It is known that shot peening (SP) of the electrolyte surface in contact with the negative electrode of a metal anode all-solid-state battery improves the battery performance. The degree of improvement depends on the abrasive grain size. However, the details of the flow fields in the solid and gas phases of the SP process and the mechanism of performance change with abrasive grain size have not been clarified. In this study, we conducted a solid-gas two-phase flow numerical simulation of the SP process to elucidate the characteristics of the flow field and to examine the effect of changes in abrasive grain size. As a result, it was clarified that the gas phase is a transonic flow with a shock wave, the solid phase does not follow the gas phase, and the force product given by the collision increases with the grain size.

Although many studies have been performed on the bubble release frequency and bubble diameter in subcooled flow boiling, sufficiently accurate prediction methods have not yet been established for these fundamental parameters. In this study, bubble nucleation process was visualized using the high-speed camera and the IR camera to measure the bubble release frequency and the bubble size in subcooled flow boiling. It was confirmed that the bubble release frequency at each nucleation site tends to decrease with an increase in the bubble size. Furthermore, it was found that the bubble release frequency is lower for the nucleation sites where the wall temperature drops due to bubble nucleation at a neighboring nucleation site. Based on the present finding, a new prediction strategy was proposed to incorporate the effect of the interaction between the neighboring nucleation sites in estimating the bubble release frequency in subcooled flow boiling.

This paper numerically investigates the mechanism of effective heat insulation characteristics on five fundamental models. The numerical model with two chambers cold and hot is divided by airflows, which have constant temperature 30 ℃ with flow velocities, 0, 2.5, 5, and 10 m/s to evaluate heat insulation performance. Two-dimensional simulation was conducted to obtain heat transmission coefficients playing a crucial role in evaluating heat insulations. As a result, it is found that heat transmission coefficients decrease in proportion to velocity of airflows and that the air curtain system is promising to enhance the heat insulation performance.

A forced air convection is applied to some stationary battery systems for heat dissipation from battery modules installed densely in the board (1). Thermal Circuit Model(TCM) allows us to calculate battery cell temperatures in the battery module with a battery electrical equivalent circuit model (2). In this study, heat transfer coefficients of TCM are calculated experimentally with a battery module in a narrow squared wind tunnel. The heat transfer coefficients are implemented to a proposed TCM model. At result, a maximum error between experimental data and proposed model is 4.6 [K] which is corresponding to 5.4 % for a battery cell operating temperature range.

According to the NEDO road map 2017, the high temperature condition over 90 °C is the target operation temperatures of PEFC systems for stationary and vehicle application from 2020 to 2025. Power generation experiments were conducted for a single cell of PEFC at 80 °C, 90 °C, and 100 °C using three different thicknesses of separator. The flow rate/relative humidity of inflow gas was varied. The temperature distribution on the separator back at anode and cathode was measured by a thermograph. The water rate difference between the outlet and the inlet at the anode and the cathode was also measured using a dew point meter. As a result, under the low relative humidity condition at cathode, the amount of electro-osmosis water was larger than that of back diffusion water, resulting in the water transfer from the anode to the cathode. In case of the separator thickness of 2.0 mm, it is confirmed that the temperature rises at the positions I and Q which are the corners of separator. The vapor remains at the positions I and Q and the concentration of vapor increases, resulting that it is condensed generating the heat. In addition, it is confirmed that the temperature decreases at the position L and near the outlet. The liquid water produced at the positions I and Q moves to the position L and near the outlet, which causes the gas diffusion inhibition, resulting in the temperature drop.

In this research, we have developed a heat balance model considering a vapor transfer in components consisting of a single cell of PEFC, and calculated the temperature distribution on the interface between PEM and catalyst layer at cathode (reaction surface) using this model. The flow rate, relative humidity of inflow gas, the relative humidity of surrounding air, and the thickness of PEM and separator were varied under high temperature operation conditions of 100 °C to evaluate the effect of them on the distribution of the reaction surface temperature (T_reat). The impact of flow rate of inflow gas and the relative humidity of surronding air on distribution of T_reat is little. The impact of thickness of PEM on distribution of T_reat in case of Nafion 115 is the largest among the investigated conditions. In addition, the impact of thickness of separator on distribution of T_reat in case of the separator thickness of 2.0 mm (Sep: 0.5 mm, Chan: 1.0 mm) is the largest among the investigated conditions. It is revealed that the power generation perfromance is improved with the decrease in the standard deviaton of distribution of T_reat.

The authors have been studying a technique for separating hydrogen from a gas mixture utilizing a thermal diffusion phenomenon called the Soret effect. The Soret effect is a separation phenomenon driven by temperature differences, and the authors aim to extract hydrogen from gas mixtures utilizing the phenomenon. The authors succeeded in reproducing the trend of hydrogen separation experiments using numerical thermo-fluid analysis, and predicted the separation performance with high accuracy. In the present paper, the results of a device structure that can provide a more effective temperature difference are reported with thermo-fluid analysis, which show a significant separation improvement.

In recent years, the heat generation density of electronic components has increased as electronic devices have become smaller and more powerful. Various types of heat pipes have been used as thermal control devices. PHP is a heat transport device that has a structure in which one flow path is arranged in a bellows shape between the heating and cooling part. However, there is a problem that pulsating vibration and heat transport in the flow path are not stable. In this experiment, it was clarified that the heat transfer was extremely efficient compared to the conventional PHPs. And the effect of heat exchange section ratio on heat transport performance was investigated.

Natural convection heat transfer from the horizontal heated disk with the cylindrical tube with the gap was investigated experimentally. To estimate the heat transfer, the temperatures of the surfaces were measured using thermocouples. The flow fields around the horizontal heated disk and the cylinders with the gaps were visualized using a particle image velocimetry system. The heat transfer was enhanced by increasing the gap width and decreasing the height of the lower cylinder. This is because the flow velocity near the side of the upper cylinder increased. Under conditions where the overall height was constant, the gap had an appropriate value for the width and the position.

The objective of this study is to improve the accuracy of numerical model by measuring the temperature and evaporation rate of the liquid film in order to investigate the water transport inside the liquid film during the coating and drying process. Polyvinyl alcohol solution was used as the test solution in the experiments. In previous experiments, the authors used a thin liquid film with a thickness of 0.2 mm, which is close to that of actual technology. However, it was difficult to measure the surface temperature in such a small thickness. Therefore, the authors measured that internal of a 5 mm-thick liquid film, and compared the results with a numerical model.

In recent years, the heat generation density of electronic devices has been rapidly increasing due to the miniaturization and the higher performance. Nucleate boiling heat transfer with a high heat transfer coefficient is an effective solution to this problem. It is also known that nucleate boiling heat transfer can be further improved by applying microstructure to the heat transfer surface. In this study, subcooled flow boiling experiment was conducted by applying microstructures directly to the surface of copper, which is suitable for practical use. A comparison of the heat transfer enhancement of microstructured surfaces with smooth surfaces is reported.

Recent years, with the development of medical methods utilizing genes and cells, the requirement for low-temperature transportation (cold chain) has increased. Also, to transport the corona vaccine, a low temperature environment up to -80 ℃ is demanded. In this study, a cooling system has been developed based on Peltier modules instead of the traditional compressor to obtain an environmentally friendly ultra-low temperature environment. In cooling experiments, the cooling mode of the heat sink and other factors has been changed to accumulate a variety data of tests. As the results of the experimentations, in the case of water cooling, it was confirmed that the minimum temperature of the surface of the cooling device could reach -38° C..

BDF (Bio-diesel Fuel) is expected to be an alternative fuel to diesel oil through methyl esterification. Therefore, the objective of this study is to propose a microwave irradiation method for synthesizing BDF based on the solid catalysts such as eggshells and clam shells, by which BDF aftertreatment is not needed and water can be saved. In the experiment, firstly, eggshells and clam shells were processed to solid catalysts and characterized by SEM and X-ray Diffractometer. Secondly, BDF was synthesized by microwave irradiation and BDF yield ratios under several experimental conditions were quantitatively analysed by GCMS. As a result, it was found that BDF yield ratio under microwaves radiation could reached 99.58%.

Heat transport characteristics of three-dimensional pulsating heat pipe (3D-PHP) have been investigated experimentally. The 3D-PHP consists of 20 tubes and heating block made of copper. The 3D-PHP has 2 layers of 5 turn flow paths (10 tubes) and the layers are interconnected. Fluorinert FC-72 was used as the working fluid and filling ratio was 50 % of the channel volume. The 3D-PHP was tested for various air velocity and heat load. Heat load increased by 10 W to 100 W and decreased by 100 W to 10 W. It was found that thermal resistance in the case of decreased heat load was lower than that in the case of increased heat load for the same heat load.

The purpose of this research is to enhance heat transfer of subcooled boiling flows in a horizontal narrow channel by using grooved and thermal spray coated surface. The V-grooves with an opening of 0.5 mm was fabricated perpendicular to the flow direction in order to supply liquid from the side walls to the middle of the channel by capillary force. Then, thermal spray coating was formed on the V-grooved surface to increase nucleation sites density. The results on heat transfer coefficient (HTC) for these surfaces were compared with those on the smooth surface. It was found that the HTC of the V-grooved surface with thermal spray coating could be drastically enhanced by the synergy effect of the V-groove and thermal spray coating.

The near-infrared region of the aqueous acid-base reaction of formed salts (NaBr, KBr, KCl, and NaCl) by neutralization between 1400-1500 nm (OH band) at microchannels was modeled experimentally and numerically. In this study, aqueous acids (HCl and HBr) and bases (NaOH and KOH) of the same molarity were injected simultaneously in a y-shaped microfluidic channel with a constant flow rate of 0.1mm/s. The neutralization reaction of the aqueous acid-base through the NIR imaging experiment was validated by numerical simulations. The measured near-infrared data of NIR imaging absorbances and wavelengths were used for regression analysis of concentration prediction. Wavelength selection techniques were implemented to reduce experimental data of near-infrared captured absorbance images. The predicted ionic salt concentration by regression and numerical simulation of each chemical reaction shows the effects of acid-base concentration and specific ions on salt generation. The constructed models of both experimental and numerical results were applied for the study of the reaction-diffusion process of acid-base reactions inside microfluidic channels.

Effects of Stephen number, Lewis number and buoyancy ratio on the melting of a solid in a two-dimensional channel are investigated by dimensionless numerical analysis. Specifically, the temperature distributions, the solvent concentration distributions, the velocity vectors and the time to complete melting are examined in this paper. Decrease ice temperature become small in the case of higher Lewis number and Stephen number. Solvent concentration near the solid become low in the case of higher Lewis number, however solvent concentration near the solid become high in the case of higher Stephen number. Roughly feature of velocity vectors is common in all cases, however upward flow become strong in the case of higher buoyancy ratio. Melting rate become small in the case of higher Lewis number, however melting rate become large in the case of higher Stephen number.

Heat generation of computer chips for autonomous driving level 4 and 5 will be much higher than the current market level. In order to solve this cooling issue, we have developed an immersion boiling cooling system working under atmospheric pressure. This system enables high cooling performance by mounting a boiling plate on the heating chips. Moreover, the atmospheric pressure system realizes easy installation in the vehicle and cost reduction. In order to improve the cooling performance, a method to quantify the nucleation site by visualization was developed. Using this method, the number of nucleation site and the thermal conductance were found to be approximately proportional.

In recent years, in order to achieve carbon neutrality, automobile manufacturers have been focusing on the development of electric vehicles and pursuing higher power density of in-vehicle inverters. The use of the next generation power semiconductor is indispensable to increase the power density, which increases the heat generation density of the cooling surface. This study focuses on subcooled flow boiling with high cooling performance. In this paper, the two-phase flow behavior in a narrow channel with fine fin structure is discussed first, and then the heat transfer performance is evaluated using a SiC module.

In the case of incinerators in which general waste is incinerated manually, there is concern that the inner walls of the incinerator may be damaged due to differences in the control of combustion temperature depending on differences in operating techniques of operators. Therefore, the feasibility of combustion behavior evaluation by numerical simulation was investigated with the aim of minimizing the influence of operation techniques between operators and realizing more stable operation. This study qualitatively clarified the effect of fuel supply quantity on the combustion behavior in the incinerator.

The authors group focused on the adsorption of nonionic surfactant molecules to the interface and examined the activity control of the supercooling degree. It was clarified that the supercooling degree could be actively controlled by the change of the surfactant concentration. In this study, the pH of surfactant-pure water mixture (surfactant mixture) was fixed for the purpose of the improvement in the controllability of the supercooling degree, and the experiment was carried out under the voltage application condition in the condition that the amphoteric surfactant used showed the cationic property. In addition, the characteristics of the supercooling degree in the case of using an amphoteric surfactant exhibiting cationic property under the voltage application condition were clarified by comparing with the results in the case of no voltage application.

Superheated vapor is used in several industrial fields including sterilization, desiccation, and dehydrogenating. MCH (methylcyclohexane) has been vastly utilized as hydrogen carrier under several advantages. Superheated vaporization is necessary for catalytically dehydrogenating MCH. Current superheated vapor generation methods including high-frequency induction heating and microwave heating are difficult to obtain rapid generation and shutdown responses due to the large heat capacity of the fluid in the tank and the heater. For the realization of a carbon-free society and a hydrogen-based society, we proposed a method to generate superheated vapor using porous material with rapid response and high efficiency. Vapor may be generated rapidly from the surface of porous material due to small heat capacity of liquid in the meniscus. The main objective of the present research was to experimentally investigate the performance of the vapor generator using different working fluid with different property. As a result, fluid with low latent heat had better performance in generating superheated vapor rapidly and efficiently. Considering both heat conduction and fluid advection in porous material, the energy utilization efficiency and surface temperature were analyzed by a simplified one-dimensional model. The calculated results were shown to be in good agreement with the experimental results. The proposed vapor generator is suitable for superheated vaporization in MCH method from the analysis of the model.

In this report, we focused on pigments and polymers, which are considered to have an influence on drying speed among ink components, and quantitatively evaluated their effects. As an experiment, we measured the drying process of ink liquid film by forced convection using a petri dish and an actual inkjet printer printing machine as a model. We investigated the relationship between the evaporation rate by changing the molecular weight and the amount of polymer added, and attempted to elucidate the mechanism of the influence of pigments and polymers on the late drying process in terms of heat and mass transfer by making integrated observations based on viscosity coefficient, temperature measurement, and visualized images.

A deeper understanding of the combustion characteristics of ammonia, a carbon-free fuel of which use is expected to increase, is needed from the viewpoint of fire prevention. In the present research, as fundamental research on diffusion flame of methane-ammonia blended fuel, the flame structure was investigated from the luminance distribution of chemiluminescence from methane and ammonia in a diffusion microflame of methane-ammonia blended fuel. As a result, it was observed that the luminescence peak from ammonia was closer to the fuel side than that from methane and that both methane and ammonia peaks moved to the air side as the flow rate of ammonia addition increased. The flames with ammonia addition tended to be lifted and blow off at a lower flow rate than those with nitrogen addition.

This paper describes the experimental results of Carnot battery system using a thermoelectric module (TEM), which has no moving parts, and is compact. Experiments were conducted on its charge-discharge characteristics. In the charging mode, TEM was driven as a heat pump to convert electricity into heat and heat was stored in a metal block coupled to TEM. In the discharging mode, electricity is generated from the temperature difference between the metal block and the heat sink. The amount of generated electricity was measured at a constant load resistance. The experimental system has worked as a Carnot battery; however, the cycle efficiency was below 1% due to heat losses and other factors.

In the present study, a simple system of three spherical heat storage bodies made of silicon carbide or alumina in a straight line in a duct was analyzed numerically considering radiation and compared with experimental results. The results of the analysis showed that there was an effect of radiation from the heated air inlet on the temperature rise of the heat storage body in the experiment. The low emissivity of the duct's inner wall and then the reflection of the radiation had the effect of heating the heat storage body far from the inlet by radiation heat transfer. In addition, the effect of radiation was more substantial farther from the inlet for the silicon carbide heat storage body, which has a higher emissivity and a lower heat capacity than that of the alumina heat storage body.

We have developed a thermofluid scanner that enables us to visualize the spatial distributions of velocity and temperature of fluid flows. This novel measuring device can scan the flow field to be measured with a rod-shaped probe equipped with hot- and cold-wires to measure velocity and temperature fields simultaneously. By combining the time-series data from the velocity and temperature sensors and the image measurement data of the probe trajectories obtained by a high-speed camera, the spatial velocity and temperature distributions can be visualized by making the best use of digital signal processing. In this study, we have verified the measurement accuracy by applying the thermofluid scanner to the measurement of a circular jet of heated air. By using a mutual compensation scheme newly developed for the constant-temperature hot-wire anemometer and the response delay of the cold-wire (resistance) thermometer, it was shown that quantitative visualization measurement can be easily realized even in a non-isothermal field with turbulent fluctuations.

Thermal design requires highly accurate measurements of thermal properties such as thermal conductivity. ASTM E1530 and D5470 require measurements of different thickness samples of the same material to measure thermal conductivity without the influence of contact thermal resistance. We have proposed a method to measure thermal conductivity from a single sample without the influence of contact thermal resistance. It has been confirmed that the proposed method is equivalent to the conventional method for homogeneous solid samples, but it has not been confirmed that the method can be applied to soft materials and composite materials. In this study, we confirmed that the proposed method can be applied to a soft composite material, a heat dissipating sheet.

The purpose of this study is to investigate the cooling performance of a ground source heat pump that use the direct expansion method with a ground source heat exchanger placed horizontally in a shallow layer. The ground source heat exchanger consists of a horizontal air/refrigerant heat exchanger, which is used in commercial air source heat pumps, inserted into a stainless-steel container filled with water. The shallow arrangement of the heat exchanger is designed to allow for insufficient heat extraction and dissipation from the ground, so a water-cooling system is used to fill the stainless-steel container with water. The experiment was conducted in cooling operation at a set temperature of 23°C. The average output power was 3.7 kW, the average power consumption was 0.57 kW, and the average COP was 6.7.

The purpose of this paper is to clarify the heating performance of a direct expansion type ground source heat pump using steel pipe pile for house. The ground source heat exchanger consisted of one copper tube with an outer diameter of 4.0 mm and an inner diameter of 3.2 mm, and two similar copper tubes connected in a U-tube at the bottom. Experiments were conducted at a set of 22.5°C for 8 hours and 23°C for 144 hours. Consequently, the average heat gain for 8 hours was 3.8 kW and COP was 4.1, and it for 144 hours was 5.3 kW and COP was 2.0.

Three dimensional numerical analysis is utilized for thermal design of electronic devices. In this calculation, power consumption of electronic component are needed for input values, and they have an important consequence for prediction accuracy. But, it is often the case that the values are imprecision, because it is not well defined to measure or calculate the values at the moment. We developed an estimation method using temperature measurements and thermal analysis. We obtained a parameter about thermal of electronic components in advance. Next, the temperature of each electronic components was measured. Then, the power consumption can be obtained using them. This estimation method is effective because it does not require special equipment.

To discuss the effect of the wavelength of surface undulation on the turbulent heat transfer，we perform direct numerical simulations of turbulent heat transfer over three-dimensional sinusoidal surfaces with different wavelength of surface undulation．The friction Reynolds ranges from 180 to 600，and the Prandtl number is set to 0.7．The sinusoidal roughness enhances both the momentum and heat transfer; however，the enhancement of the momentum transfer is found to be lager．This unfavorable dissimilarity strongly depends on wavelength and Reynolds number．The temperature roughness function, which quantifies the augmentation of heat transfer, is found to increase with decreasing the mean wavelength．

In this study, a new engine measurement system was developed to investigate the formation and emission processes of particulate matter in the DI gasoline engine. The developed engine has an optically accessible sapphire window to visualize the combustion process, in addition to particulate emission measurement. Using the developed system, the effect of injection timing on particulate emission was investigated. As a result, it is found that the fuel film is formed due to the fuel impingement on the piston top surface with the excessively early or late injection timing. At the conditions, the luminous flame can be observed during the combustion of the fuel film attached on the wall and the exhaust particulate number concentration is increased.

Cellulose nanofibers (CNFs) are known to have hydrophilic properties due to the presence of hydroxyl groups in their molecular chains. In this study, we investigated the wettability of CNF films deposited on silicon substrates. The results showed that the wettability of the substrate improved as the film thickness increased. We investigated the mechanism at the nanoscale using AFM and TEM, and found that this is attributed to the fact that the proportion of the three-dimensional CNF network capable of retaining water increases with film thickness.

In this study, hydrates growing from micro crystals on a glass cooling surface in supercooled aqueous TBAB solution were observed at concentrations of 20 and 40 wt % and supercooling of 2 ~ 6 K. In this experiment, two types of crystals were observed: type A at 40 wt % and both type A and B at 20 wt %. Crystal of type A at 40 wt % grew at an almost constant speed immediately after the crystals appeared because the concentrations of solid and liquid phases were almost equal, but the growth speed decreased with growth at 20 wt %, when the liquid phase concentration was lower.

This study focused on porous-inserted channel with radiative heating. A cubic lattice structure is assumed as an elementary porous structure. Open-source CFD code “OpenFOAM” was used to calculate conductive heat transfer in the solid region and heat transfer between fluid and solid region, simultaneously. Heat transfer medium is air. Flow is assumed as laminar flow, thus Reynolds number varied from 12.6 to 474. Otherwise, optical parameters (e.g., extinction coefficient and scattering phase function) were derived from the Monte Carlo ray-tracing technique. The calculated local radiative heat flux distribution was incorporated into the fluid analysis, and the heat transfer by radiation, convection, and conduction was investigated.

The objective of this study is to clarify the particulate emission characteristics of a direct-injection gasoline engine. Because one of the main exhaust particle formation processes is pool combustion of the fuel film attached to the piston surface, the particulate number concentration and the temperature of the piston top surface were simultaneously measured to investigate the effect of the piston surface temperature on the particulate emission characteristics. It was found that the particulate number concentration and particle size increase with decreasing the piston surface temperature.

It is important to analyze the ink evaporation mechanism to improve the printing speed of commercial inkjet printers. Whether or not the solid components are internally dispersed can be determined by measuring the change in viscosity of the liquid. In this study, we constructed a device to measure the damping constant of a liquid film and actually measured the change in viscosity of a model ink in an aqueous system. As a result, it was confirmed that the damping constant was actually decreasing.

Heat transfer between solids and gases plays an important role in various fields of engineering. In this study, we perform three-dimensional unsteady conjugate heat transfer numerical simulations of solids and fluids in a rectangular computational domain by arranging columns of cylinders parallel to the flow direction. Air is used as the fluid and ceria is used as the solid. The Reynolds number is calculated in the range of laminar flow. The heat transfer coefficient, Nusselt number, friction coefficient are calculated from the solid and fluid temperatures and the pressure drop between inlet and outlet, and the heat transfer characteristics are evaluated and applied to porous flow.

The objective of this study is to predict paper media temperature at paper outlet in electrophotographic printing in order to improve the toner fixing quality. Continuous printing experiments were conducted under various conditions of printing speed, toner quantity, paper type, etc. using an electrophotographic printing machine. The temperature of the printer components and the temperature of paper at paper outlet were measured. Using these data, a prediction model by LSTM, which is one of the neural networks, was trained. From this model, the temperature of paper at paper outlet was predicted from the printer components temperature data at several sheets in the initial stage of printing, and it was compared with the measured value.

In order to improve the heat transfer performance of a heat pipe, the screen mesh wick contained in the copper tube container was pre-coated with a silica nanoparticle layer to enhance its capillarity. Pure water was used as the working fluid. In the experiment, the one end of the heat pipe was heated using a nichrome wire heater and the other end was cooled with saturated pool boiling of water. The experimental results showed that in comparison with the normal heat pipe, the thermal resistance decreased up to 59% and the maximum heat transfer rate increased up to 1.45 times if the amount of deposited nanoparticles was sufficient. It was also shown that the heat transfer performances are improved further if the nanofluid is used as the working fluid. It was confirmed that the improvements of the heat transfer performances can mainly be attributed to the capillarity of the wick material.

Effect of insulation thickness on the flame spread over electric wire is investigated analytically. Previous study has experimentally observed that flame spread rate shows a non-monotonic trend with respect to the insulation thickness. The flame spread model developed in this study successfully reproduces the non-monotonic behavior of the flame spread rate with respect to insulation thickness. It was revealed that the effect of solid geometry on the flammability of composite materials cannot be explained by the conventional thermally thin or thermally thick theories, and the cause of the unique behavior of spread rate versus insulation thickness is discussed based on the analytical results.

The transient temperature distribution of silver nanowire network induced by Joule heating is described in this study to evaluate the path of the electric current and the heat transfer characteristics. We measured the two-dimensional temperature distribution using thermo-reflectance imaging (TRI) method and conducted the numerical computation based on the equivalent circuit model. The measurement results showed that a non-uniform temperature distribution is formed and we could represent the probability density distribution of the temperature by Weibull distribution. The computational results showed that the junctions located in the electrical paths produce large amount of heat and the heat is transferred to adjacent nanowires by heat conduction. We found that the heat transfer rate decreases at the points of high Joule heating (high temperature) where the electrical paths merge and produce high current density. This indicated that the high temperature regions of the nanowire network are augmented in transient state of Joule heating.

To evaluate the characteristic of Joule heating and heat transfer of the network consisted of Ag nanowires (Ag-NWs), we measured the temperature distribution of Ag-NWs randomly dispersed on a glass substrate using the thermoreflectance imaging (TRI) method. The TRI method measures the surface temperature by measuring the change of the reflectance distribution captured by the camera. The measurement accuracy relies significantly on the accuracy of the light intensity measurement and the alignment of the wires among the images. Therefore, the thermal deformation of Ag-NW is an essential issue for the measurement. To solve this problem, we introduced the algorithm extracting the light intensity at the centerline of Ag-NWs in this study, and evaluated the measurement accuracy and confirmed that it can be improved even for small deformation on the order of sub-nanometers.

It is known that the flow pattern of ice slurry containing bubbles in the liquid likely to become homogeneous flow. It is also known that flow pattern of ethanol solution ice slurry is changed by agglomeration of ice particles occurring when the liquid phase concentration is less than 3wt%. In this study, we investigate the effects of bubbles and liquid phase concentration on flow pattern of ice slurry made from ethanol solution of 3wt% and 5wt%. The experimental results confirm that the bubbles have a dispersing effect on the ice particles. The effect is present at all liquid phase concentrations, and the effect is higher at lower liquid phase concentrations.

In this report, the factors of heat transfer enhancement by swirling the in-pipe flow around the transition regime were considered based on the measurements of spatiotemporal heat transfer and velocity field. In the turbulent regime, the centrifugal instability due to the swirl, which leads to an increase in the streamwise velocity near the wall, is considered to be one of the factors of the heat transfer enhancement against the pressure loss. This effect is considered to be larger closer to the transition regime. In the laminar regime, the turbulent transition due to instability by the swirling is considered to be the factor of a large heat transfer enhancement against the pressure loss. This effect also becomes larger closer to the transition regime.

This paper discusses discrete and continuum models to describe combustion-wave propagation through a dust cloud. The discrete model resolves individual particles, whereas the continuum model treats the dust cloud as a continuum phase. A simple formulation that assumes constant density and thermal equilibrium between the gas phase and the dust cloud is mainly considered. The dimensionless ignition temperature, T_ig, is a key parameter that controls the phenomenon. Both the models yield the (dimensionless) propagation velocity as a function of T_ig. Propagation limits are predicted when considering the heat loss to the environment. Possible extensions of the simple models are also discussed.

The thermoelectric generator using the loop thermosiphon (LT-TEG) can generate high electric power and it is important to further increase the electric power for commercial use. In general, the exhaust heat fluctuates, and the excess heat damages the thermoelectric modules, while the lower heat leads to the lower electric power. To increase the time-averaged electric power while protecting the thermoelectric modules, the variable heating function (VHF) has been developed in this study. The VHF automatically can control the refrigerant amount in the LT-TEG to suppress the heat transfer to the thermoelectric modules for the excess heat, while keeping the electric power. The VHF has increased the time-averaged electric power by 48% in the exhaust heat generated from the steelmaking plant.

As one of the next-generation energy sources to replace the current lithium-ion battery, micro-combustors using hydrocarbon fuels with high energy density are attracting attention and have been studied widely. We conducted experiments of burning propane/air mixtures inside a small-diameter quartz glass tube combustor inserting a metal mesh. We varied the quartz glass tube thickness for the purpose of expanding the flame stabilization range. The temperature distributions on the outer tube wall or the wire mesh were also measured using infrared thermography cameras.