In Sapporo the lowest temperature is about -15℃ and amount of snowfall is about 5m in winter. The fuel cell for a residential energy system is more effective in cold region because of the high domestic heat demand, but we have to adapt it to severe weather. Hokkaido-Gas is developing the PEFC system for cold area with EBARA Corporation (EBARA BALLARD Corporation) and Panasonic, and has participated in Large-scale Demonstration Project by NEF to study the effects of its introduction. The result shows it is effective in CO2 and primary energy reduction.

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Current distribution in a Polymer Electrolyte Fuel Cell (PEFC) was determined by measuring a magnetic field around the PEFC with a Magneto-Impedance sensor. The measured magnetic field strength was converted to the distribution of generation current with the Biot-Savart's law. This method was verified with a specific separator under a PEFC running condition. The specific separator was made of acrylics, and carbon conductors were installed inside it. Current distribution was also measured with the specific separator. Comparison between these current distributions indicated very good agreement. The validity of the present method to determine current distribution in the PEFC was confirmed.

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The PEFC is a strong candidate for use as an alternative power source in future vehicle and power conditioning application. On operating PEFC, water management inside the cell is a large issue. However, the internal mechanism of water production has been less understood For understanding the mechanism, we need to figure out an internal temperature distriibution because the water production and its behavior are strongly influenced by the variation of the temperature. Up to now, there have only been measurements of in-plane direction temperature distribution. However, according to a mechanism of overvoltage increment by poor water management, information of temperature distribution across the cell is more required to analyze the water behavior. In this study, we measured temperature distribution across a cell by nipping very thin thermocouples in each layer of the cell, and figured out that the cathode catalyst layer had a maximum temperature under a steady state condition. We also figured out that this layer had a minimum when load current stopped.

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Our aim is to reveal the optimum conditions for the design of ethanol steam-reforming reactors. Experiments are carried out using a Cu/ZnO catalyst. Using a plant-scale reactor with well-controlled thermal distributions, the steam reforming at the low temperature is conducted and the reforming gas is analyzed. The main gas components are CH_4, CO, CO_2 and H_2. In addition, there are chiefly three reactions in the ethanol steam reforming; that is, (1) the steam reforming reactions, (2) the metanation reactions and (3) the water gas shift reaction. In comparison with computations based on the thermo-equilibrium theory, it is considered that the metanation reaction has not occurred. Under such assumption, the experiment shows a good agreement with the theory.

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We have successfully developed a small and simple steam-reforming reactor for n-dodecane as a heavy-hydrocarbons fuel. The reactor has satisfied the target thermal conditions. Under the conditions, we have measured the inside temperature profile and the reaction performance. By the present catalyst reaction becomes more active at the position where the temperature T> 600[℃]. Then, the present study is conducted at T_v=700[℃] steam-to-carbon ratio upon the Gas- chromatography measurements reveal the effect of the hydrogen-molecule ratio together with the molecule ratios of other main gasses such as CO,CO_2 and CH_4.In addition, We carry out the computations based in thermo-equilibrium theoryies.

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A novel measurement method for evaluating hydrogen solubility in water is developed Purified water is exposed to high-pressure hydrogen in a gas-liquid equilibrium cell of approximately 100 cc, and than gaseous component in the water sample of approximately 10 cc is analyzed with quadruple mass spectrometry. The purpose of this study is to establish hydrogen solubility data in water up to 29 MPa and to 75 ℃. Preliminary measurements under low pressure (up to 1 MPa) show that the deviation of measured solubility lies within the range of the estimated uncertainty of measurement. We reveal that the measurement uncertainty of the present method highly depends on the background intensity for hydrogen in the mass spectrometry.

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We proposed to add a hydrogen buffer tank between a natural gas reformer and a fuel cell to improve the efficiency of a fuel cell cogeneration system for residence. We developed a new hydrogen supply and storage system without forced heat exchange by using Metal-hydride (MH) as a material of the buffer tank. It is expected that this system have better energy efficiency and it is safer to use compared to conventional hydrogen storage system. In the actual operation, temperature and equilibrium pressure of MH is expected to change due to hydrogen absorption and desorption. Thus, heat exchange performance of MH vessels can have effect on the MH buffer tank's performance. Consequently, we made three types of MH vessels which have different diameters to demonstrate the effect of heat exchange performance. With the aim of obtaining the basic data, characteristics of hydrogen supply and storage were examined through the experiment.

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A model was proposed to estimate a temperature change during filling. It verifies to be a good agreement between the measured and estimated temperatures of hydrogen in a wide range of charging conditions. Seven non-dimensional parameters, which govern the temperature change, are derived from the governing equations. One of them is a controlled one related to the pressure change or mass flow rate. Some case studies have been done based on a corresponding filling test using actual tanks. The effect of two parameters of them on the temperature characteristics is explained as a example.

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It is mandatory to apply a pressure relief device (PRD) on the Fuel cell vehicles to avoid explosion of high pressure hydrogen gas container when a vehicle explore to be on fire. Several hydrogen release tests were carried out to understand how the released hydrogen behaves in a vehicle fire. These tests are to analyze the emission way of PRD as below. 1) The range of flame, flame temperature and the time of emission when PRD effused hydrogen gas in upward direction, in downward direction, and in horizontal direction respectively 2) The diffusion way of released hydrogen gas 3) The effect of diffusion box which was assumed to decrease the hydrogen concentration and flow rate. The results showed that it should be avoided to release directly hydrogen gas into the air in the horizontal direction.

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In this study, creep tests have been conducted on a P91 to identify creep rupture life property of the weld joints, and creep damage process in heat affect zone (HAZ) has been clarified by producing creep damaged materials. As results, it was found that creep rupture time of the weld joints reduced to about 1/5 of the base metal and creep voids have already initiated at 20% of the creep life in the HAZ. Size and number of voids in the HAZ increased with increasing creep damage. Creep rupture time of the weld joint can be predicted by creep strain rate in the HAZ and limited creep strain defined in this study. It was confirmed that quantitative void growth behavior could be predicted by the void growth simulation method.

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The Master Curve gives the relation between the median of fracture toughness and temperature in ductile-brittle transition temperature region. The Master Curve approach theoretically provides the confidence levels of fracture toughness in consideration of the inherent statistical distribution of fracture toughness. In this study, fracture toughness tests for Japanese reactor pressure vessel (RPV) steels, SFVQ1A and SQV2A, with various specimen sizes and shapes were conducted. The differences in test temperature, evaluation method, and specimen size and shape did not affect the Master Curves, thus, it was ascertained that the Master Curve approach could be well applied to them. The adequacy of the lower bounds based on the Master Curve was also verified by comparing with experimental fracture toughness data.

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We have conducted research for the recovery of material properties on gas turbine blades, and confirmed the refurbish treatment that hot isostatic pressing technique applied could recover metallurgical and mechanical properties of the degraded blades. After the treatment was applied to the degraded blades, those blades were reinstalled in a commercial gas turbine. After 4 years operation, various non-destructive and destructive tests were conducted to serviced blades. It was showed that no cracks or deformation in any of blades, with very little change in microstructure and mechanical properties. No acceleration in degradation rate was revealed, and we confirmed that the refurbish treatment could be a useful service-life extension method for gas turbine blades.

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In the rule on fitness-for-service for nuclear power plants of the Japan society of mechanical engineers (JSME), the two-parameter approach is prescribed for failure assessment of defects. In this study, in order to apply the reference stress method to the evaluation of J-integral value, applicability of several limit load solutions was investigated by comparing with results of elastic-plastic finite element analyses. Flawed pipes containing axial or circumferential flaw were analyzed under internal pressure or bending load. Appropriate limit load solutions were suggested for evaluation of the failure assessment curve, based on analyses of 2880 cases for different flaw and pipe geometries and material used in nuclear power plants.

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Structural integrity of the components in nuclear power plants should be evaluated by Fitness-For-Service (FFS) Codes of Japan Society of Mechanical Engineers (JSME). For the revised edition of the FFS Codes, the establishment of crack growth rate due to stress corrosion cracking (SCC) is one of the principal subjects. In order to define the crack growth rate used in the crack growth evaluation based on the data obtained from experiments, it is important to know the influence of the crack growth rate on the reliability of the components. In this study, the influence of setting of the crack growth rate due to SCC in FFS Codes on the reliability of primary loop recirculation system piping-the stress corrosion cracks have been often observed-using a probabilistic fracture mechanics analysis code. The proposal for establishment of the crack growth rate in FFS Codes was summarized based on the analytical results.

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This paper proposes an intelligent start-up schedule optimization system for a thermal power plant. This system consists of a neural network, a genetic algorithm, and an interactive multi-objective programming technique. The features of this system are as follows. (1) The start-up schedule can be optimized based on multi-objective evaluation and (2) an optimal and flexible start-up schedule can be determined with a reasonable computing time and calculation accuracy through interaction between human beings and computers.

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The main rotary machine is often an intermittent driving machine in the nuclear plant. On the other hand, it was a problem for the vibration method to detect the vibration when rotating, and very to achieve the vibration tendency management for the equipment that did not rotate though it positively worked on the introduction of the equipment diagnosis technology by the vibration method of the rotation equipment in the nuclear plant. This time, because the tendency management system of the intermittent driving equipment is developed, and the tendency management was achieved, it introduces the outline and an actual case.

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The Niigataken Chuetsu-oki earthquake attacked the Kashiwazaki-Kariwa Nuclear Power Plant (NPP) of Tokyo Electric Power Company on July 16 th, 2007. The Power and Energy System Division, JSME, started the research committee in August for the evaluation of the influences of the earthquake to the NPP. The research activities include appeal to JSME members, site visiting, load evaluation, importance classification, margin strategy, good practice collection, public communication and so on. We would like to discuss the nuclear safety for the earthquake for the safety NPPs.

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Due to the Niigataken Chuetsu-oki earthquake on 16 July 2007, Tokyo Electric Power Company's Kashiwazaki-Kariwa Nuclear Power Plant (NPP) suffered from quakes exceeding design basis. The plants consisting of seven reactors and related facilities performed its essential functions required in the nuclear safety design such as "stop", "cool", and "confine" as designed, no matter whether in operation or in outage. The fact our group found through surveys in the site tells us that the experience of the Kashiwazaki-Kariwa NPP provides all NPPs with very important scientific findings.

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Conventionally, the design of a nuclear reactor has been performed from a viewpoint of a safety function and the importance on earthquake-proof on the basis of not giving off the mainly included radioactivity outside. In this Niigataken-Chuetsuoki earthquake, there is almost no damage to the system, components and structure on safe also in the earthquake beyond assumption, and the validity of the design was checked. But, the situation peculiar to a big earthquake was also generated. The emergency plan room which should serve as a connection center with the exterior was not able to open a door and use at the beginning. Fire-extinguishing system piping fractured and self-defense fire fighting was not made. And so on. Discussion from the following three viewpoints was performed. 1st: The importance from a viewpoint which should maintain a function also with the disaster in case of an earthquake like an emergency plan room etc. 2nd: In the earthquake, since the safe system and un-safe system was influenced, the importance from a viewpoint which may have influence safely inquired when the un-safe system broke down. 3rd: Although it was not directly related safely, discussion from a viewpoint which influences fear of insecurity, such as taking out smoke, for example, was performed.

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According to Chuetsu-oki earthquake in 2007, there is no significant damage on Kashiwazaki-Kariwa Nuclear Power Station's components, even though over size earthquake compare to design use had happened. This paper describes outline how to design a nuclear plant and evaluate its seismic safety, then try to make clear what safety margins there are and how much they are. Safety margins are in Safety factors apply to Load under seismic and Strength of materials covering uncertainty, Modeling of seismic integrity analysis, Damping factors, Strain-Stress diagram, and others. Recently the design method of LRFD (Load Resistance Factor Design) is studied to apply to structural design instead of traditional method.

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This paper describes technical issues for the seismic safety of nuclear power plant components and also shows preliminary roadmaps for the solution of the issues. After the Chuetsu-oki earthquake of July, 2007, research committees were established in JSME and AESJ for the discussion of the effect of the earthquake on NPP components. Ten technical issues due to the earthquake are pointed out and the discussion concerning the roadmaps has started to solve each issue. The goal of the activity is for the advanced design methodology with seismic safety.

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When the Kashiwazaki-Kariwa Nuclear Power Plant (NPP) of Tokyo Electric Power Company was attacked by the Niigataken Chuetsu-oki earthquake on July 16th in 2007, three units were in operation, one in start-up and the other three in refueling and maintenance outage. It is important to learn lessons from this event for improvement of the design, operation and management of nuclear power plants. In this presentation, we evaluated the experience and lessons learned from technical viewpoints, and selected good practices for disseminating and sharing them among various industries not limited to nuclear.

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As for the influences of Chuetsu-Oki Earthquake on Kashiwazaki-Kariwa Nuclear Power Station, we can conclude that 'the safety function of the nuclear power station, that is, "Shutdown", "Cooling down" and "Isolating" functioned as per designed even against an earthquake beyond assumption, and fundamental nuclear safety could be assured". Nevertheless, it is said that one of the causes that harmful rumor had spread was due to mass communication media. In the press reports on some nuclear power station when affected by an earthquake and on trouble in the nuclear power station in the future, we will propose that the publication should be really useful for habitants and citizens and be promoted in the positive and expected direction, in order not to make the same mistake as this time. JSME should aim at implement the above-mentioned proposal under cooperation with other academic societies and organizations.

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Task Force on the Inspection System was established in the Nuclear and Industrial Safety Subcommittee of the Advisory Committee for Natural Resources and Energy in February 2002, and the study started. In order to make the inspection effective, communication between the regulatory body and the licensees is very important. Thus the Research Section on Optimization of Nuclear Safety Regulation was established at JSME in 2005 to support the task force. The last year, the research section visited US-NRC Region III, Davis Besse NPS and Quad Cities NPS, and compared the US and Japanese regulatory systems. The actual situation of the periodic licensee's check in Japan was investigated. These results are useful for further improvement of inspection system in Japan.

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This technical research section is surveying the nuclear regulation in the major countries. The first one was to visit Finland and France on January 2007, the second one was to visit US-NRC Head Quarter, Browns Ferry NPS and Hatch NPS on Aug 2007, the third one was to visit Switzerland and Sweden on January 2008, the fourth one was to visit US-NRC Region III, Davis Besse NPS and Quad Cities NPS on Oct 2007. This report summarized the survey results of the fourth visit (second US visit) Davis Besse NPS is so famous about one of the most scary incident which was the big hole in the reactor vessel head by the corrosion by the leakage of the boron. But the plant manager said they completely changed the safety culture and it is the safest nuclear power plant in the world right now. We found their sincere change of the culture and amazed the good results.

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As a part of the study group's work on Optimization of Nuclear Safety Regulation of JSME, we studied the current experience and information about Containment Leakage Rate Testing (CVLRT) in the U.S. and European countries. After that, we compared their methods with the methods of CVLRT used in Japan. The results of our studies were summarized as follows: 1) In the U.S., NRC de-regulated the CVLRT methods so that the utilities could select the most efficient and the safest method. 2) In France and Belgium, the OLM (Online Leakage Monitoring) is used.

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During recent years, Nuclear Power Plants in U.S.A have achieved high performance both in plant capacity factor and safety operation indices. Such high performance has come from Licensees' strong initiative towards safety operation supported by US NRC. This paper describes regulatory activities by US NRC Region III Office based upon 2^<nd> JSME Delegation Visit to U.S.A., which provides us with some useful information to comprehend the above said high performance.

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The Corrective Action Process (CAP) is one of the most important key issues on the Nuclear Reactor Safety. The experiences on the nuclear power plant operations, including safety culture, maintenance, and so on, should be continuously evaluated and influenced to the KAIZEN (improvement) of the NPP operations. The review of the CAP system in US will be useful for the NPP safety in Japan.

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Risk informed regulation for Nuclear Power Reactor is adopted widely in the U.S. In the U.S., reactor core damage frequency(CDF) is used as risk information. An acceptable value is prepared in the increment of a risk (CDF), and various actions such as online-maintenance or RI-ISI are permitted within the acceptable value. The permission time (AOT: Allowed Outage Time) when a plant can carry out continuous operation when one line of a redundant system breaks down can also utilize and search for risk information. In this report, the contents examined by the NUPEC(Nuclear Power Engineering Corporation ) are reported about the evaluation method of AOT which utilized risk information, and it proposes about future practical use.

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The emission control of CO_2 in coal thermal power generation is one of important problem for the rise of public opinions in Japan and foreign country to recent global warming prevention. Electric companies are advancing various measures like the improvement of generation efficiency and the introduction of the biomass as a fuel to this problem. In these measures, CO_2 capture and storage (CCS) technology has been brought to international attention. However, if the power generation system with CCS which has already been developed is introduced, neither a great decrease of the power generation efficiency nor the rise of the power generating cost is avoided. Therefore, the development of a new high efficient power generation system is desired. Recently, we proposed the high efficient coal gasification combined cycle (IGCC) power generation system with CCS. This system has new oxygen-CO_2 blown coal gasifier where captured CO_2 is effectively used, and the closed gas turbine in which coal gases are burnt with the gas mixed oxygen with the recycled exhaust gas. Feature of this system is that the gasification performance improves greatly, and the equipment cost decrease because it is possible to recovery CO_2 without CO_2 separation process. In this study, we have analyzed heat and mass balance of the IGCC system using software we developed. It was found that 42%(HHV) of the generation efficiency(NET) in the system 1300℃ class gas turbine can be obtained by the decrease of consumed energy at CO_2 recovery.

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Base Conventional Reciprocating Engine(charge press. 576kPa, Miller Cycle, LNG, inter cooler) that is head engine to be triple combined cycle (Gas-turbine comp. ratio5.4, inlet temp. 1200degC) is replaced by Humidity-Adding (17%vol.) Reciprocating Engine. Waste energy (inter cooling, piston-head cooling) and heat-source(under 300degC) supply Humidity Adding Energy, and improve thermal efficicency 57.6%(Base Conventional 54.1%) and increase power(to 113%). We studied to apply 2Cycle Gas-Engine(High Load BMEP22.7MPa) for Humidity Adding Reciprocating Engine. The 2Cycle Gas-Engine needs exhaust OH4-Valves, Control Valves of scavenging port open-shut, Piston Vaporizing Cooler,and Direct Water Injector, etcs.

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For the global warming solution, no-emission systems should be discussed for environment - friendly power stations. A closed cycle system was designed as the application of gas engine - gas turbine combined cycle and proposed as one of no-emission technologies. This system has the working fluid of CO_2-H_2O mixture and is expected to have a potential high performance as a future power system. In order to be free from fossil fuel, a wood derived gas fuel was utilized and the system performance was compared with the LNG firing system. Both of these systems have the thermal efficiency of around 60 %LHV, high enough with fuel flexibility.

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Advanced Humid Air Gas Turbine (AHAT) suggested by Hitachi Ltd. is a regenerative cycle gas turbine system using humidified air and can achieve higher thermal efficiency than that of the combined cycle (CC). To verify the system concept and cycle performance of AHAT, 3.6MW verification plant was constructed. As a result of the operation test, it has been confirmed the plan output achieving 3.6MW and the validity of AHAT as a power generating system. And the power generation efficiency of 40.02% LHV was achieved; this shows that there is a possibility of exceeding 43%LHV by introducing some corrections. Moreover, it has been confirmed that NOx emission is less than 10ppm at O_2 16% level, and the performance of each component satisfies its design values. Estimate of the thermal efficiency of a medium-size AHAT by using the experimental results showed that the system can achieve 57%LHV, and the performance in partial load can be superior to that of CC.

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Nickel base super alloy 'TOS1X' was developed for 700℃ class A-USC turbine rotor. TOS1X are an alloy which was improved the creep rupture strength of Inconel^<TM>617. A model rotor with a weight of 7 ton was manufactured using the TOS1X by double melt process(VIM and ESR) and forging. The model rotor have neither forging crack nor segregation. The yield and tensile strength of the model rotor were the increase of about 10% of Inconel^<TM>617. The 700℃-10^5 hours creep rupture strength of the model rotor was 160MPa or more.

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Numerical studies of 3-D incompressible viscous flow within a turbine stage based on a high order LES approach were carried out. In this work, 3-D unsteady flow was visualized to investigate the flow characteristics around the stator and rotor. Computations were carried out for quarter cycle of a turbine stage consist of 22 stator and 19 rotor blades in order to examine the unsteadiness due to the blade number difference. The visualization of the simulation results indicated that a thin vortex core was produced and a secondary vortex was formed due to the interaction with the hub wall in the stator region. These wakes were stretched toward the rotor blade. A landscape vortex at the leading edge and the large scale separation at the suction face were observed in the rotor region. The rotor wake indicated a complex 3-D structure with a roll with axis in blade height direction.

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To investigate turbulent combustion phenomena in a gas-turbine combustor, we conduct a numerical simulation of a partially premixed turbulent combustion in a practical combustor. Large-Eddy simulation and 2-scalar flamelet approach are coupled and applied to the unsteady turbulent combustion simulation in the combustor geometry for modeling turbulent and combustion reaction phenomena, and also their interactions. This paper reports an application of the LES to a 1700 degree class of new-Generation gasturbine combustor and discusses their feasibility to the practical combustor design. NOx production is also investigated by detailed reaction model.

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This paper describes the potential of existing exhaust emission reduction technologies for diesel engines fuelled with fatty acid methyl esters(FAME), named "Biodiesel". The common-rail high-pressure injection equipment and exhaust gas recirculation(EGR) for the in-cylinder combustion improvement technology, the diesel particulate filter(DPF) and diesel oxidation catalysts(DOC) for the after-treatment technology, and the cetane improver addition for the fuel treatment technology are described based on the experimental results.

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Our investigation theme was adopted as theme of biomass energy high efficacy transversion technical development / biomass energy transversion elemental technology development of NEDO business of 2006-2007 year. Report it about investigation content and the result that we wrestled with. We developed FAME manufacturing process with calciumu oxide catalysts. Manufacturing tests were peformed by laboratory trials, 20L and 200L scale machines, and the manufacturing condition was obtined to satisfy more than 96.5% FAME content. Effective utilization of by-product glycerin as a material of bioplastics were studied, and its physical properties were obtained.

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Biodiesel fuels (BDF) are expected as renewable sources in low carbon society. While palm oil methyl ester (PME) has the important advantage of supply volume, the cold flow performance of PME is less favorable than other BDF. Previous research has shown that blending ethanol to BDF improves the cold flow performance and reduces soot emission. Ad simultaneous reduction in soot and NOx was also achieved by combining the ethanol blending and EGR. However, the ethanol blending and EGR tend to increase emissions of CO, THC, and aldehydes. This paper experimentally analyzes the effect of oxidation catalyst on the emissions. Two kinds of catalysts with different Pt loading are compared.

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Bio fuel is expected to solve the global warming because of carbon neutral. The authors have studied combustion characteristics by using RME and RME50 vol. % as Bio fuel with high boost charging system, high-pressure common rail injection system and wide range cooled EGR system in a single cylinder engine. In this report, using RME could reduce NOx and PM emissions due to raised up to 401.3kPa to 451.3kPa with charging boost pressure and from 40% to 50% with EGR rate at full load to the previous report. PM of RME50% showed lowest tendency in comparison with the RME and diesel fuel. Also revealed that installation of a DPF needs to clear the Japanese emission standards in the future.

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Various kinds of vegetable oil and waste cooking oil are in fact used as car fuel all over the world. In general, 'bio-diesel' i.e. fatty acid methyl ester extracted from such oil is utilized as fuel for vehicles. However bio-diesel has some problems such as by-product and waste materials created during transesterification. An alternative method is the direct use of vegetable oil as car fuel through installation of a heater unit in the car to decrease vegetable oil viscosity. However little data has been reported concerning this method. The authors of this study carried out performance tests on the direct use of waste cooking oil using a car with a heater unit and found its high potential. Moreover, the authors compared the environmental load of direct use with bio-diesel and light oil by carrying out life cycle inventory to clarify the superiority of direct use.

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DME (Dimethyl Ether) attracts now big attention worldwide as a clean and economical carrier of alternative energy. It can be synthesized from various resources, such as natural gas, coal, wasted plastics, and biomass. Furthermore, because of its properties similar to propane, it has many potential uses such as electric power generation, household and diesel engine fuel. In this paper, we designed the hybrid systems of DME and electric power generation using coal, natural gas and biomass for a rural area and evaluated the system of LCI and economics. The analysis shows that the system using bark cannot be brought difficult to realization economically. The system using both bark and plastic wastes reduces CO_2 emission in comparison with the already existing system, and is economically possible because of the inverse onerous contract of the plastic wastes not of the scale of the plant, the distance of conveyance of ingredient or circulation income of energy.

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Hydrogen has unique combustion characteristics that influence the thermal efficiency of internal combustion engines. Particularly, hydrogen has a higher burning velocity, a shorter quenching distance, and a higher thermal conductivity than hydrocarbon fuels. These characteristics exert a strong influence on the degree of constant volume and cooling loss during combustion, both of which are major factors in the thermal efficiency of internal combustion engines. This paper provides an overview of characteristics of hydrogen utilization in engines.

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Steam gasification of activated carbon or solid carbon residues, derived from pyrolysis of Japanese cedar or particle board, was carried out in the presence of various molten carbonates or eutectic mixtures of them at 973K and 3.0 MPa. Hydrogen and carbon dioxide were produced mainly. Methane and carbon oxide were detected as a trace product. Yield of hydrogen increased significantly in the presence of the molten carbonates. Effects of molten carbonates for the rate of hydrogen formation were following order, Na_2CO_3/K_2CO_3/Li_2CO_3 (60/20/20) > Li_2CO_3/K_2CO_3 (50/50) > K_2CO_3 (100) > Li_2CO_3/Na2_CO_3 (50/50) >Na_2CO_3 (100) > none. These experimental results show that content of the carbonate and physical contact with solid carbon, molten carbonate, and steam is very important for hydrogen production.

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Adjusting the proportion of dimethyl ether (DME) and hydrogen-containing DME-reformed gas (DRG) produced from DME is quite effective to control the ignition timing in HCCI combustion engines. As the DRG can be produced with an onboard DME-reformer, utilizing the engine exhaust gas heat can be a technique to recover the waste heat. This paper investigates the influence of reforming conditions such as catalyst, temperature, oxygen concentration and steam concentration on the fundamental characteristics of the DME reforming for the HCCI engine system with waste heat recovery.

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Hydrogen is in many ways an attractive clean alternative to fossil fuel. However, as hydrogen has a higher burning velocity and a shorter quenching distance than hydrocarbons, and these characteristics of hydrogen influence the degree of constant volume combustion and the cooling loss by the heat transfer from burning gas to the combustion chamber walls. The cooling loss fraction and the degree of constant volume are two of the major factors influencing the thermal efficiency of internal combustion engines. On the other hand, hydrogen has good anti-knock properties, and hydrogen engine can run with higher compression ratios than gasoline engines. This paper analyzes the influences of compression ratio on thermal efficiency of hydrogen engine.

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The high thermal efficiency is established by increasing the compression ratio while the engine is operated in SI engine. In order to suppress knocking, the octane number of the fuel is raised by partially cracking the hydrocarbon molecules. Concept that onboard fuel reforming system utilizing waste heat produced from engine is practically effective on the high thermal efficiency. In this study, the fuel reformer was tentatively constructed and the fuel component was measured with GC-MS. The primary reference fuel 90(PRF90) was used as the test fuel. It was found that the fuel was partially cracked into small size hydrocarbons such as ethylene and propene. This fuel was supplied to the test engine, which was a 4-cylinder, 2-litter, turbo gasoline engine and the compression ratio was modified to be 12. The thermal efficiency increased by approximately 4〜6%.

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The effect of pressure on outwardly propagating turbulent flames were studied for hydrogen-air mixtures at the equivalence ratios from 0.6 to 1.0 and the initial pressures from 0.10 to 0.50MPa. Turbulence intensity, u' was set to 0.80 to 1.59m/s. The Markstein number decreased for increasing pressures and for small equivalence ratios. The ratios of turbulent to unstretched laminar burning velocities at a constant Peclet number increased with increasing turbulence Karlovitz number and decreasing Markstein number at a constant pressure. This burning velocity ratio increased with increasing pressure at the equivalence ratios of 0.6 and 0.8. At the equivalence ratio of 1.0, however, the burning velocity ratio did not increase with increasing pressure although the Markstein number reduced with pressure.

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