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Volume 4 (1987)
- Issue 3 Pages 163-
- Issue 2 Pages 71-
- Issue 1 Pages 1-
Volume 4, Issue 2
Displaying 1-9 of 9 articles from this issue
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Review Article
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Wataru NAKAYAMA1987 Volume 4 Issue 2 Pages 71-84
Published: 1987
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSThe rapid growth of data processing speed in computers has been sustained by the advances in cooling technology. This article first presents a review of the published data of heat loads in recent Japanese large-scale computers. The survey indicates that, since around 1980, the high-level integration of microelectronic circuits has brought about almost four fold increase in the power dissipation from logic chips. The integration also has invited the evolutions of multichip modules and new schemes of electronic interconnections.
Forced convection air-cooling and liquid cooling coupled with thermal connectors are discussed with reference to the designs employed in actual computers. More advanced cooling schemes are also discussed. Finally, the importance of thermal environmental control of computer rooms is emphasized.View full abstractDownload PDF (786K) -
Hidemasa MIKI, Jun-ichi NISHIMOTO1987 Volume 4 Issue 2 Pages 85-96
Published: 1987
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSThe thawing technique of frozen fish has a great effect upon the quality of thawed fish. Especially, the discoloration of red muscles in frozen skipjack and tunna is easy to occur during and after thawing.
Firstly, the present review describes about the overview of the previously reported studies related to the thawing conditions of frozen fish such as the quality before thawing, the thawing rate, the final thawing temperature and the thawing method. And then the optimum condition for minimizing the deterioration (freshness-lowering, discoloration) during thawing is discussed numerically to predict by using the kinetic parameters of the quality changes of frozen fish and the thawing curves in a skipjack. In this way, the hitherto recommended "Semi-thawing" (about -3°C~-5°C of final temperature) would be theoretically supported.
Finally the discussions are made on the problems of the storage of thawed fish, the heat transfer, the deterioration and the equipment concerning the thawing of frozen fish for a future development.View full abstractDownload PDF (728K)
Papers
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Sadanari MOCHIZUKI, Yoshinao YAGI1987 Volume 4 Issue 2 Pages 97-108
Published: 1987
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSA scale-up modeling technique was used to examine the effect of the geometrical properties of interrupted surfaces on the heat transfer and pressure drop performance of compact heat exchangers having off-set-strip and slotted fins. The test cores, each consisting of a number of machined copper finns, were tested in a subsonic wind tunnel. The heat transfer and the pressure drop for each test core was measured for various fin lengths (in flow direction) and slot distances. Flow visualization and local turbulence intensity and pressure measurements within each test core were also performed to gain insight into the mechanisms of heat transfer augmentation in compact heat exchangers with interrupted surfaces. The effect of the geometrical properties of the fins as well as the Reynolds number on the heat transfer rate and the pressure drop were determined and those results were interpreted in terms of observed flow structure. Basic heat transfer and pressure drop data are presented in terms of Colburn j-factors and Fanning friction factors plotted versus Reynolds number. An empirical correlation for heat transfer and pressure drop characteristics for off-set-strip fins are presented.View full abstractDownload PDF (955K) -
Eisyun TAKEGOSHI, Nobuyuki HOURI, Yoshio HIRASAWA, Sadahisa IMURA1987 Volume 4 Issue 2 Pages 109-114
Published: 1987
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSIn this paper, a simple and rapid measurement of the thermal conductivity of insulation materials at low temperature was achieved by a transient hot wire method.
Firstly a convenient device to maintain a given low temperature was made and the thermal conductivity of several insulation materials was measured in the range from liquefied nitrogen temperature to room temperature. In the measurement, an anisotropic nature in the insulation materials was considered. The conductivities estimated by the hot wire method were then compared with those values obtained by a one-dimensional steady state method.
Consequently, it was found that when the anisotropic nature was considered both the values agree within the deviation of 5-10% and the hot wire method is able to apply for the measurement of the thermal conductivity of insulation materials.View full abstractDownload PDF (318K) -
1st Report : Modeling of the Static CharacteristicsEiji HIHARA, Yuuji YAMAMOTO, Takamoto SAITO, Yoshikazu NAGAOKA, Noriyu ...1987 Volume 4 Issue 2 Pages 115-124
Published: 1987
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSFor the purpose of impoving the response to cooling load variations and the part load characteristics, the optimal operation of a double-effect absorption refrigerating machine was investigated. The test machine was designed to be able to control energy input and weak solution flow rate continuously. It is composed of a gas-fired high-temperature generator, a separator, a low-temperature generator, an absorber, a condenser, an evaporator, and high- and low-temperature heat exchangers. The working fluid is Lithium Bromide and water solution. The standard output is 80 kW. Based on the experimental data, a simulation model of the static characteristics was developed. The experiments and simulation analysis indicate that there is an optimal weak solution flow rate which maximizes the coefficient of performance under any given cooling load condition. The optimal condition is closely related to the refrigerant steam flow rate flowing from the separator to the high temperature heat exchanger with the medium solution.
The heat transfer performance of heat exchangers in the components influences the COP. The change in the overall heat transfer coefficient of absorber has much effect on the COP compared to other components.View full abstractDownload PDF (461K) -
2nd Report : A Multi-Variable Control Following the Cooling Load VariationsEiji HIHARA, Yuuji YAMAMOTO, Takamoto SAITO, Yoshikazu NAGAOKA, Noriyu ...1987 Volume 4 Issue 2 Pages 125-132
Published: 1987
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSBecause the heat capacity of absorption refrigerating machines is large compared with vapor compression refrigerating machines, the dynamic characteristics at the change in cooling load conditions are problems to be improved. The control method of energy input and of weak solution flow rate following cooling load variations was investigated. As the changes in cooling load and cooling capacity are moderate, the optimal operation conditions corresponding to the cooling load can be estimated with steady state characteristics. If the relation between the cooling load and the optimal operation conditions is well known, a feed forward control can be employed. In this report a new control algorithm, which is called MOL (Multi-variable Open Loop) control, is proposed. Comparing the MOL control with the conventional chilled water outlet temperature proportional control, the MOL control enables the smooth changes in cooling capacity and the reduction in fuel consumption.View full abstractDownload PDF (399K) -
Etsuro YAMADA, Masayasu KATO, Takayuki TOMIKAWA, Kaneko TAKAHASHI1987 Volume 4 Issue 2 Pages 133-140
Published: 1987
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSThe effective thermal conductivity of corrugated insulating materials which are made by polypropylene or polycarbonate have been measured by employing steady state comparison method for several specimen having various thickness and specific weight. The thermal conductivity of them evaluated are also by using the thermal resistance models, and are compared with above measured values and raw materials' conductivity.
The main results obtained in this paper are as follows:
(1) In regard to the specimen in this paper, the effective thermal conductivity increases with increasing temperature, but the increasing rate of them is small.
(2) There are considerable differences between the measured values and the predicted ones that are estimated by using the thermal resistance model in which heat flow by conduction only. This differences increase with increasing specimens' thickness. This difference become extinct by considering the coexistence heat flow of conduction and radiation in the air phase of specimen.
(3) The thermal resistance of specimen increases linearly with increasing specimens' thickness.View full abstractDownload PDF (338K) -
Hideao INABA, Takeyuki FUKUDA, Hakaru SAITO, Ikuo TOKURA1987 Volume 4 Issue 2 Pages 141-150
Published: 1987
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSThe formation of the ice growth in a pipe with water flow was investigated experimentally. The experiments were carried out under various experimental conditions over the ranges of Reynolds numbers (based on pipe i,d., 215-8300) and cooling temperature ratios (1.25-14). From the visual observation of ice formation and meaurements of the pressure drop between the inlet and outlet of a pipe, it was found that the flow condition and cooling temperature ratio played an important role in the formation of ice in the pipe. The transient behavior of ice formation was expressed by the relationship between the pressure loss coefficient and Reynolds number for various cooling temperature ratios. The non-dimensional time from the start of freezing in the pipe to a complete ice blockage was expressed with Reynolds number for various cooling temperature ratios. In addition, the critical condition for a complete ice blockage in the pipe was obtained with experimental correlation equations in terms of cooling temperature ratio and Reynolds number.View full abstractDownload PDF (868K) -
Freezing of Tuna by CaCl2 Brine Spray SystemYutaka OGAWA1987 Volume 4 Issue 2 Pages 151-162
Published: 1987
Released on J-STAGE: October 11, 2011
JOURNAL FREE ACCESSThe purposes of this study are to measure the internal pressure which causes gape and heave of frozen body during the CaCl2 brine immersion/spray freezing and to forestall these undue defects of frozen foodstuffs by the internal pressure.
The experiments were carried out on freezing of tuna fish. Both of the temperature and the internal pressure of tuna fish were measured and recorded continuously by a temperature sensor and a pressure sensor during the freezing.
The result was that gape and heave of frozen tuna fish are created by the internal pressure during the freezing, and the internal pressure or stress of frozen body was released by thermal equalizing process during freezing. And the methods which are able to prevent gape or heave of frozen body during the CaCl2 brine spray freezing were found out.View full abstractDownload PDF (863K)
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