Flow around a square cylinder in oscillatory flow was studied by a numerical simulation using a finite-volume method. The computations were carried out by assuming 3-dimensional (3-d), unsteady, incompressible and viscous flow through Keulegan-Carpenter number (KC) in the range of 2.5 ? KC ? 25 at Stokes number (β) = 95. The region in KC ? 4, “longitudinal vortex pairs” periodically arranged in span-direction were found out as well as in the case of circular cylinder. On the other hand, KC ? 5, the flow patterns called “transverse-vortex street”, “double-pair” which appeared in the case of the circuler cylinder at KC =12 and KC =16, respectively, were not formed. The drag and inertia coefficients of the Morison equation C_D and C_M, were estimated and it was found that decreasing of C_D as KC increases in the region 2.5 ? KC ? 12 is caused by the change in the position of rolling up of the flow in the wake. By calculating spanwise correlation, the effect of 3-D flow structures on the transvers force were investigated. The effect remarkably appears in the range of 2.5 ? KC ? 8 in which the “longitudinal vortex pairs” are formed.

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The properties of the numerical methods for a one-dimensional lattice model (Sakanishi model), which is associated with the material nonlinearity of the arterial vessel wall, have been investigated in order to analyze the blood flow by the numerical method which keeps the physical properties intrinsically possessed by the system. As the numerical methods for the analysis, we have focused on the integrable difference scheme and the symplectic scheme, and compared those two schemes with the general-purpose methods such as Euler method, Leapfrog method and Runge-Kutta method on the accuracy and the efficiency of the calculation. The properties of each numerical method for the Sakanishi model are shown. Especially, it is presented that the integrable difference scheme and the symplectic scheme can maintain a certain accuracy for the long time behavior of the pressure wave. Moreover, we find that the peaking and steepening can be caused by the material nonlinearity of the arterial vessel wall alone.

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Deformation and motion of lipid bilayer vesicles in a simple shear flow have been observed by phase contrast microscopy. We construct a rotating-cylinder apparatus, which can create a simple shear flow with steady shear rates. Vesicles are prepared from 1, 2-dioleoyl-sn-glycero-3-phosphocholine by the gentle hydration method. In our observation, vesicles are deformed to steady ellipsoidal shapes and show constant orientations with θ_i, which is the angle between the major axis and the flow direction. It is confirmed that the relationship between the θ_i and the swelling ratio (volume/surface ratio) S_w agrees quantitatively with the experimental result of Abkarian & Viallat [Biophys. J., Vol.89, 1055 (2005)], which is obtained with vesicles in wall bounded shear flows. It is also confirmed that our result agrees with a theoretical analysis of Keller & Skalak [J. Fluid Mech., Vol.120, 27 (1982)] and other numerical simulations. They are based on different membrane models, which are supposed to cause the different local behaviors of the membrane. This agreement indicates that the local membrane behavior does not have significant influence on θ_i.

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An experimental study of the aerodynamic characteristics of 3-dimensional flapping wing in hovering flight is conducted. Lift and power are measured in water on a scaled flapping wing of bumblebee. Two types of flapping motion are employed. One is a trapezoidal type of flapping motion which consists of translational, reversal and rotational phases; the other is a sinusoidal type of flapping motion, in which a wing is rotating continuously. The results show that the trapezoidal type has higher efficiency than the sinusoidal type. The shorter rotational phase enhances a fluid force normal to the wing surface. However, the rotational phase during the flapping translational phase contributes the increase of power rather than that of lift. This is because the enhanced fluid force vector due to the rotational phase is directed to the stroke plane, which requires more flapping power. In order to attain higher efficiency in hovering flight, the rotational phase should be done during the reversal phase rather than the flapping translational phase.

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The internal unsteady flow in the variable capacity type fluid coupling is analyzed by CFD, considering the movement of free-surface. The torque curve of CFD shows good agreement of experimental one. The fluctuation of torque is almost similar when the chamber is filled by the fluid. When it is partially filled, fluctuation has another pattern at larger speed ratio. The numerical result shows that there are two different flow patterns. In a pattern, most of working fluid is rotating in the rotor area, and fluid transfers small torque only. In another pattern, the working fluid rotates around the air area, that is concentrated at the center of fluid coupling, and fluid can translates large torque. In the area of instability of the fluid coupling, where the torque and rotational speed varies very much in the experiment, flow seems to go around between these two flow patterns.

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When developing tailored porous media, accurate assessment of the flow characteristics is essential. A numerical simulation is an effective method characterizing the properties of porous media, provided it precisely evaluates the effect of the structure of the porous medium. A lattice Boltzmann method (LBM) is expected to be a relevant tool to predict flows through such geometrically complex flow fields. Knowing the structure of the medium obtained from various steps of phase separation process of a binary mixture, it is examined through LBM simulations how the structure affects the bulk properties of porous media which include dead-end flow passages as well. After validating the accuracy of the method by comparing the simulated permeability data with experimental or empirical ones for packed beds of homogeneous spheres, the permeability of inhomogeneous porous media is related mainly to specific surface areas.

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In the present paper, a new viscous micropump using double-circular flows is proposed. Its pressure characteristics are investigated by using a theoretical analysis, a model experiment and a numerical simulation. In the theoretical analysis, the two-dimensional lubrication theory for a journal bearing with infinite length is adopted. In the model experiment, the low Reynolds number flow in practical micropumps is realized by using glycerin as working fluid, and a centimeter-scale (not micrometer-scale) model pump is examined. In the numerical simulation, the SIMPLE method is used to obtain steady-state solutions. With respect to the pressure characteristics, the theoretical results show good agreements with the experimental and the numerical ones quantitatively. The pressure at zero flow rate obtained is quite larger than that of an existing viscous micropump.

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The present paper describes the flow fields and pressure characteristics for viscous micropumps with 2 through 5 cylindrical rotors, respectively, in a rectangular duct. The experiment, the numerical simulation and the theoretical analysis are performed. In the experiments, centimeter-scale (not micrometer-scale) pump models are used and the low Reynolds number corresponding to micrometer-scale flow is realized by using glycerin as working fluid. In the numerical simulations, the commercial software, STAR-CD, is used. With respect to the flow fields and the performances, qualitative agreements between experimental and numerical results are obtained. In the theoretical analysis, the 2D lubrication theory is adopted and a new pressure performance formula is proposed. The performance curves derived from the formula show qualitatively and quantitatively good agreements with the numerical ones.

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In relation to the development of the interfacial area transport equation, axial developments of void fraction profile, interfacial area concentration and Sauter mean diameter of adiabatic nitrogen-water bubbly flows in a 9 mm-diameter pipe were measured by using a stereo image-processing method at normal-and micro-gravity conditions. The flow measurements were performed at four axial locations (axial distance from the inlet normalized by the pipe diameter, z/D=5, 20, 40 and 60) at various flow conditions of superficial gas velocity (0.008 40-0.029 8 m/s) and superficial liquid velocity (0.138-0.914 m/s). The effect of gravity on radial distribution of bubbles and the axial developments of two-phase flow parameter was discussed in detail based on the obtained data and the visual observation.

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A solid-liquid two-phase fluid was stirred by a rotating vane in a tank and it was pushed out by a piston through a pipe. There were differences between the volume concentration of particle phase of outflow and that set in a tank even when the specific gravity of fluid phase was arranged carefully to have the same value as particle phase. It became clear that the volume concentration ratios began to decrease linearly as a non-dimensional parameter expressed by the product of the velocity ratio and the diameter ratio increased. Now the volume concentration ratio meant the ratio of the volume concentration of particle phase of outflow and that set in a tank and the velocity ratio meant the ratio of the velocity caused by a rotating vane near the entrance of outlet pipe in a tank and the average velocity in a outlet pipe and the diameter ratio meant the ratio of the average diameter of particles and the diameter of an outlet pipe. These phenomena could be understood if we assumed that the fluid flowing in the layer between the wall and the plane apart a particle radius from the wall had no volume concentration of particle phase. Under this assumption the total volume concentration of outflow was calculated by using potential flow models, and it was found to agree with the experimental results fairly well. These phenomena could be considered to appear also in branch pipe flow, although they would become more complicated by the effects of boundary layer and non-uniform particle distribution. For example the flat shape of red blood corpuscle would contribute to reduce the effects of these phenomena and to increase the number of them in capillaries.

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A basic characteristic of the reacting mixing flow was investigated. The reaction between an ammonia solution [0.1mol/L] and an acetic acid solution [0.1mol/L], which produced ammonia acetic acid solution, was investigated in terms of the effect on the fluid-fluid interface of mixing flow, relative to fluids that did not react. The reaction between these solutions was negligibly exothermic, and the density and other thermo-physical properties were also not much different. The chemical reaction would only affect the mixing flow and the interfacial stability, while turbulence would enhance the chemical reaction. Two experiments were performed. In the first experiment, the mixing flow of an upward round jet and an upward ambient flow was studied. In the second experiment, the interfacial instability was investigated under parallel flow conditions in the rectangular tank. The acidic and alkaline solutions were flowed separately down individual rectangular channel 30 mm in width, and mixed only in a small region of the mixing interface, where the partition between the channels had been removed. The velocity field in the reacting mixing flow was quantitatively measured using the dynamic-PIV and the behavior of the mixing flow was qualitatively investigated using the LIF. The mixing behavior was monitored using a fluorescent dye. It was found that the mixing with chemical reaction was suppressed in both experiments. The jet width, the velocity field and the kinetic energy are qualitatively estimated and discussed.

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Jets issuing through small holes in a wall into a freestream have proven effective in the control of boundary layer separation. In this study, in order to obtain better understanding of the effect of jet orifice shape on longitudinal vortices, the suppression effect of the jet orifice shape was investigated and the jet velocity distribution was measured. The vortex generator jets with three types of jet orifice (circular, triangular and square orifices) were used in the separation control of the two dimensional diffuser. For the triangular jets, the jet velocity contours are not symmetrically elongated in the spanwise direction, and there is a significant difference in the strength between the positive and the negative vorticities. The triangular orifice produces the strong longitudinal vortices and makes effective the pressure recovery in the diffuser in contrast to the other orifice shapes.

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In order to get accurate measurements of air entrainment in a suction sump, we design a new and simple conductance-type electric bubble sensor, which can detect the existence of air bubbles inside a suction pipe with no disturbances by the sensor and with a fine spatial resolution. We focus on occurrence-time ratio γ of the air entrainment, and compare the result by the present sensor with those by conventional two methods, namely, visual and auditory ones. As a result, we show the criteria which specify lower-accuracy conditions in the conventional methods. By the visual method, the accuracy of γ becomes low, when γ is less than 0.05. By the auditory method, the accuracy of γ becomes low, when submergence depth _S of the suction pipe is close to the critical one S_c.

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This paper describes humidity characteristics of Plasma Synthetic Jet Actuator (PSJA). PSJA is flow control device using the Electro Hydro Dynamic (EHD) effect of the glow-discharge. PSJA can be downsized, controlled easily, and has quick control response. Though the flow control around an airfoil with PSJA is mainly studied, its characteristics have not been clarified. So, it is necessary to investigate humidity characteristics of induced flow by PSJA. In this paper, the induced flow from PSJA was measured in the different relative humidity. The experimental results show that the effect of induce flow by PSJA had decreased with increase relative humidity. Therefore, when PSJA was used, relative humidity becomes an important parameter.

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In this study, the improvement of the starting performance of a Darrieus wind turbine with straight wings was investigated. The numerical simulation on the starting torque generated in the stationary Darrieus wind turbine was executed. The parameters used for the numerical simulation are wing section shape and wing setting angle. The wing sections tried were NACA0018, NACA4418 (camber inside), and NACA4418 (camber outside). The following conclusions were obtained in this study. In three kinds of wing sections in which wing setting angle is set in 0 degrees, NACA0018 performs the highest minimum starting torque. In case that the setting angle of NACA0018 is set in -5 degrees, the starting performance improves more than the setting angle 0 degrees.

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The present study performed three-dimensional numerical simulations of asymmetrical flows and heat transfer around a hill in shear flows. When shear velocity distributions are given at the inlet, a vortex pair is formed asymmetrically to the spanwise direction behind the hill. Further, an asymmetrical hairpin vortex is periodically generated downstream. The leg of the asymmetrical hairpin vortex precedently collapses at the high speed side. Further downstream, the asymmetrical hairpin vortex breaks down more early than the symmetrical hairpin vortex, and the streamwise vortices appear at the high speed side. These streamwise vortices increase the heat transfer downstream. In contrast, the hairpin vortex does not appear for the case of the strong shear velocity distribution, but a streamwise vortex appears. The heat transfer decreases downstream since the turbulence generated by the streamwise vortices is weak.

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A programmed software was developed in order to numerically simulate time variation of temperature field and snow depth fround a pipe-in-pile snow-melting system, using meteorological data. The system utilized underground piles as heat exchanger between underground soil and water flowing inside the piles. The water was pumped through heat dissipation pipes embedded beneath pavement surface, on which snow melted. Unsteady three-dimensional heat conduction was solved inside the pavement and the underground soil. On the surface, heat balance of conduction, convection and radiation was considered. Snow fall depth was estimated by rainfall weather data, ratio of snowfall to rainfall, and dry density of snowfall. For simulating snow layer, unsteady one-dimensional heat conduction was solved while incorporating partial absorption of solar radiation. Experiments for measuring time variation of temperature field and snow depth around the system were conducted for verification of the software. The obtained simulation results showed good agreements with experimental data, demonstrating utility and validity of the software.

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The conventional boundary element method (BEM) needs a domain integral in convection-diffusion analysis. This paper shows that the convection-diffusion problem can be solved effectively by using the triple-reciprocity boundary element method without internal cells. In this method, the term of convection is treated as same as heat generation, and the values of the term are interpolated by using integral equations. In this method, time-dependant fundamental solutions are used. However, the CPU time for calculation does not increase rapidly with increasing number of time steps.

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It is known that the mass transfer characteristics of gas diffusion layers (GDL) are closely related to cell performance in PEFCs. In this study, a method for measuring oxygen diffusivity of microporous media by means of an oxygen sensor based on Galvanic battery has been developed. Furthermore, it is expected to be useful for measuring oxygen diffusivity in microporous media with moisture. The oxygen diffusivity of two kinds of GDL as microporous media was evaluated. Experimental results indicate that the diffusivity of microporous media cannot be specified by porosity alone, but that another factor, such as tortuosity, might be influential.

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The effect of electric field on behavior of the interface of stratified water and silicone oil has been studied experimentally. A positive plate electrode of 80×80mm², apart 30-80 mm from the interface, is installed in the oil located on water, and negative one in water. The interface becomes unstable by applying high voltage between electrodes, and the waves on the interface are generated. The drops are generated from the wave above a certain applied voltage. The phenomena of wave generation and drop formation are taken with the high-speed video camera, and analyzed. As a result, the range of an applied voltage to generate the drop exists when the distance from liquid-liquid interface to the positive plate electrode is more than 30mm. Two types are admitted in the drop formation from the waves, and great difference is seen by the type in wave hight and drop diameter. One may have the same mechanism similar to an electrostatic atomization that makes drops of small diameter. For another one, cone-wise waves expanded by the influence of the electric field become unstable, and collapse to make drops of larger dimeter. It is clarified that the wave height expands when two or more waves are composed in the electric field.

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The effects of nozzle contraction ratio on the flow and heat transfer characteristics of orifice impinging jet are investigated experimentally. The nozzle diameter is d_o=10.0mm=const., and the contraction ratio CR= (d_o/d_i) ², where d_i is pipe diameter, and the nozzle-plate distance are changed CR=1.00 to 0.11 and H/d_o=2.0 to 5.0, respectively. The Reynolds number based on d_o is Re=15000 =const. The flow characteristics are made clear by measurements of pressure and velocity distributions on the plate and flow visualization. The Nusselt number obtained by the measurements of temperature distribution on the plate for the orifice impinging jet of CR=0.11 and 0.69 were 19% and 9% higher than those of the pipe impinging (CR=1.00), respectively, because the centerline velocity of the orifice jet is larger than that of the pipe jet. Under the same operation power an orifice impinging jet has an enhanced heat transfer characteristics.

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We have separately evaluated the contact resistance, and the charge and mass transfer resistances under the channel and rib of the cathode separator in a polymer electrolyte fuel cell (PEFC) from the change of the overpotentials by removing the gas diffusion layer (GDL) under the channel. As a result, we find the ratios of current under the rib and channel for the case of the rib having the width of 2 mm. In contrast to the case of the rib having the width of 1 mm in our previous paper, the current ratios of them are almost the same when air is supplied into the cathode because the mass transfer resistance under the rib is large in the present case. On the other hand, when pure oxygen is supplied to decrease the mass transfer resistance under the rib, 80-90% of the current is generated under the rib as the case of the rib of 1 mm width. Thus the contribution of the mass transfer resistance to the current that is equivalent to the reaction rate becomes large under the rib as the width of the rib increases. The contact resistance is also found to largely contribute to the reaction rate under the channel.

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Dissociation phenomena of gas molecule on metal surface was analyzed by Molecular Dynamics Method. Platinum (111) surface and hydrogen were chosen to be the metal surface and the gas molecule, respectively. Embedded Atom Method was used as the interaction between the surface and the atoms in order to express the dependence of electron density. The parameters were determined so that the results such as the electron density, adsorption energy of an H atom on a Pt (111) surface and the interaction between H atoms of an H₂ molecule obtained by EAM method were consistent with that obtained by Density Functional Theory or empirical function. Collisions of a hydrogen molecule with a Platinum surface were simulated by Molecular Dynamics method and the dissociation probability was obtained. Using the results, effect of motion of the surface atoms or the hydrogen molecule on the dissociation probability was analyzed.

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In order to reduce CO₂ emission from combustion systems with fossil fuel, it is necessary to increase thermal efficiency of them. Heat recovery from flue gas is very effective in increasing thermal efficiency of a small furnace. Through this heat recovery, temperature of flue gas decreased with increasing a recovery amount of heat. It is feared that a decrease of temperature newly causes secondary condensed particles in a stack, and these particles become a problem in future. In this study, therefore, particulate matters (PM) in a flue gas stream from a spray combustion furnace were sampled and their compositions and size distributions were measured. As the result, it was shown that the mass of volatile matters in PM and the number of particle gradually increased along the stack. It was found that, moreover, the condensation of volatile matters probably occurred under the condition that flue gas temperature was below 460°C. From these results, it was clear that secondary condensed particles were formed in the stack.

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Flame structure of diffusion-controlled semi-spherical flame (we call “microflame”) is investigated numerically with Cl chemistry reaction model. Axisymmetric 2-D mass/heat transport processes and chemical processes (including elementary reaction steps) are considered in this study. Heat conduction and surface radiation of the burner is taken into account to predict the thermal interaction between burner and flame. Effects of thermal condition of the burner wall, preheat and flame orientation (normal and inversed direction) on flame size are discussed. Flame structures indicate that apparent flame base is formed and fuel conversion from CH₄ to CO and H₂ occurs in the fuel side. It is found that the key reaction at flame base is the chain branching reaction (H+O₂→OH +O), and most of other important reactions contributed on flame miniaturization are triggered by this reaction. Fuel preheating is naturally involved due to the thermal input from both radial and axial direction. Preheating oxidizer is much effective for the miniaturization through the chain branching reaction enhancement. Premixing is also powerful way to minimize the flame size. Comparison between normal and inversed microflames (jet direction is opposed/concurrent to the gravity vector) shows that flame base structure and mechanism are essentially held irrespective of the flame orientation.

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Velocity measurements in cylindrical combustion furnaces have been conducted to clarify the effect of flow field on the emission index of NO_x, EINO_x. Propane jet nonpremixed flames were formed on a fuel nozzle surrounded by two air nozzles. The EINO_x roughly decreases with the global equivalence ratio φ, the inner diameter of the furnace D₁, and the turbulence at the flame boundary created by the air velocity difference ΔU_a. Distributions of velocity obtained by LDV measurements have verified a large vortex at the bottom of furnace, leading to the entrainment of burned gas to the flame. The size and strength of the vortex are increased by the turbulence at the flame boundary. The recirculation vortex becomes larger in the axial direction with the increases in φand D₁. The increase in φ induces the decrease in the oxygen concentration of the burned gas. Consequently, the decrease in EINO_x with these parameters has been caused by the dilution of flame by the burned gas entrained by the recirculation vortex and by the flame stretch attributable to the turbulence increased with ΔU_a and φ.

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Accuracy of an injection rate measurement of a gaseous fuel injector was improved by modification of equations and static pressure correction. A production gaseous fuel injector for an NGV (Natural gas vehicle) was used, which is for an intake port fuel injection. The injection pressure was set at 255 kPa (g), and the injection duration was varied from 5 to 20 ms. Nitrogen gas was used as the test gas. The test gas was injected into a pipe from the injector, and the static pressure history was acquired with a piezoelectronic pressure transducer. One-dimensional, compressible, inviscid, adiabatic flow was assumed, and the instantaneous mass flow rate inside the pipe was estimated using newly modified equations. The pressure gradient due to pipe friction was corrected using Darcy-Weisbach equation. By integrating the injection rate during the injection duration, the total amount of mass flow per one stroke was calculated. The data obtained by the injection rate meter are compared to that of the calibration test, and it is shown that the injection rate measurement was carried out within the error of 2 to 3%

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Injection rate of a gaseous fuel injector was calculated by measuring the needle valve lift history. In our lab, a gaseous fuel injection rate meter using 1-dimensional pipe flow was developed. In the present study, the measurement accuracy of the injection rate meter was examined by comparing the theoretical injection rate estimated from the needle valve lift history. The needle valve lift was measured using an optical method. A small beam cut plate is attached to the needle valve of the gaseous fuel injector. A laser beam passes through the beam cut plate, and the variation of the beam intensity was measured with a photo sensor. From the beam intensity, the needle valve lift history was estimated. One-dimensional, compressible, inviscid, adiabatic flow was assumed, and the instantaneous mass flow rate through the needle valve sheet, the injector sack, and the injection hole was estimated. The estimated injection rate was compared with that obtained with the gaseous fuel injection rate meter. The estimated and measured injection rates agree relatively well even at transient duration. It is shown that the injection rate meter has high reliability and accuracy.

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In a DI diesel engine, reducing the compression ratio is effective to reduce smoke emissions without deterioration of NO_x and thermal efficiency. However, with lower compression ratios, a low coolant temperature, or during the transient state, THC emissions significantly increase when using ordinary diesel fuel. The THC emissions during increasing loads significantly increased to very high concentrations from just after the start of the load increase until around the 10th cycle, rapidly decreased until the 20th cycle, and then gradually decreased to a steady state value after 1000 cycles. The dominant components present in the THC transient spike were lower hydrocarbons with carbon numbers around or below eight. In particular, ethylene showed a much higher concentration than the other components. In fully-warmed steady state operation with a compression ratio of 16 and diesel fuel, THC is reasonably low, but THC increases with lower coolant temperature or during the transient period just after increasing the load. This problem can be eliminated with a low distillation temperature fuel such as normal heptane. Benzene, butadiene, and other unregulated harmful emissions also increase under the high THC conditions with diesel fuel.

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The objective of this study is to obtain a strategy for selecting the combination of injection conditions and combustion chamber geometry to achieve low emissions with high thermal efficiency in direct-injection PCCI operation of a diesel engine. To this end, an experimental study was conducted using a single-cylinder test engine equipped with a common-rail injection system and a cooled EGR system. The injection conditions, including injection timing, spray angle and injection quantity, and combustion chamber geometry were varied under a reduced compression ratio and a high EGR rate conditions. The results indicate that CO emission can be reduced by selecting injection timings that provide high peak heat release rate. To improve the CO-NO_x trade-off relation, the spray angle should be properly selected depending on the combustion chamber geometry.

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Hydrogen has a potential alternative to conventional hydrocarbon fuels, because no CO₂ is emitted followed by combustion and it is able to make it by electroanalysis of water. This study aims to obtain stable ignition timing and combustion processes of hydrogen when it is applied into the direct-injection diesel engine. This report, it thought about the influence of the ambient conditions on the auto-ignition and combustion behavior of the hydrogen jet was investigated with a rapid compression and expansion machine (RCEM). First, the ambient temperature in combustion chamber is raised by adding argon into the ambient gas. Second, that is raised through the oxidation process of lean DME mixture. In addition, the effect of intermediates of DME reaction on the autoignition of hydrogen jet was investigated by use of CHEMKIN III code. Moreover, this effect was experimentally clarified.

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This study experimentally deals with turbulent flow inside transverse-or angled-rib-roughened square two-pass channel in stationary condition. Details of the two-dimensional flow field were quantitatively measured by using a particle image velocimetry to which was applied Frame-staddling method with high-resolution CCD camera. Angled-ribs generated secondary flow along the rib, flow separation, and reattachment similar to the transverse-rib case. A secondary flow of turning flow caused by a centrifugal force in a sharp turn was stronger than that caused by the angled ribs. Furthermore, the interference between the secondary flow by the sharp turn and the angled ribs was observed and high turbulence intensity between the ribs and after the sharp turn as a result of highly fluctuating unsteady fluid motion was clearly captured.

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The adsorption refrigerator makes waste heat a useful energy source. Therefore, it is effective for improvement in energy efficiency. We proposed a multistage adsorption system, which makes it possible to bring out useful performance even under the high ambient temperature. In the previous report, the authors examined the effect of adsorption isotherm line shape. We proved it is possible to increase performance from between 2% to 40% with applying mesoporous silica, FSM-C10. In particular, it can be expected to observe the greatest effect at an ambient temperature of around 45°C.

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The adsorption refrigerator makes waste heat a useful energy source. Therefore, it is effective for improvement in energy efficiency. We proposed a multistage adsorption system, which makes it possible to bring out useful performance even under the high ambient temperature. In the previous report, the authors decided the optimal number of stages by the simulation and the experiment. In this paper, the effect of a performance of a system changing the weight ratio of the silica-gel was studied by the simulation. It was clarified that the performance was improved by 4% with increasing the ratio of adsorption weight on the low temperature stage.

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