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Publishing type：Research paper (scientific journal)   Publisher：SAGE Publications  

In automatic transmissions, hydraulic oil in the oil sump is strongly agitated by gears during operation; thus, the oil is mixed with great amounts of air. Air-mixed oil is sucked and discharged by a hydraulic pump to shift the gears. Although air bubbles mixed in the oil may affect the behavior of the rotors, driving torque, and discharge flow rate, they have hardly been measured. In this study, we measure them using a balanced vane pump and a gerotor pump used for automatic transmissions under varying air bubble contents and operating conditions. The experimental results revealed that the inclusion of air bubbles in the oil somewhat influenced the rotor behavior of both test pumps but it did not seem to increase the contact between the rotor and the surrounding stationary parts. Furthermore, as the bubble content increased, friction torque decreased to some degree, while discharge flow rate decreased to a great degree. This work proposed a new friction torque model, in which bubble content is included as a parameter, and the proposed model demonstrated relatively good agreement with the measured friction torque characteristics. The results also revealed that the rotor behavior and friction torque characteristic were mainly affected by bubble content and less so by bubble size.

DOI： 10.1177/09544062241236086

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Other Link： http://journals.sagepub.com/doi/full-xml/10.1177/09544062241236086

Publishing type：Research paper (scientific journal)  

DOI： 10.1063/5.0193029

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.ijthermalsci.2023.108652

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Language：Japanese   Publisher：Japan Solar Energy Society  

<p>The research purpose is to build a system for collecting and transporting solar heat without electricity using LHPs. The LHP evaporator needs to accommodate multiple tilt angles so that solar heat collection can be maximized. Experiments were therefore conducted with a prototype using a heater as an alternative heat source and varying the tilt angle of the evaporators. As a result, the LHP operated at all evaporator angles. Heat transport to the condenser was observed when the evaporator angle was 15°. However, no heat transport to the condenser was observed at other angles. Since large heat leakage occurs inside the wick, insulation between the vapor and liquid in the evaporator and the atmosphere must be improved.</p>

DOI： 10.24632/jsesc.2023.0_243

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

In this study, simulations based on the three-dimensional compressible Navier–Stokes equations were conducted to clarify a control method with a plasma actuator to reduce the acoustic power loss in the oscillatory flow under acoustic excitation (acoustic oscillatory flow) in a curved duct. The acoustic power loss for the curved duct exceeds that for the straight duct, particularly at a high acoustic Reynolds number based on the amplitude of the velocity fluctuations in the duct. Flow control by a plasma actuator, which was installed near the curvature in the straight section, was applied to suppress the periodically occurring flow separation around the curvature, which leads to energy loss in the baseline flow. The plasma actuator was intermittently driven at the same frequency as the acoustic oscillatory flow. It was thus demonstrated in the present numerical simulations that the acoustic power loss around the curvature was reduced by the flow control with the plasma actuator. Furthermore, efficient control conditions for the number of plasma actuators and the driving voltage are discussed considering the power consumption of the plasma actuator, although the power efficiency of the control needs to be improved for actual application. Moreover, the relatively effective intermittent control conditions of the phase and duty ratio for the reduction of acoustic power loss are presented with the predicted flow fields around the curvature.

DOI： 10.1016/j.apacoust.2023.109274

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1109/TIA.2022.3233558

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>Loop-Heat-Pipes (LHPs) are promising for cooling of electric devices in spacecraft. However, the LHP operation must be shut down in some cases (e.g., lunar rover on cold nights) to avoid overcooling or reduce heater energy consumption. In this study, we placed an electrohydrodynamic (EHD) conduction pump in the liquid line of the LHP, which operates against the normal LHP flow. The pressure generated by the EHD pump overcomes the capillary pressure developed in the evaporator, then LHP operation stops. An EHD conduction pump was developed and evaluated to demonstrate our approach. As a result, the LHP was shutdown successfully when an appropriate high voltage was applied to the EHD pump, and the shutdown continued until applied voltage to EHD pump has decreased.</p>

DOI： 10.1299/jsmeted.2023.c114

CiNii Research

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.ijheatmasstransfer.2022.123137

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Language：Japanese   Publishing type：Research paper (scientific journal)  

For a small axial fan in a duct, the effects of acoustic resonance occurring in the duct on the flow around the fan are focused on. To clarify the condition for the intense acoustic resonance, the effects of the rotational speed and duct width on the flow and acoustic fields around the fan were investigated by compressible flow simulations with a volume penalization method. The computational methods were validated by comparing the predicted static pressure rise and aerodynamic sound by the fan with those measured. The sound pressure level became most intense for a specific rotational speed, where the acoustic resonance occurs at the blade passing frequency in the upstream duct. Although the overall tendency of the increase in the static pressure coefficient was found for a higher rotational speed with the thinner momentum thickness around the blade surface, the static pressure coefficient drops at the rotational speed for the acoustic resonance. Moreover, the acoustic resonance became more intense for a narrower duct width. In this condition, flow disturbances occur near the wall of the bell-mouthed inlet of upstream duct due to the acoustic resonance, which prompts the inflow turbulence to the fan. To clarify the effects of the acoustic resonance on the flow around the fan, the computation with the artificially suppressed acoustic resonance was also performed and the predicted flow fields were compared with those with intense acoustic resonance for the same rotational speed and duct width. The incoming flow to the fan is confirmed to become more turbulent when the acoustic resonance occurs, which promotes the spreading of the tip vortices between rotor blades. As a result, the blade loading decreases and the turbulence in the blade wake leading to mixing loss becomes intense, causing the static pressure rise by the fan to decrease.

DOI： 10.1299/transjsme.22-00044

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Computations of coupled phenomena between the fluid and acoustic interactions in the cavity flow and heat conduction in the flat plates (stack) installed in the cavity were performed to investigate the flow conditions for an effective thermoacoustic heat pump driven by acoustic radiation in cavity flows. This research presents the first computational approach for an aeroacoustically excited thermoacoustic heat pump. The effects of the freestream Mach number on the thermoacoustic heat pump were investigated by conducting computations with Mach numbers 0.087 and 0.26, where intense self-sustained oscillations occurred. Sound pressure levels of the cavity tone and power of the related velocity fluctuations in the shear layer were reduced by the installation of the stack compared with the cavity flow without a stack, particularly at a lower Mach number. A steeper temperature gradient along the stack was acquired at a higher Mach number, and thermoacoustic heat pump effects were confirmed in the predicted acoustic oscillatory flow between the stack plates. The computational results present that the interaction between the recirculation flows in the cavity and the stack cause the heating of the flow around the cold top end of the stack. The thermoacoustic heat pump effects are reduced due to the interaction. The present computational method is expected to be useful for investigating the utilization of aerodynamical sound energy through conversion to heat energy. (c) 2021 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijheatmasstransfer.2021.122424

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：ターボ機械協会 ; 1973-  

CiNii Books

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

In a cavity flow with acoustic radiation, self-sustained oscillations are controlled by a continuously or intermittently driven plasma actuator with elongated electrodes in the streamwise direction, which induces spanwise non-uniformity of the incoming boundary layer. To evaluate the control effects, wind tunnel experiments and compressible flow simulations were conducted. As indicated by sound pressure measurements at the fundamental frequency, the sound reduction level afforded by the intermittent control may be higher than that provided by the continuous control, although both have the same power consumption. In particular, the sound reduction was highest at a certain intermittent frequency (i.e., effective frequency) under a constant driving voltage and duty ratio. To clarify the mechanism for the influence of the intermittent frequency on the control effects, the time variation of the incoming boundary layer and cavity flow during the intermittent period was investigated. The oscillations remained weak under the control of the effective intermittent frequency, while the attenuation and amplification of the oscillations were repeated in the actuator-on and actuator-off durations, respectively, under the control of intermittent frequencies lower than the effective frequency. The amplification rate of the oscillations was found to be correlated with the quality factor of the radiated sound without control. The relationship between the effective frequency and characteristic time for this amplification is also discussed in this paper.

DOI： 10.1063/5.0017658

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASME International  

<title>Abstract</title>
Small axial fans are used for cooling electronic equipment and are often installed in a casing with various slits. Direct aeroacoustic simulations and experiments were performed with different casing opening ratios to clarify the effects of the flow through the casing slits on the flow field and acoustic radiation around a small axial fan. Both the predicted and measured results show that aerodynamic performance deteriorates at and near the design flow rate and is higher at low flow rates by completely closing the casing slits compared with the fan in the casing with slits. The predicted flow field shows that the vortical structures in the tip vortices are spread by the suppression of flow through the slits at the design flow rate, leading to the intensification of turbulence in the blade wake. Moreover, the pressure fluctuations on the blade surface are intensified, which increases the aerodynamic sound pressure level. The suppression of the outflow of pressurized air through the downstream part of the slits enhances the aerodynamic performance at low flow rates. Also, the predicted surface streamline at the design flow rate shows that air flows along the blade tip for the fan with slits, whereas the flow toward the blade tip appears for the fan without slits. As a result, the pressure distributions on the blade and the torque exerted on the fan blade are affected by the opening ratio of slits.

DOI： 10.1115/1.4047807

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers ({IEEE})  

DOI： 10.1109/TIA.2019.2951119

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

The heat and mass transfer in a loop heat pipe evaporator with microgrooves are investigated in a three-dimensional numerical model. The design of the microgroove wick must consider the pressure loss of the vapor. The simulation obtains the detailed pressure distribution of the vapor flow in the grooves. The simulated heat flux distribution in the evaporator revealed that the applied heat flux concentrates along the three-phase contact line (TPCL) within the casing, wick, and grooves. The effect of TPCL length was investigated in three microgroove wicks with circumferential and axial grooves and a classical wick with only axial grooves. The heat-transfer coefficient initially increased with TPCL length increasing, but thereafter decreased because when the TPCL becomes too long, a large pressure loss occurs in the grooves. The developed model was validated experimentally. In both the model and experiment, the heat-transfer coefficient was locally maximized at a certain TPCL length. The proposed method is expected to provide a simple approach for wick design; especially, the wick shape can be optimized merely by varying the TPCL length. The effect of thermal conductivity of the wick material is also discussed.

DOI： 10.1299/jtst.2020jtst0034

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.1109/IAS44978.2020.9334813

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

DOI： 10.1016/j.tsep.2019.03.022

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Nature  

DOI： 10.1007/s12217-018-9668-8

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier Masson SAS  

The liquid–vapor phase distribution and displacement in the capillary evaporator of a loop heat pipe (LHP) are key phenomena affecting the steady-state and transient operating behavior. This study conducts optical observation of liquid–vapor phase behavior in the evaporator using a transparent glass tube heated by far-infrared radiation during start-up of the LHP. A quartz wick-acetone LHP system is designed, fabricated, and operated successfully with a heat flux of 1 W/cm2 transported by the cylindrical evaporator. To investigate effect of the liquid–vapor phase distribution in the evaporator at the initial state, start-up experiments with eight phase patterns—which are either liquid-saturated or two-phase in each of the inlet of the vapor line, grooves, and compensation chamber (CC)—are performed. The phase distribution affects the temperature profile although it has no effect upon the steady-state characteristics, and nucleate boiling occurs in the wick or groove simultaneously with evaporator-temperature drop when both the grooves and the inlet of the vapor line are completely filled with liquid. Liquid–vapor displacements from start-up to the steady-state are classified into four transient behaviors, which include boiling in the CC and meniscus oscillation at the three phase contact line within the case, wick, and groove.

DOI： 10.1016/j.ijthermalsci.2018.03.023

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

This paper reports a numerical investigation into the effects of interactions between two mechanisms of charge injection and dissociation on overall Electrohydrodynamic (EHD) pump characteristics. The following three types of electrode configurations are modeled: a plate and a bar, two plates on a channel wall, and embedded two-plate electrodes. The simulation results show that when the both mechanisms act in concert, the total developed pressure is augmented to be larger than the sum of the pressures developed by each mechanism separately. The degree to which the pressure is synergistically augmented depends on the configuration of electrodes.

DOI： 10.1016/j.elstat.2018.04.009

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

&lt;p&gt;Liquid-vapor phase distribution and displacement in the capillary evaporator of loop heat pipes (LHP) is a key phenomenon to understand the steady state and transient behavior. However, the phenomenon has not been investigated sufficiently thus far. In this study, the liquid-vapor phase behavior on the contact surface between the wick and evaporator case at start-up is observed with a transparent evaporator case coated with an ITO heater. Visualization experiments are conducted during the LHP operation at 0.59 - 5.6 W/cm&lt;sup&gt;2&lt;/sup&gt; of heat flux applied to the evaporator. Nucleate boiling and temperature drop on the evaporator wall by superheating are observed when the grooves and vapor line inlet are initially saturated with liquid. Right after nucleate boiling, the whole surface of the wick is dried instantaneously, then liquid in the compensation chamber (CC) wets the wick. In the imbibition, two regimes where the liquid filling rate into the wick is different are found. At a high heat flux, vapor pockets are observed at the contact surface between the wick and evaporator case even in a steady state. Thermo-fluid simulations which take into account disordered porous media and effective thermal conductivity of the wick obtained from directly solving a heat conduction equation in reconstructed porous media using X-ray computed tomography are conducted. The simulation results of evaporator wall temperature and saturation at the contact surface agree with the observation at 5.6 W/cm&lt;sup&gt;2&lt;/sup&gt; of heat flux. Both simulation and observation results show residual liquid phase along the three-phase contact lines within the case, wick, and grooves.&lt;/p&gt;

DOI： 10.1299/TRANSJSME.17-00576

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

An important consideration while designing the shape of a capillary evaporator is the phase distribution in the wick. However, the distribution depends on the working fluids and porous materials. This study investigates the heat-transfer characteristics of a loop heat pipe (LHP) evaporator by using a threedimensional pore network model with a dispersed pore size wick. The simulation considers saturated and unsaturated wicks. A stainless steel (SS)-ammonia, polytetrafluoroethylene (PTFE)-ammonia, and copper-water LHP are simulated. The copper-water LHP has the highest transition heat flux to the unsaturated wick. When the optimum evaporator shape of the copper-water LHP is designed, it is reasonable to assume that the phase state is saturated. On the other hand, for the ammonia LHP design, the state is assumed to be unsaturated. Simulation results sliuw the heal-Liatisfer strut:Lute in the evaporator and indicate that the applied heat flux concentrates on the three-phase contact line (TPCL) within the case, wick, and grooves. An evaporator configuration with circumferential and axial grooves is simulated to investigate the effect of the TPCL length. Results indicate that the optimum shape can be realized by varying the TPCL length. The proposed method is expected to serve as a simple approach to design an evaporator. (C) 2017 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.applthermaleng.2017.02.050

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

This paper reports on a visualization study investigating the characteristics of the liquid vapor interface behavior on the surface of a wick in the capillary evaporator of loop heat pipes. Observations were conducted with a microscopic infrared camera and a microscope. Nine different samples simulate a part of a wick were made by two different materials: polytetrafluoroethylene (PTFE); and stainless steel (SS). First, three types of liquid vapor interface behavior are reported. They are (a) evaporation at the menisci that formed at the boundary line between the heating plate, wick, and groove, (b) evaporation at the surface of small liquid bridges through nucleate boiling at the contact surface between the heating plate and wick, and (c) evaporation at the menisci in the wick. Secondly, the effect of the groove width on the maximum heat flux and the depth of a vapor pocket in the wick are reported. It was found that, as the groove width reduced, a higher heat transfer capacity was observed in both of the materials, except in the wick that had the smallest groove width. Additionally, it was found that the wick with the smallest fin width had the greatest potential for preventing vapor pockets formation in the wick. (C) 2017 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.applthermaleng.2017.03.113

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Fluid Power System Society  

<p>This paper reports the trajectories of contaminant particles in the charge-injection type of electrostatic oil filter, and the effects of the supply flow velocity, the oil viscosity, and the filter element shape on the particle collection efficiency are investigated. The flow and electric fields in the filter are numerically simulated based on an assumption about the charge injected by the emitter electrode. Then, the particles' trajectories are calculated by numerically solving their equations of motion with different initial positions at the inlet of the filter. The simulated particle collection efficiency is compared with its measured value. The numerical results agree qualitatively with the experimental results. This particle trajectory analysis will be useful for improving the structure of the charge injection type of electrostatic oil filter.</p>

DOI： 10.5739/jfps.48.39

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Simple, lightweight electrohydrodynamic pumps having no moving parts and producing no mechanical vibration or noise can enhance heat transfer, control fluid flows, and increase drying. This paper reports a numerical investigation of electrohydrodynamic (EHD) pumps having one centrally located emitter and two collector electrodes. Results show that optimum sizes exist in the length of and spacing between the collectors. Collector electrodes with triangular cross-sections can yield better performance than those having rectangular cross-sections. The magnitude and distribution of the charge density significantly influence pump performance. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.elstat.2016.08.001

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Other Link： http://orcid.org/0000-0003-0090-6112

Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS INC  

The use of two-phase heat transfer devices using capillary action in a microscale porous structure such as a loop heat pipe (LHP) is a promising heat transport technology. This is because they have characteristics of higher heat transfer power and longer heat transport distances with no electrical power compared with conventional heat pipes. The thermal performance of an LHP is governed by the thermofluid behavior in a microscale porous structure called the wick. In this research, high-performance wicks made of polymer have been developed, and their pore distribution and permeability were evaluated. The effects of the vapor channel's shape on the loop's thermal performance have been investigated by calculation and experiment to enhance evaporator performance. A mathematical model of the evaporator considering super heat in the channel, pressure drop across the wick, and two-phase pressure loss on the boundary face between the wick and the evaporator case was newly developed. The experiment was also conducted as a function of the groove shapes. From calculations and test results, it was found that in order to increase the maximum heat transport capability and decrease the operating temperature, the groove should be well distributed.

DOI： 10.1080/01457632.2015.1098176

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Other Link： http://orcid.org/0000-0003-0090-6112

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER  

A mathematical model to investigate the heat transfer characteristics of a capillary evaporator in a loop heat pipe with a microgap between the case and the wick was developed, and the gap effect on the evaporator heat-transfer coefficient is discussed. The model was validated by comparison with experimental results obtained for a polytetrafluoroethylene ethanol loop heat pipe. Calculated and experimental results agreed well below a 100 mu m gap distance, with both approaches indicating the existence of an optimal gap between 0 and 50 mu m. We clarify why the heat-transfer coefficient had a local maximum against the gap distance. The effect of the gap is determined for a change in heat flux to the evaporator, wick shape, working fluid, and thermal conductivity of the wick. The simulation showed that an optimal gap exists on the evaporator, except for the stainless steel wick. The microgap evaporator was workable for a wick made from a low thermal conductivity material. When a microgap is introduced in the loop heat pipe, the evaporator heat-transfer coefficient can be enhanced, hysteresis of the liquid vapor interface in a porous structure can be prevented, and the evaporator thermal performance can be predicted easily. Therefore, the microgap is an effective approach for thermal performance enhancement. (C) 2015 Elsevier Masson SAS. All rights reserved.

DOI： 10.1016/j.ijthermalsci.2015.11.008

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Other Link： http://orcid.org/0000-0003-0090-6112

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.4236/JECTC.2016.62003

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Heat Transfer Society of Japan  

Heat and mass transfer of an evaporator of a loop heat pipe (LHP), which had a liquid-vapor interface inside a porous wick, was analyzed by a three-dimensional model. Pore network model (PNM) was used to simulate the two-phase flow in the porous structure with a distribution of pore radius. The calculation includes two behaviors of phase distribution in a wick: the wick saturated with liquid fully and unsaturated with liquid and vapor. The evaporator heat-transfer coefficient as a function of heat flux had local maximum. The relation between the heat-transfer coefficient and liquid-vapor phase distribution in the wick were discussed.

DOI： 10.11368/tse.23.71

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER  

A miniature loop heat pipe (LHP) with polytetrafluoroethylene (PTFE) wicks was fabricated and its evaporator thermal performance was investigated with parametric experiments. The variables considered were the clearance between the cylindrical evaporator casing and the wick, the working fluid inventory, the properties of the working fluids, and the sink temperature. Micro-gaps between the outer surface of the wick and inner surface of the evaporator casing were included in the experiments with variables of clearance to investigate their effect on the evaporator heat-transfer coefficient. Ethanol, acetone, and R134a were charged in the LHP to evaluate the effect of the properties of the working fluids. The LHP tests were conducted with several W/cm(2) of applied heat flux to the evaporator under controlled sink temperature. The clearance seriously affected the evaporator heat-transfer coefficient, with a gap of 20 mu m between the wick and casing having the best effect on the evaporator heat-transfer across a range of tested heat fluxes. The effects of the working fluid inventory and fluid properties on the evaporator heat-transfer were also clarified. Finally, the developed LHP was tested using ethanol as a working fluid under a stepwise heat load and sink temperature. (C) 2014 Elsevier Masson SAS. All rights reserved.

DOI： 10.1016/j.ijthermalsci.2014.05.016

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Other Link： http://orcid.org/0000-0003-0090-6112

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.4236/JECTC.2014.44013

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1615/HEATPIPESCIETECH.V5.I1-4.320

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST AERONAUTICS ASTRONAUTICS  

A transient mathematical model is developed to study the transient response and analyze the distribution of heat load in a loop heat pipe. The model is based on the one-dimensional and time-dependent conservation equations for heat and fluid flow. The momentum and energy conservation equations for each of the loop heat pipe components are solved. The model results are compared against the data obtained from two miniature loop heat pipes using polytetrafluoroethylene wicks, ethanol, and acetone as working fluids. The mathematical model satisfactorily predicts the dynamic behavior of the loop heat pipe unit. It is shown that the percentage of heat leak across the wick decreases and the ratio of latent heat increases with increasing heat load. Some temperature overshoots observed in the calculation results are not observed in the experimental data. When a new power is applied, no time lag is observed in the loop heat pipe response between the simulation and experimental results.

DOI： 10.2514/1.T3888

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Other Link： http://orcid.org/0000-0003-0090-6112

Language：English   Publishing type：Research paper (scientific journal)   Publisher：THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES  

A loop heat pipe (LHP) is a two-phase heat transfer device that utilizes the evaporation and condensation of a working fluid to transfer heat, and the capillary forces developed in fine porous wicks to circulate the fluid. LHPs have been gaining increased acceptance for spacecraft missions, and recently, small LHPs on the order of a few hundred watts have been investigated for this purpose. In this study, a 100W class small LHP with a polytetrafluoroethylene wick as the primary wick was designed and fabricated for thermal vacuum testing. The LHP has a thermoelectric converter (TEC) to control the loop operating temperature. The thermal vacuum test was conducted to evaluate the LHP's thermal performance under a space-simulated environment such as ultra-high-vacuum, and black body radiation, except for a gravitational effect. The loop showed large thermal hysteresis before and after the large and small head loads. The TEC was able to control the loop operating temperature with a small amount of electrical power.

DOI： 10.2322/tastj.10.pc_27

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

In this paper, fabrication and test results of a small loop heat pipe (LHP) for electric cooling over a distance of 1100mm are discussed. Poly(tetrafluoroethylene) porous material with 1.2 mu m pore radius was used as a wick material for a primary pump of the loop to satisfy in both high thermal performance and low cost. High-grade ethanol was selected as a working fluid inside the loop. The small LHP with an outer diameter of 12mm and length of 77mm of an evaporator was made of stainless steel. The vapor and liquid transport lines are 1.8mm in inner diameter and 1100mm in length respectively in order to demonstrate the long-distance heat transport in a small tube, against the frictional resistance in the loop. The start-up process was monitored with an infrared camera, and quick start-up and its stable operation after the start-up were visually demonstrated. The loop could operate up to 50W heat load with the operating temperature of around 70 degrees C in the evaporator. The thermal resistance between the evaporator and the condenser of the loop was 0.58K/W at 50 W. (C) 2011 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.50.11RF02

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Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.10

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.8

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2020.6

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.3

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2019.6

Language：English  

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Event date： 2012

Language：Japanese  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：豊橋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：豊橋  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：弘前  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：浜松  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：東京  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大宮  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：京都  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

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Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11368/nhts.2011.0.86.0

CiNii Research

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11368/nhts.2010.0.236.0

CiNii Research

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：調布  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大宮  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：相模原  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：相模原  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：高知  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：札幌  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：松山  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：English   Presentation type：Oral presentation (general)  

Venue：Charleston, USA  

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Language：English   Presentation type：Oral presentation (keynote)  

Venue：Kyoto, Japan  

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Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai, Japan  

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Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka, Japan  

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Language：English   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京  

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Language：English   Presentation type：Oral presentation (general)  

Venue：Jeju, Korea  

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Language：Japanese   Presentation type：Oral presentation (general)  

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.

DOI： 10.1299/jsmeted.2013.423

CiNii Research

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya, Japan  

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Language：English   Presentation type：Poster presentation  

Venue：Nagasaki, Japan  

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Language：English   Presentation type：Oral presentation (general)  

Venue：Hawaii, USA  

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Language：English   Presentation type：Oral presentation (general)  

Venue：Jeju, Korea  

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Language：English   Presentation type：Oral presentation (general)  

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Language：English   Presentation type：Oral presentation (general)  

Venue：Pisa, Italy  

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Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai, Japan  

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Language：English   Presentation type：Oral presentation (general)  

Venue：Kyoto, Japan  

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Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai, Japan  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：豊橋  

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