The Experts below are selected from a list of 5412 Experts worldwide ranked by ideXlab platform
Taegyu Kim - One of the best experts on this subject based on the ideXlab platform.
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Development of NaBH4-Based Hydrogen Generator for Fuel Cell Unmanned Aerial Vehicles with Movable Fuel Cartridge
Energy Procedia, 2019Co-Authors: Soonmo Kwon, Kang Shinuang, Taegyu KimAbstract:Abstract NaBH4-based Hydrogen Generator for fuel cell Unmanned Aerial Vehicle (UAVs) with movable fuel cartridge was developed in the present study. The main fuel of Hydrogen Generator is Sodium borohydride (NaBH4) that is a kind of chemical hydride and has a high Hydrogen storage density. In the previous studies, Hydrogen Generators were developed in which Hydrogen was directly generated from solid state NaBH4. However, it was a prototype, so inconvenient to replace the fuel after used up and lacked user convenience. Therefore, the performance evaluation and the development procedure of NaBH4-based Hydrogen Generator that was designed taking user convenience in consideration for commercialization were described in this paper.
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Compact PEM fuel cell system combined with all-in-one Hydrogen Generator using chemical hydride as a Hydrogen source
Applied Energy, 2015Co-Authors: Jincheol Kim, Taegyu KimAbstract:Compact fuel cell system was developed for a portable power Generator. The power Generator features a polymer electrolyte membrane fuel cell (PEMFC) using a chemical hydride as a Hydrogen source. The Hydrogen Generator extracted Hydrogen using a catalytic hydrolysis from a sodium borohydride alkaline solution. A novel concept using an all-in-one reactor was proposed in which a catalyst, Hydrogen chamber and byproduct separator were combined in a volume. In addition, the reactor as well as a pump, cooling fans, valves and controller was integrated in a single module. A 100W PEMFC stack was connected with the Hydrogen Generator and was evaluated at various load conditions. It was verified that the stable Hydrogen supply was achieved and the developed system can be used to drive fuel cell-powered unmanned autonomous systems.
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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, 2014Co-Authors: Taegyu KimAbstract: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.
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Fully-integrated micro PEM fuel cell system with NaBH4 Hydrogen Generator
International Journal of Hydrogen Energy, 2012Co-Authors: Taegyu KimAbstract:Abstract A fully-integrated micro PEM fuel cell system with a NaBH 4 Hydrogen Generator was developed. The micro fuel cell system contained a micro PEM fuel cell and a NaBH 4 Hydrogen Generator. The Hydrogen Generator comprised a NaBH 4 reacting chamber and a Hydrogen separating chamber. Photosensitive glass wafers were used to fabricate a lightweight and corrosion-resistant micro fuel cell and Hydrogen Generator. All of the BOP such as a NaBH 4 cartridge, a micropump, and an auxiliary battery were fully integrated. In order to generate stable power output, a hybrid power management operating with a micro fuel cell and battery was designed. The integrated performance of the micro PEM fuel cell with NaBH 4 Hydrogen Generator was evaluated under various operating conditions. The hybrid power output was stably provided by the micro PEM fuel cell and auxiliary battery. The maximum power output and specific energy density of the micro PEM fuel cell system were 250 mW and 111.2 W h/kg, respectively.
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Micro PEM fuel cell system with NaBH4 Hydrogen Generator
Sensors and Actuators A: Physical, 2012Co-Authors: Jongkwang Lee, Taegyu KimAbstract:Abstract A micro PEM fuel cell system with a NaBH 4 Hydrogen Generator is presented. The micro PEM fuel cell contained glass bipolar plates and a microreactor that initiated a catalytic hydrolysis reaction in the NaBH 4 solution. The entire system was developed using MEMS technology. The total system comprised the micro PEM fuel cell, a catalytic microreactor, Hydrogen separator, micropump, and a NaBH 4 solution cartridge. The microreactor generated a Hydrogen flow rate of 16.1 ml/min from a NaBH 4 feeding rate of 60 μl/min. The conversion efficiency was 98.8% and the reactor temperature was 41 °C during the operation. The maximum power output of micro fuel cell was 174.6 mW for a current of 0.45 A. Cyclic performance tests were conducted in order to assess the practical operation of the micro fuel cell system.
Daniel Węcel - One of the best experts on this subject based on the ideXlab platform.
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Investigation on System for Renewable Electricity Storage in Small Scale Integrating Photovoltaics, Batteries, and Hydrogen Generator
Energies, 2020Co-Authors: Daniel Węcel, Michał Jurczyk, Wojciech Uchman, Anna Skorek-osikowskaAbstract:In this article the solution based on Hydrogen generation to increase the flexibility of energy storage systems is proposed. Operating characteristics of a Hydrogen Generator with integrated electrical energy storage and a photovoltaic installation were determined. The key role of the electricity storage in the proposed system was to maintain the highest operating efficiency related to the nominal parameters of the Hydrogen Generator. The Hydrogen Generators achieved the highest energy efficiency for the nominal operating point at the highest power output. Lead-acid batteries were used to ensure the optimal operating conditions for the Hydrogen Generator supplied with renewable energy throughout the day. The proposed system reduces significantly the Hydrogen Generator nominal power and devices in system operate in such a way to improve their efficiency and durability. The relations between individual components and their constraints were determined. The proposed solution is fully in-line with previously investigated technologies for improving grid stability and can help incorporate renewable energy sources to increase the sustainability of the energy sector and green Hydrogen production.
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The possibilities of cooperation between a Hydrogen Generator and a wind farm
International Journal of Hydrogen Energy, 2020Co-Authors: Janusz Kotowicz, Michał Jurczyk, Daniel WęcelAbstract:Abstract In this paper, a Hydrogen Generator and a wind farm were taken as the research objects. The H2 Generator consisted characteristics of laboratory-tested electrolyzers were determined as a function of the Hydrogen mass flow. Determining the auxiliary power index of the device allowed the efficiency of the Hydrogen Generator to be determined as a function of Hydrogen mass flow as well as the Hydrogen Generator relative power. The dynamic characteristics of a Generator were also presented. The possibility of a given wind farm cooperating with Hydrogen Generators that are characterized by different powers and various efficiencies was simulated. Algorithm enables determination of Hydrogen Generators efficiency for devices with various performance in nominal operation point is shown. It has been shown that proper selection of the power of the Hydrogen Generator in relation to the power of the wind farm can ensure a high efficiency for the device.
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Analysis of component operation in power-to-gas-to-power installations
Applied Energy, 2018Co-Authors: Janusz Kotowicz, Daniel Węcel, Michał JurczykAbstract:Abstract This article presents results of research into Hydrogen Generators and fuel cells (basic elements in Power-to-Gas-to-Power systems) together with an economic analysis of this installation type. A Hydrogen Generator containing two AEM (Anion Exchange Membrane) alkaline electrolyzers with a performance of 0.5 Nm3 H2/h and a PEM fuel cell with an electrical power of 0.72 kW were tested. A methodology is presented for determining gross and net efficiency characteristics of the tested devices using measurement results. These operations allowed assessment of the efficiency characteristics as a function of electrical power and identification of the power needs of a Hydrogen Generator and a fuel cell system. This is important because in P2G2P installations integrated with renewable energy sources these devices operate with variable loads. For a nominal power value, the efficiency of the Hydrogen Generator was 63% and the efficiency of the fuel cell system was about 40%. For an energy storage system in Hydrogen form, a simplified methodology for determining the price ratio of the electric energy sales to the purchase price of the electricity was determined, in order to discover whether the system could be economically efficient. This allowed the determination of the components of this relationship related to the efficiency of the installation and the investment costs of each element. Economic analyses assumed the installation operated with nominal power for a certain period of time throughout the day, strictly connected to the valley and peak of electricity demand. Analysis results are presented as a function of P2G2P system efficiency and working time of Hydrogen Generators and fuel cells during twenty-four hours. Studies and analyses were performed for P2G2P installations with the most commonly considered elements in energy storage systems. These are considered a very promising solution to the energy balance process, for connecting a high amount of power from renewable energy sources to the power grid.
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Hydrogen Generator characteristics for storage of renewably-generated energy
Energy, 2017Co-Authors: Janusz Kotowicz, Łukasz Bartela, Daniel Węcel, Klaudia DubielAbstract:The paper presents a methodology for determining the efficiency of a Hydrogen Generator taking the power requirements of its auxiliary systems into account. Authors present results of laboratory experiments conducted on a Hydrogen Generator containing a PEM water electrolyzer for a wide range of device loads. On the basis of measurements, the efficiency characteristics of electrolyzers were determined, including that of an entire Hydrogen Generator using a monitored power supply for its auxiliary devices. Based on the results of the experimental tests, the authors have proposed generalized characteristics of Hydrogen Generator efficiency. These characteristics were used for analyses of a Power-to-Gas system cooperating with a 40 MW wind farm with a known yearly power distribution. It was assumed that nightly-produced Hydrogen is injected into the natural gas transmission system. An algorithm for determining the thermodynamic and economic characteristics of a Power-to-Gas installation is proposed. These characteristics were determined as a function of the degree of storage of the energy produced in a Renewable Energy Sources (RES) installation, defined as the ratio of the amount of electricity directed to storage to the annual amount of electricity generated in the RES installation. Depending on the degree of storage, several quantities were determined.
Mark A Shannon - One of the best experts on this subject based on the ideXlab platform.
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An on-demand microfluidic Hydrogen Generator with self-regulated gas generation and self-circulated reactant exchange with a rechargeable reservoir
Microfluidics and Nanofluidics, 2011Co-Authors: N. Kroodsma, J. Yeom, J. L. Haan, Mark A Shannon, D. D. MengAbstract:This article introduces an on-demand microfluidic Hydrogen Generator that can be integrated with a micro-proton exchange membrane (PEM) fuel cell. The catalytic reaction, reactant circulation, gas/liquid separation, and autonomous control functionalities are all integrated into a single microfluidic device. It generates hydrated Hydrogen gas from an aqueous ammonia borane solution which is circulated and exchanged between the microfluidic reactor and a rechargeable fuel reservoir without any parasitic power consumption. Ammonia borane is chosen instead of sodium borohydride because of its faster Hydrogen generation rate, higher Hydrogen storage capability, stability, and better catalyst durability. The self-circulation of the ammonia borane solution was achieved using directional growth and selective venting of Hydrogen bubbles in micro-channels, which leads to agitation and addition of fresh solution without consumption of electrical power. The self-regulation mechanism ensures that Hydrogen can be supplied to a fuel cell according to the exact demand of the current output of the fuel cell. The circulation flow rate of ammonia borane solution is also automatically regulated by the venting rate of Hydrogen at the gas outlet. Design, fabrication, and testing results of a prototype system are described. The Hydrogen Generator is capable of generating Hydrogen gas at a maximum rate of 0.6 ml/min (2.1 ml/min cm 2 ) and circulating aqueous ammonia borane at a maximum flow rate of ~15.7 μl/min. The device has also been connected with a micro-PEM fuel cell to demonstrate the feasibility of its practical applications in a high-impedance system.
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A self-regulating Hydrogen Generator for micro fuel cells
Journal of Power Sources, 2008Co-Authors: Saeed Moghaddam, Eakkachai Pengwang, Richard I. Masel, Mark A ShannonAbstract:The ever-increasing power demands and miniaturization of portable electronics, micro-sensors and actuators, and emerging technologies such as cognitive arthropods have created a significant interest in development of micro fuel cells. One of the major challenges in development of Hydrogen micro fuel cells is the fabrication and integration of auxiliary systems for generating, regulating, and delivering Hydrogen gas to the membrane electrode assembly (MEA). In this paper, we report the development of a Hydrogen gas Generator with a micro-scale control system that does not consume any power. The Hydrogen Generator consists of a hydride reactor and a water reservoir, with a regulating valve separating them. The regulating valve consists of a port from the water reservoir and a movable membrane with via holes that permit water to flow from the reservoir to the hydride reactor. Water flows towards the hydride reactor, but stops within the membrane via holes due to capillary forces. Water vapor then diffuses from the via holes into the hydride reactor resulting in generation of Hydrogen gas. When the rate of Hydrogen consumed by the MEA is lower than the generation rate, gas pressure builds up inside the hydride reactor, deflecting the membrane, closing the water regulator valve, until the pressure drops, whereby the valve reopens. We have integrated the self-regulating micro Hydrogen Generator to a MEA and successfully conducted fuel cell tests under varying load conditions.
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Integrated micro-power source based on a micro-silicon fuel cell and a micro electromechanical system Hydrogen Generator
Journal of Power Sources, 2008Co-Authors: Likun Zhu, Richard I. Masel, Kevin Lin, Robert D. Morgan, Vikhram V. Swaminathan, Hee Soo Kim, Bogdan Gurau, Daejoong Kim, Byunghoon Bae, Mark A ShannonAbstract:Abstract Micro-power sources that are comparable to or smaller than the size of the micro-devices needing power are needed for many applications. This paper introduces an integrated millimeter scale power source based on a micro-silicon fuel cell and a MEMS Hydrogen Generator, with passive control. The integrated devices are fabricated from silicon wafers using conventional MEMS fabrication processes. In this design, the hydrolysis reaction of calcium hydride and water is used to generate Hydrogen, and the Hydrogen generation rate is controlled by a microfluidic self-regulating mechanism, which can control the hydrolysis reaction based on the load. Design, fabrication, and testing results of a prototype system are described. One of the devices can produce 90 μW for 6 h with a maximum power of 0.17 mW, and another one can produce 30 μW for 26 h with a total energy density of 100 Wh L −1 .
Sejin Kwon - One of the best experts on this subject based on the ideXlab platform.
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Fuel cell system with sodium borohydride Hydrogen Generator for small unmanned aerial vehicles
International Journal of Green Energy, 2018Co-Authors: Eun Sang Jung, Hyuntak Kim, Sejin KwonAbstract:ABSTRACTA 100 W proton exchange membrane fuel cell (PEMFC) system with a sodium borohydride (NaBH4) Hydrogen Generator was investigated for small unmanned aerial vehicles (UAVs). The performance of a cobalt–phosphorous/nickel foam catalyst was evaluated to determine the change in catalytic activity under real operating conditions. The response time increased owing to oxidation of the metals and accumulation of sodium; however, the catalyst remained active at high reaction temperatures. A NaBH4 Hydrogen Generator with the catalyst was developed for a 100 W PEMFC system. The Hydrogen generation rate was stable for 3 h, and the conversion efficiency was 97.8%. Finally, a 100 W PEMFC system with the NaBH4 Hydrogen Generator was investigated for small UAVs. The maximum power and energy density of the PEMFC system were 95.96 W and 185.2 Wh/kg, respectively.
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Simple catalyst bed sizing of a NaBH4 Hydrogen Generator with fast startup for small unmanned aerial vehicles
International Journal of Hydrogen Energy, 2016Co-Authors: Hyuntak Kim, Sejin KwonAbstract:Abstract A flow-type Hydrogen Generator with cobalt- and phosphorus-coated nickel foam catalyst was evaluated for a 500 W PEM fuel cell. Hydrogen was produced by catalytic hydrolysis of sodium borohydride. Startup characteristics and adequate catalyst bed sizing were considered in developing the Hydrogen Generator, tailored especially to small UAV applications. Gradual increase of the liquid fuel flow rate expedited the startup time to less than 5 min at 20 °C, which is practical for flight preparation. The effect of the cross-section on maximum Hydrogen generation rates was investigated as preliminary input for catalyst bed sizing. Final dimensions of the 500 W-scale Hydrogen Generator were determined and validated using the space time concept. Endurance and restart characteristics were tested over two 2-h operating sessions with a 2-h rest in-between. The startup time was 2.5 min for both operations. The Hydrogen generation efficiency decreased from 94% in the first operation to 81.6% in the second operation because of borate precipitation on the catalyst surface.
Janusz Kotowicz - One of the best experts on this subject based on the ideXlab platform.
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The possibilities of cooperation between a Hydrogen Generator and a wind farm
International Journal of Hydrogen Energy, 2020Co-Authors: Janusz Kotowicz, Michał Jurczyk, Daniel WęcelAbstract:Abstract In this paper, a Hydrogen Generator and a wind farm were taken as the research objects. The H2 Generator consisted characteristics of laboratory-tested electrolyzers were determined as a function of the Hydrogen mass flow. Determining the auxiliary power index of the device allowed the efficiency of the Hydrogen Generator to be determined as a function of Hydrogen mass flow as well as the Hydrogen Generator relative power. The dynamic characteristics of a Generator were also presented. The possibility of a given wind farm cooperating with Hydrogen Generators that are characterized by different powers and various efficiencies was simulated. Algorithm enables determination of Hydrogen Generators efficiency for devices with various performance in nominal operation point is shown. It has been shown that proper selection of the power of the Hydrogen Generator in relation to the power of the wind farm can ensure a high efficiency for the device.
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Economic analysis of an installation producing Hydrogen through water electrolysis
Journal of Power of Technologies, 2019Co-Authors: Janusz Kotowicz, Michał JurczykAbstract:This paper presents an economic analysis of an installation that produces Hydrogen through water electrolysis. The purpose of the economic analysis performed for the Hydrogen Generator was to determine the break-even price of Hydrogen. In calculations the NPV (Net Present Value) indicator was used. The reference system had installed power of 10 MW and worked 8 hours a day (2920 hours per year) during the valley of demand for electricity. The installation’s lifetime was assumed to be 100,000 hours. The efficiency of the Hydrogen Generator was assumed to be 80% during operation at maximum power.
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Analysis of component operation in power-to-gas-to-power installations
Applied Energy, 2018Co-Authors: Janusz Kotowicz, Daniel Węcel, Michał JurczykAbstract:Abstract This article presents results of research into Hydrogen Generators and fuel cells (basic elements in Power-to-Gas-to-Power systems) together with an economic analysis of this installation type. A Hydrogen Generator containing two AEM (Anion Exchange Membrane) alkaline electrolyzers with a performance of 0.5 Nm3 H2/h and a PEM fuel cell with an electrical power of 0.72 kW were tested. A methodology is presented for determining gross and net efficiency characteristics of the tested devices using measurement results. These operations allowed assessment of the efficiency characteristics as a function of electrical power and identification of the power needs of a Hydrogen Generator and a fuel cell system. This is important because in P2G2P installations integrated with renewable energy sources these devices operate with variable loads. For a nominal power value, the efficiency of the Hydrogen Generator was 63% and the efficiency of the fuel cell system was about 40%. For an energy storage system in Hydrogen form, a simplified methodology for determining the price ratio of the electric energy sales to the purchase price of the electricity was determined, in order to discover whether the system could be economically efficient. This allowed the determination of the components of this relationship related to the efficiency of the installation and the investment costs of each element. Economic analyses assumed the installation operated with nominal power for a certain period of time throughout the day, strictly connected to the valley and peak of electricity demand. Analysis results are presented as a function of P2G2P system efficiency and working time of Hydrogen Generators and fuel cells during twenty-four hours. Studies and analyses were performed for P2G2P installations with the most commonly considered elements in energy storage systems. These are considered a very promising solution to the energy balance process, for connecting a high amount of power from renewable energy sources to the power grid.
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Hydrogen Generator characteristics for storage of renewably-generated energy
Energy, 2017Co-Authors: Janusz Kotowicz, Łukasz Bartela, Daniel Węcel, Klaudia DubielAbstract:The paper presents a methodology for determining the efficiency of a Hydrogen Generator taking the power requirements of its auxiliary systems into account. Authors present results of laboratory experiments conducted on a Hydrogen Generator containing a PEM water electrolyzer for a wide range of device loads. On the basis of measurements, the efficiency characteristics of electrolyzers were determined, including that of an entire Hydrogen Generator using a monitored power supply for its auxiliary devices. Based on the results of the experimental tests, the authors have proposed generalized characteristics of Hydrogen Generator efficiency. These characteristics were used for analyses of a Power-to-Gas system cooperating with a 40 MW wind farm with a known yearly power distribution. It was assumed that nightly-produced Hydrogen is injected into the natural gas transmission system. An algorithm for determining the thermodynamic and economic characteristics of a Power-to-Gas installation is proposed. These characteristics were determined as a function of the degree of storage of the energy produced in a Renewable Energy Sources (RES) installation, defined as the ratio of the amount of electricity directed to storage to the annual amount of electricity generated in the RES installation. Depending on the degree of storage, several quantities were determined.
