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Technical Paper

Characteristics of Electrode Poisoning by Carbon Monoxide and/or Hydrogen Sulfide in the Anode Feed of Polymer Electrolyte Fuel Cells as Analyzed by AC Impedance Spectroscopy

The results of this study make clear the characteristics of electrode performance deterioration in terms of cell voltage reduction in polymer electrolyte fuel cells (PEFCs) caused by the presence of certain quantities of carbon monoxide and/or hydrogen sulfide in the anode feed. AC impedance measurements of the anode and cathode potentials revealed that both electrode potentials showed deterioration in the presence of each type of poisoning gas. This suggests that the poisoning gases permeated the electrolyte membrane and transferred to the cathode, causing performance deterioration by poisoning the catalyst. In addition, AC impedance measurements indicated that the presence of hydrogen sulfide in the anode feed increased the membrane impedance, thus implying some poisoning effect even on the electrolyte membrane.
Technical Paper

Controlling Onset of Heat Release by Assisted Spark Ignition in Hydrogen HCCI Engine Supported by DME Supplement

The results of our previous study showed that applying hydrogen (H2) to homogeneous charge compression ignition (HCCI) combustion with the assist of di-methyl ether (DME) as a supplement improved thermal efficiency compared with homogeneous hydrogen-fueled spark ignition (SI) combustion [1, 2]. As a general characteristic of HCCI combustion, however, stable engine operation is limited to a narrow region by the occurrence of misfiring and abrupt combustion like knocking. The onset of heat release is still not sufficiently controllable to achieve optimum engine performance. The objective of this study is to control the onset of the main heat release of hydrogen-fueled HCCI combustion by adopting spark ignition to assist autoignition. The results showed that improved thermal efficiency and reduced combustion fluctuation were achieved by attaining MBT operation with the support of spark ignition.
Technical Paper

Development Project of a Multi-cylinder DISI Hydrogen ICE System for Heavy Duty Vehicles

The planned development of a hydrogen ICE system for trucks is one of the technological candidates for air pollution reduction and global warming prevention for the large-sized (heavy-duty) trucks supporting Japanese freightage. This project is the first to develop a DISI multi-cylinder hydrogen ICE system aimed at combining high power output and low NOx generation.
Technical Paper

HCCI Combustion Characteristics of Hydrogen and Hydrogen-rich Natural Gas Reformate Supported by DME Supplement

Hydrogen is expected to be a clean and energy-efficient fuel for the next generation of power sources because it is CO2-free and has excellent combustion characteristics. In this study, an attempt was made to apply Homogeneous Charge Compression Ignition (HCCI) combustion to hydrogen with the aim of achieving low oxides of nitrogen (NOx) emissions and high fuel economy with the assistance of the di-methyl-ether (DME) fuel supplement. As a result, HCCI combustion of hydrogen mixed with 25 vol% DME achieved approximately a 30% improvement in fuel economy compared with HCCI of pure DME and spark-ignited lean-burn combustion of pure hydrogen under almost zero NOx emissions and low hydrocarbon (HC) emissions. This is attributed to control of the combustion process to attain the optimum onset of combustion and to a reduction of cooling losses.
Technical Paper

Optimization of Hydrogen Jet Configuration by Single Hole Nozzle and High Speed Laser Shadowgraphy in High Pressure Direct Injection Hydrogen Engines

A new ignition-combustion concept named PCC (Plume Ignition Combustion Concept), which ignite rich mixture plume in the middle of injection period or right after injection of hydrogen is completed, is proposed by the authors in order to reduce NOx emissions in high engine load conditions with minimizing trade-offs on thermal efficiency. In this study fundamental requirements of hydrogen jet to optimize PCC are investigated by using single and multi-hole nozzle with a combination of high speed laser shadowgraphy to visualize propagating flame. As a result, it was infered that igniting the mixture plume in the middle of injection period with minimizing jet penetration to chamber wall is effective reducing NOx formation even further.
Technical Paper

Study of NOx Emissions Reduction Strategy for a Naturally Aspirated 4-Cylinder Direct Injection Hydrogen ICE

Hydrogen engines are required to provide high thermal efficiency and low nitrogen oxide (NOX) emissions. There are many possible combinations of injection timing, ignition timing, lambda and EGR rate that can be used in a direct-injection system for achieving such performance. In this study, NOX emissions of natural aspirated 4 cylinders engine with management strategies involving the injection timing, ignition timing, lambda and the EGR rate were evaluated under a Japanese JE05 emissions test cycle. Finally, the paper projects the potential of direct injection hydrogen engine for obtaining high output power and attaining low NOX emissions of 0.7 g/kWh under the emission test cycle.
Journal Article

Summary and Progress of the Hydrogen ICE Truck Development Project

A development project for a hydrogen internal combustion engine (ICE) system for trucks supporting Japanese freightage has been promoted as a candidate for use in future vehicles that meet ultra-low emission and anti-global warming targets. This project aims to develop a hydrogen ICE truck that can handle the same freight as existing trucks. The core development technologies for this project are a direct-injection (DI) hydrogen ICE system and a liquid hydrogen tank system which has a liquid hydrogen pump built-in. In the first phase of the project, efforts were made to develop the DI hydrogen ICE system. Over the past three years, the following results have been obtained: A high-pressure hydrogen gas direct injector developed for this project was applied to a single-cylinder hydrogen ICE and the indicated mean effective pressure (IMEP) corresponding to a power output of 147 kW in a 6-cylinder hydrogen ICE was confirmed.
Technical Paper

Unsteady Three-Dimensional Computations of the Penetration Length and Mixing Process of Various Single High-Speed Gas Jets for Engines

For various densities of gas jets including very light hydrogen and relatively heavy ones, the penetration length and diffusion process of a single high-speed gas fuel jet injected into air are computed by performing a large eddy simulation (LES) with fewer arbitrary constants applied for the unsteady three-dimensional compressible Navier-Stokes equation. In contrast, traditional ensemble models such as the Reynolds-averaged Navier-Stokes (RANS) equation have several arbitrary constants for fitting purposes. The cubic-interpolated pseudo-particle (CIP) method is employed for discretizing the nonlinear terms. Computations of single-component nitrogen and hydrogen jets were done under initial conditions of a fuel tank pressure of gas fuel = 10 MPa and back pressure of air = 3.5 MPa, i.e., the pressure level inside the combustion chamber after piston compression in the engine.