日本冷凍空調学会論文集
Online ISSN : 2185-789X
Print ISSN : 1344-4905
ISSN-L : 1344-4905
16 巻, 3 号
選択された号の論文の11件中1~11を表示しています
研究レビュー
  • 原 利次
    1999 年 16 巻 3 号 p. 195-206
    発行日: 1999年
    公開日: 2011/09/08
    ジャーナル フリー
    Technical trend of refrigeration system using natural refrigerants (or natural working fluids) was generally overviewed mainly by the proceedings of the International Conference of Natural Working Fluids past these few years. Hydrocarbon, carbon dioxide, water and air are mainly used as new refrigerants. Risk assessment of these flammable refrigerants was widely discussed. Hydrocarbon has been already widely used for refrigerators in Germany. Carbon-dioxide is now focused as a new refrigerant for air-conditioners of automobiles and water heaters. Turbo chiller with water as refrigerant has been tested in Germany. Air cycle refrigeration systems were applied to commercial freezer and for transportation. Natural refrigerants are also paid attention as secondary refrigerants.
論文
  • 橋詰 健一, 松江 孝博
    1999 年 16 巻 3 号 p. 207-212
    発行日: 1999年
    公開日: 2011/09/08
    ジャーナル フリー
    An experimental study was performed on ice formation around a brine-cooled tube embedded horizontally in a liquid-fluidized bed. Tested particles for fluidization were total 4 kinds of glass and ceramics having a diameter of 1.87 to 2.50mm. Experimental data of ice layer thickness for single-phase flow (without particles) agreed with an existing correlation within ± 15%.When particles were charged in the test section and fluidized, the ice layer thickness became remarkably thinner than that for the single-phase flow. Applying the heat transfer coefficient obtained for the liquid-fluidized bed without ice formation, analytically calculated ice layer thickness agreed with the experimental data within ± 0.5mm.
  • 目黒 貴敏, 梶 信藤, 三宅 圀博
    1999 年 16 巻 3 号 p. 213-219
    発行日: 1999年
    公開日: 2011/09/08
    ジャーナル フリー
    Hydrocarbon refrigerators are now on sale in European countries. However, hydrocarbons are flammable. A common claim is that concentration of hydrocarbon in the refrigerator could exceed the lower explosive limit by a sudden leak and then a spark ignites a flame causing overpressure. There is the need of the studies on potential risks originated from the use of flammable refrigerants. Thus, the flow rate of the fresh air into the refrigerator cabinet has been defined experimentally, and the spatial average concentration in the refrigerator cabinet has been analyzed theoretically to predict the dangerous time in excess of the lower explosive limit.
  • 酒井 康行
    1999 年 16 巻 3 号 p. 221-228
    発行日: 1999年
    公開日: 2011/09/08
    ジャーナル フリー
    Applying actual cooling tower water analyses together with air pollution and meteorological records to the theoretical equation calculating M-alkalinity of cooling tower water which is formulated in consideration of air pollution, capture efficiencies of typical air-conditioning cooling tower for each air pollutant have been estimated approximately as 25% for SO2, 30% for NO2, and 40% for NO. Using the equation, the method to establish adequate cycles of concentration of a cooling tower water is explained.
  • 山口 英宏, 今井 八郎, 山本 哲也, 山本 勉, 植木 裕, 滝沢 貴久男, 福島 清司
    1999 年 16 巻 3 号 p. 229-238
    発行日: 1999年
    公開日: 2011/09/08
    ジャーナル フリー
    From the standpoint of lubricative deficit under the alternative refrigerant/lubricants coexistence, the influence of additives on friction and wear characteristics for compressor parts have been investigated by the wear tester reappeared on friction condition similarly to actual compressor. It has been shown that an ester type base oil containing TCP (tricresyl phosphate) as an extreme pressure agents indicates satisfactory lubrication because of its EP effect. However owning to the deterioration of base oil caused by a cresol which is a reactant of TCP, a hydrolysis inhibitor must be necessary. The results indicates that a hydrolysis inhibitor added to POE is able to not only prevent the base oil from deteriorating but also feed the strength into oil films. On the other hands, in such a case that TCP concentration added in an alkylbenzen type base oil is excess or wear track temperature is higher, wear amounts of compressor parts are increased on account of corrosion wear. The reactivity of TCP depends on wear track temperature and its concentration. Consequently, it is possible that EP effect of TCP has been considered in terms of its concentration and temperature to be appropriated.
  • 福田 充宏, 柳沢 正, 小木 康博, 田中 順也
    1999 年 16 巻 3 号 p. 239-248
    発行日: 1999年
    公開日: 2011/09/08
    ジャーナル フリー
    In general, refrigeration oil of good solubility with refrigerant is used in refrigeration compressors, and development of a concentration sensor of refrigerant dissolved in the oil is needed. In this study, oil and refrigerant concentrations are measured with newly developed capacitance sensor which measure the change of dielectric constant with the concentration. It is found that in most cases of oil-refrigerant combinations the dielectric constant of refrigerant is two to three times as large as that of refrigeration oil and the dielectric constant of mixtures increases linearly with the concentration of refrigerant. When measuring the refrigerant concentration of R410A, t he measurement of the concentration by the dielectric constant is also feasible as long as the composition of each refrigerant component dissolved in the oil does not change from the nominal composition. Prototypes of small sensors, such as a cylindrical type and a needle type, are developed and the performance of the needle sensor with shield is preferable. A correlation for a given oil-refrigerant mixture obtained by a large capacitance sensor is applicable for the small sensors after correcting for stray capacitance. Flow of fluid in the sensors does not affect the capacitance measured by the sensors, while bubbles due to foaming do affect the measurement.
  • 測定の適用性拡張の試み
    佐伯 幸弘, 山田 悦郎, 小野江 孝裕
    1999 年 16 巻 3 号 p. 249-256
    発行日: 1999年
    公開日: 2011/09/08
    ジャーナル フリー
    The object of this study is to research the possibility of in-line measurement of the thermal diffusivity on composite materials by previously developed apparatus for the dynamic viscosity. The basic method to obtain thermal diffusivity has been proposed in the 1st report. In this study, the influence of the factors, such as the heating rate from heater and the distance between heater and temperature measurement probe, are studied to apply more wider range on composite materials. The new data having within ±10% accuracy are obtained about various food materials. The arrangement expressions are tried on calibration curve, and we propose Eqs. (2) and (3) as 1st approximation.
  • 羽倉 義雄, 岡本 清, 鈴木 寛一, 久保田 清
    1999 年 16 巻 3 号 p. 257-262
    発行日: 1999年
    公開日: 2011/09/08
    ジャーナル フリー
    We have proposed a new cutting method for frozen fish named "cryo-cutting". This method applied tensile fracture force or bending fracture force to the frozen fish at appropriate low temperatures. In this paper, to clarify cryo-cutting mechanism, we analyzed tensile fracture behavior of the frozen fish muscle. In the analysis, the frozen fish muscle was considered unidirectionally fiber-reinforced composite material which consisted of fiber (muscle fiber) and matrix (connective tissue). Fracture criteria (maximum stress criterion, Tsai-Hill criterion) for the unidirectionally fiber-reinforced composite material were used. The following results were obtained: (1) By using Tsai-Hill criterion, muscle fiber orientation angle dependence of the tensile fracture stress could be calculated. (2) By using the maximum stress theory jointly with Tsai-Hill criterion, muscle fiber orientation angle dependence of the fracture mode of the frozen fish muscle could be estimated.
  • 白 香蘭, 白樫 了, 西尾 茂文
    1999 年 16 巻 3 号 p. 263-271
    発行日: 1999年
    公開日: 2011/09/08
    ジャーナル フリー
    The thawing of ice crystal is very important for thawing of frozen foods and cryopreserved biomaterials. It was found that an alternative current (AC) electric field may effect the thawing process of frozen foods and cryopreserved biomaterials. In the present study, the spectrum of dielectric loss of ice crystal (50Hz~1.8GHz) was measured at various temperatures(-60°C to -2°C). The experiments of heating ice crystal using electric field were done to investigate the absorption of AC electric energy, which changes with the frequency of electric field. In order to evaluate the rapidness and the uniformity of thawing quantitatively, a numerical simulation of one-dimensional heat transfer was also conducted based on the measured spectrum of the dielectric loss of ice. The results showed that AC electric field have the uniform heating effect, only when the value of the frequency multiplied by dielectric loss (fε") decreases as the temperature increases. One of the optimum frequencies for a rapid and uniform thawing was found to be at around 3MHz.
  • 上西 浩史, 荒木 徹也, 相良 泰行
    1999 年 16 巻 3 号 p. 273-281
    発行日: 1999年
    公開日: 2011/09/08
    ジャーナル フリー
    Drying Characteristics and the transport properties have been measured for the dried layers of 9.6-28.8% miso paste undergoing freeze-drying. Optimum freeze-drying condition was investigated based on the relationship between the heating temperature and color change by scorching at the sample surface. The samples were freeze-dried at the constant surface temperatures ranging from 0 to 65°C under the usual pressure range of commercial operations. Thermal conductivities and permeabilities were determined by applying the uniformly-retreating-ice front model to the dried layer of samples undergoing freeze-drying. The surface temperature of 28.8% miso paste was allowed to heat up to 55°C, and its drying rate was limited by the heat transfer rate across the dried layer. Optimum drying condition to produce a cup of freeze-dried miso soup was found to be about 22% in solute concentration and 55°C at surface temperature during drying. Values of thermal conductivity were found to increase with increasing solute concentrations, while no marked effect of the solute concentration was observed on the data of permeabilities, indicating the pressure dependence under our experimental conditions.
  • 共焦点レーザー走査顕微鏡を用いた実時間計測
    石黒 博, 堀水 貴, 片折 暁伸, 梶ヶ谷 博
    1999 年 16 巻 3 号 p. 283-295
    発行日: 1999年
    公開日: 2011/09/08
    ジャーナル フリー
    Three-dimensional behavior of ice crystals and cells during the freezing and thawing of biological tissues was investigated microscopically in real time by using a confocal laser scanning microscope(CLSM) and a fluorescent dye, acridine orange (AO). Fresh tender meat (2nd pectoral muscles) of chicken was stained with the AO in physiological saline to distinguish ice crystals and cells by their different colors, and then frozen and thawed under two different thermal protocols: a) slow-cooling and rapid-warming and b) rapid-cooling and rapid-warming. The CLSM noninvasively produced optical tomograms of the tissues to clarify the pattern of freezing, morphology of ice crystals in the tissues, and the interaction between ice crystals and cells. Also, the tissues were morphologically investigated by pathological means after the freezing and thawing. Typical freezing pattern during the slow-cooling was extracellular-freezing, and those during the rapid-cooling were extracellular-freezing and intracellular freezing with a lot of fine ice crystals in the cells. Cracks caused by the extracellular and intracellular ice crystals remained in the muscle tissues after the thawing. The results obtained by using the CLSM/dye method were consistent with pathologically morphological changes in the tissues through freezing and thawing.
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