We aim to achieve high efficient of the biomass gasification power generation (BGPG) system. To achieve higher efficiency, BGPG was composed by using exergy recuperation concept. This concept can explain the potential of heat recuperation for increasing the thermal efficient. Exergy can show a barometer of the quality of energy. We used the data of gasification of four feedstocks (corn stover, switchgrass, wheat straw and wood) by the National Renewable Enegy Laboratory (NREL). The results from this study show that significant differences between the feedstocks. The target of system is as follows; Feed biomass: 126 kg-dry/h, Cold gas efficiency: 51〜63%, Energy efficiency: 26%. System are modeled with HYSYS. Primary progression, the feedstocks pass from a Dual Fluidized Bed (DFB) to a thermal cracker. This progression make the syngas(H_2, CO and CH_4) with the pyrolysis and steam reforming. Secondary progression, the side products (Char and Tar) were removed by cyclonic separator and then entered a scrubber. Finaly progression, syngas is burned in the 200kW of micro gas turbine (MGT), then exergy recuperation was performed using hot exhaust gas from MGT.

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This work presents a control strategy for the reduction of the impact of intermittent renewable sources, such as solar and wind power, in the frequency regulation of Kitami's power system, by using sodium-sulfur (NAS) batteries and a Model Predictive Control (MPC)-based control system. First, the effects of the introduction is evaluated considering the current load frequency control (LFC) capabilities and limits of Hokkaido's power system. Secondly, the proposed controller is applied to the NAS battery and high-penetration scenarios of wind and solar power are considered. Results show that the controller keeps satisfactorily the system's frequency inside permitted ranges.

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When the surface temperature of a solid is below the solidification point of water, water vapor in air condenses on the solid surface to from the frost. This phenomenon is generally known as the frost formation, and is a transient phenomenon in which both heat transfer and mass transfer take place simultaneously. In engineering, the frost formation is a process associated with such consumer products as refrigerators and heat pumps. In this study, the effect of air temperature on heat transfer with frosting phenomena under the natural convection was investigated.

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Economical CO_2 reduction will be possible to use the combination system of photovoltaic power generation (PV) and Electric vehicles (EV). In order to spread the EV, it's necessary to solve some problems, such as high energy consumption of air-conditioner. In this paper, the authors have proposed and studied an Air-conditioner Integrated Electric Vehicle (AI-EV) which is a new concept EV. The EV is installed a small engine to supply the power of air-conditioner. In addition we studied the effects of AI-EV using in the PV & EV combined system. As a result, the engine power requires below 120cc displacement. So, AI-EV can reduce CO_2 emissions by 19% and AI-EV is able to gain the cruising range twice as long as the conventional EV with the same battery capacity

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Adsorption heat pump can cool with effective use of low-temperature waste heat, and can heat up as a thermally driven heat pump. Therefore, it is the useful technology for saving energy, and it has already been commercialized. However, Adsorption heat pump isn't popular because it is large and expensive in current technology level. This study deals with an adsorption equipment which has become a bottleneck of downsizing and cost reduction in adsorption heat pump. We significantly improve performance by applying "micro-fin" technology to the adsorption equipment.

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This paper proposes a new concept of thermal switch with the electrowetting-on-dielectic(EWOD) method. The proposed thermal switch plays a role of thermal insulation and transport in the magnetic refrigeration systems and has remarkably expected features of low power consumption, high-response performance, simple structure and easy miniaturization. The experiment on the unsteady motion characteristic of EWOD-driven mercury droplets on the two-electrode type EWOD with Pt-electrode and dielectric layers of water-repellent fluorocarbon and Parylene membrane was conducted. The minimum electrical potentials required for the movement of the droplets 0.5 to 3 mm in diameter, the effect of flow channel geometry, and the relation between the contact area and moving speed of the droplets are discussed in the paper.

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Chemical heat storage has been researched as a method for utilization of low temperature heat under 150℃ In this study, focus on hydrated Na_2S (Sodium sulfide) for its high heat storage density (308 kJ/mol). We describe examining analysis method, and how shorten time of hydration/dehydration. Through this study, we got the conclusion that composite material makes dehydration time shorten for its high thermal conductivity. However, since hydration is influenced by mass transfer, the composite method does not make hydration time shorten. Consideration for method for shortening hydration time is needed.

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An experimental study was conducted on gas-liquid flow distributions in a multi-pass channel with horizontal headers and upward-flow branches. Branches of the channel were heated to simulate a real operating condition of the evaporator. The refrigerant flow was visualized under the heated condition and it was compared with the adiabatic flow. Moreover, temperature distributions of branches were measured to estimate liquid distributions to branches, and they were compared with gas-liquid distribution ratios measured in an isothermal air-water flow. The refrigerant flow characteristics under the heated condition agreed qualitatively with those observed under the adiabatic condition, and the temperature distributions of branch surfaces were consistent with the water distributions. These results mean that gas-liquid distributions measured in the isothermal air-water flow can well reproduce the refrigerant flow distributions in an evaporator under operation.

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Heat transfer enhancement of the film flow falling along vertical fluted plates is investigated in this study. We have calculated the temporal evolution of the film flow by using the CLSVOF and GF methods, and obtained the steady state film and velocity distributions. It is found that the film flow goes inside the fluted part due to the effect of the surface tension for the fluted plate and the thickness near the fluted edge is thinner. This may lead to the heat transfer enhancement. Therefore, the temperature distribution is calculated in the thermally inlet region, which corresponds to the problem of two-phase version of the well known Graetz-Nusselt's one. Finally, we will show the relation among the heat transfer, fluted geometries and the surface tension effect.

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It has been required to develop small and high efficient heat exchangers in order to manufacture high efficiency in small energy equipments such as heat pump system using CO_2 refrigerant. Thus, stacked high pressure resistance micro-channel heat exchangers have been developed. The purpose of this study is to reveal heat transfer properties of the stacked high pressure resistance micro-channel heat exchangers when water and steam are respectively supplied test fluids entrance of low and high temperature fluid with. In conclusion, it is found that the longer length of a straight section is, the smaller size of each channel and the more number of stacked layers are, the higher heat transfer rate is.

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Condensing heat transfer performance of a blazing plate heat exchanger was examined on the basis that the heat exchanger will be used as a condenser in a heat pump water heater. The effects of number of refrigerant paths and setting placement, such as a vertical placement with downward refrigerant flow or a horizontal placement, were evaluated. HFC134a was used as the refrigerant. Water was supplied to form a counterflow heat exchange. Three kinds of heat exchangers with different refrigerant paths of 6, 10, and 14 were used. Refrigerant temperatures at the exit of paths were measured by inserted thermocouples to evaluate the flow distribution. As a result, it was shown that vertical placement produced higher heat transfer rate than the horizontal placement. For the horizontal placement, heat transfer rate decreased with an increase of refrigerant channels due to uneven refrigerant distribution.

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In this study, we investigated means to improve the heat transfer performance on the water side of heat exchangers in hot-water supply systems. And we experimentally verified the pressure drop and the heat transfer in single-phase flow using a smooth tube, a helical-grooved tube, and corrugated tubes with six different corrugation shapes and outside tube diameters of 12.7 mm. The effects of the difference in corrugation pitch and corrugation depth on pressure drop and heat transfer in low flow-rate region were reported and those results clarified the optimum corrugated design.

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Experimental data and mathematical model have been used in the present analysis to understand the condensation characteristics, especially the heat transfer degradation of binary zeotropic mixtures of R1234ze(E) and R32 inside a horizontal smooth tube of which inside diameter is 4.35 mm. The variations of the mass fractions of mixtures R1234ze(E)/R32 are 0.25/0.75, 0.55/0.45, 0.75/0.25 and the variations of mass fluxes of refrigerants are 50〜400kg m^<-2>S^<-1>. The temperatures and concentrations at the bulk and interface regions are obtained to understand the heat transfer degradation due to the mass transfer resistance of both the vapor-side and liquid-side. Considering the heat transfer degradation effect, the experimental local heat transfer coefficients are predicted by the obtained interface temperatures and correlation of pure refrigerant condensation.

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A series of numerical simulations has been conducted to determine the interfacial convective heat transfer coefficient in a porous media filled with nanofluid. Numerical computations results were carried out using the microscopic governing equations based on the modified Buongiorno model. These results were integrated to obtain both interfacial convective heat transfer coefficient and Nusselt number. Substantial increase in the Nusselt number was observed for the case of nanofluid. The interfacial convective heat transfer coefficient exceeded the level expected from the increase in the effective Prandtl number.

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Nanofluid forced convection cooling and heating in a channel for hydrodynamically and thermally fully developed flow under constant heat flux was investigated analytically. Exact solutions show that the distributions of particles volume fraction, velocity and temperature for the case of heating differ substantially from those for the case of cooling. This non-similar heat transfer characteristics have been captured for the first time. Furthermore, a theoretical answer to the controversial issue on the anomalous heat transfer in nanofluids has been provided in this study. Only the solutions for the case of cooling suggest the anomalous heat transfer, in which the heat transfer rate exceeds the level expected from the increase in the effective thermal conductivity of nanofluids.

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Critical Heat Flux (CHF) is enhanced by deposited nano-particle on metal surface. So, nuclear reactor safety performance is likely to be improved by using nano-fluid. CHF enhancement by nano-fluid is unstable and enhanced mechanism is not clear. So, it is hard to use nano-fluid for nuclear reactor. Then, stabilizing and Maximizing CHF enhancement is important. In this study, experiments with various diameter and material (TiO_2, SiO_2, Al_2O_3) of nano-particle is carried out. The experimental result showed that, using 14nm(smallest size) TiO_2 particle, the CHF enhancement is higher and time scale required for CHF enhancement is shorter than other diameter and material.

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Good heat dissipation and insulating properties are required for the insulating sheet mounted on the power module. The sheet is filled with plate-like hexagonal boron nitride (BN) particles. The plate like particles can result in anisotropic thermal conductivity in the sheet, isotropic properties are ensured by orientation suppression. The application of agglomerate BN powder has been studied extensively. This study examines the relationship between orientation and powder characteristics of the agglomerate BN powder. Agglomerate BN powder with a large specific surface area, (i.e. a small particle size and aspect ratio) was most effective in improving the thermal conductivity of the insulating sheet. This is due to the high c-plane orientation suppression when using this powder.

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Two horizontal metal hydride tanks with a double coil heat exchanger that contained 50 kg of MmNi_5 metal hydride alloy with different Pressure-Composition-Temperature (PCT) isotherm properties were developed and tested in this study. One was designed for the experiments in USA and the other was designed for the experiments in Japan in which there is the high pressure gas safety act. The reaction heat recovery rates of these tanks were compared and it was confirmed that the reaction heat recovery rates were almost the same. However it could not be filled the tank up with hydrogen in the case of the Japanese specifications.

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In this study, methane steam reforming in a hydrogen separation membrane reactor was investigated experimentally. Through the permeance measurement experiments, it was disclosed that the silica membrane had H_2 permeance as high as 5×10^<-7> mol m^<-2> s^<-1> Pa^<-1>, which was 5 times as high as CO_2 permeance, under the conditions of temperature of 800℃ and of atmospheric pressure. The methane steam reforming experiments were conducted under the conditions of S/C ratio of 5 and of operation temperature of 800℃. It was clarified that methane conversion of the membrane reactor was smaller than that of the conventional reactor, but H_2 molar fraction of the membrane reactor became larger than that of the conventional reactor.

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In binary systems of hydrogen and hydrocarbons, the fluid-phase thermodynamic behavior is unique in having the divergence of the critical curves to a high pressure region. The mixing parameter of a Peng-Robinson equation of state (PR EOS) for the binary systems including hydrogen with methane, ethane, propane, and carbon dioxide were determined. The mixing parameter of the present EOS has a functional form of temperature generalized by the critical temperatures of the hydrocarbons and carbon dioxide. Based on the corresponding state principle, the coefficients of the parameter were obtained with a non-linear least squares fitting to the experimental critical points of the mixtures. The developed PR EOS shows good agreement with the experimental data of not only the critical points but also the phase equilibria.

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In this study, the reaction mechanism and growth rate of TiN film by thermal Chemical Vapor Deposition(CVD) has been investigated. A horizontal tubular reactor was used for coating of the TiN film. the growth rate increased rapidly near the reactor inlet and then it decreased exponentially along an axial position of the reactor. Although the growth rate increased with the total gas flow rate and the setting temperature, a configuration of the growth rate distribution along the axial position in the reactor didn't change. From these experimental results, it was suggested that the coating progressed successively from gas phase reaction to surface reaction.

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In this study. CaBr_2 liquid-solid hydration is applied for heat storage without heat exchanger. Two experiments of the reaction were conducted. The amount of generated vapor in equilibrium state was evaluated. The vapor was generated instantly in this reaction. The maximum vapor of 6.5 mol/L-solution could be generated. and its COP was 0.12. The regeneration of CaBr_2・2H_2O completed after 320 seconds at the temperature of 190℃ and the salt layer thickness of 1 mm. In other cases. the reaction times were all longer than that in the above condition, due to detachment of the layer from the heating surface and high thermal resistance.

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This paper presents an experimental investigation of the thermal characteristics in a layer of an exothermic powder mixture that is utilized in body warmers, hot compresses, etc. 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. This powder mixture is composed of iron powder, activated carbon powder, vermiculite and NaCl. The variation over time of the temperature distribution and the generated heat in a layer of the exothermic powder mixture is measured. Absorbent polymer and nonwoven fabric are used to control the water and oxygen volume supplied into the layer, and their effects are examined.

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In the present report, he SEMOS (Self-Excited-Mode Oscillating Flow) heat pipe of aluminum substrate made of pressed. The overall size of SEMOS heat pipe was 60mm in length, 36mm in width and 1.1mm in thickness. The working fluids were water, ethanol, R141b and n-pentane, the experiments were performed changing amount of heat transport. The result of experiment shows that in case of R141b and n-pentane the thermal resistance were 0.5K/M in the condition of amount of heat transport of 20 to 40W. Further, in the case of water the thermal resistance was 0.8K/W in the condition of amount of heat transport of 100W.

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Effect of the miniaturization in diameter on the performance of a single, straight-tube pulsating heat pipe, the diameter of the heating section of which is slightly larger than that of the heat transport tube section, is investigated experimentally. Periodic oscillation of a vapor plug with a large stroke (approximately 120mm) continues without any cease even in the case that the inner diameter of the heat transport tube is reduced to 1.6mm which is 60% that of the original model (standard one) invented by the authors. Based on the parametric study, it is suggested for realizing the stable oscillation that the pressure drop of the liquid flow through the wick inside the heating section and the imposed heat flux do not exceed threshold values. Amplitude of pressure fluctuation in the heating section and frequency of the oscillation in the miniaturized model are significantly larger than those of the original model. The heat transport rate and the effective thermal conductivity in the miniaturized model increase up to approximately 26W and 28kW/(m・K), respectively.

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Fan performance (PQ curve) of new fan suitable for narrow space is examined. To do this measurement apparatus for small fan is newly assembled. The PQ curves of thin new fan and commercial small side flow fan are measured with different upper space. As a result, the upper space of 3mm or more is required in order to give full performance of the side flow fan. When upper space is 0mm performance of side flow fan is significantly reduced. For thin new fan, it is possible to operate under the condition of the upper space of 0mm. And, with the upper space of 0mm, fan performance of new fan is higher than commercial side flow fan.

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Our study aims to apply the flow and thermal resistance network analysis (coupled network analysis) to thermal design of fan-cooled high-density packaging electronic equipment. This paper especially tried to predict a net cooling performance of the finned heat sink when there is top bypass on the heat sink by using the coupled network analysis. In order to predict an accurate cooling performance of the finned heat sink, a net flow rate between the heat sink fins has to be predicted. We developed a flow resistance network model around the finned heat sink. In order to predict a distribution of flow rate around the heat sink, both the flow resistance between the heat sink fins and the resistance of bypass were considered.

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This study describes a performance characteristic of a piezoelectric micro blower which may be available for a cooling device of portable electronic equipment. We especially focus on the investigation whether the micro blower is available for a cooling method of high-density packaging electronic equipment or not. In this paper, the effects of the obstruction, which simulates the electrical components and is mounted very near the blower, on the performance characteristic is investigated. From the experiment, it is found that the performance characteristic of the proposed micro blower is almost not changed regardless of the existence of the obstruction.

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Heat transport characteristics of liquid column oscillated forcedly in a straight channel with square cross section have been investigated. The channel wall was cooled in the inlet and heated in the end. The channel was initially evacuated, and ethanol was charged to form a liquid column, which is called single component system. In addition, the ethanol was charged in the channel with air in the gas phase at atmospheric pressure, which is called two components system. The results in single component system were compared with those in two components system. The contributions of latent heat transport and sensible heat transport are reported.

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Cooling characteristic of the thermosiphon type heat pipe with variable tilt angle is examined. Sodium myristate and potassium oleate those have good hydrophilicity and foamability are used as surfactants and added to pure water. The experimental results show reduction of thermal resistances for surfactant solutions is about 20% with concentration of 10ppm compared to pure water. Further, thermal resistance is reduced with increases in tilt angle θ. However the difference in thermal resistance between θ=30° and 60° is small compared with that between θ=0° and 30°.

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Heat-transfer characteristics of an evaporator of a miniature loop heat pipe (LHP), which had a FIFE porous wick filled with liquid fully, was analyzed on 3D. Pore network model (PNM) was used to simulate detailed liquid flow in the porous structure. Temperature and pressure fields of x-y, x-z, and y-z plane were presented. The results indicated that condensation at bottom of the grooves-wick interface occurred. The condensation behavior depended on the applied heat flux to the evaporator. The effect of the groove width on the evaporator heat-transfer coefficient and heat leak to a compensation chamber was clarified.

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This paper presents flow visualization results obtained by using open-loop pulsating heat pipe made of pyrex glass tubes. The tubes have internal and external diameter of 1.8mm and 3.0mm, and the number of turns was 10. The PHP was tested at horizontal orientation. The working fluids employed were water and 1-Butanol aqueous solution (so-called self-rewetting fluids). Flow visualization results indicate that 1-Butanol aqueous solution showed anomalous liquid film behavior when liquid slug moved from heating section to cooling section. And the interface between the liquid film and vapor plug was unsteadily ruffled. Similar tendency was observed at vertical bottom heat mode.

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In order to measure the time-dependent pressure change in Oscillating Heat Pipe, we used T-shaped glass tube as flow path, and measured surface temperatures of the glass tube and the operating pressure at the same time. We are confirmed that the frequencies of temperature and pressure oscillation are equal. Also, we tried to insert a thermocouple into flow path so as to measure the temperature of the working fluid directly. A large temperature gradient was found in the liquid column close to vapor-liquid interface, while on the other hand, temperature gradient of vapor phase is very small.

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Thermal performance of an O-shaped Oscillating Heat pipe (OHP) for balloon-borne General Anti-Particle Spectrometer (GAPS) experiment has been investigated. The developed OHP is a closed type and O-shaped for using the gravity assist. R410A is selected as the working fluid for the use at low temperatures. At -50 deg-C, we achieved a thermal conductance of 20 W/K for 150 W heat input with 32 loops and -40 deg-C heating section. We also found for the first time that this large-scale OHP can be operated at low temperatures. It is found that this OHP can satisfy the GAPS thermal control requirement.

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This study conducted experiments to measure pressure drop across a tube bank with tube-to-baffle leakage for various orifice shape factor Z and its effect upon the pressure drop through tube-to-baffle clearance and across the bank is shown. The results show that the former pressure drop for Z=29-55 behaves in a close manner whereas the pressure drop for Z=67 behaves differently from the others, implying laminar flow in the clearance. Meanwhile, it is also shown that the pressure drop across the tube bank is not affected by the Z factor. However, the pressure drop across the tube bank behaves differently when the leakage flows into or out of the tube bank through the clearance. This implies that the leakage has different influence upon the flow field between those two cases.

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The vortex generator of the trapezoidal shape is mounted on the bottom wall of the channel, their angles with respect to main flow are taken to 30°, 45° and 60° and their inclination angles with respect to bottom wall are set to 45°, 60° and 90°. The effects in the wake of VG are examined in above condition and Nusselt number, pressure drop, bulk temperature and velocity distribution are compared with the various VG conditions. In the rectangular channel, the effect of heat transfer enhancement with the trapezoidal shape fin is higher performance than with the isosceles right triangle shape one.

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Wavy-fin is used in the heat exchanger of the fuel cell for the characteristic of low-pressure resistance. The heat transfer efficiency is reduced because the heat transfer surface is contaminated by precipitates. In the heat exchanger of the fin type, the meandering channel is difficult to accumulate the sediment. But in the field to use the cooling water a lot of impurities, the heat exchanger with fins will not be able to use the channel of the heat exchanger is clogged. In this study, we investigated by changing systematically the value of the amplitude, wave length and channel pitch. As the result of this investigation, the difference of the channel shape was found to affect the heat transfer and pressure loss.

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This paper describes the three-dimensional numerical computation of viscoelastic fluid flow in a serpentine channel under low Reynolds number condition. The results showed that the main flow, at which the velocity is maximum, flows along the curvature with its position located close to the outside of the channel, particularly downstream of the curvature. This flow was generated by two pairs of longitudinal vortices like secondary flows appearing in the channel due to the normal forces of the viscoelastic fluid. The main flow will, therefore, flow from the outside of one curvature toward the outside of the next curvature in the serpentine channel. This, in combination with the normal stress distribution, accompanies a strong secondary flow of single pair of vortices in the downstream area of the channel inflection point.

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Two-dimensional jet impingement heat transfer enhanced by a square rib has been studied by direct numerical simulation (DNS) to compare predicted Nusselt number with that given by naphthalene sublimation method. In addition to Prandtl number (Pr) of 0.71 for air, Pr of 2.29 equivalent to the Schmidt number in the mass transfer experiment was selected for comparison. The DNSs with different Pr numbers give the local value of the exponent, which is assumed uniform in the conversion of mass transfer coefficient to heat transfer coefficient in the experiments. As a result, it is clarified that the local discrepancy of Nusselt number between the former experiments and simulations has come from the assumption of uniform exponent in the mass transfer experiment.

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The heat transfer of natural convection from upward-facing horizontal heated surface with a heated cylindrical pipe is investigated experimentally. The purpose of this study is to determine the relationships of the heat transfer from the horizontal heater to flow characteristics around the heated cylinder. In the case of no flow reversal and flow reversal occurred in the heated cylinder, the heat transfer showed the same tendency and increased with increasing the heat flux of the cylindrical heater. On the other hand, when flow reversal reached to the horizontal heater, the heat transfer decreased with increasing the temperature in the cylindrical heater.

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In this paper, the turbulent natural convection for parallel plates was calculated by Large Eddy Simulation (LES) in order to clarify the thermo fluidic characteristics of turbulent natural convection between the heated vertical parallel plates. LES with the dynamic Smagorinsky model was selected for the turbulent model. Velocity and temperature fields were analyzed and the local heat transfer rate of each modified Rayleigh number was compared to that of the single vertical case. In addition, the averaged heat transfer rate was estimated with each modified Rayleigh number and compared to the laminar natural convection of parallel plates.

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Unsteady measurement of convective heat transfer was performed to a water flow in a horizontal circular pipe using a high-speed infrared thermograph. The test surface was fabricated from a 22μm thick titanium foil coated with black paint. The removable turbulence promoter was attached at entrance of the pipe. From the time-series data of the heat transfer distribution, we could obtain the rms value of fluctuating heat transfer coefficient and mean spanwise wavelength of the thermal streaks and the mean period of heat transfer fluctuation.

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In general, fluctuating flow with a temperature difference causes a wall-temperature fluctuation due to the unsteady heat transfer. This effect called "unsteady conjugate heat transfer" leads to more or less an erroneous prediction of total amount of heat transfer due to the nonlinear relationship. In order to provide quantitative information on this, we tried to model the temporal fluctuation of the heat transfer coefficient caused by flow turbulence on the basis of the measured data obtained using high-speed infrared thermography. This model seems to be available to predict the conjugate effect easily by applying it as a boundary condition of a simple heat conduction simulation inside a solid wall.

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The objective of this study is to investigate an entrance region of thermal field in turbulent boundary layer having thermal stratification by means of direct numerical simulation (DNS), which conducts the spatially developing boundary layer with heat transfer using the generation of turbulent inflow data method. In this study, present DNS clearly provides a fundamental and characteristics turbulent statistics in an entrance region of thermal field in turbulent boundary layer having thermal stratification, in which four conditions of thermal stratification are set, i.e., neutral, unstable, weak stable and strong stable thermal stratifications.

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