In the present study, we conducted a fog harvesting experiment using a unit which composed by 3 wires. Enhanced fog harvesting performance was seen with the unit contained hydrophobic wires at upstream side and superhydrophilic wire at downstream side. Directional droplet transportation from upstream to downstream side with the help of fog stream and a wettability difference of wires prevents to decrease the cross sectional area which can collide with fog particles. In addition, the effect of wire arrangement on the harvesting performance was experimentally investigated. Distance between two wires was important because it affected to the occurrence of droplet transportation.

There is narrow space called a crevice in engines. In the narrow space, if wall surfaces are close enough to the flame, the flame is extinguished due to heat loss to the wall surfaces, causing the emission of unburned hydrocarbons. Therefore, it is important to investigate the flame penetration behavior into narrow space in order to improve the thermal efficiency of engine. This study investigated the penetration of a propane/air premixed flame into a narrow space with flow at high temperature and high pressures using a diverging channel combustor.

Phonon transmission across a solid–vacuum–solid nanogap can be induced by thermal resonance owing to the quasi-Casimir coupling between interfacial solid layers. However, the thermal energy transport across the nanogap with the existence of adsorbed liquid layers on solid surfaces is still not well understood. Here, the thermal resonances between adsorbed liquid layers were investigated using the classical non-equilibrium molecular dynamics simulations. The existence of thermal resonance between the solid–solid or liquid–liquid interfacial layers separated by the vacuum nanogap was verified through the analyses of the atomic vibrational displacements and the vibrational density of states.

Phonon heat transfer across a vacuum nanogap can be induced by quasi-Casimir coupling without electromagnetic fields. For the thermal energy transport of diatomic molecules, the contribution of the atomic surface termination to the phonon heat transfer across a solid–vacuum–solid nanogap is still not well understood. Here, we investigated the thermal energy transport across a SiC–SiC nanogap with four kinds of atomic surface terminations using classical non-equilibrium molecular dynamics simulations. The thermal resonance between interfacial layers of identical atomic termination results in significant heat transfer enhancement across the SiC–SiC nanogap, while that of non-identical atomic termination is unnoticeable.

In order to improve the efficiency of internal combustion engines, it is necessary not only to improve combustion technologies but also to improve fuel technologies. The purpose of this study is to elucidate the effect of nitromethane addition to the isooctane / air mixture on the combustion characteristics under a high temperature and high pressure environment. Therefore, in addition to the experimental measurement of the laminar flame speed, this research developed the reaction mechanism of nitromethane / isooctane / air mixture and conducted numerical calculation to investigate the factors that affect the laminar flame speed. (95words)

Ion probes have a high level of flexibility in their installation on the engine and require minimal engine modifications, thus minimizing the influence of the measurement on engine performance. In the present study, taking advantage of these characteristics of ion probe measurement, 12 ion probes were installed in an air-cooled, single-cylinder, two-stroke gasoline engine with a displacement of 58 cc, and the propagating flame in the engine was measured. The cycle variation of the test engine was investigated in detail by reconstructing the shape of flame front based on the flame detection signal obtained from the ion probe.

We conducted experiments to investigate the synergetic effects of the channel size and liquid properties on capillary-driven flow in open rectangular microchannels. Pure water, 20 wt% glycerol solution and 20 wt% ethanol solution were used as the working fluids in the Si superhydrophilic microchannels. We found that a larger ratio of surface tension to viscosity of the working fluid results in a greater imbibition rate. The optimal channel size was obtained when the aspect ratio of channel width to height was 2, in spite of the discrepancy in the working fluids. The experimental results were consistent with the theoretical model proposed in this work.

Increasing the capillary limit is essential to improve the heat transfer performance of heat pipes. In this study, we theoretically estimated the driving force of capillary permeation in an open rectangular microchannel with temperature difference along the flow direction. The theoretical prediction enables the channel optimization for increasing the maximum heat transfer rate of heat pipe. Experimentally, there kinds of microchannels with same channel width but different channel heights were fabricated on Si substrate for the micro heat pipe. The micro heat pipe with channel optimization demonstrated the better heat transfer performance than those of the others and thus verified the theoretical prediction.

The authors have developed a Bio-calorimeter with nano-watt level resolution with a MEMS thermopile sensor. Important factors of the development are a highly sensitive heat sensor, a stable amplifier system of minute sensor signal and stable temperature control of the isothermal bath. In this study, we improved the stability of the isothermal bath in one milli-Kelvin level by using a current control type Peltier drive circuit. Compensation heating type differential calorimeter was also introduced to improve quantitativeness in calorimetry. A prototype calorimetry was tested in thermometry in a yeast growth process and a germination process of a single seed.

The processing performance of smart devices such as smartphones is improving, and the power density is increasing. In addition, smart devices cannot use an active thermal management such as water or air cooling. Therefore, a passive thermal management technology attracts attention. Thermal management technology using phase change materials (PCM) is one of the passive thermal management technologies, and level the temperature fluctuation of electronic chip by the latent heat associated with the phase change. This thermal management technology has the advantage that it can be miniaturized and does not require additional power. In this study, we focus on the thermal management technology using solid-solid PCM, which does not change to the liquid phase, and clarify the relationship between the thermophysical properties and the optimum thickness of the PCM.

When a fuel cell is used in an environment below the freezing point, there is a problem that the generated water freezes and blocks the flow path that connects the bipolar plate and the manifold. In this study, we clarified the conditions under which water freezes and blocks the flow path in nitrogen-water two-phase flow in a microchannel in which a part of the wall surfaces was cooled below the freezing point. We tested two channels with a flat cross section of 1.2mm × 0.3mm and a square cross section of 0.6mm × 0.6mm, and measured the wall temperature at which the flow path was blocked due to freezing of water under the hydrophilic and hydrophobic wall-surface treatments. It was found that the heat transfer coefficients of the square channel were slightly higher than those of the flat channel under both wall-surface treatments.

Influence of fiber structure on flame extinction of cellulose materials has been investigated varying oxygen concentration. Filter paper and Washi (Japanese paper) were used as the samples with fiber structure, whereas bacterial cellulose was used as the sample without fiber structure. Thermogravimetric analysis reveals that char production in pyrolysis in an air atmosphere is suppressed when the sample has fiber structure. The limiting oxygen concentration and burning rate were obtained by downward flame spread experiments. The limiting oxygen concentration for the sample with fiber structure is lower than the sample without fiber structure. On the other hand, it is implied that the dependency of flame spread rate on fiber structure is weak.

In this paper, a methodology, to identify parameters of Cauer thermal network which represents heat transfer path and power ratio of the microprocessor, is explored, targeting an embedded computing motherboard. Seven parameters are optimized from transient power curve of whole motherboard and transient junction temperature of the microprocessor, by utilizing Bayesian optimization technique. Predicted junction temperature obtained by created model matches well with measurement result.

Robot systems capable of experiencing remote environments are urgently required for future lack of manpower and aging society. In this study, the development of the tele-existence robot arm in which human beings can experience not only the haptic environment but also the thermal environment was focused on. In this report, the temperature transmission system was actually developed and the trial operations were conducted. In the operations, a remote finger-tip-like temperature measuring unit touching a moderately (50degC)-heated test block (aluminum or PMMA) transmitted a PWM signal of a temperature variation to an on-site wearable unit. Consequently, the reproduction of the remote temperature sensing data was succeeded by controlled heating based on the transmitted information in the wearable unit. In this paper, the reproducibility was indicated by the result of the temperature variation of the temperature measurement unit of the on-site finger probe in the wearable unit.

Nanopores on two-dimensional (2D) materials have recently attracted growing interest in biosensing due to the atomic thickness, close to the gap between nucleotides. Consequently, they have become a suitable candidate to improve molecule sensing resolution, having huge potential to characterize the structure of DNA molecules for precision medicine and DNA vaccine development. To acquire precise genetic information from DNA molecules, getting precise ionic current in nanopore is essential. The ionic current of nanopore is related to the conductance of the electrolyte, geometrical features of nanopore, and the external applied bias. On the other hand, decreasing the size of nanopore can slow down migration speed of DNA and thus enhancing temporal resolution of DNA sequencing. Albeit the merits of small nanopore, ion transport through nanopores on 2D materials is poorly understood so far due to challenging fabrication processes, especially as the pore diameters are comparable to the single stranded DNA size. Therefore, the objectives of this work are to (i) experimentally investigate ionic current behavior in sub-10 nm pores on monolayer molybdenum disulfide (MoS2) and (ii) improve the understanding of ionic current blockage variation due to DNA translocation through nanopores. On this account, the contributions of the bulk conductance, surface conductance, being the current from the electric double layer, and entrance effects will be examined.

The output power density of microfabricated thermoelectric generators (μTEGs) based on solid materials is insufficient near room temperature. Adopting an electrochemical nanopore system, we theoretically demonstrate the possibility to achieve a higher power density by improving the ionic selectivity. When a temperature difference (△T) of 30 K across a two-dimensional material membrane having a pore diameter of 1 nm, separating two reservoirs filled with a 0.1 mM aqueous KCl solution, is imposed, a power density of ca. 10³ W/m2/K is estimated. The constructed theoretical model includes thermogalvanic effects from the electrodes arising from △T. The theoretical predictions provide important information for the design of energy retrieving systems used in internet of things (IoT).

We performed transient film boiling experiments of water under the atmospheric pressure on vertical cylinders with various bottom shapes. We photographed the aspect of the vapor film near the film boiling lower limit point using a high speed video camera, and detected the image feature points. We analysed the observed images with the time, place, number of the feature points, and the vapor film collapsing rate. And in order to examine the start time of the vapor film collapse in line with the boiling characteristics, we newly classified the images into several boiling phases according to the boiling curve.

The eVTOL is a battery-powered vehicle that travels through the air. According to the road map "Flying Vehicles" proposed by METI. A specific eVTOL vehicle for short-distance two-point transportation, which can be considered close to practical applications such as emergency transportation and commuting to work and school, was modeled and discussed in this research. Since its purpose is to transport passengers, it requires an air condition system to maintain cabin comfort, but the evaluation of air conditioning performance of the eVTOL differs from that of land vehicles due to its characteristics of airborne transportation. In this study, we proposed and discussed a numerical air condition evaluation method, including the heat balance method for eVTOL vehicles. The result shows that the optimal method can effectively evaluate the HVAC system performance for eVTOL.

Even if we use conventional aerial firefighting methods, it is not easy to extinguish huge-forest fires. In this paper, we have proposed a new extinguishing method using gel balls containing high-viscosity fluid, which acts as an extinguishing agent, and attempted to fabricate physically cross-linked gel particles of sodium alginate in which xanthan gum aqueous solution is retained. Then, in order to examine the basic properties of the gel particles in high-temperature atmosphere, we observed the temporal changes in shape and mass of the gel particles on a high-temperature wall. As a result, it was confirmed that the gel particles contained more than 96% water and can supply water vapor over a long period of time.

Vertical serpentine channels have complex heat transfer and flow characteristics due to the repetitions of upward and downward flow. In order to gain an understanding of a critical heat flux in vertical serpentine channel, heat transfer experiments were conducted. The serpentine channel was consisted of five straight uniformly heated tubes and four non-heated U-bend. The working fluid, water, flows as upward flow in the first, third and fifth heated tube, while flows as downward flow in the second and fourth heated tube. As a result, two types of critical heat fluxes were obtained, i.e., a liquid film dryout in steady state flow and a periodically dryout in oscillatory flow.

In this study, we conducted the bursting experiments of a rubber balloon filled with water or a thermo-reversible gel solution (thermo-gel solution) to widely disperse these filling contents in space. The rubber membrane ruptured due to a small-scale explosion produced by an electric fuse for fireworks or needle piercing. The maximum dispersal distance of the solution blown off from the bursting balloon was measured. The maximum distance for the explosion was found to be larger than one for the balloon burst with a needle. The distance was also varied depending on the viscosity of the solution.

The partial wetting at nano/microstructured surfaces can be described using the intermediate wetting state between the Cassie-Baxter and Wenzel state. However, the limitation of partial wetting model is still unclear. In this study, surface free energy analysis at the microstructured Si-water interface was performed from both theoretical and experimental aspects to verify the partial wetting model. The effective wetting area was estimated by electrochemical impedance spectroscopy method for the further analysis of the surface free energy experimentally. The partial wetting model was verified at the fabricated microstructured surfaces with its geometrical parameters smaller than 400 μm.

Measurements of evaporation rate and temperature drop are simultaneously carried out while a sessile droplet evaporates on a PET film. Evaporation of inkjet droplets is a complex phenomenon involving airflow, temperature and vapour diffusion. As the evaporation of droplets is dominated by vapour diffusion and the saturated vapour concentration at the droplet surface depends on the droplet surface temperature, it is important to understand the surface temperature drop due to evaporation. The relationship between droplet size, evaporation rate and surface temperature drop is discussed through experiments and numerical calculations.

In this paper, I calculated one - dimension shock tube problem by continuous mechanics and molecular dynamics. Then I tried to explain why the difference occur between them, and considered on thermal conduction and definition of temperature in nano scale phenomenon. I suppose only Newton’s low and Fourier’s low at continuous mechanics. Compared to molecular dynamics simulation, I was forced to modify conventional analysis of thermal conduction and definition of temperature in nano scale phenomenon. In nano scale phenomenon, we must think temperature at one point not as continuous scalar but as discrete tensor.