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Natural Convection Melting in a Rectangular Heat Storage Tank of Carbon Nanotube Dispersed Latent Heat Storage Material

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Journal of Thermal Science 2024年第3期33卷 847-855页

作者： Shin-ichi MORITA Tomoya SAITO Kazunori TAKAI yasutaka hayamizu Naoto HARUKI Division of Mechanical and Electrical Engineering Kitami Institute of Technology165 Koen-choKitami-shiHokkaido090-8507Japan National Institute of Technology Yonago College4448 Hikona-cyoYonago-shiTottori683-8502Japan Okayama Prefectural University 111 KubokiSoja-shiOkayama719-1197Japan

A dispersion system fluid can convect even if the dispersoid is a solid ***,heat exchange performance can be improved while maintaining fluidity using a material with high thermal conductivity as the *** study presents the melting performance evaluation results of a latent heat storage material with a carbon nanotube(CNT)dispersion system with high thermal conductivity,which enhances the thermal conductivity of the latent heat storage material and does not limit free *** the thermal conductivity and enhancing the melting convection of the heat storage material result in increased latent heat storage *** this study,the thermal conductivity of the latent heat storage material was successfully increased by dispersing CNTs in the *** 0.1%(in mass)of multi-wall CNT(MWCNT)was dispersed in a paraffin-based latent heat storage material,the shear stress increased by 1.5 times at a shear rate of 500 s^(-1),while taking into account the potential effects of convective ***,a latent heat storage experiment was conducted in a rectangular heat storage tank using the CNT dispersion composition ratio as a parameter.A rectangular vessel with a heated vertical surface was used for the latent heat storage *** melting speed was determined by comparing the amount of latent heat stored in a CNT-dispersed latent heat storage material and a single-phase latent heat storage material *** experimental results show that the time required for the latent heat storage material to completely melt in the heat storage tank was the shortest for the single-phase latent heat storage material ***,the fastest melting progress was observed for the sample with 0.02%(in mass)MWCNT content in the melting rate range of up to approximately 40%in the *** results indicate that this phenomenon is caused by the difference in the melting rates in the upper part of the *** generated data are useful for det

关键词： latent heat storage phase change carbon nano tube free convection heat transfer

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The Study of Latent Heat Transport Characteristics by Solid Particles and Saccharide Solution Mixtures

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Journal of Thermal Science 2011年第2期20卷 155-160页

作者： Shin-ichi MORITA yasutaka hayamizu Hideo INABA Department of Mechanical Engineering Yonago National College of Technology Tsuyama National College of Technology

The purpose of this study is the development of latent heat transport system by using the mixture of the minute latent heat storage materials and the saccharine solution as medium. The experimental studies are carried out by the evaluation of viscosity and pressure loss in a pipe. Polyethylene (P.E.) is selected as the dispersed minute material that has closeness density (920kg/m3) of ice (917kg/m3). D-sorbitol and D-xylose solutions are picked as continuum phase of the test mixture. The concentration of D-sorbitol solution is set 48mass% from measured results of saturation solubility and the melting point. 40mass% solution of D-xylose is selected as the other test continuum phase. The non-ion surfactant, EA157 Dai-ichiseiyaku CO. Ltd, is used in order to prevent of dispersed P.E. powder cohere. The pressure loss of test mixture is measured by the straight circular pipe that has smooth inner surface. The measuring length for pressure loss is 1000 mm, and the inner diameter of pipe is 15mm. The accuracy of experiment apparatus for measuring pressure loss is within ±5%. The pressure loss data is estimated by the relationship between the heat transport ratio and the required pump power. It is clarified that the optimum range of mixing ratio exists over 10mass% of latent heat storage material.

关键词： Latent heat transport Heat storage Multiphase flow

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Heat Transfer Efficiency Evaluation for Outward and Inward Multi-Flame-Hole Gas Burner

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Journal of Thermal Science 2012年第2期21卷 189-195页

作者： Shin-ichi MORITA yasutaka hayamizu Takashi KATAYAMA Hideo INABA Department of Mechanical Engineering Yonago National College of Technology 4448 Hikona-cho Yonago city Tottori 683-8502 Japan Department of System Production Engineering Yonago National College of Technology Advanced Course 4448 Hikona-cho Yonago city Tottori 683-8502 Japan Tsuyama National College of Technology 624-1 Numa Tsuyama city Okayama 708-8509 Japan

The purpose of this study is to understand the factor that influence the heating efficiency of the outward and inward multi-hole gas burner. The flame-hole angle and the distance from flame hole to heating object are chosen as the experimental parameters. The measurement of the flame temperature distribution is carried out on each experimental condition. The observation of combustion flame, by the Schlieren method, is done from the purpose to understand the combustion phenomenon on the heating efficiency. LPG (Liquefied petroleum gas) is used for the test fuel gas. The compositions of LPG are propane 97.5vol%, butane 0.2vol% and methane + ethylene 2.3vol%. The optimum ranges of the flame-hole angle and the distance from flame hole to heating object are clarified. The experimental correlation equations for the outward and inward multi-flame-hole gas burner are proposed.

关键词： Burner Heat Transfer Design Thermal Efficiency Energy Saving

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Experimental Study of the Flow in Helical Circular Pipes:Torsion Effect on the Flow Velocity and Turbulence

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Journal of Thermal Science 2008年第3期17卷 193-198页

作者： yasutaka hayamizu Kyoji YAMAMOTO ShinichiroYANASE Toru HYAKUTAKE Toru SHINOHARA Shinichi MORITA Department of Mechanical Engineering Yonago National College of Technology Graduate School of Natural Science and Technology Okayama University

An objective of the present paper is to experimentally clarify the torsion effect on the flow in helical circular pipes. We have made six helical circular pipes having different pitches and common non-dimensional curvature δ of about 0.1. The torsion parameter β0, which is defined by β0 = τ/（2δ）1/2 with non-dimensional torsion r, are taken to be 0.02, 0.45, 0.69, 1.01, 1.38 and 1.89 covering from small to very large pitch. The velocity distributions and the turbulence of the flow are measured using an X-type hot-wire anemometer in the range of the Reynolds number from 200 to 20000. The results obtained are summarized as follows： The mean secondary flow pattern in a cross section of the pipe changes from an ordinary twin-vortex type as is seen in a curved pipe without torsion （toroidal pipe） to a single vortex type after one of the twin-vortex gradually disappears as β0 increases. The circulation direction of the single vortex is the same as the direction of torsion of the pipe. The mean velocity distribution of the axial flow is similar to that of the toroidal pipe at small β0, but changes its shape as β0 increases, and attains the shape similar to that in a straight circular pipe when ,β0 = 1.89. It is also found that the critical Reynolds number, at which the flow shows a marginal behavior to turbulence, decreases as ,β0 increases for small ,β0, and then increases after taking a minimum at ,β0 ≈ 1.4 as ,β0 increases. The minimum of the critical Reynolds number experimentally obtained is about 400 at ,β0 ≈ 1.4.

关键词： Helical Circular Pipe Torsion Effect Critical Reynolds Number Turbulence

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Experimental Study on Latent Heat Storage Characteristics of W/O Emulsion-Supercooling Rate of Dispersed Water Drops by Direct Contact Heat Exchange

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Journal of Thermal Science 2013年第2期22卷 145-151页

作者： Shin-ichi Morita yasutaka hayamizu Akihiko Horibe Naoto Haruki Hideo Inaba Department of Mechanical Engineering Yonago National College of Technology Graduate School of Natural Science and Technology Okayama University Tsuyama National College of Technology

Recently, much attention has been paid to investigate the latent heat storage system. Using of ice heat storage system brings an equalization of electric power demand, because it will solved the electric -power-demand-concentration on day-time of summer by the air conditioning. The flowable latent heat storage material, Oil/Water type emulsion, microencapsulated latent heat material-water mixture or ice slurry, etc., is enable to transport the latent heat in a pipe. The flowable latent heat storage material can realize the pipe size reduction and system efficiency improvement. Supercooling phenomenon of the dispersed latent heat storage material in continuous phase brings the obstruction of latent heat storage. The latent heat storage rates of dispersed water drops in W/O (Water/Oil) emulsion are investigated experimentally in this study. The water drops in emulsion has the diameter within 3 ~ 25μm, the averaged water drop diameter is 7.3μm and the standard deviation is 2.9μm. The direct contact heat exchange method is chosen as the phase change rate evaluation of water drops in W/O emulsion. The supercooled temperature and the cooling rate are set as parameters of this study. The evaluation is performed by comparison between the results of this study and the past research. The obtained experimental result is shown that the 35K or more degree from melting point brings 100% latent heat storage rate of W/O emulsion. It was clarified that the supercooling rate of dispersed water particles in emulsion shows the larger value than that of the bulk water.

关键词： Heat Storage Latent Heat W/O Emulsion Direct Contact Heat Exchange

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Experimental Study of the Viscous Pump with a Helical Channel Rotor:Torsion Effect of the Channel

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Journal of Thermal Science 2010年第2期19卷 154-159页

作者： yasutaka hayamizu Kyoji YAMAMOTO Shinichiro YANASE Toru HYAKUTAKE Shinichi MORITA Shigeru OHTSUKA Department of Mechanical Engineering Yonago National College of Technology4448 Hikona-choYonago-shiTottori 683-8502 Graduate School of Natural Science and Technology Okayama University3-1-1 TushimanakaOkayama-shiOkayama 700-8530

The viscous pump,which has a rotor with a helical square channel,is studied *** non-dimen-sional channel curvature is taken to be about *** types of torsion of the channel are made to investigate the torsion effect on the flow *** measure the flux through the channel at a constant rotor speed by changing the pressures at the entrance and exit of the *** also observe the secondary flow at a cross-section of the *** of the results obtained are shown as follows:The friction factor along the channel to get the same flux is large for large channel torsion at a constant rotation,and becomes small when the favorable rotation of the rotor to the flow is *** for the secondary flow in a cross-section,there appear several types of *** there is no rotation,the secondary flow is almost a symmetric two-vortex type for small flux as is the ordinary Dean vortex,but it changes to a four-vortex type when the flux is *** secondary flow becomes asymmetric as the rotation is *** have unsteady flow patterns at large flux and rotation.

关键词： Viscous Pump Helical Channel Torsion Effect Secondary Flow Flow Visualization Dean Number Taylor Number

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Study of Cycle Output Improvement by Work-Fluid Including Phase Change Material

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Journal of Thermal Science 2016年第6期25卷 558-563页

作者： Shin-ichi MORITA Kota TANIMURA yasutaka hayamizu Takanobu YAMADA Akihiko HORIBE Naoto HARUKI Toshiaki SETOGUCHI Department of Mechanical Engineering National Institute of TechnologyYonago College Three S Techno Corporation Tottori factory Department of Mechanical Engineering Kitami Institute of Technology Graduate School of Natural Science and Technology Okayama University Department of Advanced Technology Fusion Saga University

This paper deals with the output improvement of heating and cooling cycle by using the work-fluid including phase change *** experimental study is carried out by heat exchange between work-fluid and heat transfer *** work-fluid is flown to a high temperature or a low temperature heat transfer surface from the narrow *** order to increase the amount of the heat transmission,a trace of Diethylether(boiling point 34.8 ℃),as a phase change material(PCM),is added to the *** parameters of the experiment are additive amount of PCM,the rotational speed of the displacer piston and the temperature of heat transfer *** is clarified that the increasing of engine cycle output is brought by the PCM *** effect of PCM addition is evaluated by output ratio which is defined from the experimental cycle output *** requirements for acquiring the increasing effect of output by adding PCM are clarified.

关键词： heating boiling adding cycle piston clarified narrow additive brought reaches

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Structure of Periodic Flows through a Channel with a Suddenly Expanded and Contracted Part

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Open Journal of Fluid Dynamics 2023年第S1期13卷 232-249页

作者： Takuya Masuda Toshio Tagawa Miah Md. Ashraful Alam yasutaka hayamizu Department of Integrated Engineering National Institute of Technology Yonago College Tottori Japan Department of Aeronautics and Astronautics Tokyo Metropolitan University Tokyo Japan Department of Mechanical Engineering for Transportation Faculty of Engineering Osaka Sangyo University Osaka Japan

With respect to flows in a two-dimensional sudden expansion and contraction channel having a pair of cavities, numerical simulation was performed by imposing inlet/outlet boundary conditions giving a velocity distribution to the inlet. Periodic flows have been reproduced, which have a discrete spectrum about frequency. A fundamental wave occupies most part of the disturbance components, but higher harmonic waves are also included. The disturbance is excited by Kelvin-Helmholtz instability in a cavity section, where only the fundamental wave is generated. A wavenumber is regulated by a channel length under a periodic boundary condition, but there is no restriction in a main flow direction under the inlet/outlet boundary conditions, and therefore, some wavenumbers can occur. Therefore, an arbitrary frequency component of disturbance is a synthesized wave composed of various wave numbers. There are two kinds of components constituting this synthesized wave: a maximum of a velocity distribution is near a wall and in the center of the channel, which are called as wall mode and central mode in linear stability analysis of the plane Poiseuille flow. The synthesized wave composed of some modes shows a tendency to lower wavenumbers at the center of the channel.

关键词： Frequency Spectrum Harmonic Wave Number Phase Velocity Superposition Eigenfunction Profile

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Experimental Study on Latent Heat Storage Characteristics of W/O Emulsion by Ultrasonic Wave Impression

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Open Journal of Fluid Dynamics 2013年第2期3卷 48-54页

作者： Shin-ichi Morita yasutaka hayamizu Akihiko Horibe Naoto Haruki Hideo Inaba Issei Higashi Department of Mechanical Engineering Yonago National College of Technology Yonago Japan Edit Inc. Fukuoka Japan Graduate School of Natural Science and Technology Okayama University Okayama Japan Shujitsu University Okayama Japan

The flowable latent heat storage material like Oil/Water type emulsion, microencapsulated latent heat material-water mixture or ice slurry, etc., is enabled to transport the latent heat in a pipe. Supercooling phenomenon of the dispersed latent heat storage material in continuous phase is obstructed by a latent heat storage. The latent heat storage rates of dispersed waterdrops in W/O (Water/Oil) emulsion are investigated experimentally in this study. The waterdrops in emulsion have the diameter within 3 - 25 μm, the averaged diameter of waterdrops is 7.3 μm and the standard deviation is 2.9 μm. Supercooling release of waterdrops in emulsion is examined by short time impressing of the ultrasonic. The direct contact heat exchange method is chosen as the phase change rate evaluation of waterdrops in W/O emulsion. The supercooled temperature is set as parameters of this study. The previous obtained experimental result, as the condition without impressing ultrasonic wave, showed that the 35 K or more degree from melting point brings 100% latent heat storage rate of W/O emulsion. It is clarified that it is possible to reduce 20 K of supercooling degree by impressing the ultrasonic.

关键词： Heat Storage Latent Heat W/O Emulsion Direct Contact Heat Exchange Ultrasonic

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A Micromixer Using the Taylor-Dean Flow: Effect of Inflow Conditions on the Mixing

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Open Journal of Fluid Dynamics 2014年第5期4卷 463-471页

作者： Toshihiko Kawabe yasutaka hayamizu Shinichiro Yanase Takeshi Gonda Shinichi Morita Shigeru Ohtsuka Kyoji Yamamoto Technical Division Tsurumi Manufacturing Co. Ltd. Tottori Japan Department of Mechanical Engineering Yonago National College of Technology Tottori Japan Graduate School of Natural Science and Technology Okayama University Okayama Japan

Chaotic mixing in a curved-square channel flow is studied experimentally and numerically. Two walls of the channel (inner and top walls) rotate around the center of curvature and a pressure gradient is imposed in the direction toward the exit of the channel. This flow is a kind of Taylor-Dean flows. There are two parameters dominating the flow, the Dean number De (∝ the pressure gradient or the Reynolds number) and the Taylor number Tr (∝ the angular velocity of the wall rotation). In the present paper, we analyze the physical mechanism of chaotic mixing in the Taylor-Dean flow by comparing experimental and numerical results. We produced a micromixer model of the curved channel several centimeters long with square cross section of a few millimeters side. The secondary flow was measured using laser induced fluorescence (LIF) method to examine secondary flow characteristics. We also performed three-dimensional numerical simulations for the exactly same configuration as the experimental system to study the mechanism of chaotic mixing. It is found that good mixing performance is achieved for the case of De ≤ 0.1Tr, and that mixing efficiency changes according to the difference in inflow conditions. The flow is studied both experimentally and numerically, and both results agree with each other very well.

关键词： Taylor-Dean Flow Chaotic Mixing Secondary Flow LIF CFD

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