The Japan Atomic Power Company (JAPC) was established in 1957, by 9 electric power companies, Electric Power Development Co., Ltd and related industries. The mission of JAPC is to supply electricity by constructing and operating nuclear power plants, then to contribute nuclear development by experience and knowledge obtained through construction and operation. For this objective Tokai, Tsuruga, Tokai-2 and Tsuruga-2 Nuclear Power Plants were constructed. The history and activities of JAPC are described in the paper.

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We had proposed the noble hybrid cycle with epoch-making high efficiency and CO_2 recovery capability. In former study, we designed the 300MW plant conceptually, and the result shows that the efficiency of this system can reach 70% (HHV). However, in order to realize this system, huge MCFC manufacturing facilities are necessary. So, a smaller capacity plant should be developed first. Then we performed the examination on 1MW class unit that can be achieved in the near future. The thermal efficiency calculation result shows that the efficiency of this system is over 50% even with this smaller capacity.

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In this work, an experimental study is carried out to obtain the combustion characteristics of the cluster nozzle burner used under high temperature and high humidity condition of the advanced humid air turbine (AHAT) system. Both high temperature condition of AHAT system and the recirculation zone generated by swirl of center burner air sustain flame stability. So, the flame stability of cluster nozzle burner is enough for AHAT operation. Low flame temperature caused by high humidity condition is effective to decrease NO_x emission, which is less than 10ppm at 50-100% load of AHAT system. The result shows that it is possible to cope with both flame stability and NO_x reduction in AHAT system with the cluster nozzle burner.

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The final purpose of this study is the investigation of the ability to increase the system efficiency by introducing the chemical exergy recuperation for the integrated system of a low temperature gasifier of coal and a gas-turbine or SOFC. In this paper, for the discussion of theoretical optimum point, the system performances were calculated under the several conditions of the carbon conversion ratio with steam.

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IGCC is a promising clean coal technology to harmonize the reduction of greenhouse gas and coal utilization. Clean Coal Power R & D Co., Ltd. started the 250MW IGCC demonstration project supported by METI and nine regional utility companies, EPDC (Electric Power Development Company) and CRIEPI (Central Research Institute of Electric Power Industry) in 2001. Currently, the demonstration plant is under construction since August 2004, and a series of operation tests will start in 2007. This paper presents the latest status of the project of the plant.

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Two-dimensional photonic crystals were fabricated through submicron lithography and deep reactive ion etching of silicon substrate. Transmission and emission propeties of those photonic crystals were examined toward control of emission spectra for high-efficiency thermophotovoltaic power generation system. Measurement data of the transmission spectra were in accordance with the results of the FDTD numerical analysis.

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Development of a micro electret generator prototype for energy harvesting application is presented. MEMS-friendly perfluoropolymer, CYTOP is adopted as high-performance electret material. When corona charging is employed. charge density as large as -0.93mC/m^2 is obtained for a 20μm-thick CYTOP film, which is much larger than that of Teflon AF. In power generation experiments using a prototype seismic generator. maximum output power of 0.28mW is obtained with 1.2mm_<pp> oscillation at 20Hz.

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Large-eddy simulation (LES) of compressible low-Reynolds-number (Re) flows in small radial turbines with rotor diameter of 46mm and 8mm are performed by 6^<th>-order compact difference and 10^<th>-order filtering method. In the computation, the conditions of pressure ratio of 1.5 and isentropic velocity ratio of 0.6 are assumed, and the tip clearance of 2.5% of the blade height is taken into account. In addition to the difference between the computed results by conventional Reynolds-averaged numerical simulation (RANS) based on Baldwin-Lomax turbulence model and LES regarding the prediction of loss, Reynolds number effects on the internal flows are also discussed.

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Our in-house CFD code originally developed for the analysis of compressible external flow, has been modified for cascade flows, and validated through the comparison with experimental data and existing numerical results. The present code employs Spalart-Allmaras turbulence model. The tip-clearance is modelled by overset grid system which enables better spatial resolution of clearance flows. The comparison revealed that the present code accurately predicts the pressure ratio and efficiency, although there is still discrepancy in the choke flow and operating range for the centrifugal impeller. The flowfields were also compared with experiment. The tip clearance flow was well resolved, and the overall flowfield showed satisfactory agreement with the experiment.

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In order to improve the performance of vertical axis wind turbines, numerical investigation was carried out. Since the angles of attack of VAWT are widely changed during rotor rotation, unsteady flow simulations are necessary for this purpose. A large eddy simulation and unsteady RANS were tested to simulate the flow around a VAWT. The numerical results showed the large separated flow can be observed with LES. On the other hand, RANS was not suitable to simulate the flow around a VAWT. The torque coefficient of VAWT reduced at the upstream region. In this region, uniform flow hit on the suction side of the airfoil. To improve the aerodynamic performance of VAWT, control of the angle of attack is required in this region.

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As one of systems for an offshore wind farm, a floating structure system with some wind turbines is thought. This system has close-set wind turbines on floating unit, then one wind turbine which lie behind others are strongly affected by the wake. For example, a wind speed is decelerated, an output of power is fluctuated, and fatigue of wind turbine is increased since turbulence intensity is high. Hence, a design tool of wind turbine with wake effects is needed. This paper describes a basic study of three-dimensional wake simulation near a wind turbine. The flow field is simulated with a Detached-Eddy-Simulation (DES). These results are compared with the NREL Phase VI experiments data.

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The change in turbulence structure in the wake of wind turbine with the inflow turbulence (IFT) was investigated with a wind tunnel. Special attention was paid to the effects of length-scale of inflow turbulence. Through the measurements of relation of thrust coefficient-tip speed ratio, and with the measurements of turbulence statistics, including higher-order moments, it was confirmed that the scale effects of wind turbine model on the wake characteristics was quite small. Then, it was found that the turbulence characteristics in the wake region strongly depend on the length-scale of IFT, i.e., the development of turbine wake becomes more active with the increase in length-scale of IFT, regardless to the intensity of fluctuating velocity of inflow turbulence.

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This report describes a experimental study related to the pressure distributions on a field horizontal axis wind turbine. It was known that a dynamic stall was occurred on a wind turbine blade. A cross-correlation function is used for the data reduction to analyze the occurrence condition of the dynamic stall. As a result, when local angle of attack is kept at the high angle, it turned out that dynamic stall occurs. The parameter of judgment for occurrence condition of dynamic stall is also suggested.

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As the large scale wind turbine generator systems over one mega-watt spread in the world, development of more effective and low cost wind turbines are required. In the mechanical point of view, more precise estimation of the aerodynamic load and fatigue life is indispensable. In order to reduce the cost, the weight and the aerodynamic load of the rotor blade and the tower, "flexible structural design" has been proposed. The purpose of the study is to develop the reliable and powerful tool for the design and estimation of the load calculation on the horizontal axis wind turbine. In the present paper, the influence of the blade oscillation to the flow field around the rotor blade and the blade load are analyzed by a panel method with free wake model along with one dimensional blade oscillation model.

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A micro wind turbine with rated power of 400W has been examined about its acoustic noise characteristics, experimentally. The turbine was installed at the rooftop of the building and the noise measurements and data analyses were conducted in accordance with the standard of IEC 61400-11. The sound pressure level increases with wind speed in the turbine operating condition, whereas the level of background noise is remained approximately constant irrespective of the wind speed. Therefore, it was confirmed that the acoustic noise characteristics of the wind turbine depend on the inflow velocity. The frequency analysis indicates dominancy of the high frequency component due to the turbulent flow noise in comparison with the low frequency band such as the blade passing frequency. Slight directivity of the acoustic emission has been observed in the horizontal plane and the largest noise is emitted in the downstream.

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A prototype wind turbine generator was designed on the concept that even small wind turbine generators need a variable pitch control system and low speed type blades especially to set on the roof of individual houses. The prototype machine is a 2.5kW rated power, 4m diameter, horizontal, upwind, free yaw and having three variable pitch blades wind turbine. Three blades are designed with thin airfoil and tip speed ratio of three. To make lighter blades, the blade shape has been improved, i.e., shortening the cut-off side chord lengths. The prototype wind turbine set on the roof floor of the engineering faculty building and has been applied two control methods of the variable pitch angle and regulating the field current of generator. This paper describes characteristics of thin airfoil blade calculated by the blade element and momentum theory and performances of the machine such as rotational speed, generator outputs as well as its stability for wind speed changes. In a pre-test under the average wind speed 6.0m/s, the wind turbine showed the average generator outputs of 194W, average rotational speed 56rpm, power coefficient 0.12.

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It is necessary to establish an autonomous monitoring for small stand-alone wind turbine-generator systems, which are operated in unelectrified regions. This paper focuses attention on a performance deterioration of a straight-wing vertical axis wind turbine, which is one of the primary performance deteriorations of the system. This system is mainly operated at a constant tip speed ratio, which means the maximum power coefficient point, without an anemometer. The influence of the wind turbine performance deterioration on the dynamic behavior of the system is investigated with a dynamic simulation model. Furthermore, how to detect the performance deterioration of wind turbine from the system output is investigated.

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State-of-art about the recent innovative waste treatment and management system are reviewed with focusing mainly on the both technological and social systemic aspects about increasing in the waste-to-energy together with minimizing the environmental risk problems. Future problems predictable and uncertainties in the advanced environmental technologies which have been recently introduced in practical service will be demonstrated in order to analyze and solve reasonably as soon as possible. An importance of considering the harmonization between Japanese skill and spirit for establishment of the reasonable waste management system in Japan will be emphasized.

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This paper describes high temperature corrosion of SUS310J1 superheater tubes in FBHE on RDF firing circulation fluidized bed combustor boilers (CFB). The scale deposited on the corroded surface of superheater tubes was mainly composed of metal (Fe, Ni, Cr) oxides and NaCl, KCl. Also, the surface of circulation particles was being corrosive materials such as Na, K, S, Cl, etc. The high temperature corrosion in these case was caused by chlorination reaction of metal surface with chlorides compound such as NaCl, KCl from circulation particles surface. The prevention methods of high temperature corrosion to superheater tubes in FBHE on actual FBC boilers are hopeful to application metal (alloy625, other)+ceramic(ZrO2-Y2O3/Al2O3) duplex thermal sprayed coatings.

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An investigation of hot corrosion behavior of various heat resistant alloys has been carried out in simulated environment of a pyrolysys gasification waste treatment system. Test results as follows, (1) the ash coat test results agrees with the corrosion behavior in actual system. (2) the Ni base super alloy shows a good corrosion resistance in the test environment.

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After examining practical structural materials for use in the high-temperature environments of waste incinerators, it was found that a Ni-Cr-W casting alloy is promising. However, the corrosion reaches its peak in the vicinity of 900℃. This peak is related to the behavior of chlorides that form in the interior of the alloy. As the chlorides continuously generate and decompose, the Cl recycles, accelerating corrosion. It is thought that when the temperature rises, the chlorides vaporize outside the alloy, suppressing Cl recycling and thus reducing the amount of corrosion. Adding Al to the alloy generates highly volatile AlCl_3, making it possible to prevent the accumulation of chlorides in the vicinity of 900℃ and lower the corrosion peak. As a result of conducting exposure testing for a year at an actual incinerator, it was demonstrated that adding Al is an effective way to improve corrosion resistance.

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We experimentally evaluate a performance and exhaust emissions of a single-cylinder, four stroke direct injection diesel engine operating on Mixed waste food oil methyl ester (Recycle BDF). The combustion characteristics, emissions such as NO_x, CO, HC, O_2, CO_2, smoke, particle size distribution and first stage durability test are compared with the case of JIS #2 gas oil. We found that (1) the NO_x emissions of Recycle BDF are slightly higher than gas oil in the almost load range. (2) CO and Smoke emissions of BDF fuels are lower than gas oil especially in the high load range. (3) PM emissions of Recycle BDF are 1/2 times its gas oil. (4) Smoke and PM concentrations of Recycle BDF are lower than gas oil at high load condition. (5) It is important to remove impurity of BDF such as soap, methanol and so on. (6) Also discussed are the usability of the Recycle BDF, as well as the validity of application to a treatment process of the waste food oil.

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This report describes the experimental results of a small-scale generation plant by woody biomass gasification. The gasification reactor is a fixed floor type. The test was done by up draft operation. The diameter of roaster is 0.5m. A small gasification plant was tested with woody chips. In the experiment multi point temperatures, pressures flow rates were measured.

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This study is devoted to clarifying the biomass gasification characteristics in a lab-scale fluidized bed gasifier coupled to a pneumatic char combustor. The experimental parameter is fuel residence time in gasifier. It was shown that the conversions of C and H as well as the corresponding cold gas efficiency increased with increasing the fuel residence time in gasifier. Nonetheless, the increases in conversion and efficiency were confined to a few percents (<5%) when prolonging the time from 160s to 1200s. Corresponding to this, the increase of the fuel particle residence time from 3s to 160s resulted in much obviously increased fuel conversion efficiency. Consequently, for the tested gasification technology the required explicit fuel residence time in gasifier can be lower than 160s but must be above 3s in order to assure the finish of fuel pyrolysis.

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This study is aimed at efficient use of biomass resources. For the efficient use, making solid fuel by pyrolyzing and generating liquid and gases fuel by pyrolyzing and gasification were focused on. However, there is not enough information for understanding pyrolysis and gasification reaction of biomass resources, especially other than wood. In this report, biomass and polyester waste were used for samples ; the gases that generated at pyrolyzing and gasification were analyzed, and evaluated for fuel. And so the pyrolysis and gasification reaction were understood based on this result.

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Dimethyl ether (DME) is suitable fuel for on-board reforming. We have developed 30kW autothermal on-board DME reformer. This reformer is packed in 50 litters. The load change response is under 10 seconds and CO concentration in reformed gas is kept under 10ppm. In addition to these experiments, we have developed a DME reforming FC simulator. By inputting experimental data of reformer, we have got required battery size, fuel consumption. Through these experiments and simulation, we have evaluated the convenience of on-board DME reforming system for fuel cell vehicles.

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We developed 1kWe and 30kWe class reforming systems for application to polymer electrolyte fuel cells, in which dimethyl ether (DME) as fuel and a high-activity and high-selectivity copper-zinc-alumina catalyst were used. It is concluded that the developed reforming system can be downsized and also its efficiency can be improved combining with a heat recovery system. We carried out the demonstration of 1kWe DME-FC system for about 100 hours and confirmed the performance of the system as follows ; (i) steam generation for the DME reforming can be produced by exothermic heat in CO removal reactor, (ii) heat for the DME reforming can be supplied by combustion heat of fuel cell off-gas and (iii) reforming system efficiency is 72.8% (LHV). In addition, our engineering study suggests that the developed reforming technology can apply to a compact reformer for fuel-cell vehicles, under scale up study. 30kWe reforming system is improved compactness and response for use in vehicle-use fuel-cell systems.

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We have developed a highly-active DME steam reforming catalyst with high activities of DME hydrolysis and methanol steam reforming. The addition of a certain kind of alumina to a Cu-Zn catalyst improved the steam reforming performance of DME. Two types of fuel-cell reforming systems have been evaluated under development ; external-heating type and autothermal type. The combination of a precious metal catalyst and a Cu-Zn-alumina catalyst has been found to be effective in the durability improvement to autothermal type.

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In PEFC reformer fueled with kerosene, carbonization of kerosene may be a crucial problem for reforming process. To prevent fuel carbonization, the evaporation of kerosene and water was conducted by two steps. In the first step, the evaporation temperature was kept at 100℃ producing gas-liquid flow of water. After mixing with liquid kerosene, in the second step, the liquid components of the mixture were vaporized completely by additional heating and fed into reforming catalyst. The experimental result showed the effectiveness of the procedure for stable vaporization.

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SOFC Power Generation System is able to attain extremely high efficiency over 70%, as Gas Turbine Combined Cycle System. Mitsubishi Heavy Industries (MHI) has been developing SOFC, since 1984 for material and production technology of Tubular Type Cell Stack, SOFC module, and system integration. In 2004, MHI has been commissioned to a new national project "Development of SOFC-Gas Turbine Combined Cycle System with Tubular Type Cell" by New Energy and Industrial Technology Development Organization (NEDO). The aim of this project is development and demonstration operation of 200kW class SOFC-Gas Turbine Combined Cycle System, with Tubular Type SOFC and Micro Gas Turbine. The target of performance is 200kW class electricity power output and 50%-LHV of power generation efficiency. This 200kW class SOFC-Micro Gas Turbine Combined Cycle System will be manufactured and operated in 2007.

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Osaka Gas Co., Ltd. and Kyocera Corporation have developed 1kW class solid oxide fuel cell (SOFC) cogeneration system. We installed SOFC residential cogeneration system in a house, living a family of four. From the end of November 2005 to the beginning of March 2006, total 2000 hours, we carried out the first trial operations for actual home use of SOFC residential cogeneration system. SOFC system showed high net ac efficiency under the condition of following the electric load of the actual house. At rated power, ac 1kW, net ac efficiency and hot water heat recovery efficiency were 49% (LHV) and 34% (LHV), respectively. The mean net ac efficiency of each days, that is total efficiency of 24 hours, ranged 42-48% (LHV), when the mean net ac power of SOFC were 480-680W.

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Fuel cells (FC) can hardly react a hundred percent of fuel, because the cell potential becomes zero if all of the fuel is consumed at FC. Therefore a small amount of fuel is released from FC, even when pure H_2 gas is used as fuel. If the space, where the exhaust H_2 is released, is closed up such as the space of deep underground or undersea, the released amount of H_2 may be restricted to an allowable level. The depleted H_2 can be recovered by the hydrogen pump, which is proposed here. When we supply electricity to the polymer electrolyte by an external power source, H_2 can easily be separated and pumped up from anode to cathode according to the principle of "concentration cell". In this study we have preliminarily tested the HSP, and our experimental results show that the HSP can work as a good separation and compression pump of exhausted hydrogen from FC.

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This paper describes an evaluation method for PEFC, which is calculating local entropy generation and its distribution in each segment of cell. In this method, we considered energy conservation equation and three sets of transport equation based on non-equilibrium thermodynamics. We numerically calculated them with an assumed boundary condition, and obtained distribution and flux related on temperature, electric potential and species concentration, and then we derived the entropy generation map. From this map, it was understood that the entropy generation took the maximum at catalytic layer, corresponding to large activation over potential.

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In this study, the effect of gas fuel composition whose components are CH_4, N_2 and CO_2 on combustion was experimentally investigated to propose a small gas engine system for appropriate combustion with biomass gas fuel. As a result, longer combustion duration and cyclic variation of pressure profile with increasing dilution rate were observed. This trend was more apparent in CO_2 dilution than N_2. Therefore, we can conclude that not only dilution rate but also kind of chemical species influenced engine combustion. Subsequently, effect of spark timing on combustion was investigated. As increasing dilution rate, to advance spark timing is necessary to keep high thermal efficiency and low cyclic variation in gas engine operation.

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Chemically Recuperated Gas Turbine (CRGT) fueled by Dimethyl Ether (DME), which is attracting attention as an alternative fuel for versatile use, has been developed as the project funded by METI since 2002FY, and this project is scheduled to conduct a demonstration test using 30kW Micro Gas Turbine (MGT). To use for DME steam reformer that is the key component of the CRGT system, 0.5wt%-Pt catalyst supported by γ-alumina was selected by LHV increase of reformed gas related to four reactions of DME hydrolysis, methanol decomposition, CO shift and methanation. The reformer installed directly in the exhaust duct with superheater, evaporator, DME preheater and economizer was designed by the numerical analysis code modeling the catalyst packed-bed as axisymmetric pseudohomogeneous media and combining conservation equations of mass, momentum, energy and seven chemical species using the reaction rate equations. The reformer designed to fit into the MGT consisted of 96 SS316-tubes, top and bottom headers and rectangular duct, and its heat recovery and LHV increase at the outlet was estimated to be 25kW and 8.0%, respectively.

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Sewage biosolid collection system almost has been established and is easy to collect. So sewage biosolid has high potentiality for prospective biomass utilization. Tokyo Gas Co., LTD has been conducting a research work of gasification technology of sewage biosolid for using gas appliances. The way of gasification is focused on pyrolysis system. Becaouse pyrolytic gasification has a characteristic of high gasification efficiency. Next, biomass-derived fuel like sewage gas is treated as carbon free fuel and biomass utilization contribute to reduction of CO_2 emission. One of sewage gas's applications is onsite generation facility, for example gas engine co-generation. But sewage gas has some difficulties to use, for example sewage gas is low caloric value and includes harmful components which have influence on metallic corrosion. So gas engine co-generation system for research work was installed into the sewage gas plant to aim for stable operation and high durability. This paper mainly describes designing concept and feature of installed gas engine for sewage gas. Furthermore, overview of sewage gas plant is mentioned.

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This research seeks to propose an atmospheric pressure turbine (APT), based on the Inverted Brayton Cycle, which puts new, distributed power generation technology to practical use by using various gases at normal pressures and high temperature, from industrial furnaces, waste gasification furnaces, gas turbines, and fuel cells which work at high temperatures, (ex. MCFC, SOFC) and attempts to save energy and reduce CO_2. However, no research has been presented about the operation of a real APT. This paper describes an outline for the results of a trial run, as well as the production of an APT prototype. The simulation results show that a 30kW system has a generator end efficiency (LHV) of about 32%, which is comparable to the performance of other equipment of a similar power rating, such as micro gas turbines. Based on this simulation result we build a 3-5kW APT prototype and operate. The result of this operation clarifies the basic characteristics of an APT including a performance of 8.7% thermal efficiency. An APT has a smaller specific power than a gas turbine. Accordingly, since its mechanical and dissipative heat losses are larger by comparison, it is important to reduce these losses to attain higher efficiency. Our APT was operated stably and the possibility can be used as a new system for distributed power generation using waste heat was confirmed.

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A program was developed for selecting energy systems of consumers, and optimizing operation of the systems. The program is enables to improve the accuracy and to reduce the analysis time when the effect is evaluated in the case that energy systems are installed in each type of business. The program can deal with co-generation and storage battery and so on as energy systems.

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Nowadays the lager plant for electric power generation has attained the higher efficiency. However its partial load efficiency is relatively low and it is not easy to follow the transient demand of electricity. So the network system of distributed small power units with high ability of load change is expected to replace a part of the conventional large power plants. SMART (SMall advanced Regional-energy Technology) is the local energy production and consumption system for Tokyo University of Marine Science and Technology. For the system design, energy (electric power and gas) of the campus was investigated and its characteristics were recognized. In the campus, the cost merit of introducing the distributed generation could be obtained only with reducing the contracted maximum demand of electricity. So the large-scale network of distributed generation was necessary for backup of the system malfunctions

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Energy consumption for commercial buildings is increasing and it is also necessary to save energy consumption in residential houses as living standard is rising. Recently lifestyles vary to each their own, energy consumption are various from households. In this paper, electric and thermal load in residential houses is simulated and the difference of load characteristics affected by insulating performance of dwelling materials, types of household and levels for energy saving consciousness of residents is investigated. The main result is that the average of primary energy consumption in typical household model is 54.9GJ/year, and the difference of energy consumption among households is more than 3 times. Types of household and levels for energy saving consciousness have influence on energy consumption.

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A small scale micro grid model system consisted of several types of distributed generators has been constructed. Frequency response of each generator has been measured. Based on the measured frequency characteristics of the generators, a simple combination control method is proposed to compensate load fluctuations: each generator is responsible for a frequency band into which the load fluctuations are divided. Experiments have been carried out with the model system. The load fluctuations have been leveled well by the proposed control method.

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A new type of MEMS-based radial hydrostatic gas bearing for MEMS-based gas turbines was developed. In this radial bearing, gas inlet ports are formed on the journal, and several types of restriction such as orifice and slot restriction can be realized. To fabricate this radial bearing, novel "cavity-trough deep reactive ion etching (DRIE)" was developed. 80μm square inlet ports and 5μm wide slots were fabricated on a journal with 4mm diameter and 350μm length, and the features of cavity-though DRIE was investigated for more precise fabrication. Also, the direct bonding technology of silicon wafers with closed cavities at the bonding interface was developed. By inserting mechanical spacers between the wafers and then proceeding the bonding process in vacuum, the inside of the cavities at the bonding interface becomes vacuum. As a result, bonding failures caused by the expansion of air inside the cavities during annealing can be avoided. Voids at the bonding interface did not appear by an appropriate cleaning process of the mechanical spacers.

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In order to improve the adiabatic efficiency of ultra-micro gas turbines, aerodynamic performance was measured for a two-dimensional small radial turbine. Clearance between the rotor and the casing is an important parameter of the ultra-micro gas turbines. The adiabatic efficiency depended on the ratio of the tip-clearance, C_r to the rotor height, H_r. In the case of conventional rotor, the loss of adiabatic efficiency was proportional to the clearance-ratio of C_r/H_r. However, the loss of small turbine was found to be expressed by the third-polynomial function of C_r/H_r. As a result, the loss was almost constant around C_r/H_r of 0.1. The loss decreases drastically at C_r/H_r of 0.05. However, it is practically difficult to manufacture a rotor with such small clearance by MEMS-processing. Both of the aerodynamics and MEMS-processing points of view, C_r/H_r of 0.1 was found to be a reasonable value for ultra micro gas turbine.

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