The Experts below are selected from a list of 19554 Experts worldwide ranked by ideXlab platform

Taegyu Kim - One of the best experts on this subject based on the ideXlab platform.

  • Accelerated hydrolysis of solid-state NaBH4 by injecting NaHCO3 solution for hydrogen generation
    Applied Energy, 2015
    Co-Authors: Ju-hyeong Sim, Taegyu Kim
    Abstract:

    Sodium bicarbonate (NaHCO3) was used as a catalytic solution and the solid-state sodium borohydride (NaBH4) were stored in a reacting chamber. The NaHCO3 solution was injected when the hydrogen is needed. The hydrogen generation rate was measured as various conditions such as the temperature, and the concentration and injection speed of NaHCO3 solution. The hydrogen generation was initiated immediately when the NaHCO3 solution was injected. The hydrogen generation rate and NaBH4 conversion increased with increasing the NaHCO3 concentration but decreased with increasing the injection speed of NaHCO3 solution. Based on above results, a prototype of hydrogen generation system was developed. The system consisted of a chamber containing solid NaBH4 particles, an aqueous NaHCO3 tank, a Liquid Pump, valves, cooling fans and sensors. The Liquid Pump supplied the NaHCO3 solution to the NaBH4 chamber through an injector. The temperature and pressure of the NaBH4 chamber were monitored during the reaction and maintained into 70°C and 2bar, respectively. The Liquid Pump was stopped when the pressure reached 2bar, while it was restarted to generate hydrogen when the pressure was less than 2bar because the fuel cell consumed hydrogen during the operation. The hydrogen generation system can provide the stable hydrogen to operate the fuel cell.

  • Hydrogen Generation from Solid-state NaBH4 Particles Using NaHCO3 Agents for PEM Fuel Cell Systems☆
    Energy Procedia, 2015
    Co-Authors: Ju-hyeong Sim, Chung Jun Lee, Taegyu Kim
    Abstract:

    Abstract Sodium borohydride (NaBH 4 ) has drawn a great attention as a high hydrogen storage density material. Catalytic hydrolysis has been widely used to extract hydrogen from NaBH 4 alkaline solution but is still problematic in terms of the catalyst durability and byproduct disposal. In the present study, sodium bicarbonate (NaHCO 3 ) was used as a catalytic solution and the NaBH 4 solid particles were stored in a reacting chamber. The NaHCO 3 solution was injected when the hydrogen is needed. The rate of hydrogen production was measured as various conditions such as the temperature, NaHCO 3 concentration and injection speed. The hydrogen production was initiated immediately when the NaHCO 3 solution was injected. The rate of hydrogen production and NaBH 4 conversion increased with increasing the NaHCO 3 concentration but decreased with increasing the injection speed of NaHCO 3 solution. Based on the above results, a prototype of hydrogen generation system was developed. The system consisted of a chamber containing solid NaBH 4 particles, an aqueous NaHCO 3 chamber, a Liquid Pump, valves, cooling fans and sensors. The Liquid Pump supplied the NaHCO 3 solution to the NaBH 4 chamber through an injector. The temperature and pressure of the NaBH 4 chamber were monitored during the reaction. The temperature and pressure were maintained into 70 o C and 2 bar, respectively. The Liquid Pump was stopped when the pressure reached 2 bar. The Liquid Pump was restarted to generate hydrogen when the pressure was less than 2 bar because the fuel cell consumed hydrogen during the operation. The hydrogen generation system provided the sufficient hydrogen to operate the 100W fuel cell system.

  • nabh4 sodium borohydride hydrogen generator with a volume exchange fuel tank for small unmanned aerial vehicles powered by a pem proton exchange membrane fuel cell
    Energy, 2014
    Co-Authors: Taegyu Kim
    Abstract:

    A proton exchange membrane fuel cell system integrated with a NaBH4 (sodium borohydride) hydrogen generator was developed for small UAVs (unmanned aerial vehicles). The hydrogen generator was composed of a catalytic reactor, Liquid Pump and volume-exchange fuel tank, where the fuel and spent fuel exchange the volume within a single fuel tank. Co–B catalyst supported on a porous ceramic material was used to generate hydrogen from the NaBH4 solution. Considering the power consumption according to the mission profile of a UAV, the power output of the fuel cell and auxiliary battery was distributed passively as an electrical load. A blended wing-body was selected considering the fuel efficiency and carrying capability of fuel cell components. First, the fuel cell stack and hydrogen generator were evaluated under the operating conditions, and integrated into the airframe. The ground test of the complete fuel cell UAV was performed under a range of load conditions. Finally, the fuel cell powered flight test was made for 1 h. The volume-exchange fuel tank minimized the fuel sloshing and the change in center of gravity due to fuel consumption during the flight, so that much stable operation of the fuel cell system was validated at different flight modes.

J H J Fluitman - One of the best experts on this subject based on the ideXlab platform.

  • Integrated micro-Liquid dosing system
    [1993] Proceedings IEEE Micro Electro Mechanical Systems, 1993
    Co-Authors: Theodorus S J Lammerink, Miko Elwenspoek, J H J Fluitman
    Abstract:

    An integrated micro-Liquid dosing system consisting of a microPump and a microLiquid flow sensor is demonstrated. The dosing system allows accurate dosing of Liquid in the microliter regime and can easily be integrated with components such as mixers and detectors in micro-Liquid handling systems. The Liquid Pump is of the reciprocating type with a thermopneumatic actuator. The microLiquid flow sensor is based on the thermal anemometer type. Both Pump and flow sensor are realized in a 3-in

  • a thermopneumatic microPump based on micro engineering techniques
    Sensors and Actuators A-physical, 1990
    Co-Authors: F C M Van De Pol, Miko Elwenspoek, H T G Van Lintel, J H J Fluitman
    Abstract:

    The design, working principle and realization of an electro-thermopneumatic Liquid Pump based on micro-engineering techniques are described. The Pump, which is of the reciprocating displacement type, comprises a Pump chamber, a thin silicon Pump membrane and two silicon check valves to direct the flow. The dynamic pressure of an amount of gas contained in a cavity, controlled by resistive heating, actuates the Pump membrane. The cavity, chambers, channels and valves are realized in silicon wafers by wet chemical etching. Experimental results are presented. Maximum yield and built-up pressure equal 34 ?l/min and 0.05 atm, at a supply voltage of 6 V. Results of simulations show good agreement with the actual dynamic behaviour of the Pump.

Ju-hyeong Sim - One of the best experts on this subject based on the ideXlab platform.

  • Accelerated hydrolysis of solid-state NaBH4 by injecting NaHCO3 solution for hydrogen generation
    Applied Energy, 2015
    Co-Authors: Ju-hyeong Sim, Taegyu Kim
    Abstract:

    Sodium bicarbonate (NaHCO3) was used as a catalytic solution and the solid-state sodium borohydride (NaBH4) were stored in a reacting chamber. The NaHCO3 solution was injected when the hydrogen is needed. The hydrogen generation rate was measured as various conditions such as the temperature, and the concentration and injection speed of NaHCO3 solution. The hydrogen generation was initiated immediately when the NaHCO3 solution was injected. The hydrogen generation rate and NaBH4 conversion increased with increasing the NaHCO3 concentration but decreased with increasing the injection speed of NaHCO3 solution. Based on above results, a prototype of hydrogen generation system was developed. The system consisted of a chamber containing solid NaBH4 particles, an aqueous NaHCO3 tank, a Liquid Pump, valves, cooling fans and sensors. The Liquid Pump supplied the NaHCO3 solution to the NaBH4 chamber through an injector. The temperature and pressure of the NaBH4 chamber were monitored during the reaction and maintained into 70°C and 2bar, respectively. The Liquid Pump was stopped when the pressure reached 2bar, while it was restarted to generate hydrogen when the pressure was less than 2bar because the fuel cell consumed hydrogen during the operation. The hydrogen generation system can provide the stable hydrogen to operate the fuel cell.

  • Hydrogen Generation from Solid-state NaBH4 Particles Using NaHCO3 Agents for PEM Fuel Cell Systems☆
    Energy Procedia, 2015
    Co-Authors: Ju-hyeong Sim, Chung Jun Lee, Taegyu Kim
    Abstract:

    Abstract Sodium borohydride (NaBH 4 ) has drawn a great attention as a high hydrogen storage density material. Catalytic hydrolysis has been widely used to extract hydrogen from NaBH 4 alkaline solution but is still problematic in terms of the catalyst durability and byproduct disposal. In the present study, sodium bicarbonate (NaHCO 3 ) was used as a catalytic solution and the NaBH 4 solid particles were stored in a reacting chamber. The NaHCO 3 solution was injected when the hydrogen is needed. The rate of hydrogen production was measured as various conditions such as the temperature, NaHCO 3 concentration and injection speed. The hydrogen production was initiated immediately when the NaHCO 3 solution was injected. The rate of hydrogen production and NaBH 4 conversion increased with increasing the NaHCO 3 concentration but decreased with increasing the injection speed of NaHCO 3 solution. Based on the above results, a prototype of hydrogen generation system was developed. The system consisted of a chamber containing solid NaBH 4 particles, an aqueous NaHCO 3 chamber, a Liquid Pump, valves, cooling fans and sensors. The Liquid Pump supplied the NaHCO 3 solution to the NaBH 4 chamber through an injector. The temperature and pressure of the NaBH 4 chamber were monitored during the reaction. The temperature and pressure were maintained into 70 o C and 2 bar, respectively. The Liquid Pump was stopped when the pressure reached 2 bar. The Liquid Pump was restarted to generate hydrogen when the pressure was less than 2 bar because the fuel cell consumed hydrogen during the operation. The hydrogen generation system provided the sufficient hydrogen to operate the 100W fuel cell system.

Chiharu Takeuchi - One of the best experts on this subject based on the ideXlab platform.

  • Magnetic Suspension Performance of a Bearingless Brushless DC Motor for Small Liquid Pumps
    IEEE Transactions on Industry Applications, 2011
    Co-Authors: M. Ooshima, Chiharu Takeuchi
    Abstract:

    This paper presents the experiment results from the testing of a magnetic suspension system in a bearingless brushless dc motor. This machine is suitable for use in small Liquid Pumps. The bearingless motor structure, the principle of the suspension force generation, and the magnetic suspension control strategy are proposed by the author. A prototype bearingless brushless dc motor is designed using computed results from a finite-element method simulation of the system. The simulation is experimentally verified using a prototype machine where the rotor is successfully suspended without mechanical contact when it drives a Liquid Pump at the maximum rotational speed of 2200 r/min and the maximum fluid flow of 8.2 L/min. This result shows that the proposed bearingless brushless dc motor is suitable as the drive for small Liquid Pumps.

  • Magnetic suspension performance of a bearingless brushless DC motor for small Liquid Pumps
    2009 International Conference on Electrical Machines and Systems, 2009
    Co-Authors: M. Ooshima, Chiharu Takeuchi
    Abstract:

    This paper presents the experiment results of the magnetic suspension in a bearingless brushless DC motor to apply in small Liquid Pumps. The bearingless motor structure, the principle of the suspension force generation and the magnetic suspension control strategy in the bearingless brushless DC motor have been proposed by the author. A prototype bearingless brushless DC motor has been designed based on the computed results by Finite Element Method (FEM) to apply a small Liquid Pump. It is confirmed by the experiments using the prototype machine that the rotor is successfully suspended without mechanical contact when it drives a Liquid Pump at the maximum rotational speed of 2,200 r/min and the maximum fluid flow of 8.2 l/min. This result shows that the proposed bearingless brushless DC motor is enough suitable as the drive for the small Liquid Pumps.

Tomohiro Akiyama - One of the best experts on this subject based on the ideXlab platform.

  • DIRECT PRODUCTION OF PRESSURIZED HYDROGEN FROM WASTE ALUMINUM WITHOUT GAS COMPRESSOR
    Materials Issues in a Hydrogen Economy, 2009
    Co-Authors: Takehito Hiraki, Noriyuki Okinaka, Hiroyuki Uesugi, Tomohiro Akiyama
    Abstract:

    An innovative environment-friendly hydrolysis process for generating high-pressure hydrogen with recycling waste Al has been proposed and experimentally validated. The effect of the concentration of NaOH solution on H2 generation rate was mainly examined. In the experiments, distilled water and Al powder were placed in the pressure-resistance reactor made of Hastelloy, and was compressed to a desired constant water pressure using a Liquid Pump. The NaOH solution was supplied by Liquid Pump with different concentrations (from 1.0 to 5.0 mol/dm) at a constant flow rate into the reactor by replacing the distilled water and the rate of H2 generated was measured simultaneously. The Liquid temperature in the reactor increased due to the exothermic reaction given by Al + OH + 3H2O = 1.5H2 + Al(OH)4 – + 415.6 kJ. Therefore, a high-pressure H2 was generated at room temperature by mixing waste Al and NaOH solution. As the H2 compressor used in this process consumes less energy than the conventional one, the generation of H2 having a pressure of almost 30 MPa was experimentally validated together with Al(OH)3—a useful by-product. The energy losses in the proposed system (150.9 MJ) is 55% less than that in the conventional system (337.7 MJ) in which the gas compressor and production of Al(OH)3 consume significantly more energy.

  • Process for recycling waste aluminum with generation of high-pressure hydrogen.
    Environmental Science & Technology, 2007
    Co-Authors: Takehito Hiraki, Satoru Yamauchi, Masayasu Iida, Hiroshi Uesugi, Tomohiro Akiyama
    Abstract:

    An innovative environmentlly friendly hydrolysis process for recycling waste aluminum with the generation of high-pressure hydrogen has been proposed and experimentally validated. The effect of the concentration of sodium hydroxide solution on hydrogen generation rate was the main focus of the study. In the experiments, distilled water and aluminum powder were placed in the pressure-resistance reactor made of Hastelloy, and was compressed to a desired constant water pressure using a Liquid Pump. The sodium hydroxide solution was supplied by Liquid Pump with different concentrations (from 1.0 to 5.0 mol/dm3) at a constant flow rate into the reactor by replacing the distilled water, and the rate of hydrogen generated was measured simultaneously. The Liquid temperature in the reactor increased due to the exothermic reaction given by Al + OH- + 3H2O = 1.5H2 + Al(OH)4- + 415.6 kJ. Therefore, a high-pressure hydrogen was generated at room temperature by mixing waste aluminum and sodium hydroxide solution. As th...