Faculty of Engineering, Okayama UniversityActa Medica Okayama0475-00712921995Numerical Study on Transient Heat Characteristics of a Rectangular Latent Heat Storage Vessel512ENHideoInabaKoichiOzakiTransient characteristics of the rectangular latent heat storage vessel packed with shape-stabilized phase change (solid-liquid) material (PCM) are investigated numerically
by solving the governing equations of both the PCM and the heat transfer medium(water) simultaneously as a conjugate problem with the finite difference technique. It's found that the heat storage characteristics are greatly affected by the flow direction of the heat transfer medium since the natural and forced convection coexists in the heat storage vessel. That is, it is classified that the effectively thermal efficiency of the latent heat storage system is obtained by the downflow along vertical PCM for heat storage process and the upflow for heat release process. The effect of the inlet velocity of heat transfer medium(water) on transient heat characteristics of the latent heat storage system is also revealed in the present study.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016605741994狭い円環状空隙に溶融プラスチックを流入させた場合の凝固特性323330ENHideoInabaHideakiIkegamiKoichiOzakiThis paper deals with solidification and flow characteristics of high-density polyethylene plastics as polymer plastics in a narrow annular cavity cooled on an inner circular tube. The experiments are carried out with various parameters (plastics temperature, flow velocity of the plastics and cooling surface temperature). The obtained results show that the solidification layer formation of polymer plastics is affected by flow behavior and viscosity of molten polymer plastics. The useful dimensionless equations for predicting the amount of polymer plastics and the time of finishing the injection of the polymer plastics into the cavity are derived as a function of Reynolds number, cooling temperature ratio and Stefan number.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016605711994ワイヤーコイルを用いた円管内熱伝達促進と流動抵抗軽減に関する基礎研究 : 第2報,ワイヤーコイルによる管内熱伝達の評価と最適配置283288ENHideoInabaKoichiOzakiShinichiKanaokaAn experimental investigation on wire-coil-inserted tubes as a turbulence promoter has been undertaken for enhancement of heat transfer and reduction of flow friction factor in water flow. The performance of wire-coil-inserted tubes has been evaluated in terms of two different criteria based on the fixed flow rate and pumping power. In order to enhance the heat transfer rate and reduce the How friction factor, some experiments have been carried out wherein coils with various lengths were partially inserted into the tube. As a result, it is noted that there is an optimum arrangement of the wire coil in the tube for the enhancement of heat transfer and the reduction of friction factor.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016605691994ワイヤーコイルを用いた円管内熱伝達促進と流動抵抗軽減に関する基礎研究 : 第1報,ワイヤーコイルによる管内流動抵抗および熱伝達特性240247ENHideoInabaKoichiOzakiShinichiKanaokaExperimental studies have been carried out on heat-transfer enhancement and flow-drag reduction in a tube by means of wire coil insert. Heat-transfer rate and pressure-drop data of tubes with wire coil inserts have been taken under various experimental conditions of wire coil diameter and pitch, water flow rate and heating-surface temperature. The performance of these tubes with wire coil inserts has been evaluated concerning the increase of heat-transfer rate and flow resistance. The useful nondimensional correlations of heat-transfer rate and flow-resistance factor have been derived as functions of Reynolds number and wire coil pitch-to-diameter ratio.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016615811995矩形流路内における溶融高密度ポリエチレンの流動・凝固現象223230ENHideoInabaKoichiOzakiHideakiIkegamiSolidification and flow characteristics of molten high-density polyethylene flowing in a rectangular cavity having a cooling wall are investigated experimentally. Experiments are carried out under various parameters of molten polyethylene temperature, flow velocity of the polyethylene, cooling wall temperature and the thickness of the cavity. The obtained results reveal that the solidification layer formation of the polyethylene is affected by flow behavior, polyethylene temperature and cooling wall temperature. The useful non-dimensional equations, which predict the amount of polyethylene and the time required for injecting the polyethylene into the cavity, are derived as a function of Reynolds number, cooling temperature ratio and Stefan number.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016595671993比較的浅い底面加熱を受ける上部開放矩形くぼみに球状粒子を一段充填した場合の共存対流熱伝達286294ENHideoInabaKoichiOzakiShigeruNozuHeat transfer measurements were performed during forced and natural mixed convections of a rectangular open cavity which was packed with spherical particles arranged in a one step orthorhombic array. Air flowing over the cavity was heated from the bottom surface of the cavity via the particle layer. Three kinds of spherical particles having almost the same diameter of 10 mm and different thermal conductivities were used as the spherical packing material. The cavity depth was varied from 0 mm (flat plate) to 10 mm. The particles suppressed the air motion near the heating surface and decreased the heat transfer coefficient. In the case of particles having large thermal conductivity, those particles behaved as an extended heat transfer surface and turbulence promoter so that the heat transfer coefficient was enhanced. The Nusselt number ratio as a dimensionless heat transfer coefficient was expressed in terms of Reynolds number, ratio of particle diameter to depth of the cavity and modified Prandtl number.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016595601993比較的大きな球状粒子を充填した下面加熱・上面冷却を受ける水平粒子層の対流熱伝達192199ENHideoInabaKoichiOzakiShigeruNozuHeat transfer and pressure drop measurements were performed in a forced convection of air flow through a rectangular duct packed with spherical particles, which had upper cooled and lower heated surfaces. Four kinds of particles with different diameters and thermal conductivities were used as the packing materials. The effects of solid boundaries on fluid motion and heat transfer were discussed. The heat transfer rate from the surfaces was promoted by a thermal dispersion effect caused by a fluid mixing motion. However, it was decreased in the vicinity of the near-wall region due to low effective thermal conductivity and weak fluid mixing motion. It was clarified that the ratio of the thermal boundary layer thickness developed from the heat transfer surfacec to the size of the near-wall region was important in order to reduce the heat transfer data. Nondimensional heat transfer correlation equations were derived, using parameters expressing the average characteristics of the porous bed packed with spherical particles.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016615891995界面活性剤添加水溶液の管内流動抵抗軽減と熱伝達206212ENHideoInabaKoichiOzakiNaotoHarukiHideakiAsanoThe reduction characteristics of flow resistance and heat transfer of water solution flow with the surfactant (Cetyltrimethyl-ammonium Bromide) in tubes were investigated experimentally. The flow resistance and heat transfer of Water solution flow with the surfactant were markedly reduced as compared with those of pure water flow. Useful nondimensional correlative equations of flow resistance and heat transfer were derived in terms of various non-dimensional parameters.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016625941996比較的浅い底面加熱を受ける上部開放矩形くぼみに球状粒子を一段充填した場合の共存対流熱伝達 : 第2報, くぼみ長さの効果330337ENKoichiOzakiHideoInabaForced-natural-mixed convection heat transfer characteristics of a one-stage spherical particle layer in an air flow are investigated experimentally. The one-stage spherical particle layer is provided in a rectangular cavity having a heating bottom surface and is installed at the lower part of a rectangular air channel. Three types of spherical particles, which have almost the same diameter (about 10 mm) but different thermal conductivities, are tested. The cavity length is varied from 19.6 mm to 90 mm, and the cavity depth is varied between 0 mm and 10 mm. The variation of the heat transfer coefficient with the length of the heating surface can be explained by the flow behavior around the particle layer ; that is, the case of the zero cavity depth, the flow is suppressed by the particles within about three rows from the leading edge. Therefore, the heat transfer coefficient increases with a derease in the length of the heating surface. In the case with a shorter heating surface (about twice the diameter of the particle), a considerable increase in the heat transfer coefficient is achieved because the flow from the upstream runs through the particle layer. In the case of the cavity depth having almost the same value as the diameter of the particles, air flows over the particle layer and air near the cavity bottom is almost still. In this case, a decrease of the length of the heat transfer surface decreases the extent of the flow in the depth direction, and the heat transfer coefficient is also decreased. The heat transfer coefficient can be expressed as a nondimensional heat transfer correlation, where the effects of the cavity length, the cavity depth, the air velocity and the temperature difference between the air and the bottom surface of the cavity are taken into consideration.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016625961996比較的大きな球状粒子を充填した下面加熱・上面冷却を受ける水平粒子層の対流熱伝達 : 第2報, 充填層厚さの影響208215ENKoichiOzakiHideoInabaConvection heat transfer and pressure drop measurements were performed with a rectangular duct, having a cooled upper and a heated lower surface, which was packed with spherical particles. Air was used as the test fluid and four kinds of spherical particles having different diameters and thermal conductivities were used as the packing materials. The ratio of the diameter of the spherical particle to the distance between the cooled and the heated surfaces, d/H, was varied from 0.173 to 1. The thermal conductivity of the particle layer was also measured under the still air condition. The thermal conductivity of the particle layer was not affected by the value of d/H. In the case of the one stage arrangement of spherical particles (d/H = 1), the flow resistance took on a remarkably small value compared with the flow resistance of a homogeneous spherical particle layer. Moreover the flow resistance of the particle layer formed with some layers of particles was able to be predicted by combining the flow characteristic of the one stage particle layer and that of the homogeneous spherical particle layer. The heat transfer coefficient of the particle layer was larger than that of turbulent air flow on a flat plate. At a constant superficial air velocity, there existed the value of d/H which gave a maximum value of the average heat transfer coefficient. Nondimensional heat transfer correlation equations were derived in terms of parameters expressing the average characteristics of the spherical particle layers.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016626031996固体境界壁近傍の影響を考慮した球状粒子充填層の強制対流熱伝達の数値解析モデルの提案172179ENKoichiOzakiHideoInabaA simple model for the heat transfer and pressure drop characteristics in a layer of spherical particles is proposed in the present study. The layer of spherical particles bounded by two parallel boundary walls is considered to consist in two regions, one of which is the near-wall region of particles within a half-diameter of the spherical particle from the wall, and the other is the core region of particles over a half-diameter of the spherical particle away from the wall. The characteristics of the near-wall region, such as the permeability, the Forchheimer coefficient, and the thermal dispersion coefficient, are determined based on the experimental data for a one-stage spherical particle layer. For the core region, the permeability and the Forchheimer coefficient are evaluated using previous correlations for a homogeneous spherical particle layer, while the thermal dispersion coefficient is modified from that given by the previous correlation for a homogeneous spherical particle layer to include the effect of the thermal conductivity ratio of the spherical particle and the fluid. The effective thermal conductivity of the layer of spherical particles is assumed to be constant in the present model. The validity of the model is proved by comparing the results of this analysis with experimental results under various conditions.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016636091997球カプセル化潜熱蓄熱体を充填した小型潜熱蓄熱槽の蓄熱特性に関する数値解析274281ENKoichiOzakiHideoInabaAkihiroShigemoriWe numerically investigate heat storage characteristics of a small heat storage vessel packed with phase-change material (PCM) encapsulated into a spherical hollow. The heat storage vessel is dealt with as a porous medium, and the flow of the working fluid is analyzed two-dimensionally using the modified Darcian momentum equation which takes into account both the buoyancy effect and the channeling effect. The heat transfer in the encapsulated PCM is analyzed using a one-dimensional heat conduction model. It is clarified that the completion of the heat storage process is delayed by natural convection, since the incoming hot working fluid flows mainly near the upper part of the vessel. It is also found that the nonhomogeneity near the boundary walls prolongs the heat storage process since it decreases the flow resistance near the walls and promotes a bypass flow near the upper wall due to the natural convection. A nondimensional equation is derived for the time taken to complete heat storage, where the Fourier number is expressed as a function of the modified Stefan number, the modified Reynolds number and the modified Grashof number.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016636161997形状安定化球状潜熱蓄熱粒子を用いた流動層型潜熱蓄熱槽の放熱特性207214ENHideoInabaAkihikoHoribeKoichiOzakiTakayukiYamazawaThis paper deals with heat energy release characteristics of shape-stabilized latent heat energy storage particles packed into a fluidized bed-type cylindrical heat energy storage vessel. This type of latent heat energy storage material consists of normal paraffin (pentacosane C_<25>H_<52>, latent heat : 164 kJ/kg, melting point of 327.2K) as a latent heat material, and polyethylene as a shape-stabilizing material. The effects of cold inlet air temperature and flow rate, and the amount of heat energy storage particles on the outlet air temperature from the heat storage vessel and the completion time of the heat energy release process were investigated. As a result, the non-dimensional correlations for the outlet air temperature from the heat storage vessel and the completion time of the heat energy release process were expressed in terms of non-dimensional pumping power, Stefan number and ratio of the packed particle layer height to the diameter of the cylindrical heat storage vessel.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016646181998傾斜配置した平板状形状安定化潜熱蓄熱材充填矩形蓄熱槽の蓄熱特性200207ENHideoInabaTuPingAkihikoHoribeKoichiOzakiThe present study deals with the heat storage characteristics of the inclined rectangular vessel packed with spape-stabilized paraffin plates as a latent heat storage material by numerical analysis. It was found that the heat storage characteristics were remarkedly affected by the inclination angle of the rectangular vessel and the heat transfer medium flow direction, due to the presence of natural convection in the fluid flow channel between the paraffin plates. Numerical results revealed flow patterns, temperature profiles and heat storage characteristics for various inclination angles, inlet velocities and temperatures of the heat transfer medium fluid, and widths of the fluid flow channel.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016646211998繊維質系流動抵抗軽減剤添加水の直管内流動抵抗および熱伝達特性178185ENHideoInabaNaotoHarukiAkihikoHoribeKoichiOzakiSome kinds of surfactants are useful to reduce flow drag in a turbulent pipe flow by Toms effect. However, it needs a lot of cost to make these surfactant harmless material to the environment. On the other hand, the fibrous substance such as pulp fibers and cellulose are harmless additives to the environment. This paper has dealt with the flow drag reduction and heat transfer characteristics of the water suspension flow mixed with fine fibers in a straight pipe. Measurements of velocity and temperature profile in a circular pipe flow were made in order to examine the flow drag and heat transfer characteristics of the turbulent and laminar flow. The nondimensional equations of pipe flow resistance and heat transfer were derived in terms of various nondimensional parameters.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016646271998フッ素系不活性液体を熱回収用媒体として用いた液-液直接接触熱交換に関する研究 : 温水中を降下するフッ素系不活性液滴群についての伝熱特性312319ENHideoInabaAkihikoHoribeKoichiOzakiNaokiYokoyamaThis paper deals with the heat transfer characteristics of a liquid-liquid direct contact operation in which a Perfluorocarbon (PFC) liquid is released in a hot water stream, a low-grade heat source such as urban sewage, for the purpose of heat recovery from it. The paper reports on a set of experiments in which a PFC liquid (1800 kg/m^3 at 20℃) was continuously injected from a single, downward-facing nozzle into a slow, upward flow of hot water to be disintegrated into droplets descending in, and thereby heated from the water flow. The results of the experiments show how the size distribution and the translational motions of the droplets affect the overall coefficient for the water-flow-to-droplets heat transfer and also the temperature effectiveness for the droplets.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016656311999架橋ポリエチレン粒子充填潜熱蓄熱槽の非定常放熱特性161168ENHideoInabaZhongminLiAkihikoHoribeKoichiOzakiTransient heat release characteristics of a latent heat storage vessel packed with surface cross-linked form stabilized high-density polyethylene pellets as a phase change material (PCM) have been investigated numerically and experimentally. The obtained results revealed the effects of the inlet velocity, the inlet temperature of ethylene glycol/water solution as a heat transfer medium, and the amount of the PCM on the heat release characteristics. As a result, the nondimensional correlation equation of the completion time of the heat release process was derived as a function of some nondimensional parameters.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016656351999直接接触熱交換法を用いた中温度潜熱蓄熱槽の放熱特性268275ENHideoInabaAkihikoHoribeKoichiOzakiKazuoEmotoHiroyukiKakiuchiExperiment has been performed of heat transfer characteristics of the middle temperature latent heat storage system of the direct-contact heat transfer by using m-E (meso-Erythritol, melting point of 119℃, latent heat of 375 kJ/kg) droplets as a latent heat storage material and silicone oil as a heat transfer medium. In the present study the liquid m-E was injected into the heat tranfer medium through a circular nozzle. The m-E droplets changed from liquid to solid phase during falling in the heat transfer medium at low temperature. From the measuring results of m-E droplet diameter, falling velocity, and solidification rate, the nondimensional empirical equations of the arithmetic mean diameter of the droplets and falling velocity, the solidification rate and the overall heat transfer coefficient were derived as a function of the characteristic arithmetic mean diameter, the terminal velocity, temperature and physical properties.No potential conflict of interest relevant to this article was reported.社団法人日本機械学会Acta Medica Okayama0387-5016656391999繊維系有機吸着剤の過渡的脱着特性239246ENHideoInabaKoichiOzakiAkihikoHoribeRikioShimoyamaTakahisaKidaAn experimental investigation was performed to determine the transient desorption characteristics of a fibrous type organic adsorbent, which was composed of the bridged complex of sodium polyacrylate as a new kind of adsorbent. The test fibrous adsorbent was packed in a cylindrical vessel, and dry air was passed through it. The experiments were conducted under various conditions of air velocity, temperature, relative humidity and vessel length. As a result, the pressure loss for the packed bed of the test fibrous adsorbent showed a similar tendency to that for the packed bed of spherical particles. The mass transfer data was correlated by the modified Sherwood number, the Reynolds number, the Schmidt number, the ratio of desorbed water vapor mass to fibrous adsorbent mass, the nondimensional temperature and the ratio of vessel length to fiber diameter. Fourier number for the completion times of adsorption processes were also correlated by Reynolds number, and the ratio of desorbed water vapor mass to fibrous adsorbent mass, the nondimensional temperature and the ratio of vessel length to fiber diameter.No potential conflict of interest relevant to this article was reported.