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At the time of a vehicle fire, high pressure hydrogen gas in a tank (a high pressure hydrogen gas cylinder) of a fuel cell vehicle (FCV), which is a passenger vehicle, must exhaust through a pressure relief device (PRD) as quickly as possible in order to prevent any accidental bursts by a temperature rise of hydrogen gas in the cylinder. The high temperature region surrounding a vehicle develops when the hydrogen gas is released through a small nozzle to the air directly. Therefore, to suppress the high temperature region, the effectiveness of a diffusion box is considered further. A pressure relief device (PRD) detects differences in temperature of the environment surrounding an FCV on fire and releases hydrogen gas in a tank to the air by which the valve opens when the temperature in the environment becomes high. The PRD also releases hydrogen gas through a nozzle, e.g. installed upward or downward, to the outside of the vehicle. The PRD is required to be installed in an FCV.

The objective of this study was to develop a test method for heavy-duty HEVs using a hardware-in-the-loop simulator (HILS) to enhance the type-approval-test method. To achieve our objective, HILS systems for series and parallel HEVs were actually constructed to verify calculation accuracy. Comparison of calculated and measured data (vehicle speed, motor/generator power, rechargeable energy storage system power/voltage/current/state of charge, and fuel economy) revealed them to be in good agreement. Calculation error for fuel economy was less than 2%.

In order to assess the effect of PEM-FC poisoning resulting from impurities on PEM-FC performance, this paper investigated contents as follows; · Estimation for composition and concentration of impurities contained within hydrogen fuel and air. · The prediction of poisoning extent and proposal of assessment index for impurity poisoning. · Allowable mixing concentration of impurities for the standard H2 fuel. The analysis and experiment are conducted under 70 °C and 1 bar for operating temperature and pressure. PEM-FC with Pt and Pt-Ru type catalytic-electrode was used. It was observed that: · CO poisoning was reversible but H2S and SO2 poisonings were irreversible. It was also confirmed that sulfur compounds poisoning was very strong. On the contrary, poisoning of HCHO and CH4 etc. was slight or negligible. · In case of cathode electrode, the effect of NO2 and SO2 poisoning on PEM-FC performance was severe when CO poisoning was negligible.

The increase in number of automobiles due to its convenience brought serious increases in environmental load. The rate of attainment of environmental standards for nitrogen dioxide (NO2) and suspended particulate matter (SPM) in urban areas is still low in Japan. Diesel vehicles emit the vast majority of air pollutants from exhaust. Therefore, developing emission measures, particularly for diesel vehicles, is an urgent task for addressing air pollution. Furthermore, at the Third Conference of the Parties to the UN Framework Convention on Climate Change (COP 3) held in Kyoto in December 1997, Japan pledged to reduce greenhouse gas emissions to 6 percent below 1990 levels for the first commitment period of 2008 to 2012. To address vehicle emissions, Japan is gradually introducing increasingly strict NOx and particulate matter regulations.

Particulate matter (PM) and polynuclear aromatic hydrocarbons (PAH) were measured under steady state engine operating conditions in the exhaust of a DI diesel engine that meets the Japanese 1994 heavy-duty vehicle standards. In this study, to examine and discuss the effects of pyrene and sulfur contents in fuels on PM and PAH emissions, experiments were performed using both ordinary diesel fuel and a specified fuel having simple hydrocarbon components and very few aromatics. In the experiments, pyrene and sulfur contents in the fuels were changed by the addition of reagents to the fuel. The following conclusions were obtained. (1) From the experiments using ordinary JIS No. 2 diesel fuel with a pyrene reagent added to yield 400ppm pyrene, it was found that pyrene addition brings about an increase in soluble organic fraction (SOF) under low load engine operating conditions.

In this study, the series hybrid electric system is recommended as suitable power systems of the motor vehicles in urban area. It is important for this system to improve the comprehensive energy efficiency when components are combined, and to evaluate it appropriately. In this report, the technique to grasp energy loss in detail that occurs when electric power flows complicatedly in the series hybrid power system has been examined and the energy efficiency of the series hybrid power system on urban driving has also been evaluated.

A very small electric vehicle, powered with a proton exchange membrane fuel cell operating on reformed methanol, is planned and designed in this paper to solve social problems associated with air pollution and heavy traffic conditions. Next, the driving range is simulated by the experimental data of the output and the performance. The conclusions of this paper are as follows: (1) The power train employing the fuel cell and compact brushless DC motor serves to realize high efficiency and reduce weight for energy saving.

Recently, studies and developments have been underway in many countries to introduce a new type of car (hereinafter referred to as “Commuter car”), characterized by ultra smallness, energy saving and low pollution, for short-range purposes, for example commutation, in urban areas (1).In our previous study, the characteristics of electric motors were noticed, and the series hybrid system was focused to power commuter cars.Therefore, a simulated commuter car based on a small electric vehicle (EV) was set on a chassis dynamometer to test the basic items (2) . From these results, a new simulated series hybrid type commuter car that uses a high-power AC motor and a high-efficiency power generator was set on the bench.By acceleration/deceleration bench tests, selection of the reduction gear ratio and optimization of power supply from the generator were investigated in order to achieve both the performance necessary and sufficient for the city driving and power management.

The experiments were performed with two types of test engines, '72 model year type and '94 model year type engine, using both of conventional diesel fuel and synthetic diesel fuel, which has simple hydrocarbon components and no aromatics or sulfur content. SOF is extracted from the particulate sample exhausted out from the engines, then GC and GC-MS analyses were carried out. By comparing the results obtained, the role of high boiling point components in diesel fuel on SOF emission were observed. Further, by adding an artificially sulfur-containing compound and pyrene, which is a four ring polynuclear-aromatic-hydrocarbon (PAH), into the synthetic fuel, the effect of PAH content in fuel on PAH emission in SOF and the increase of SOF with increased sulfur content in fuel, were observed.

The purpose of this study is to examine a proper power system for a miniature vehicle called as “Commuter-car” that is expected to be used for commutation or shopping in urban areas. Before starting experiments, an investigation of actual commutation driving was made. It was found that the driving distance was generally short and that start-stop frequency was high at commutation driving in urban areas. As a result of this driving investigation, it was educed to introduce an electric motor traction method into commuter-cars. First, a small generator was added to a conventional electric vehicle (EV) to convert it into a series hybrid vehicle. The running range of this vehicle was confirmed experimentally to be extended much more than the base EV in transient driving. Therefore, it was judged that series hybrid system is reasonable to be applied to commuter-cars.

The Thermogravimetry SOF measurement method is developed as simple and time-saving method. It is experimentally revealed that this method is useful for SOF measurement and the method has potential to distinguish SOF component. The oxidation catalysts can effectively reduce particulate matter under actual driving conditions. Sulfate formation suppressing oxidation catalyst reduces high molecular number paraffins. However, it is important for further development of oxidation catalyst to improve the oxidation ability of polar hydrocarbons included in SOF. The oxidation catalysts can effectively reduce CO, HC emissions under actual driving conditions. This is caused by the temperature rise of oxidation catalysts during accelerations.

An attempt was made to optimize NOx and particulate emissions from heavy-duty diesel powered vehicles under heavy load engine operating regions by combining EGR and methanol fumigation and the effects on exhaust emissions were experimentally studied. The results under steady states tests show that, the smoke concentration is decreased and total fuel consumption is improved according to the increase in methanol energy ratio. As NOx reduction effect of EGR does not affected by methanol fumigation, drastic NOx reduction can be thereby possible at heavy load regions with the combined use of EGR and methanol fumigation. Then, this method was applied to new Japanese 13 mode test procedure and it was recognized that the NOx mass emissions were reduced to almost one half without increase in particulate emissions. However, drastic increase in CO, HC and aldehyde emissions were observed also.

Combined system with EGR and Manifold water injection was developed for trial to control exhaust NOx emissions from heavy-duty diesel powered vehicles and its effects were experimentally studied under not only steady-state but also actual driving conditions including transient. From the experimental analyses under steady-state conditions, it was recognized that higher NOx reduction may be possible with this combined system compared with the use of each method alone under the same level of other pollutants. Then, several control conditions of the system were chosen and their effects to exhaust emissions were investigated under actual driving conditions, and consequently, about 50% of NOx reduction was recognized without significant increase of other pollutants by the combination of EGR at light and medium load regions and limited water injection at heavy load regions where accelerator opening is 70% or over.

Experiments and analyses were carried out to determine the effects of EGR on NOx and other pollutants for heavy-duty direct injection diesel engines under steady state conditions. Then based on them, optimum EGR control method was examined for effective NOx reduction without causing substantial increases of other pollutants under transient conditions. A simple EGR control system was developed for trial to achieve almost the same effects of the said method. Results of experiments with this system indicated that the EGR control method was capable of substantial reduction of NOx mass emission during transient engine operations equivalent to actual driving conditions, with different pay-loads and average vehicle speeds. REDUCTION of the NOx mass emission from heavy-duty diesel powered vehicles during actual driving operations, is one of the most important demands in automobile technologies.