We investigate the decomposition of phenol using a hybrid reactor that combines a pulsed electrohydraulic discharge plasma with ultrasound application to increase the efficiency of wastewater treatments. The discharge and grounded electrodes are a needle-type electrode and a perforated plate, respectively. Ultrasound is directly applied to the plasma reactor through water by using ultrasonic oscillators. Hybridization of the pulsed high-voltage discharge with ultrasound generates a continuous streamer discharge by cavitation bubbles. The phenol removal efficiency becomes higher than that corresponding to the sum of the efficiencies of the pulsed high-voltage discharge and ultrasonic applications.

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Hydrogen, CCUS, renewable energy & energy stock, and power electronics are expected as technologies that contribute to a large CO₂ reduction toward the realization of a carbon-free society. The results of the Delphi survey conducted by the National Institute of Science and Technology Policy also indicate the high importance of related science and technology topics. Hydrogen technology are highly evaluated for their importance and international competitiveness. CCUS technology is expected to take a relatively long time, from 2031 to 2039, for social realization. To continue long-term research and development, it is necessary to secure and develop human resources. Regarding renewable energy and stock energy, battery products are recognized as having an extremely high importance. Regarding power electronics, strengthening competitiveness as a total system is mentioned as an issue.

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In this study, a series of the sensitivity analysis of the human thermal load to the changes in wind speed and temperature was made at the points where the sunny and shade periods were switched. The effects of changes in skin temperature, core temperature, sweat rate, and heat budget on the human body were investigated. The thermal load on the human body decreased as the wind speed increased, and increased as the temperature increased. It was found that the instantaneous thermal load and total thermal load of human body change according to their order even if the sunny and shade durations are the same.

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Numerical analysis of heat balance of isolated trees under hot environment was conducted taking into account the detailed leaf orientation distribution. The net radiation was estimated by Ross radiative transfer model and the latent heat transfer was estimated by Jarvis model. Leaf temperature was as the heat balance including sensible heat transfer is satisfied. Analysis is performed to camphor tree in sunny day of August in Osaka. It is resulted that latent heat transfer is predominant compared with sensible heat transfer in day time and sensible heat transfer in night is negative due to the radiative cooling. In comparing with case of randomly oriented foliage or case of zenith aligned foliage, there was no significant difference.

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A simulation was conducted for the purpose of predicting the concentration of nitrogen oxides (NO_x) generated from pulverized coal combustion. In this research, simulations were carried out for each tube flow furnace and turbulent flow furnace and the obtained results are compared. The reactor network model of each furnace was also examined. We investigate the effects of Volatile N, which greatly contributes to the generation of NO. Although the peak NO concentration was largely reproducible, the actual NOx profile obtained during the initial and reduction stages during combustion did not match the simulated NO_x profile. It was found that the NO_x formation profile changed greatly depending on the composition of the reactor model. Most of the generated NO was found to originate from Volatile N. The future challenges in this study are further optimization of the reactor model and improvement of the rate constant of elementary reaction in the NO reduction stage.

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These years, air pollution caused by exhaust gas from automobiles has been problematic. So diesel engines have been paid attention from the viewpoints of thermal efficiency and low emissions of CO2. However, soot and nitrogen oxides contained in the exhaust gas of diesel engines have become a social problem. Therefore, we focused on the improvement of fuel itself. This time, We focused on emulsion fuel. In this study, we operated a diesel engine with W / O type emulsion fuels, and verified the effect of water droplet diameter profile in emulsion fuel on power characteristics and the exhaust gas composition of diesel engine. As a result, a trend was seen both power characteristics and exhaust gas components as the water droplet diameter profile is broadened.

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The two kinds of vessels with small or medium size were fabricated to make an experiment for heat saving. The effect of thermal insulation materials (method) and kinds of heat storage materials on the behaviors of heat saving (temperature change) were investigated in detail. These experimental data was analyzed in comparison with FEM simulation on heat conduction. The vacuum insulation system with porous silica powder suits the cold storage (ice, 0℃). In case of hot storage (80~300℃), the vacuum insulation system needs porous silica powder with the addition of carbon power to suppress radiation heat conduction. The FEM simulation can represent roughly the experimental date, but further investigation is needed to design large scale equipment for practical application.

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Thermosiphon utilizing vapor bubble pumping, which can realize the heat transfer from the upper part to the lower part without the utility power source, has been studied intensively. However, some problems have been left for the practical use. One of the problems is unstable heat transfer, that is, intermittent circulation flow rate of working fluid, which happens in the condition of small solar radiation in morning and evening. This phenomenon, which causes equipment failure, was investigated by the field experiment using model house. Hence, a thermosiphon control system to realize the stable heat transfer, namely almost constant flow rate of working fluid is proposed. This is achieved by means of reducing the pressure of working fluid to lower the boiling point. In this report, the feasibility of the proposed control method is confirmed by the model experiment in the field. The experimental result demonstrates that almost constant flow rate of working fluid can be realized by reducing the pressure to lower the boiling point.

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The demand for cooling has increased in the world, which causes increase in electric power consumption. The reduction of carbon dioxide emissions caused by the generation of electricity is important to inhibit global warming. As a solution, we can use ejector refrigeration cycles driven by thermal energy such as solar energy and exhaust heat. This report aims to evaluate ejector refrigeration cycles by using exergetic efficiency. Two evaluation methods by using exergetic efficiency are applied. The first one is that exergetic efficiency of the system, which is not included heat exchanger part, is calculated under constant temperatures at a generator, an evaporator and the environment for comparing other performances reported so far. The second one considers the temperature change of external fluids in the heat-exchangers in a generator and an evaporator for analyzing the details in the system. The experiments with R-245fa were conducted in the low generating temperature range from 60°C to 72°C. We can operate the ejector refrigeration cycle in the lower generating temperature range compared with the other reports. The operations at the lower-temperature heat sources indicate the possibility of utilization of solar heat and exhaust heat of air-compressors in the industrial fields. The exergetic efficiency is lower than that of the other reports using the higher generating temperature because the technology for using smaller exergy of lower-temperature heat source becomes difficult. Another exergy in the case of changing the temperature of working fluids in the process of heat transfer becomes about a half of the exergy of constant-temperature calculation.

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In this study, numerical simulation on vapor flow in the absorber in an absorption heat pump have been performed in order to investigate the behavior of non-absorbable gas and its effect on absorption phenomena. Various factors affect the behavior of non-absorbable gas, such as heat and mass transfer due to vapor absorption and flowing down of the absorption solution. We clarify the dominant factors for the distribution of non-absorbable gas by decomposing the factors that affect the distribution of non-absorbable gas and understanding the individual effects. In this study, we focused on effect of behavior of vapor absorption in absorption solution. In particular, the difference in the distribution of non-absorbable gas due to changes in difference depending on the inflow direction of steam was investigated. As a result, it was found that a large amount of non-condensed gas stays on the downstream side.

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In recent years, demand response has been emphasized due to the introduction of renewable energy with unstable power supply. Liquid desiccant systems have a heat storage effect, so it may be suitable for demand response, but it has not been studied. Therefore, in this research, we focused on using liquid desiccant systems as a power supply and demand adjusting regulator. We evaluated the unsteady behavior of this system by numerical simulation when it is used as a power supply and demand adjusting regulator. We created a mathematical model consisting of a gas-liquid contactor, a solution tank, and a room, and investigate the duration of power control without compromising comfort. As a result, it was clarified that a duration of about 30 minutes can be obtained by enlarging the solution tank and increasing the solution circulation amount appropriately. It was shown that the liquid desiccant air-conditioning system can be sufficiently used as a power supply and demand regulator.

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Producing activated carbon (AC) with favorable properties using conventional physical activation from local biomass and understanding its water vapor adsorption behavior is essential to find renewable and low-cost material for dehumidification application. In this study, AC was prepared from Japanese Acorn Nutshell (JAN) under different preparation conditions. The prepared activated carbons were used to adsorb water vapor under diverse humidity range. The experimental results showed that Japanese Acorn Nutshell is suitable to be used as a precursor of activated carbon. The activated carbons produced in this study have the surface area up to 864 m²/g. On the other hand, water vapor adsorption isotherms on all prepared materials are following type V with steep uptake between P/Po of 0.4 to 0.6. From the water sorption isotherm data, the prepared activated carbon shows a promising ability to be used as a desiccant material.

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The study aims at producing activated carbons from low-cost materials, such as agricultural and botanical waste, without using expensive chemicals. The activated carbons produced by low-cost methods would enhance the possibility of installing desiccant dehumidification in developing countries in hot and humid regions. In this paper, we report dehumidification capacity of activated carbons prepared from Japanese Acorn Nutshell under different preparation conditions based on the water adsorption isotherms. Firstly, the adsorption isotherm equations were generated based on the measured data. Then, the dehumidification capacity was predicted under several ambient air conditions.

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Since the Great East Japan Earthquake, Japan's energy problems have becoming a social problem that deeply affected people's living and businesses due to damage to nuclear power plants. Securing core energy, such as nuclear power generation and thermal power generation and reconstruction of the living energy for the local area is desirable. For one of the methods to secure living energy, an TES (thermal energy storage) system which using air as HTF (heat transfer fluid) and stone as the storage material have been developed. By constructing a stone heat storage system, it gives a possibility of securing the basic living energy of disaster area residents. In this study, the influencing factors of TES, which affect the thermal stratification, related to the performance of a stone heat storage tank, such as the porosity and mass flow rate, were investigated.

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With the on-going heightened issues on climate change, there is a global objective and shared responsibility to significantly reduce the CO₂ emissions. Based on 2013 CO₂ emissions, Japan is targeting a reduction by 26.0% in 2030 and by 80% in 2050. The proportion of solar energy in primary energy supply volume is expected to increase. Furthermore, because of the fall of electric power selling price, the use of surplus energy obtained by solar power generation is changing from selling to self-consumption. From these considerations, the solar energy systems are on the turning point. Therefore, there is a need to optimize the solar energy utilization systems from the point of view of CO₂ emissions and costs. In this paper, we constructed a simulator by creating mathematical models they are experimentally validated. This can analyze the CO₂ emissions and costs of various solar energy utilization systems constituted of PV panel, solar collector, heat pump water heater, and storage battery. By using this simulator, we compared the annual performance of introducing various solar energy utilization systems for a certain residential household in Japan.

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In the authors’ previous reports, a new wind energy harvesting method using flexible piezoelectric films bonded on the surface of a flexible cylinder, termed as Piezoelectric Cylindrical Shell-type Wind Energy Harvesting Flag (PCSWEHF) was proposed. In order to overcome the low power generation of the piezoelectric wind energy harvesting method at small wind speeds, vortex-induced vibrations (VIVs) of the flexible cylinder excited by the Karman vortex generated downstream of PCSWEHFs was used and it was shown in the preliminary experiment that more than ten times larger power was generated by PCSWEHFs compared with the conventional planar-type piezoelectric energy harvesting flags. When applications of these energy harvesting flag are considered, more detailed structural designs are needed. However, the effects of structural parameters on the electric generating performances of the proposed wind energy harvesting flag were still unknown. In this study, several PCSWEHFs with different structural parameters, especially radius and thicknesses were considered, and by comparing their natural frequencies and vortex induced frequencies, the method to construct superior PCSWEHFs which could generate large power at a specific wind speed was investigated.

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Recently, the interest in environmental problem increases cause the attention of the ice thermal storage systems. Ice slurry, which consists of water and fine ice can be used for this system because it has high fluidity and cooling efficiency. However, the ice slurry has the problems that ice particles gradually cohere with each other with passage of storage time. The Cohesion is caused by buoyancy and gravity and it reduce the efficiency of cold utilization. Therefore, to clarify the factor of cohesion is an important issue. We have clarified the cohesion of ice particles in low IPF ice slurry focusing on the cohesive force and porosity. In this paper, we added silane coupling agent or nonionic surfactant in an ice slurry, and we clarified the effect of each addictive by measuring the cohesive force of ice particles at each storage time.

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Ice adhesion to a cooling solid surface often causes the serious problems. So, it is important to unravel a mechanism of ice adhesion and prevent it. In past studies, ice adhesion force have been measured in a macro-scale. However, in the case of the metal plate, ice was broken and measured force included the force to breaking ice due to roughness of the metal surface. it was impossible to measure accurately because of breaking the ice. On the other hand, one of authors were developed the measurement method in a nano-scale by Scanning Probe Microscope （SPM） without breaking the ice. In this study, ice adhesion force to copper test plate was measured in a nano-scale using described above. From measurement results of view, oxidation characteristic of the copper test plate was investigated. Exposed the copper surface in the atmosphere and measuring ice adhesion force at various oxidation times, Relationship the oxide layer on the copper surface and ice adhesion force was clarified.

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