Experimental study was made on promotion and control of turbulent mixing of hot and cold airflows in a T-junction, which simulated an HVAC unit for automobile A/C system. Two kinds of delta wings were used as a mixing promoter, and the influence of their attack of angles on the thermal mixing and flow field were examined in detail. It was found that the thermal mixing is promoted by longitudinal vortices and strong turbulence produced by the delta wings, and the degree of mixing promotion can be controlled by changing the angle of attack of the wings.

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The present study aims at improving the impinging jet heat transfer by placing an open-cellular porous plate on a heated surface, which a circular jet nozzle with a flange is installed. The annular porous plate was use as a heat sink. In the experiment, N2 gas was used as a coolant and Ag, Cu, Ni and Ni-Cr porous plates having various porosities, pores per inch and thickness were examined. It is found that the impingement heat transfer can be augmented appreciably by placing an appropriate porous plate in a heating surface.

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In order to improve evaporation rate of fuel droplets in the combustion chamber such as diesel engine, it has been proposed to use a porous plate on the surface of a piston. The aim of this study is to understand the effects of porous characteristic on the fuel droplet evaporation phenomena. The fuel droplet after contacting with the hot porous plate were observed using high speed camera, and life time of the droplet and transient temperature of the porous surface were measured. It was found that the thermal conductivity and the pore diameter of the porous plate play important roles in the evaporation phenomena.

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Single layer flow insulation using a wire mesh for high temperature combustion furnaces is proposed. The gas temperature drop and heat transfer characteristics across a wire mesh were measured experimentally. Temperature drop increases with increasing inlet gas temperature, on the other hand, decreases with increasing modified Reynolds number and the porosity of wire mesh. In order to characterize heat transfer characteristics, relationships of modified Nusselt number Nu' and modified Reynolds number Re' were obtained. These relations are indicated as Nu'=a+b×Re'^c, and each coefficients a,b,c changes mainly by the porosity of wire mesh.

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The dry-ice blasting is used for cleaning the parts of semiconductor producing equipment. The residual level of contamination after the cleaning on the electrode is affected by the blasting pressure and the diameter of DIP (dry-ice pellets) for the dry-ice blasting process. The blasting pressure and the diameter of DIP are varied and the residual contamination is measured by laser-induced fluorescence spectroscopy. The residual level of contamination varies with the blasting conditions.

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For growing the single crystal in the Czochralski (Cz) configuration, the rotational magnetic field (RMF) is applied to the melt in a crucible and the temperature distribution in the melt is measured for various rotating rates of magnetic field and magnetic strengths. Temperature distributions in the melt are asymmetric and the periodical temperature oscillation is caused by the rotation of asymmetric temperature distribution. The rotating velocity is suppressed under the RMF.

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The silicon single crystal is use for the semiconductor device and it is mainly manufactured by the Czochralski crystal growing method (Cz method). Under the Cz method, the forced convection and natural convection caused by the crystal rotation and the temperature difference between the crystal and crucible. In traditional system, the melt convection is controlled by the heater power, the crystal and crucible rotation. In this study, electromagnetic filed apply to the melt for control the melt convection in the crucible which is caused by the electric current and the magnetic field. The amplitude of electric current and the strength of magnetic field are varied and the velocity of fluid at the circumferential direction is measured. The melt convection is strongly affected by the intensity of electric current and magnetic field.

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Exact numerical solutions have been obtained for the laminar flow between a rotating and a stationary disk, which are infinitely large compared to the gap between the two disks. The gap space are assumed to be filled with an electric conducting fluid which has a small magnetic Prandtl number in order to control the flow by the Lorentz force and to neglect the influence of the induced magnetic field. The flow depends on both the Reynolds number and the Hartmann number. As the Reynolds number increases, the region of rigid body rotation is observed between the two boundary layers, whose thickness become thinner in proportional to the square root of the Reynolds number. On the other hand, as the Hartmann number increases, the Lorentz force suppresses the secondary flow significantly and boundary layer thickness of the azimuthal component is proportional to the inverse of the Hartmann number.

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A two-dimensional numerical analysis is made, concentrating on the effect of aspect ratio on heat transfer characteristics of natural convection in a slender fluid layer enclosed between two vertical plates of different temperatures. It is shown that the boundary layer instability induces the secondary and the tertiary hook-shaped flows, which cause the renewal of the boundary layer. Then it is suggested that there exists the transition region where the average Nusselt number increases with the increase of the relative height, the aspect ratio, even for natural convection in a vertical fluid layer, as is seen in the tendency that the Nusselt number in the transition region from laminar to turbulent convection along a single vertical plate depends on the 2/5 power of the height-based Rayleigh number.

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In this paper, natural convection in an enclosure which two parallel heated plates are included is investigated experimentally. In the area of between cooled ceiling and heated surface, vortex motion arises when the ascending flow from the upper plates and the accompanying flow to the rising flow from lower area are interfered. Heat transfer around heated surface is enhanced by the vortex motion. In the other areas, the flow is circulated along the heated surface, and average Nusselt number is proportional to modified Rayleigh number at the power in general.

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The drag reduction by using surfactant is expected to contribute for saving energy in heat exchangers. Measurements of pressure drop and heat transfer were conducted to investigate the heat transfer characteristics of the drag reduction with changing the mole ratio ξ and the concentration of the solution. The drag reduction effect was obserbed under the conditions of over 300ppm of the solution at ξ =10. The pressure drop decreased with increasing of the surfactant concentration. Heat transfer coefficient decreased when the drag reduction occurred. Corburn analogy was applicable to the experimental results for low flow velocity conditions.

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Devices such as robots have become increasingly sophisticated and compact, the amount of energy required for their operation has increased . For those devices, small portable distributed power sources with higher energy density than the conventional battery are required. In this research, we focused on the small glow-ignition engine developed for model airplanes to verify a possibility that glow-ignition small engines replace electric cells as an energy source for micro-size machines. In order to clarify the combustion process, a miniature pressure sensor was built into the cylinder head, and pressure fluctuation was measured. Analysis was conducted to detect heat release and ignition timing. The base engine was a commercial glow-ignition four-stroke engine with a swept volume of 4.89 cc.

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The mixture consist of 34 vol% of syngas, air and gasoline could keep drive a general-purpose engine, spark ignition engine. This experiment is a part of feasibility study of new proposed gasoline engine system, which consists of two spark ignition engines. The powers of two engines are united, or are transmitted to different axles. In the system, the smaller engine generates syngas by partial combustion of gasoline. The syngas is supplied to the larger engine. Experimental data shows the possibility that the reduction of throttle loss by syngas use. The effect and the syngas generation may improve thermal efficiency of power generation system under partial load condition.

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Homogeneous Charge Compression Ignition (HCCI) combustion has attracted considerable interest in recent years as a new combustion concept for internal combustion engines. The HCCI combustion process has four issues to be resolved: ignition timing control, slower combustion (maximum heat release rate), difficulty expanding stable operation to the high load region and avoidance of knocking. In this study, an attempt was made to overcome these issues by using double componential fuels. As the result, by using double componential fuels, the ignition timing can be controlled and the rise of combustion can be slower.

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Dynamic properties of combustion oscillations in a lean premixed gas turbine combustor have been experimentally investigated from the viewpoint of nonlinear dynamics based on chaos theory. As equivalence ratio φ increases from 0.45 to 0.50, the dynamic behavior of combustion oscillations undergoes a significant transition from low-dimensional chaos to periodic oscillation. The deterministic nature for shortly predicting the combustion oscillations sufficiently persists in the trajectories of phase space constructed from the time series of pressure fluctuations.

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Temperature distribution of premixed flame between methane gas and air has been measured using laser speckle method. The gas flow rate of methane changes from 0.9 l/min to 1.2 l/min. The flow rate of air is ten times of methane gas flow rate. The flame is almost steady state due to the visualization. On the other hand, from the movie of speckle patterns, the motion of the premixed flame is unsteady and oscillatory. The more methane flow rate makes the more the unsteady domain of diffusion flame. Furthermore, from Fermat's principle and Gladstone-Dale's equation, the temperature distribution of the unsteady and oscillatory premixed flame has been predicted.

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A simultaneous measurement technique of velocity and temperature distribution in a fluid flow was developed. Particle image velocimetry (PIV) was combined with a lifetime based scalar measurement technique. A measurement method based on the luminescent lifetime is appropriate for detecting the transient temperature field. Developed method needs a high speed camera, a laser (one excitation wave length) and temperature sensitive particles (TSParticles). The luminescence from TSParticles doped with EuTTA was detected by the high speed camera, which was not equipped with any image intensifier, at 15000 frames per second. Imaging at the high frame rate has a possibility to carry out PIV with a wide dynamic range. A decay of luminescent intensity was detected in detail. The decay curves at various temperature conditions were fitted well to exponential functions, from which the decay constant at each temperature was obtained. The proposed technique was applied to measure the temperature and the velocity field in a natural convection driven by Marangoni force and by buoyancy in a rectangular tank. The accuracy of the temperature measurement of the proposed technique was ±0.℃.

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In order to improve an engine performance, it is important to understand the temperature and velocity field information in a flow field at high temperature such as a combustion chamber in the engine. In such the field, it has been hard to apply the conventional technique. A new combined velocity and temperature measurement approach is proposed, using a high speed camera, a single-pulsed UV laser and temperature sensitive phosphor particles (TSParticles). TSParticles, the powders of rare earth-doped ceramics are utilized as tracer particles of particle image velocimetry (PIV). The purpose of the present study was to establish this technique in a flow field at high temperature. In the present report, thermal properties of TSParticles were investigated. At first the phosphor material was painted on the solid wall in an engine cylinder, and the instantaneous temperature was measured.

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At the commercial use stage in next generation nuclear energy systems such as sodium-cooled fast breeder reactors and advanced light-water reactors, securing maintenance and repair better than an equal to those of current water-cooled reactors is needed. Especially, establishment of a repair technology that secures the plant integrity for long-term operation period becomes indispensable. Then, experimental and analytical studies are started aiming at the world standardization of welding technology with a laser. As a part of those, in order to investigate the possibility of the laser welding simulation, melting characteristics of very small fine metal powders on a stainless steel plate were analyzed numerically. The fine metal powder is made of iron, and is heated by the laser beam, and then melts exceeding the melting temperature. This paper reports the predicted results of fine metal powders with the laser welding.

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High time-resolution flow measurement of curing process by UV is performed by micro-DHPTV system. The photo-curable resin is packed between the glass plate and the covered glass. The measurement is performed during two seconds; the measurement time is covered for the curing time. The theoretically curing time is estimated from the irradiation flux of UV source. Moreover, photo-curable resin with the changing of temperature is measured to evaluate dependence of temperature. Consequently, the three-dimensional displacement can be obtained by the movement of the tracking particles. The displacement is dominant at the depth direction. The value is in good agreement with the theoretical displacement from UV irradiation flux. Moreover, it is found that the photo curing of the displacement appears to be proportional to increasing the temperature.

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A lot of solidification and melting phenomena exist in our environment and many industrial processes. The present research focuses on the ice formation around a vertical circular cylinder. The copper cylinder, whose surface was lowered to subzero temperatures by circulating refrigerant, was set vertically in a rectangular container filled with distilled water. The bottom of the container was fixed at 15℃, so that vigorous convection is present during the solidification. The ice layer growth on the cylinder was measured for various cooling temperatures. One dimensional approximate analysis was proposed by considering the heat balance at the solid-liquid interface. The model was solved by the Runge-Kutta technique for transient ice-growth. The average ice-layer thicknesses predicted by the one-dimensional analysis are found to agree well with the experimental results.

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This paper reports visual observation results of liquid-solid contact situations when a water droplet impacts on a superheated surface, in order to obtain fundamental data such as diameter of liquid-contact outer region for future numerical simulations of limiting process of localized liquid-solid contact on a superheated surface. A single crystal sapphire plate was used for the superheated surface because of its transparency and relatively higher thermal conductivity. The obtained results show that liquid-solid contact is gradually restrained and limited as initial surface temperature increases; i.e. maximum liquid-solid contact diameter decreases. On the other hand, the increase of height of droplet falling promotes liquid-solid contact such that both maximum liquid-solid contact diameter and its spreading speed are increased.

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The process of rapid liquid heating with time dependent boundary temperature condition has been simulated by using the idea of ID semi-infinite heat conduction in conjunction with theory of homogeneous nucleation boiling. A control volume adjacent to the boundary and having the size of critical cluster is considered and the corresponding energy balance is made for two parallel competing processes taking place inside: transient external heat addition and internal vaporization heat consumption due to bubble nucleation and subsequent growth. Results obtained are presented in terms of the maximum attainable liquid temperature and the corresponding time to reach the temperature limit. For water heating with the identical initial and boundary conditions as reported in some literatures, the model results are found to be in good agreement with the experimental counterparts for lower boundary temperature rising rates. However, for higher values of boundary temperature rising rate, the model predicts earlier attainment of maximum liquid temperature and boiling explosion.

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Rapid vapor generation during impact of a single ethanol droplet on a hot surface was observed for well understanding of wetting phenomena. Photographs during a single droplet impacting on a surface at 190 - 210 oC were taken by a high speed digital camera with a microscope. Copper and carbon steel were used for the surface material. The liquid subcooling was varied from 10 to 50 K. The boiling situation changes from nucleation boiling to film boiling like as the boiling transition in pool boiling. Delay time to develop vapor film on the hot surface was measured from the observations. While the delay time increases with increase of subcooling and decrease of thermal inertia of the solid for the lower surface temperature, it shows constant for the higher surface temperature above the superheat limit of liquid.

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The present study investigates experimentally the effects of the droplet diameter, its velocity, the surface roughness and thermal conductivity on the direct contact of droplet with the hot surface. Cylindrical blocks made of SUS304 and Brass with different roughness, Ra0.04, 0.2, 3, 10 were used. The droplet diameter and velocity were independently controlled in ranges of 300-700μm and 1.0-4.0m/s, respectively. The behavior of droplet during the collision with hot surface was observed with the high-speed camera in the range of surface temperature from 600℃ to room temperature. The experimental results show that the solid-liquid contact time decreases with the increase in droplet velocity and it increases when Ra=10. It is also found that maximum spread of droplet over the surface increases with the increase in droplet velocity.

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Carbon nanotube has superior characteristics and it is expected for diverse applications. Vertically aligned single-walled carbon nanotubes (VA-SWNT) film can be made on a substrate with high-density nano catalysts particles. This film is expected to apply to reduce the contact resistance because this film possesses an enough thermal conductivity and high stability for erosion and heat on comparing with present silicon grease or something. In this study, VA-SWNT was synthesized on the substrate by using alcohol, and thermal resistance was measured. Consequently, the thermal resistance was about ten times larger than silicon grease with 10 μm thickness.

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We investigate the thermal rectification of the nano thermal diode using a phonon scattering of a single carbon nanotube (SWNT) with vacancy defect. The heat transport analysis is conducted using non equilibrium molecular dynamics simulation. The defects are located randomly in the half of SWNT. The over 10 percent rectification effect is observed. The heat prefers to transport from SWNT with defects to without defects. In order to reveal the mechanism of the thermal rectification by defects, the phonon density of state is calculated and discussed.

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Scattering process of helium molecules on vertically aligned single-walled carbon nanotubes (VA-SWNTs) was investigated using the molecular beam technique. We found that the modification of quartz surface with VA-SWNT films significantly enhances the energy transfer between gas molecules and the surface at room temperature and makes the energy accommodation coefficient of helium, which tends to be small even for contaminated surfaces because of the large mass mismatch between helium and surface atom, close to unity. The high porosity of the film enables gas molecules to penetrate into the film and suffer multiple collisions with carbon nanotubes, leading to the efficient energy transfer.

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Growth rate of TIN film by thermal chemical vapor deposition has been investigated. When the setting temperature, Ts, is 1200℃, the growth rate at an almost uniform temperature zone decrease exponentially with the distance. In this case , the growth rate is controlled by the diffusion of TiCl_4. The controlling step doesn't depend both on the pressure and the bubbling flow rate of TiCl_4. On the other hand, at Ts<1200℃, the growth rate at the almost uniform temperature zone is divided by two steps. Therefore, growth rate of TiN film depends not only the diffusion of TiCl_4 and the surface reaction but also the gas phase reaction.

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Temperature distributions inside the operating PEFC at high current density were measured by thermocouples, thermal probes and temperature-sensitive paints, which were different devices and methods. Thermocouples of 0.1mm in diameter penetrated the separator and GDL and measured the temperatures on catalyst layer that corresponded to underneath of rib and channel, respectively. Polyimide-coated thermal probes of 0.02mm in diameter were inserted between GDL and catalyst layer and calibrated by temperature sensitivity of thermal resistance using four-terminal method. A very small amount of commercial temperature-sensitive paints, which were provided at 5 deg-C intervals, were coated onto the surface of GDL. Each method has different uncertainness and error due to the disturbance of sensing device.

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Heat transfer performance of two-stream parallel-flow gas-to-gas micro-double-tubes-heat exchangers was investigated numerically. The flow passages of the micro- double-tubes-heat exchanger are a circular tube for hot passage and a concentric annular tube for cold passage. A circular tube of r= 50 μm and a concentric annular tube of r_1=51 μm and r_0=71 μm with an identical cross-sectional area were chosen and the selected length was 20mm, respectively. Then, the partition wall is assumed to be a stainless steel tube with 1 μm in thickness. Numerical methodology is based on the arbitrary-Langrangian-Eulerian method. Computations were performed for wide flow range to find the effects of capacity ratio on the heat transfer characteristics of gas-to-gas micro-double-tubes-heat exchangers. The results are presented in form of temperature contours, bulk temperature, total temperatures and heat flux variation along the length. Also, the effectiveness and the number of transfer units approach and the estimation of the heat exchange rate were discussed.

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The boundary layer is formed on micro-channel walls and its thickness becomes 0 at the exit of the channel. And, it plays a role of a wall of a converging and diverging nozzle and the flow becomes supersonic at the micro-channel outlet. Then outlet Mach number is beyond unity. This fact is not widely known. Therefore, experimental investigations on behavior of super sonic flow at the outlet of straight micro-tubes whose diameter ranges from 150 to 500 μm are conducted. The successive expansion and recompression waves of under-expanded state were visualized by Schlieren method and a high-speed camera. The numerical investigations are also performed for straight micro-tubes with diameter ranging from 50 to 400 μm. Numerical methodology is based on the aribitary-Langrangian-Eulerian (ALE) method. The experimental correlation for the distance from the micro-tube outlet to the Mach disk as a function of pressure at the outlet was proposed for the prediction of outlet pressure of micro-tube in under-expanded.

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Nanoparticles in the atmosphere affect the energy balance of the earth. In general, it is known that they have a cooling effect on the atmosphere near the surface of the earth. Therefore, we are now focusing on the cooling effect by considering artificially formed nanoparticle layer which are dispersed in the atmosphere so that we can control global warming. In this study, the feasibility of global warming control by dispersing nanoparticles in the atmosphere is examined. The equivalent temperature decrease by nanoparticle layers is converted to a reduction of CO_2, and this CO_2 reduction is compared with the CO_2 output required to form the nanoparticle layers in the atmosphere. The reduction of CO_2 equivalent to temperature decrease due to nanoparticle dispersion is very large compared with the CO_2 output due to the object launch. Therefore, it is inferred that this method presents a feasible solution to the global warming problem.

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Key issues to enable heat removal exceeding 10MW/m^2 of heat flux are evaluated by summarizing experimental and numerical data ever obtained. Porous media focused on are bronze particle-sintered compacts. The experiments clarify that the heat transfer characteristics strongly depend on the level of the heat flux input and suggest that the heat transport by capillary effect works effectively under several MW/m^2. However, under the conditions of over the maximum heat flux transport by the capillary effect, the permeability for the vapor discharge becomes the most important factor to make it possible to remove the extremely high heat flux. In order to evaluate the effect of porous material, the two-phase flow characteristics are simulated by the two-phase mixture model. The results show that applying higher thermal-conductivity matrix leads to delay of onset of the two-phase formation and to much higher cooling performance even at higher liquid saturation.

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A theoretical study has made on the effective thermal conductivity for porous media. We consider the periodic structure of porous media, and define the effective thermal conductivity without the assumption of local thermal equilibrium. Furthermore, we determine the temperature distribution on the interfacial area between the fluid and solid phases from one-dimensional analysis of heat conduction through the series arrangement, and propose the effective thermal conductivity for any porous structure. The effective thermal conductivity predicted by the present model is in good agreement with the experimental data of beds of spherical particles given by Nozad et al.

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A porous media approach was proposed to investigate the characteristics of the bifurcating airflow and mass transfer within a lung. The theory of porous media was introduced in order to deal with a large number of bifurcations and a vast scale difference resulting from bifurcations. Upon introducing a two-medium treatment for the air convection and the diffusion in its surrounding wall tissue, the oxygen mass transfer between the inhaling air and the tissue was considered along with the effects of the blood perfusion on the mass transfer within the tissue. The overall mass transfer resistance between the inlet of the trachea and the blood in the capillaries was obtained on the basis of the porous media approach. The analysis reveals that there exists the optimal number of the bifurcation levels, namely, 23, that yields the minimum overall mass transfer resistance for the mass transport from the external air to the red blood cells. The finding is consistent with Bejan's constructal law, namely, that for a flow system to persist in time, it must evolve in such a way that it provides easier access to its currents.

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The longitudinal thermal dispersion in non-thermal-equilibrium flow in a porous media has been investigated by means of numerical experiments, using a periodic structure consisting of square rods. It has been found that the thermal dispersion coefficient obtained on the basis of local non-thermal-equilibrium is higher than that obtained on the basis of local thermal-equilibrium. However, the difference between them is so small that the thermal dispersion thermal conductivity obtained on the basis of local thermal equilibrium may well be used for the case of local non-thermal equilibrium.

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Residual gas trapping by capillarity is considered to be an important trapping mechanism in CO_2 geological storage. In this paper, gas trapping in porous media of vertical and horizontal sandstone cores is investigated from a microscopic point of view. A high-resolution X-ray CT scanner is utilized to get the images of pore structure and trapped gas bubbles inside the sandstone cores. Using image analysis software, statistical porosity and trapped gas saturation are obtained. Almost the same results are obtained for both vertical and horizontal cores. Porosity fluctuates with the layered structure, and correspondingly, trapped gas saturations fluctuate with the porosity. Most of the injected gas would be trapped in dense layers. Besides, Trapped gas bubbles are examined to be stable against the elevated capillary number from 1.0×10^<-6> to 1.0×10^<-5>.

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An important aspect of any enhanced oil recovery (EOR) process is the effectiveness of process fluids in removing oil form the rock pores at the microscopic scale. Capillary and viscous forces govern phase trapping and mobilization of fluids in porous media. Understanding the role of pore-level mechanisms is essential to the design of EOR process in oil-fields. In present study, we observed the pore-scale mechanisms of surfactant flooding and water-alternated-gas (WAG) scheme by using the porous plates.

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The swelling is an increase of volume of material due to absorption of a solvent and is an important phenomenon in soil and gel sciences. We have investigated the swelling behavior experimentally, using cross-linked polyacrylic acid sodium hydro gel which has three-dimensional cross linked polymeric structure. The swelling behavior was studied under two experimental cases. One is swelling under load to polymer gels and the other is swelling under contact of two different gels. It was found that both cases of the load to gels and gels diffusion in another gels reduced swelling because diffusion of polymer chains was restricted.

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This paper presents an analytical investigation on the thermal characteristics in a layer of an exothermic powder mixture that is utilized in body warmers, hot compresses and so on. The research objective is to develop a manufacturing method that enables the exothermic temperature to be controlled in order to prevent cases of low-temperature burns. The authors analyze numerically variation over time of the temperature distribution and the generated heat in a layer of the exothermic powder mixture. Although the analytical and experimental results are in accordance qualitatively, the analysis overestimates dependence of temperature distribution on time.

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Flow boiling experiments were carried out to investigate the critical heat flux characteristics of water flowing in a uniformly heated single microtube. Stainless steel test tubes of 0.31mm and 0.49mm inner diameters were heated ohmically and the heated length was 200 times the inner diameter. Constant mass flux conditions were achieved by suppressing backflow with a pressure drop element. The mass flux and inlet subcooling was varied between 100-1000 kg/(m^2s) and 5-77 K respectively. Results showed a strong dependency on inlet subcooling over certain flow rates, and the threshold differed according to the tube inner diameter.

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Flow and the heat transfer characteristics of boiling two-phase flow of water in flat mini-rectangular-channels were examined. The cross-sections tested were 1.0x10 to 0.2x10 mm and the flow channel length was 250 mm. Boiling heat transfer of 0.5 mm high and 10 mm wide cross section was similar to that of the usual size. However, that 0.2 mm high and 10 mm wide cross section was a little different from that of the usual size. An increase in the heat flux after the onset of nucleate boiling on the boiling curve is milder than that of the usual size. Thus, the critical heat flux was lower than that of the usual size. Subcooled boiling was observed widely in the test section.

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The approach method to investigate boiling heat transfer mechanism with MEMS (Micro-Electro-Mechanical systems) sensor has been developed. The MEMS sensor includes trigger electrode and eight thin film thermocouples on the top side of a silicon substrate and two thin film heaters on the back side. In the experiment, Temperature variation beneath an isolated bubble during nucleate boiling of water was measured with the sensor. Measured temperature data presents formation and strong evaporation of microlayer and expansion of dry-out area in bubble growth process and rewetting of the dry-out area in bubble departure process. Additionally, heat transfer from the heated surface was evaluated by transient heat conduction analysis with the measurement data as a boundary condition. As the result, it was indicated microlayer evaporation contributed to surface heat transfer predominantly.

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To assess the stability of components which comprises parallel channels like steam generators in fast breeder reactors, Japan Atomic Energy Agency has been developing a prediction method for thermal-hydraulic instability based on system analysis code TRAC-BF1. In the present paper, TRAC-BF1 code was modified to simulate both primary and secondary coolant flow with VESSEL component. The calculation model was established and tested with preliminary simulations in which the primary sodium was expediently replaced by high pressure water.

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