The Experts below are selected from a list of 87 Experts worldwide ranked by ideXlab platform
Tadashi Shiraishi - One of the best experts on this subject based on the ideXlab platform.
-
Development of the advanced accumulator for the pressurized water reactor
Nuclear Engineering and Design, 2012Co-Authors: Tadashi Shiraishi, Hisato WatakabeAbstract:With the increased requirement for nuclear power generation as an effective countermeasure against global warming, Mitsubishi has developed the advanced pressurized water reactor (APWR) by adopting a new component of the emergency core cooling system (ECCS), a new instrumentation and control system, and other newfound improvements. The ECCS introduces a new passive component called the advanced accumulator which integrates both functions of the conventional accumulator and the Low-Pressure Pump without any moving parts. The advanced accumulator uses a new fluidic device that automatically regulates flow rates of injected water in case of a loss of coolant accident (LOCA). This fluidic device is referred to as a flow damper. The design method of the flow damper and the standpipe was separately published (Shiraishi, 2011). This paper, then, describes the development and experiments with scale models of the advanced accumulator, and the satisfactory results obtained.
-
Design of the advanced accumulator for the pressurized water reactor
Nuclear Engineering and Design, 2011Co-Authors: Tadashi ShiraishiAbstract:With the increased requirement for nuclear power generation as an effective countermeasure against global warming, Mitsubishi has developed the advanced pressurized water reactor (APWR) by adopting a new component of the emergency core cooling system (ECCS), a new instrumentation and control system, and other newfound improvements. The ECCS introduces a new passive component called the advanced accumulator which integrates both functions of the conventional accumulator and the Low-Pressure Pump without any moving parts. The advanced accumulator uses a new fluidics device that automatically regulates flow rates of injected water in case of a loss of coolant accident (LOCA). This fluidics device is referred to as a flow damper. This paper describes the design method of the flow damper and the standpipe.
-
The Advanced Accumulator: A New Passive ECCS Component of the APWR
Advances in Light Water Reactor Technologies, 2010Co-Authors: Tadashi ShiraishiAbstract:With the increased requirement for nuclear power generation as an effective countermeasure against global warming, Mitsubishi has developed the advanced pressurized water reactor (APWR) by adopting a new component of the emergency core cooling system (ECCS), a new instrumentation and control system, and other newfound improvements. The ECCS introduces a new passive component called the Advanced Accumulator which integrates both functions of the conventional accumulator and the Low-Pressure Pump without any moving parts. The Advanced Accumulator uses a new fluidics device that automatically controls flow rates of injected water in case of a loss-of-coolant accident (LOCA). This fluidics device is referred to as a flow damper. In this chapter, the Advanced Accumulator is introduced from the background of its development to its principle, with some experimental results. Furthermore, the features of the flow damper are explained in detail.
Frank Hensel - One of the best experts on this subject based on the ideXlab platform.
-
Introduction of a new Energy Recovery System—optimized for the combination with renewable energy
Desalination, 2005Co-Authors: Kay Paulsen, Frank HenselAbstract:The ENERCON Desalination Department has developed a new energy recovery system for RO desalination plants, optimized for the combination with wind energy converters. The main problem for the combination of desalination processes and wind energy is the fluctuation of power supply generated through renewable energies. Conventional desalination plants (and the belonging energy recovery systems) work at a fixed operation point or in a very small range. ENERCON developed a system that can adjust the operation in a range of 12,5 - 100% energy availability - in a very energy efficient way! The energy recovery system consists of a low pressure Pump (20bar) and three combined pistons (there is no need for a second/booster Pump). This “piston type accumulator” is able to transfer the pressure up to 70 bar, needed for the desalination process. As a side effect we can also avoid the use of chemicals for the antiscaling and antifouling problem. We managed to avoid additives by a low recovery rate. In the combination with the very efficient energy recovery system we experienced an energy consumption within the RO unit between 2-2,8 kWh / m3 for sea water and between 0,8-1,3 for brackish water with our prototype plants in the Mediterranean sea. The ENERCON design enables a reduction of operation costs through low energy consumption and the avoidance of chemicals. Furthermore it is also a benefit for the environment. Our goal: A reliable, sustainable drinking water production of finest water quality!
Ta Hui Lin - One of the best experts on this subject based on the ideXlab platform.
-
Nitrogen Dilution Effect on Flame Synthesis of Carbon Nanostructures with Acoustic Modulation
The Journal of Physical Chemistry C, 2011Co-Authors: De Hua Chung, Ta Hui LinAbstract:Several allotropes of the element carbon can be found in nature, such as amorphous carbon, graphite, and diamond. More recently discovered allotropes, such as fullerene (C60), carbon nanotubes (CNTs), and carbon nano-onions (CNOs) have received a lot of attention due to their low density, high structural intensity, and good electrical conductivity. CNOs were quasispherical carbon nanoparticles made of concentric graphitic shells. CNOs have already been shown suitable for a wide variety of potential applications, for instance, solar cells, field emission, fuel cells, optical limiting, electromagnetic shielding, lubricants, and so on. Common methods of synthesizing carbon nanomaterials included the laser ablation method, DC arc discharge method, and chemical vapor deposition (CVD). These methods usually required some special apparatus, such as a low pressure Pump, a high voltage power supply, or a high temperature heater. Therefore, a simple, continuous, and energy-efficient method for synthesizing carbon nanomaterials for large-scale applications is desirable. Combustion synthesis usually has a high temperature (heat source) and a rich carbon environment (carbon source) provided by the hydrocarbon flame itself under ambient pressure. 30 Suitable synthesis conditions can be obtained by adding a catalyst (e.g., Fe-, Co-, or Nialloy) to the reaction. Most studies on the combustion synthesis of CNTs can first be classified, according to the premixture of fuel and oxidizer, into diffusion flames 24,29,30 or premixed flames. 28 Diffusion flames can be categorized by their structure, such as stagnation flow, counterflow, normal jet flow, 21 and inverse jet flow. 24 Fullerene has also been synthesized with low pressure combustion. Recently, some research had reported the application of flames for the synthesis of metal-oxide nanostructures and powders. Iron nanorods could be synthesized from amorphous iron inside the CNTs using an ethylene-fueled inverse diffusion flame. ZnO nanostructures, long nanowire, short nanorod, nonoribbon, nanocone, and short nanoneedle, could be observed with zincplated-steel wire in a methane-fueled inverse diffusion flame. Molybdenum-oxide microstructures, polygonal cubic shape, elongated channels, leaf-like shape, and dendritic structures, were formed in a counter-flow oxy-fuel flame using molybdenum probes, and the growth mechanism was described. CNTs produced in stagnation-flow flames on the stagnation plane were in the shape of donuts due to the trumpet shape of the flow fields and high temperature fields. Counterflow flames provided a planar flame which allows the large-scale production of CNTs with a 14% volumetric concentration of C2H4/N2 and a prolonged resident time (obtained by the rigid body rotation of the burners). Furthermore, only high density CNTs could be synthesized with a fuel mixture of 5% C2H4 and moderate CH4 concentration (25%) in the upper flow and air in the lower flow. However, when the oxygen concentration was increased to 50%, only CNOs were synthesized; the diameter increased from 5 to 60 nm when the methane concentration of the fuel mixture (CH4/C2H4) was increased. Single-walled carbon nanotubes (SWCNTs) were synthesized with a normal jet diffusion flame and their growth mechanism was studied. The steps of growth included (a) metal nanoparticle formation, (b) hydrocarbon deposition on the metal nanoparticles, (c) carbon migration diffused through the particles, and (d) precipitation that forms the nanotubes. Yuan et al. synthesized straight and bamboo-like carbon nanotubes in a methane diffusion flame using a Ni Cr Fe wire as a substrate and proposed a segregation growth mechanism for
Kay Paulsen - One of the best experts on this subject based on the ideXlab platform.
-
Introduction of a new Energy Recovery System—optimized for the combination with renewable energy
Desalination, 2005Co-Authors: Kay Paulsen, Frank HenselAbstract:The ENERCON Desalination Department has developed a new energy recovery system for RO desalination plants, optimized for the combination with wind energy converters. The main problem for the combination of desalination processes and wind energy is the fluctuation of power supply generated through renewable energies. Conventional desalination plants (and the belonging energy recovery systems) work at a fixed operation point or in a very small range. ENERCON developed a system that can adjust the operation in a range of 12,5 - 100% energy availability - in a very energy efficient way! The energy recovery system consists of a low pressure Pump (20bar) and three combined pistons (there is no need for a second/booster Pump). This “piston type accumulator” is able to transfer the pressure up to 70 bar, needed for the desalination process. As a side effect we can also avoid the use of chemicals for the antiscaling and antifouling problem. We managed to avoid additives by a low recovery rate. In the combination with the very efficient energy recovery system we experienced an energy consumption within the RO unit between 2-2,8 kWh / m3 for sea water and between 0,8-1,3 for brackish water with our prototype plants in the Mediterranean sea. The ENERCON design enables a reduction of operation costs through low energy consumption and the avoidance of chemicals. Furthermore it is also a benefit for the environment. Our goal: A reliable, sustainable drinking water production of finest water quality!
John E. Keba - One of the best experts on this subject based on the ideXlab platform.
-
Component test results from the bearing life improvement program for the Space Shuttle Main Engine oxidizer turboPumps
1992Co-Authors: John E. KebaAbstract:Interim results from a component test program to improve ball bearing life in the Space Shuttle Main Engine oxygen turboPumps are presented. Two specific bearing applications, using liquid oxygen as the bearing coolant, are addressed. The first, the thrust bearing of the low pressure Pump, operates at relatively slow speed with predominantly axial load and little temperature rise in the bulk coolant. Testing has demonstrated a very significant reduction in bearing wear by increasing the bearing internal clearance. Heat generation data was obtained that indicates heavy, intermittent cage-to-ball contact occurs, providing a possible explanation for the observed wear. The second application is the turbine end bearings of the high pressure Pump. These bearings operate at high speed and load with the possibility of significant coolant vaporization. Tests on production bearings and bearings having modified internal clearance and curvature yielded scattered but generally poor lives. A dramatic improvement was achieved by coating the standard cage with a thin film of fluorinated ethylene propylene and 15 percent molybdenum disulfide. Very promising results have also been obtained by replacing the standard balls with ones made of silicon nitride, especially in combination with the coated cage.
