The purpose of this study is to investigate the fluid drag reduction of a circular disk by coaxial type dielectric barrier discharge (DBD) plasma actuator. Plasma actuator installed on the pressure side of the circular disk was used to inject axisymmetric jet, generating the vortex region. Drag was measured by compression type load cell. The vortex with the axisymmetric jet and flow around circular disk were visualized by particles method. This study revealed drag reduction of a circular disk by coaxial type plasma actuator and the volume of vortex varying according to plasma actuator edge diameter.

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The objective of this research is to demonstrate the advantage and characterize the thrust performance and the induced flow field generated by the TED plasma actuator with sawtooth electrode. The induced body force of the sawtooth TED plasma actuator was investigated on quiescent air, by measuring thrust of the induced jet. A time-resolved PIV was used to acquire velocity field. From the results of the thrust measurement, it was confirmed that the sawtooth TED actuator enhances the thrust compared to the straight-edge TED actuator. From the PIV analysis, it was clearly found that the sawtooth TED actuator generates uniform facing jet from both of the electrode, by the uniform generation of the plasma from the sawtooth vertexes.

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Three dimensional numerical simulation of ion transports in a plasma actuator is performed. The effects of sinusoidal spanwise voltage variations on the ion density and the body force field are investigated. The stronger body force is generated in the case with spanwise voltage variations as compared to the uniform voltage case. The enhanced body force is observed to be due to the selective concentration of positive ions in the region of stronger electric field. Based on this result, we aim at improving the thrust using a waveform electrode as an upper electrode. In some cases with the waveform electrode, a stronger body force is generated as compared to the uniform electrode case.

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This study is concerned with the flow control of backward-facing step flow with periodic disturbance when a dielectric barrier discharge (DBD) plasma actuator is mounted on the step edge. Pressure measurement on the wall and flow visualization behind the step were carried out for the on and off modes of the plasma (pulse modulated drive) in a variety of step height and free stream velocity conditions. As a result, the relationship between the modulation frequency and the reattachment point revealed. Further, the mechanism that the reattachment point moves upstream is thought to be different from that it moves downstream.

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A vortex is generated backward bluff body. This vortex causes vibration of bluff body, drag and noise. In the present study, we attempted to suppress this vortex using a dielectric barrier discharge-plasma actuator (DBD-PA). Using stereo particle image velocimetry (Stereo PIV), we attempted to measure the velocity field backward a circular cylinder which applied to DBD-PAs. We compared velocity distribution of streamwise direction in the case that DBD-PAs do not be driven (NC) with the case that DBD-PA are driven (PA). Average spatial velocity of streamwise direction and Average spatial velocity fluctuation of vertical direction backward a circular cylinder in PA improve comparing with that in NC. And these experimental results in NC and in PA had good agreement with results of numerical simulation in the previous study.

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Large eddy simulation of a flow around a circular cylinder is performed to study the effect of plasma actuators for suppression of vortex shedding. The subgrid stress is modeled by the standard Smagorinsky model and the body force generated by the plasma actuators is modeled by using the Suzen model. The Reynolds number based on the free-stream velocity and the cylinder diameter is 85,000, which is the same as that used in the experiment by Kozlov & Thomas (2006). The present results show that the drag coefficient and the lift fluctuations are reduced by 36% and 13%, respectively. The computed flow statistics without and with plasma actuators are also found to be in fair agreement with the experimental data of Kozlov & Thomas (2006).

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We carried out both aerodynamic forces measurements and flow visualization tests of a NACA0012 airfoil model at Re = 30,000 in order to verify what kind of effect does operating of a pulsed plasma actuator on both flow field and aerodynamics of the airfoil. Modulation frequency of pulsed operating mode of the plasma actuator was varied as non-dimensional modulation frequency F^+ from 1 to 10. The aerodynamics of the airfoil were improved by operating of the plasma actuator regardless of operating mode. And stall characteristics were clearly changed by pulsed operating mode that both the maximum lift value and the stall angle of attack were increased by depending on F^+. The flow field over the airfoil in pulsed operating mode show different characteristics from continuous operating mode; vortices were shed simultaneous with modulation frequency f_m and vortex structure including vortex street formed reattached turbulent flow on the airfoil. This change of flow phenomenon by depending on F^+ contributes suppression of extensively separation on the airfoil, therefore, it is important to clarify the details of relationship between the change of F^+ and the flow field which influenced by operating of pulsed plasma actuator.

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The present study focuses on the multiple separation-control mechanisms of burst actuation with a dielectric barrier discharge plasma actuator. Control of separated flow around a NACA 0015 airfoil at the Reynolds number of 63,000 is investigated using a plasma actuator mounted at 5% chord length from the leading edge. A parametric study on burst frequency and input voltage are conducted on three post-stall angles of attack using time-averaged pressure measurements and time-resolved particle imaging velocimetry (PIV). The trailing edge pressure is chosen as the index of separation control and indicates that the optimum burst frequency is different for each angle of attack. Several flow fields are discussed in detail and two flow-control mechanisms are clarified: the utilization of a large vortex and promotion of turbulent transition. With regard to the first mechanism, the phase-lock PIV indicates that a vortex structure, the size of which increases as the burst frequency decreases in this experimental range, is shed from the shear layer for each burst actuation. With regard to the second mechanism, time-averaged pressure and PIV measurements reveal that burst frequency of F^+ = 6-10 has the capability to promote turbulent transition. At higher angle of attack, only the utilization of a large vortex structure is effective for separation control, whereas, near the stall angle, the promotion of turbulent transition provides better separation control.

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Large-eddy simulations of the separated flow over an NACA0015 airfoil controlled by the DBD plasma actuator are conducted and the flow fields and the aerodynamic performances are compared with the Ishii airfoil, one of the high performance airfoil at the low Reynolds number. The DBD plasma actuator is set at the 5% chord length from the leading edge of NACA0015 airfoil and operated in burst mode at the Reynolds number Re=63,000. In both cruise and post stall angle of attack, Ishii airfoil show higher aerodynamic performance than NACA0015 airfoil when DBD plasma actuator is OFF. However, when the DBD plasma actuator is activated, NACA0015 show higher aerodynamic performance.

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We have conducted large-eddy simulations of laminar separation control by the DBD plasma actuator over NACA0015 airfoil. The control effects are investigated for the case of the single plasma actuator and the case of the multiple plasma actuator. Reynolds number based on the chord length is 63,000 and the angle of attack is 16 degs. For the case of the single plasma actuator, the reattached flow separates again near the trailing edge. On the other hand, separation control by the multiple plasma actuator can suppress the re-separation near the trailing edge. This suppression leads to improvement of the lift coefficient compared to the case of single plasma actuator.

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Active control of lift force on NACA0015 airfoil by jets induced by a dielectric barrier discharge plasma actuator (DBD-PA) was experimentally investigated. The exposed electrode of DBD-PA was varied at x/c=0.6, 0.7, 0.8 and 0.9 on the pressure surface of NACA0015. Tangential jet, which maximum velocity in terms of the free stream is u_<j-max>/U_∞ &ap; 0.12, was induced by applying 5.0 kV_<p-p> at 20 kHz toward the upstream direction under Reynolds number Re = 3.3×10^4. It was found that lift coefficient increases in the cases of x/c=0.8 and 0.9 whilst it tends to decrease for x/c = 0.6 and 0.7. It was confirmed by PIV analysis that v component of velocity in the downstream from the trailing edge decreases in comparison with that of no flow control when lift coefficient is enlarged.

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Velocity distributions near the outlet of a centrifugal compressor were measured by PIV for investigating the leakage flow changes by ring-type plasma actuators. The ring-type plasma actuator was attached on the casing's surface near the impeller tip. The rotating speed of the impeller was set at 500 rpm, 1,000 rpm, and 1,500 rpm. The peak-to-peak input voltage was set at 8kV, 10kV, and 11.7 kV, with a fixed frequency of 40 kHz. In all the rotating speeds, the velocity distributions with the plasma actuator off had a gradient that the velocity at the impeller tip side is lower than that at the impeller root side. Mitigation of the velocity gradient, which indicates the suppression of tip leakage flow, were found at the higher input voltage and lower rotating speed condition.

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Dielectric barrier discharge plasma actuators (DBD-PAs) have been developed for active flow control devices. However, it is necessary to reduce ozone produced by DBD toward practical applications using DBD-PAs. In this study, variations of ozone concentration, flow velocity, power consumption were investigated by changing exposed electrodes of DBD-PAs. It was found that span-type DBD-PA shows lower power consumption and higher flow velocity than that of normal-type DBD-PA for V_<p-p> = 4.0 and 6.0 kV. Ozone concentration of span-type DBD-PA higher than normal-type DBD-PA for V_<p-p> = 4.0 and 8.0 kV. In addition, it was confirmed that catalyst located in downstream from the exposed electrode can reduce ozone concentration between 18 and 42%.

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In medical field, sterilization devices have been used to prevent surgical site infection. Sterilization is a method which eliminates microorganisms completely. In medical processes, common sterilization methods such as a high pressure stream, an ethylene oxide gas (EOG) and a hydrogen peroxide plasma have been utilized. However, heat damages by a high pressure stream, toxicity by EOG and high costs for a hydrogen peroxide plasma are disadvantages. Therefore, development of a new sterilization method with low temperature, rapid, safe and low-cost is demanded. Plasma has been expected as a novel sterilization method to solve the disadvantages mentioned above. Plasma can generate UV and reactive chemical species at low temperature and it is known that these stimuli generated by plasma have a biocidal effect. In this study, a sterilization device using atmospheric pressure plasma was developed for a practical application. This plasma device was able to generate reactive chemical species such as NOx and show good sterilization performance. To verify the completion of sterilization, biological indicators (BIs) which assure the sterility were used. In addition, plasma-induced flow with low temperature without gas feeding improved a sterilizing performance.

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A coaxial dielectric barrier discharge plasma actuator (DBD-PA) is applied to control the burner flame stability. DBD-PA consists of an exposed electrode, an insulated electrode, and a dielectric layer. In a convergent round nozzle having an exit inner diameter of d=6 mm, the electrode set was arranged coaxially with the nozzle. DBD-PA is applied to the control of the flame stability on condition equivalence ratio: φ=0.8, 1.0. Premixed gas of air and propane was used for fuel. The applied voltage is 4 kV to 16 kV and OFF, and frequency is 4 kHz and 8 kHz. Flame stability limit is taken with a high speed camera. Two of the action occurs when the plasma is generated. One is blowing force by the plasma, which increases the velocity of the boundary layer, slowing the velocity of the central portion. The other is the generation of active species by the plasma. Active chemical species is intended to activate the combustion reaction; there is action to stabilize the flame even in lean-burn conditions. Plasma both coexist at the time of occurrence, by both the balance with the applied voltage, and a case where the flame front is stabilized, when blown away.

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This study concerns an implementation technique of scientific programs based on Object-Oriented Programming via Modern Fortran, well-known as Fortran 2003. Object-Oriented Programming features make maintain, reuse and extend of existing program source codes easy. A program calculating two-dimensional incompressible viscous flow is implemented on a CPU based on Object-Oriented Programming. The Fractional step method and SOR method are adopted as a numerical simulation and solver for the pressure Poisson equation. The implemented program is simpler than that based on the procedural programming which is popularly used for the programming of numerical simulation methods, confirming the Object-Oriented Programming's suitability for the scientific programming including fluid flow simulations. A porting of the CPU program to CUDA Fortran is successfully completed, avoiding some restrictions attributed to PGI compiler's features. This porting process discovers reuse technique of existing FORTRAN 77 codes.

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A dynamical model of dipolar vortices in two-dimensional incompressible flows is derived. The dipolar vortex consists of equal and opposite vortices. In the moment model, the dipolar vortex is characterized by time-dependent variables: the centroid position, vorticity moments, and the length scale which is the distance between the positive vortex and the negative vortex comprising the dipole. The motion of the dipolar vortex is described by a set of ordinary differential equations for these variables derived from the conservation of momentum. In this paper, we consider the role of the second-order vorticity moment, called an angular impulse.

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In this study, unsteady aerodynamical effects of 2-D airfoil (NACA0012) at the attack of angle 7deg under acceleration or deceleration condition was numerically investigated using a grid-free vortex method. The aerodynamical forces and vortical flow field were compared with each accelerated or decelerated condition at Re=4.0×10^5. In this analysis, firstly, airfoil was moved at a constant speed, and then, each acceleration or deceleration condition was given to the airfoil from the non-dimensionless time T=7.5 at which the fluctuation of fluid forces became stable. The results showed that the aerodynamical forces changed compared with the steady state. Under the large acceleration condition, the lift and drag forces increased with the increase of velocity. Under the large deceleration condition, the lift and drag forces decreased with the decrease of velocity. In addition, Vortex structures generated at the steady motion moved at backward and forward by the acceleration and deceleration motion respectively. Furthermore, it was confirmed that the movement of the vortex structure changed the aerodynamical force.

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This is a basic research on a solar unmanned aerial vehicle (UAV). It is operated at low Reynolds number region of around 10^5. Therefore, low Reynolds number aerodynamics is important for the design. Furthermore, solar panels are mounted on the upper wing surface. The surface roughness causes reduction of the wing performance. Consequently, the unsteady vortex dynamics are important to realize the optimum design and examine the flow characteristics because the vorticity region and its unsteady evolution have significant effects on the aerodynamic forces. In this study, numerical simulation of a two dimensional SD7037 airfoil was carried out by using a grid-free vortex method in order to investigate the roughness effect. In the method, generation of numerical grid in flow field is not necessary. Accordingly, it is easy to calculate flow around complex or moving geometries. From these reasons, vortex methods are useful methods to confirm the effect of surface roughness. Surface panels including zigzag panels are set on the upper surface of the airfoil. The roughness is set at 14-17% of chord length from the leading edge. Form the calculation results, it was confirmed that vortex structure was formed at the surface roughness position. In addition, aerodynamic forces were decreased compared with the regular surface condition.

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Though a lot of researches on boundary layers around a moving body have been conducted, not only details of growing process of vortices but also relation between moving wall and vortices in the boundary layers are not clarified. In this study, the growing process of vortices near moving wall is explored numerically in case of heaving and elastic thin airfoil during one cycle Re=4,000 and St=0.36 using ANSYS 14.5. As a result, the time and space variations of vorticity on the wall is similar between rigid and elastic airfoils. The vorticity on the wall is strongly depended on the effect of the moving condition, so the effect of the deformation is small. The deformation influence the vorticity near the trailing edge. Consequently, the vortex rolling up from the rigid airfoil is released earlier than that of elastic airfoil.

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Recently, Many researchers are interested in the flight mechanism of insects. In all the insects, especially butterfly has a larger wing area and less frequency of flapping motion than the other insects. Therefore, the butterfly is able to fly efficiently. If the flying mechanism of butterfly is revealed, it would be believed to apply the flying mechanism to engineering field. The purpose of this study is to clarify vortex structure and its dynamic behavior in the wake of the butterfly in free flight. Specifically, the authors was visualized the flow after the flight to butterfly by a stereo particle image velocimetry (stereo-PIV). As a result, we were able to visualize the end of the vortex ring. In addition, it was also found out that there is the presence of induced flow with three-dimensional expanse in the vortex ring.

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An Integrated coal Gasification Combined Cycle (IGCC) is the power generation system that gasifies coal, leads the gasified gas to a gas turbine, and generates electricity along with a steam turbine. It is the coal fired power generation technology by which high thermal efficiency is obtained. The Nakoso IGCC Demonstration Plant was constructed by Clean Coal Power R&D Co., Ltd. (CCP) and CCP conducted the various tests for commercialization since September 2007. The Demonstration Project finished in March 2013. CCP was absorbed by Joban Joint Power Co., Ltd. on April 1st, 2013. The IGCC plant has been called Nakoso Power Station unit No.10 and is operating as a commercial plant. In this report, it is described about the commercial operation condition of Nakoso Power Station unit No.10 of Joban Joint Power Co., Ltd.

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J-POWER has conducted R&D on coal gasification technology by constructing a pilot plant with a coal feed rate of 150 tons/day at the Wakamatsu Research Institute. A chemical CO_2 capture facility using an MDEA solvent was installed in 2008. The facility has two different regeneration modes: conventional stripping regeneration and heated flash regeneration. In the heated flash mode, the solvent is regenerated by heating it to around 60-80 degrees Celsius and reducing the pressure. Testing showed that chemical absorption with heated flash regeneration uses about 50 percent less energy than conventional stripping regeneration. Furthermore, a physical CO_2 capture facility implementing the Selexol process was installed in 2012. Eight parameters including lean solvent flow rate and semi-lean solvent flow rate were evaluated in terms of their effect on energy penalty and CO_2 recovery rate. Net plant efficiencies for IGCC with CO_2 capture were optimized and calculated by applying operational results from the chemical and physical CO_2 capture facilities. We found that IGCC with physical CO_2 capture has a low efficiency penalty of 6.4 points compared to a penalty of 10.8 points with conventional chemical CO_2 capture.

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As a gas turbine for high-efficiency oxy-fuel IGCC system corresponds to a semi-closed type gas turbine, there is concern that a very small amount of ingredient contained in fuel and oxygen affects the purity of captured CO_2. In this study, the atmospheric pressure combustion tests were performed by using fuel including NH_3 as minor components and by using diluent including NO as the exhaust circulation gas, and NOx emission characteristics were examined. As the results, the conversion ratio to NOx from NH_3 was approximately 30% when NH_3 concentration was 2000ppm, and the most of the NOx emission consisted of NO. And when NH_3 is contained in fuel and NO is contained in diluent corresponding to the exhaust circulation gas, it was confirmed that NOx emission corresponds to the sum of NOx emission formed by NH_3 in fuel and NOx emission formed by NO in diluent.

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In order to combat global warming CO_2 emission reduction from the iron and steel making industry is necessary. The Active Carbon Recycling Energy System for the iron making process (iACRES) has been developed as a technical option for substantial CO_2 reduction. Lithium ortho-silicate (Li_4SiO_4, LS), which can separate high purity CO_2 at high temperatures, is a suitable solid sorbent to capture CO_2 from the iACRES process. In our previous studies, a spherical LS pellet was analyzed via numerical analysis using the unreacted core model. The diffusion resistance resulting from decreased porosity as CO_2 absorption occurred was found to be the dominant factor inhibiting the CO_2 absorption rate. In this study, the effect of a cylindrical LS pellet was analyzed using commercial FEM software with diffusion resistance and chemical reaction incorporated into the model. The result of the numerical analysis showed a trade-off between CO_2 loading capacity and absorption rate.

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Domestic light water reactors are expected to restart sequentially after given permission in condition to meet the new regulatory requirements. Since several safety related systems were added to the plants through this corresponding process, the numbers of components to be inspected, which is already a large amount, will increase even more after the restart. Effective measure will be required to command maintenance activities by reasonably assigning limited resource. The authors have planned a research project aiming optimization of maintenance considering influence of fluid leakage behavior with pipe failure, mainly targeting less-safety related piping and components. Outline of the project is presented, including a series of research items to evaluate the influence, experimentally and analytically

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Since several safety related systems were added to the plants through the process of the new regulatory requirements, the numbers of components to be inspected, which is already a large amount, will increase even more after the restart. Effective measure will be required to command maintenance activities by reasonably assigning limited resource. The authors have planned a research project aiming optimization of maintenance considering influence of fluid leakage behavior with pipe failure, mainly targeting less-safety related piping and components. The experimental equipment which has the ability to evaluate the fluid leakage behavior with pipe failure was constructed. By using this equipment, it is able to conduct the mock test of the flushing and the steam flow leaked from various flaw geometries of the piping (crack, pinhole and guillotine break).

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Flow accelerated corrosion (FAC) and liquid droplet impingement erosion (LDI) are the main pipe wall thinning phenomena in piping system of power plants. At present, the management is based on thinning rate and residual lifetime evaluation using pipe wall thickness measurement results. For future improvement of the management, introduction of domestic prediction code is expected in Japan. We have developed original prediction software for pipe wall thinning "FALSET", which predicts maximum thinning rate in each element in pipelines one-dimensionally by simplifying our prediction models for local thinning rate of FAC/LDI, and verified FALSET with FAC data in domestic PWR secondary system. In this study, FAC prediction model in FALSET was verified with FAC data added from previous verification and prediction accuracy at present was discussed.

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The volumetric test for piping of a sodium cooled fast reactor (SFR) is difficult from the poor accessibility. Therefore, detection of a crack in a pipe is difficult until its penetration, and an SFR has a plan to detect sodium leakage from a through wall crack before fracture of a pipe. Plant safety is ensured by detection of sodium leakage in small quantity and by shutting down a plant as soon as possible, even if crack penetrates a pipe wall. Consequently, it is important to ensure establishment of leakage-before-break (LBB) in this plan. High chromium steel (Mod. 9Cr-1Mo steel) is one of the candidates for fast reactor piping material. Effects of a fracture resistance curve (J-R curve) on fracture strength of a cracked pipe made of this material are evaluated in this study, and requirements for a J-R curve to achieve the LBB were proposed.

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A liquid metal sodium leak and pool fire experiment has provided the transient temperature data measured in more than 100 positions for atmospheric gas and structures. The experiment was performed in an air-filled 2-cell geometry that was made by partitioning the room of rectangular cell with an opening between the cells. The analyses of the measured data clarified the basic characteristics of sodium pool combustion and consequential heat and mass transfer in the cells. The data also suggested several features of multi-dimensional thermal-hydraulic behaviors that occurred in the experimental geometry during the fire. The measured data are expected to be utilized for the validation study of numerical sodium fire analysis tools.

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As a part of series of "Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities", the seismic isolation technology applied to nuclear power facilities is developed. And isolated systems applied to nuclear power facilities is based on nation's biggest Lead Rubber Bearing (LRB) with φ1600mm diameter. As one of applicable isolated systems, Tin Rubber Bearing (SnRB) is adopted in the future. In this paper, the basic characteristic test of SnRB, horizontally hardening test and vertically softening test, carried out and compared with LRB. As a result, analyzing the test result about the design characteristic and non-linear characteristic at the large deformation, SnRB is evaluated the effectiveness as the alternate material of LRB.

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In order to respond the regulatory requirement of residual risk evaluation, a research on residual risk evaluation of the seismic isolated plants is proceeding as a part of the Japan national project of seismic isolation. Seismic response characteristics of the seismic isolated buildings show strong non-linearity and large displacement because of the vibration characteristic of the seismic isolation system. Therefore, response characteristics specific to the seismic isolated buildings such as non-linear response and relative displacement between isolated building and non-isolated building shall be considered in the fragility evaluation methodology for equipment of the seismic isolated plants. This paper focuses on the seismic fragility evaluation of equipment of the seismic isolated plants considering the relative displacement and non-linear response of the buildings.

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This study is part of a series titled "Development of an evaluation method for seismic isolation systems of nuclear power facilities". In this study, seismic Level 1 probabilistic risk assessment (PRA) was performed for a nuclear power plant equipped with a seismic isolation system in order to evaluate its effects under the design basis and also design extension conditions. The study also clarifies the risk feature of the seismically isolated plant and suggests ways to improve the plant reliability by comparing the results of PRA with those of a conventional nuclear power plant.

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After the Fukushima nuclear accident, Tokyo Electric Power Company (TEPCO) launched a project to develop the Filtered Containment Venting System (FCVS), in which our very bitter experiences in the accident are reflected. One of the main purposes of the development of the FCVS is to enhance operability of venting under the severe plant conditions such as the SBO during progressing of severe core damage, and another is to enhance removal performance of radio-nuclides with the newly added filtering equipment, which is installed in the venting line from the PCV to the outer. The Kashiwazaki-Kariwa NPS unit 6 and 7 are the first reactors applied the FCVSs. Performance of the FCVS has been verified by an extensive test program which includes scaled filter venting test under various conditions. In this paper, we show new test filters of actual height conditions and some test results on aerosol decontamination factor (DF). The test results have the same tendency as the existing test filter and also show that our performance evaluation method is valid.

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The development of distributed generation systems using renewable energy has advanced in Japan due to the influence of the Fukushima Daiichi nuclear accident in March 2011. In this work, a distributed energy system which exploits the unique state-change property of a CO_2 hydrate through a heat cycle is proposed. The proposed system is environmentally friendly because no fossil fuel is burnt and no carbon dioxide is emitted to the atmosphere. Furthermore, the inputs of heat energy are supplied by renewable sources such as the outdoor cold air and the geothermal heat, as cold and hot mediums, respectively. In this study, we determined the characteristics of the output of the proposed generation system by experiments performed in a prototype constructed in our laboratory. As a result, a maximum power output of 105.8W and a maximum efficiency of 6.95% were obtained.

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Thermoelectric power generation system using the thermoelectric conversion device can convert the thermal energy between the hot spring and waste water to electric power. The amount of power generation of the device depends on the temperature difference between each surfaces of the device. However, the cold water is sometimes not provided around the hot spring. In this study, we adopted the natural air cooling as a cooling method which does not require the cooling water. We investigate whether the cooling performance is different by various fin positions (top cooling, bottom cooling and side cooling), and optimize it. Experimental apparatus consists of heat sink, peltier device, and rubber heater. The heating temperature was set to 40 ℃. The voltage was measured at various fin positions. As the result of the experiment, it was found that bottom cooling generated the largest power and side cooling generated the lowest.

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Since a micro gas turbine (MGT) generally has higher heat/electric ratio to the other prime movers in cogeneration system (CGS), it is much available at a sewage treatment plant of cold district where large amount of heat is usually required in a year. However, it sometimes gives lower generating efficiency, especially in summer, because of higher intake air density. As another problem it is difficult to keep higher level of generating efficiency on partial loads of MGT operation. On the other hand CGS with fuel cells commonly shows the higher efficiency and is significantly expected to improve the total energy performance in the system without those defections. In this study, several models with cooperative usage of MGT and PAFC are analytically proposed for a sewage treatment plant of cold district. As the result of the calculation CGS operation properly mixed with MGT and FC can produce both much generation capacity and more effective use of biogas in the plant.

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The objective of this paper is to identify the model parameter of PEM fuel cell cogeneration in order to contribute to the building performance simulation for design and operation. As cogeneration system has many operational alternative strategies, the simulation using the mathematical model of cogeneration needs to predict accurate prime mover's thermal and electrical output, and also needs to represent characteristics of both steady state and transient state, for the aim of evaluate accurate energy performance and CO2 emissions. We made a test environment for parameter identification of PEM fuel cell cogeneration, and examined operational characteristics on steady state and transient state. As a result, the model parameter of PEM fuel cell cogeneration was identified, and was also validated.

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In Teuri Island and Yagishiri Island, in Haboro, Hokkaido, local production for local consumption of energy has become a challenge from the points of view of fuel transportation and conservation of local environment. Due to this, the "Eco Island Concept Demonstration Project" has been launched in Haboro, and the introduction of renewable energy is being considered. Therefore, this study aims at the developing of an optimal clean energy system in Teuri Island and Yagishiri Island. In this paper, the study of the optimization of the installed capacity and the suppression of frequency variation in the microgrid comprising these two island is performed. For the optimization of the infrastructure capacity, the objective function of the economics of the system is considered, and the most economically advantageous system with the less environmental impact is found. Moreover, focusing on the moment of inertia of the generator, whether the frequency variation falls or not within the permitted range for this economically optimum capacity is evaluated. Furthermore, this study reveals the differences between the experimental results and the simulation results by performing experiments using a smart grid simulator.

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The demand for renewable energy has been expanding driven by the influence of global environmental issues and the Fukushima nuclear accident. Among the renewables, the introduction of solar generation is especially thriving. However, a solar cell used for solar power generation has issues because the power generated depends on the installation area and the relative position between the sun and the solar cell. It is considered that plants have grown and evolved into a defined shape in order to receive as much sunlight as possible, and have also adapted to the local environment. So far, we have developed an analysis method to maximize the light receiving density for a solar cell module by simulating the shape of a plant shoot. However, previous analysis method has not been yet simulated for large plants like trees. In this paper, the light receiving characteristics for shapes of plant shoots simulating trees are determined. According to results, the plant shoots simulating the shape of trees grow to increase the amount of light received and in this way attain a high light receiving density.

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Generally, the output characteristics of the power sources are nonlinear. Furthermore, because multiple power sources are used in compound energy system as microgrids, many variables must be considered to optimize the system. Although the operation of energy systems has been optimized, nonlinear problems with many variables have been approximated by linear formulas with mixed-integer-programming. Moreover, the conjugate gradient method and genetic algorithm (GA) were also used. Analysis using GA is capable of responding flexibly to operational planning of such a complex system. However, case of large system, requires lengthy analysis time, generates many suboptimal solution, and unsatisfactory solutions of energy balance equations are obtained. To analyze operation of actual energy system by GA, significant improvements are needed. As this solution, reported the orthogonal table -GA hybrid analysis method for planning the optimal operation of a compound energy system in the previous study. This analysis method limits the operation range of a system with an orthogonal table and factor-effect-diagram, which are widely used techniques in experimental designs. Next, a GA was introduced for system operation within a limited range to search for the optimal solution. The Orthogonal table-GA hybrid analysis method was predicted that it will improve the analysis accuracy of independent microgrids with many design parameters. Analysis examples of independent microgrid using fuel cell or gas engine generator are given in this study.

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This paper proposes four cycles driven by low temperature waste heat. Four cycles are modified from Absorption Heat Pump cycle - Absorber Heat Exchanger cycle. First cycle is installed compressor between pre cooler and absorber heat exchanger (AHX) to increase pressure of absorber. Second cycle is changed AHX to solution heat exchanger (SHX). Third cycle is installed compressor between pre cooler and SHX. Last cycle is installed ejector between pre cooler and SHX. All of these cycles were carried out with NH_3-H_2O. The cycles are compared with coefficient of performance (COP) and exergetic efficiency. Results of the simulation show that installing compressor with AHX increases COP_H 0.15 point on heating mode and COP_C 0.18 point on cooling mode at rate point (T_<H,in>=88). Installing ejector with AHX increases COP_H 0.1 point on heating mode and increases COP_C 0.18 point on cooling mode at rate point. In addition, installing compressor decreases heat source temperature.

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The main objective of this study is to clarify the impact of energy demand prediction accuracy on optimal operating result of residential energy supply system. In this paper, the energy system consists of polymer electrolyte fuel cell cogeneration system and electrical-driven heating, ventilating and air conditioning system. Primary energy of operational results with various demand prediction patterns are calculated in order to analyze the effect of demand prediction error. As a result, it is concluded that prediction error of energy demand causes 54.3 MJ/day increase of daily primary energy in the worst case, and annual primary energy consumption can be reduced by 13.2% with the best prediction in comparison with the worst one. Furthermore, the impact of energy demand prediction accuracy on daily primary energy has relationship with the amount of hot water demand. Therefore, the effectiveness of using the amount of hot water demand as a parameter for demand prediction is suggested in terms of energy saving.

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A big difference in pressure is obtained with a small difference of temperature when a CO_2 hydrate dissociates. A pressure difference of about 3 MPa is possible with a temperature difference of about 10 ℃. Using this difference in pressure, we aim at the development of a small clean generation system. In this generation system, the CO_2 hydrate is the working fluid and has the function of energy storage. Energy can be stored by the CO_2 hydrate during generation. In the present study, from the heat cycle characteristics of a CO_2 hydrate (Dissociation-expansion characteristics) and using a plate-type heat exchanger with superimposed thin corrugated metal plates the following results are obtained. When the CO_2 hydrate is generated and the provided amounts of heat by the heat medium are 152 kJ and 790 kJ, the CO_2 hydrate can store 522 J and 582 J, respectively.

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In this study, we focus on the design of a gas-hydrate clean generation system which uses the dissociation-expansion properties of a CO_2 hydrate. Generation of a gas hydrate occurs when a mixed fluid of a certain gas and water is pressurized to a certain temperature and then cooled. If this gas hydrate is heated, a very high pressure is obtained from the dissociated gas released in the dissociation process. Therefore, by utilizing the difference of temperature between a renewable low-temperature heat source and the outdoor cold temperature in a cold district for the formation-dissociation cycle, the obtained high pressure gas can be applied to an actuator, and a very low environmental impact generation system can be obtained. However, a power generation system applying the dissociating gas from a gas hydrate as a working fluid in an actuator has not yet been studied. To perform the study in this work, first, the modeling of the gas hydrate generator system is prepared, and then, the power quality using this model is analyzed. Usually, demand side such as general housing and factories is composed not only of simple constant impedance loads but also of a variety of loads. Therefore, in this study, different loads on the demand side are used to investigate the differences in output characteristics of the proposed system.

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The ship Shirase in charge of transporting fuel and research equipment to the Japanese Showa Base in the Antarctica is approaching its loading capacity limit due to the increasing research activities and new requirements for ambient comfort in the base. Also, due to the negative effects of the emissions caused by the burning of fossil fuels, the increasing utilization of renewable energy and the reduction of fuel consumption represent important challenges. In order to reduce fuel consumption and to increase the utilization of renewable energy, we are considering the implementation of a microgrid for the base named the Showa Base Microgrid (SBMG). In this work, the microgrid is considered to be composed, together with the solar and wind generators, of distributed engine generators, a seawater source heat pump and electric thermal storage heaters, and an operation plan is implemented. In this work, as analysis methods, we propose a mixed integer linear programming (Analysis A) and genetic algorithm (GA) (Analysis B). For these two methods, the amounts of fuel consumption are calculated, and the difference between the amounts of fuel consumption for each method, together with the differences in operation for the engine generators are evaluated.

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The authors proposed the concept that CHPs, which is combined heat and power and sometimes called co-generation, are installed to buildings with large heat demand and excessively generated electricity is consumed in buildings in the grid network. The analysis demonstrated significant effect of the system for the reduction of CO_2 with keeping cost advantage, compared to the non-networked CHPs. This paper analyses dependence of the effect on regions, CHP devices, and cost conditions. The results show that the networked CHP system keeps its significant effect even in Tokyo area, although the effect is larger in Sapporo. Compared to the non-networked system, CO_2 can be reduced twice by the networked CHPs. This is due to the fact that houses have high heat/electricity demand ratio even in Tokyo. The paper also shows the effectiveness of fuel cell CHPs compared to gas-engines, due to higher efficiency of electric generation. Cost analysis indicates that the supply unit cost ratio of grid electricity and town gas linearly influences the cost benefit of CHPs.

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Mitsubishi Hitachi Power Systems, Ltd. (MHPS) has so far proceeded with development of a combined power generation system which Solid Oxide Fuel Cell (SOFC) operating at high temperature and another power generation system are assembled, and we implemented a demonstration test in order to commercialize the hybrid system at Senju Techno Station in Tokyo Gas Co., Ltd. MHPS started operating a 200 kilowatts (kW) - class pressurized hybrid system incorporating SOFC and micro gas turbine (MGT) in March, 2013 and achieved 4,100 hours durability operation which was first time in the world. MHPS received an order from Kyushu University for a SOFC-MGT hybrid system in December 2014. Kyushu University plans to use the system for verification of an industrial-use power generation fuel cell system, with verification operation to begin in spring 2015. The idea that internal reforming of a SOFC hybrid system fueled by natural gas enables a simultaneous supply of electricity, heat and hydrogen to a low-carbon and hydrogen society is the main body of Quatrogen[○!R] concept. Local production of energy for local consumption using renewable energy by sewage plant in urban area is also introduced.

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Power fluctuation suppression can be achieved by the interconnection of distributed renewable generation in a wide area. In this way, renewable energy placed in appropriate proportions can reduce system instability and backup power source. However, there is a need to define which type of renewable energy generator to install and how much capacity is needed in each region. In this paper, a computer algorithm based on genetic algorithm (GA) to optimize the location, the type and capacity of the renewable generators, is developed. In order to validate the developed algorithm, the installation of wind farms and solar farms are considered in 7 cities and in 14 cities, respectively, in Hokkaido. Then, the optimal location, type and capacity of the generators are investigated for January, April and July. Results show that the introduction of a very high amount of renewable energy is possible through the whole year.

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In recent years, the increasing energy demands in the residential and commercial sector have resulted in increased carbon dioxide emissions (CO_2). In response, local authorities have proposed the compact city, a collection of business facilities such as a hospitals, hotels, offices and stores, with the intent to reduce energy consumption and improve the utilization efficiency of energy. Reducing energy consumption in business facilities is of critical importance, as urban areas continue the trend of concentration of people and services. In previous research, the evaluation of CO_2 emissions in the commercial sector was carried out using a combined system, composed of a micro-grid and district heating and cooling. The purpose of this research is to clarify the optimal combination of energy conversion technologies for each facility. A middle scale city in Japan that included 4 facilities (hospital, hotel, office, and store) was assumed, and 27 combinations of energy conversion technologies were evaluated. The objective function for optimization was installation and running costs. The combination of technologies was optimized to minimize the objective function. The optimization model was built using the GAMS/BARON solver. Comparing the results for each case, the optimal combinations were determined. The lowest the running costs for any facility type were achieved when photovoltaics, heat pump water heaters and turbo refrigerators were utilized.

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