) tri-block copolymer with CO2-phobic anchor and CO2-philic tail group was used as a stabilizer for the preparation of stable dispersions of BPA-DPC mixture in a CO2 continuous phase. As the reaction was proceeding, phenol formed from the reaction was dissolved and diffused into supercritical CO2 phase. The PC nanoparticles were isolated by simple venting of the supercritical CO2 from the reactor. Spherical morphology of PC particles was confirmed by scanning electron microscopy. Particle size and morphology of PC particles were modified upon variation of the process conditions. The resulting PC particles with a nano-size of 30-140 nm have a high molecular weight ( M w) of 3.1×105 (g/mol).

  17. Preparing silica aerogel monoliths via a rapid supercritical extraction method.

    Science.gov (United States)

    Carroll, Mary K; Anderson, Ann M; Gorka, Caroline A

    2014-02-28

    A procedure for the fabrication of monolithic silica aerogels in eight hours or less via a rapid supercritical extraction process is described. The procedure requires 15-20 min of preparation time, during which a liquid precursor mixture is prepared and poured into wells of a metal mold that is placed between the platens of a hydraulic hot press, followed by several hours of processing within the hot press. The precursor solution consists of a 1.0:12.0:3.6:3.5 x 10(-3) molar ratio of tetramethylorthosilicate (TMOS):methanol:water:ammonia. In each well of the mold, a porous silica sol-gel matrix forms. As the temperature of the mold and its contents is increased, the pressure within the mold rises. After the temperature/pressure conditions surpass the supercritical point for the solvent within the pores of the matrix (in this case, a methanol/water mixture), the supercritical fluid is released, and monolithic aerogel remains within the wells of the mold. With the mold used in this procedure, cylindrical monoliths of 2.2 cm diameter and 1.9 cm height are produced. Aerogels formed by this rapid method have comparable properties (low bulk and skeletal density, high surface area, mesoporous morphology) to those prepared by other methods that involve either additional reaction steps or solvent extractions (lengthier processes that generate more chemical waste).The rapid supercritical extraction method can also be applied to the fabrication of aerogels based on other precursor recipes.

  18. Synthesis of fatty acid starch esters in supercritical carbon dioxide

    NARCIS (Netherlands)

    Muljana, Henky; van der Knoop, Sjoerd; Keijzer, Danielle; Picchioni, Francesco; Janssen, Leon P. B. M.; Heeres, Hero J.

    2010-01-01

    This manuscript describes an exploratory study on the synthesis of fatty acid/potato starch esters using supercritical carbon dioxide (scCO(2)) as the solvent. The effects of process variables such as pressure (6-25 MPa), temperature (120-150 degrees C) and various basic catalysts and fatty acid der

  19. Supercritical flows past a square cylinder with rounded corners

    Science.gov (United States)

    Cao, Yong; Tamura, Tetsuro

    2017-08-01

    Large-eddy simulations were used to investigate the supercritical aerodynamics of a square cylinder with rounded corners in comparison with those in the subcritical regime. First, the numerical methods, especially the dynamic mixed model, were validated on the basis of their prediction of supercritical flows past a circular cylinder. Then, the supercritical flows past a rounded-corner square cylinder were simulated and systematically clarified. Strong Reynolds number (Re) effects existed in the forces and local pressures as Re increased from o(104) to o(106). Changeover of flow patterns occurred as Re increased. At the supercritical Re, the free stream overall flowed along the cross sections of the cylinder, separated from the leeward corners and generated Karman vortices behind the cylinder. This pattern resulted in a much smaller recirculation region behind the cylinder compared with the subcritical flow. At the micro level, the flow experienced laminar separation and flow reattachment near the frontal corners, followed by the spatial development of turbulent boundary layers (TBLs) on the side faces and turbulent separation near the leeward corners. The feedback by large-scale primary vortex shedding and the small-scale turbulent motions in the high-frequency region with a slope of -5/3 were detected in the TBL. Their interaction affected the spanwise correlations of wall pressure fluctuations. The TBL on the side face differed from the zero-pressure-gradient flat-plate one; it was subjected to pressure gradients varying in space and time.

  20. Hydrogel Nanoparticles from Supercritical Technology for Pharmaceutical and Seismological Applications

    Science.gov (United States)

    Hemingway, Melinda Graham

    This research focuses on hydrogel nanoparticle formation using miniemulsion polymerization and supercritical carbon dioxide. Hydrogel nanopowder is produced by a novel combination of inverse miniemulsion polymerization and supercritical drying (MPSD) methods. Three drying methods of miniemulsions are examined: (1) a conventional freeze drying technique, and (2) two supercritical drying techniques: (2a) supercritical fluid injection into miniemulsions, and (2b) the polymerized miniemulsion injection into supercritical fluid. Method 2b can produce non-agglomerated hydrogel nanoparticles that are free of solvent or surfactant (Chapter 2). The optimized MPSD method was applied for producing an extended release drug formulation with mucoadhesive properties. Drug nanoparticles of mesalamine, were produced using supercritical antisolvent technology and encapsulation within two hydrogels, polyacrylamide and poly(acrylic acid-co-acrylamide). The encapsulation efficiency and release profile of drug nanoparticles is compared with commercial ground mesalamine particles. The loading efficiency is influenced by morphological compatibility (Chapter 3). The MPSD method was extended for encapsulation of zinc oxide nanoparticles for UV protection in sunscreens (Chapter 4). ZnO was incorporated into the inverse miniemulsion during polymerization. The effect of process parameters are examined on absorbency of ultraviolet light and transparency of visible light. For use of hydrogel nanoparticles in a seismological application, delayed hydration is needed. Supercritical methods extend MPSD so that a hydrophobic coating can be applied on the particle surface (Chapter 5). Multiple analysis methods and coating materials were investigated to elucidate compatibility of coating material to polyacrylamide hydrogel. Coating materials of poly(lactide), poly(sulphone), poly(vinyl acetate), poly(hydroxybutyrate), Geluice 50-13, Span 80, octadecyltrichlorosilane, and perfluorobutane sulfate (PFBS