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Part1. Exergy Analysis of COP Ratio as a Performance Index
Shigeyasu NAKANISHI, Yousuke KAWASHIMA, Kazuhiro MURAI
1993 Volume 10 Issue 1 Pages
1-9
Published: 1993
Released on J-STAGE: October 11, 2011
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We conduct a series of investigations in order to introduce a exergetic viewpoint into the performance analysis of heat pumps and refrigerators. In this paper, we propose a new performance index, which has the ability to evaluate the qualitative aspect of heat pumps and refrigerators, and examine its thermodynamic foundation. This index, named as the COP ratio, is defined as the degree of attainment of the limiting COP corresponding to the reversible units without any thermodynamic loss. Then, we deduce its calculation formulae based on the exergy analysis and find its relationship with the exergy efficiency properly defined, which means that an analysis based on the COP ratio is equivalent to the one based on the exergy. Finally, estimation of the COP ratio is given for the units on the market.
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Koichi ICHIMIYA, Yasuhiro FUJII, Haruka SAITOH
1993 Volume 10 Issue 1 Pages
11-17
Published: 1993
Released on J-STAGE: October 11, 2011
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A numerical estimation was performed for the laminar flow and heat transfer by porous medium in a flow passage with miter-bend. Local heat transfer and dimensionless stream function were compared for the flow with and without porous medium. The behavior of the flow and Nusselt number with Darcy number was represented, and mean Nusselt number increased with decrease of Da number (from Da=10
-2 to Da=10
-4). Effect of effective thermal conductivity of porous medium was also evaluated numerically.
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2nd Report: Grooved surface with 0.34mm of the groove pitch
Osao KIDO, Hiroshi YONEDA, Koichi NAKAYAMA, Haruo UEHARA, Akio MIYARA
1993 Volume 10 Issue 1 Pages
19-28
Published: 1993
Released on J-STAGE: October 11, 2011
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Internal grooves are widely used as means to improve the heat transfer performance of tubes, but their optimum shape has not been clarified. In this paper, a rectangular channel with the test surfaces is used instead of circular tube. Two kinds of grooved surface with 0.34mm of the groove pitch are tested, the grooved surface 1 has 18 degree of lead angle and the grooved surface 2 has 0 degree of lead angle. The rectangular channel, 10mm in width, 5mm in height, and 500mm in length, was set horizontally, and the upper and lower surfaces were heated electrically with Nichrome heaters. HCFC22 was used as a working fluid. Evaporating pressure was 0.49MPa, heat flux was 4.65kW/m
2, vapor quality was varied from 0.1 to 0.9, and mass velocity was varied from 86 to 345kgj(m
2s). Heat transfer coefficient for the grooved surface 1 compared well with that for grooved tube with 18 degree of lead angle except for low mass velocity region where the heat transfer coefficient of the upper surface was much lower than that of the lower surface. Heat transfer coefficient for the grooved surface 2 was lower than that for the grooved surface 1.
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Yutaka OGAWA
1993 Volume 10 Issue 1 Pages
29-35
Published: 1993
Released on J-STAGE: October 11, 2011
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Considering that gape and heave produced during the freezing of tuna fish derive from changes in the thermophysical properties of tuna fish itself during freezing, the coefficient of linear and cubical expansion of tuna meat were measured continuously between the temperature before freezing and during freezing.
The results of measurement were shown that the coefficient of thermal expansion of tuna meat displayed special temperature dependence as sudden change at the boundary temperature of freezing beginning as summarized below: 1) the coefficient of linear expansion of tuna meat were anisotropic according to the tissue and structure of the fish body, but these properties varied according to the test temperature; and 2) the coefficient of cubical expansion during freezing assumed a maximal value when tuna meat was partially frozen.
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Makoto TAGO, Shoichiro FUKUSAKO, Masahiko YAMADA, Akihiko HORIBE
1993 Volume 10 Issue 1 Pages
37-47
Published: 1993
Released on J-STAGE: October 11, 2011
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An experimental study has been performed to investigate the freezing heat-transfer, characteristics in a return bend with rectangular cross section. The experiments were carried out for two kinds of duct heights of 30mm and 50mm with duct width of 300mm and convex radius of curvature of 159mm under the condition that both the convex and concave walls of a return bend were kept less than the freezing temperature of water. It was found from the present experiment that the freezing behavior on the convex wall was much different from that on the concave wall of a return bend and that the cooling temperature ratio was important parameter on the freezing heat transfer.
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Mamoru OZAWA, Ichiro KIMURA, Koichi UCHIDE
1993 Volume 10 Issue 1 Pages
49-56
Published: 1993
Released on J-STAGE: October 11, 2011
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Thermo-sensitive liquid-crystal sheets are a useful means to measure thermal fields under steady and/or unsteady operating conditions of heat exchangers. With application of a color image processing technique to an image of the thermal field visualized, quantitative data of the temperature can be obtained. When such liquid-crystal sheet is adopted to measure unsteady temperature, it is necessary to take into account the frequency response, i.e., the phase shift and gain. This paper describes an experimental investigation and simplified formulation of the temperature response of the sheet, and a Bode diagram of the temperature response is presented. It is confirmed that the liquid-crystal sheet is applicable to the measurement of the temperature fluctuation up to 0.2Hz.
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Masafumi KURIYAM, Xiangyi LI, Eiji HARADA, Hirotaka KONNO
1993 Volume 10 Issue 1 Pages
57-65
Published: 1993
Released on J-STAGE: October 11, 2011
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An investigation was performed on the flow and cooling characteristics of highly viscous liquids in the channel with a large number of right-angled bends. The variation of flow pattern and temperature profile according to Reynolds number and Prandtl number were presented by solving numerically the Navier-Stokes equations with energy equation under the condition that the fluid properties were independent on temperature. Average heat transfer cofficient and friction factor were also calculated and compared with the experimental data regarding aqueous solutions of corn syrup. Through the comparison, the effect of the variable viscosity of the test fluid on the flow and heat transfer characteristics was considered in connection with the channel configuration.
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Yoshinori TAKAISHI, Hajime NAKAGAWA, Kosei OGUCHI
1993 Volume 10 Issue 1 Pages
67-73
Published: 1993
Released on J-STAGE: October 11, 2011
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The paper presents measurements of the vapor pressure for the solutions of HFC-134a and ester based oil. The oil employed is eater based synthetic lubricant that is thought to be one of the lubricants compatible with alternative refrigerant HFC-134a.The measurements have been carried out for the range of temperatures between 263.15 K and 323.15 K for the HFC134a/ester based oil solutions. The uncertainty of the measurments is estimated as ±10mK in temperature, ±5kPa in pressure and ±0.5% in concentration,respectively. Correlations that interpolate the experimental vapor pressure as a function of temperature and concentration are presented for practical use.
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Masato FUKUSHIMA, Naohiro WATANABE
1993 Volume 10 Issue 1 Pages
75-86
Published: 1993
Released on J-STAGE: October 11, 2011
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Thermodynamic properties of HCFC-124, such as saturated densities, vapor pressures and PVT properties, were measured and the critical parameters were determined through those experimental results.
The correlations for vapor pressure, saturated liquid density and PVT properties deduced from those experimental results were compared with the measured data and also with the estimates of the other correlations published in literatures.
The thermodynamic functions, such as enthalpy, entropy, heat capacity, etc., can reasonably be calculated from the correlation equations in this paper.
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Masato FUKUSHIMA
1993 Volume 10 Issue 1 Pages
87-93
Published: 1993
Released on J-STAGE: October 11, 2011
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The thermodynamic properties of HFC-143a (1,1,1-trifluoroethane) have been measured. The vapor-liquid coexistence curve near the critical point was measured by a visual observation of the meniscus in an optical cell. Twenty-eight saturated density data points in the range of 213.5 to 661.1 kg/m3 were obtained between the temperature of 339 K and the critical temperature. The uncertainties of temperature and density are less than ±20 mK ±2.4kg/m
3, respectively. The vapor pressure was measured by means of the constant-volume method. Eighteen vapor pressure points were obtained in the range of temperature from 274.6 to 345.7 K and pressure from 0.64 to 3.75 MPa. The uncertainties of temperature and pressure are less than ±20 mK and ±5KPa, respectively. On the basis of the experimental measurements, the critical temperature, pressure and density were determined to be 345.97±0.03K, 3.769±0.005MPa and 429±3kg/m
3 respectively. In addition, correlations of the vapor pressure and vaporliquid coexistence curve were developed.
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Shigeru KOYAMA, Lei GAO, Tetsu HUJII
1993 Volume 10 Issue 1 Pages
95-101
Published: 1993
Released on J-STAGE: October 11, 2011
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Condensation heat transfer and pressure drop characteristics of nonazeotropic refrigerant mixtures (NARMs) of HCFC22 and CFC114 inside horizontal smooth and micro-fin tubes are experimentally investigated. The local Nusselt number for both tubes based on the temperature difference between bulk refrigerant and tube wall is compared. Data for the micro-fin tube are about 50% higher than those for the smooth tube in both cases of pure refrigerants and NARMs. In case of NARMs, however, the decrease of Nesselt number due to vapor mass transfer resistance is observed for the micro-fin tube as well as for the smooth tube. By assuming that heat transfer characteristics of the condensate of NARMs are similar to those for pure refrigerants, the vapor mass transfer coefficient of NARMs is evaluated. Comparison of frictional pressure drop for both tubes is also performed in the Lockharte-Martinelli relation. Data for the micro-fin tube are higer than those for the smooth tube. The maximum increase of the frictional pressure drop is about 30%.
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Shigeru KOYAMA, Lei GAO, Tetsu FUJII
1993 Volume 10 Issue 1 Pages
103-110
Published: 1993
Released on J-STAGE: October 11, 2011
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Condensation heat transfer coeffcient and pressure drop of CFC12 and its substitute HFC134a Were measured inside a horizontal smooth tube with an inner diameter of 7.9mm. The mass velocity ranged from 113 to 340kg/(m
2s) and the saturation temperature ranged from 40 to 60°C. The local heat transfer coefficient of HFC134a is 10 to 25% higher than that of CFC12 at the same values of saturation temperature, mass velocity, heat flux and vapor quality. The local Nusselt number for both refrigerants is correlated well by an equation which is obtained by modifying a semi-empirical equation proposed by Fujii et al. Experimental results of frictional pressure drop for both refrigerants expressed in the coordinates of Lockhart-Martinelli parameters have the same tendency, while those are lower than the values predicted using previous emprical equations. Judging from the standpoint of condensation heat transfer HFC134a is an appropriate substitute for CFC12.
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Experimental Study Using Daphnia
Ichiro TANASAWA, Shinichi NAGATA, Naohiro KIMURA
1993 Volume 10 Issue 1 Pages
111-116
Published: 1993
Released on J-STAGE: October 11, 2011
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Cryopreservation is considered to be the most promising way of preserving living organs or tissues for a long period of time without casuing any damage to their biological functions. However, cryopreservation has been succeeded only for simple and small-size tissues such as spermatozoon, ovum, erythrocyte, bone marrow and cornea. Cryopreservation of more complex and large-scale organs are not yet succssful. The authors have attempted to establish a technique for cryopreservation of larger living organs. An experiment was carried out using daphnia (water flea). The optimum rates of freezing and thawing were determined together with the optimum selection of cryoprotectant. High recovery rate was achieved under these conditions.
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Hiroyasu OGIWARA, Hideki NAKAGOME, Tohru KURIYAMA
1993 Volume 10 Issue 1 Pages
117-123
Published: 1993
Released on J-STAGE: October 11, 2011
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A series of R & D of magnetic refrigerators has been done in order to realize an advanced type cryocooler for superconducting magnets of maglev trains and MRI medical system.
As a result of efforts on both the magnetic refrigerator and superconducting magnets, a parasitic type magnetic refrigeration system was proposed.
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Yukishige MAEZAWA, Haruki SATO, Koichi WATANABE
1993 Volume 10 Issue 1 Pages
125-133
Published: 1993
Released on J-STAGE: October 11, 2011
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Three methods to correlate and estimate the saturated-1iquid density of refrigerant mixtures are compared and evaluated on the basis of the measurements for five bibary and one ternary mixtures performed by the present authors. The first of them is a method using Peng-Robinson equation (PR-method) proposed originally by Peneloux et al. Since this method dose not require any measurements of the saturated-liquid density of mixture, it is useful for the estimation. However, the applicability of this method to various substances may be restricted. The second is the modified Rackett equation proposed by Spencer and Dannar (mR-method). The temperature functional form of this equation is quite simple, so it is useful to use it as a functional form of the fitting. Unfortunately this method can not be used for strongly non-ideal mixtures. The last one is the Hankinson-Brobst-Thomson equation (HBT-method). This method can provide the most accurate density values among the three methods with two kinds of binary parameters where these binary parameters are introduced by the present authors. In the case that many experimental saturated liquid densities of mixtures are available in the wide range of temperatures, the HBT-method is recommended for the practical use.
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Uniformization of the Process by Means of Chamber Wall Temp. Control
Masakazu KOBAYASHI, Konomi HARASHIMA, Hiroichi ARIYAMA, Ai-ru YAO
1993 Volume 10 Issue 1 Pages
135-144
Published: 1993
Released on J-STAGE: October 11, 2011
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Significant inter-vial variance in the sublimation rate has been pointed out by several authors in relation to the placement of the vials on a well controlled shelf. All the previous reports have described the phenomena observed in the experiments or the production processes, and have made some suggestive remarks, but have not clearly proposed a solution to the problem. In the shelf freeze-drying of pharmaceuticals, one of the major ploblems is how to achieve inter-vial uniformity and batch to batch uniformity or consistency. In this study, We have developed a new model of laboratory-scale freeze-dryer which has temperature-controllable chamber walls, and using this new model we have analyzed causes of inter-vial variance in the sublimation rate. The higher sublimation rate for the vials placed on the shelf edge is due to additional heat input from the wall and also due to further additional heat from the shelf surface on which no kissing vial is placed. It is possible to cancel out the additional heat input from the shelf by maintaining an optimum wall temperature, which must be lower than the material temperature. This paper discusses a method for eliminating the inter-vail variance in drying conditions and shortening the drying time by means of chamber wall temperature control.
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Development of a Vertical Shell and Tube Type Freeze-dryer
Masakazu KOBAYASHI, Konomi HARASHIMA, Hiroichi ARIYAMA, Ai-ru YAO
1993 Volume 10 Issue 1 Pages
145-155
Published: 1993
Released on J-STAGE: October 11, 2011
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Up to the present, the conventional freeze-drying method for bulk pharmaceticals and other liquid materials has employed a tray/shelf system, while the development of a closed system has been desired for many years, especially for the manufacturing of sterile bulk pharmaceuticals. Seffinga (1964) devised a method, which he called "vertical tube dryer", however, this system was not established due to several drawbacks.
Having restudied Seffinga's method, we have succeeded in eliminating the drawbacks of this method and have developed a closed system for the batch/continuous freeze-drying of liquid materials. Two of the drawbacks of Seffinga's method, namely (a) supercooloing followed by sudden freezing and (b) adherence of dried material to the tube surface, have been eliminated by the formation of an ice lining. Another drawback (c) that a substaintial part of the liquid poured into the chamber must be drained has been solved through multistage frozen layer formation. All of the stage of freeze-drying can be performed using the closed system developed in this study. Further, since the interior dose not have a complicated structure, internal cleaning and steam sterilization can be easily performed. This paper discussed the closed system and the behavior of materials in the freeze-drying process.
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