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Volume 66 (2004)
- Issue 6 Pages 623-
- Issue 5 Pages 541-
- Issue 4 Pages 463-
- Issue 3 Pages 341-
- Issue 2 Pages 149-
- Issue 1 Pages 3-
Volume 66, Issue 4
Displaying 1-4 of 4 articles from this issue
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1st report: Heat transfer characteristics between ice-particle bed and water in a batch-type experimentYoshitaka KAWADA, Shuichi YAMADA, Masataka SHIRAKASHI, Masaru HATTORI2004 Volume 66 Issue 4 Pages 463-472
Published: July 15, 2004
Released on J-STAGE: August 07, 2009
JOURNAL FREE ACCESSIn order to put a new district cooling system utilizing ice/water mixture to practical use, a demand-side heat exchanger must be developed to transfer cooling energy from ice/water mixture to cold water. In this study, the heat exchange characteristics between the ice-particle bed and water flowing through the bed in a vertical cylindrical vessel were investigated in a batch-type experiment to obtain design guidelines for the ice-water direct contact heat exchanger (DCHE). Chip ice test particles of about 10 mm particle size were made using a commercial ice making machine. The outlet/inlet temperature ratio of water through the ice particle bed in the vessel was shown to be a function of the amount of ice per unit area irrespective of water velocity, inlet water temperature or vessel diameter, showing that the heat transfer coefficient is proportional to the water velocity. The heat exchange performance was better and more stable for upward flow than for downward flow. Consequently, when ice particles are relatively coarse, as is the case with chip ice, a vertical cylinder with upward flow is recommended as the DCHE structure he since it is simplest in structure and the heat exchange performance is both reasonably good and stable.View full abstractDownload PDF (12281K) -
Norihito OOSAWA, Yusuke FUKUSHIMA2004 Volume 66 Issue 4 Pages 473-483
Published: July 15, 2004
Released on J-STAGE: February 05, 2010
JOURNAL FREE ACCESSA large part of Japan is mountains. Many villages and large structures are vulnerable to damage by powder snow avalanches. In order to prevent these disasters, the understanding of the characteristic of powder snow avalanche is necessary. A hazard map can be made based on such.knowledge. Facilities can be constructed to prevent these disasters.
The flow mechanisms of powder snow avalanches are similar to that of thermal flow on an inclined boundary. A model and the numerical simulator for such flows are developed considering the three dimensional topography (digital map). Such a model was originally proposed by Fukushima (1986). The present simulation model can use the digital map and analyze the route and the lateral spread of powder snow avalanches in addition to the travel speed, the particle concentration and the turbulent kinetic energy of powder snow avalanches.View full abstractDownload PDF (7293K) -
(Part II) Creep behavior of ice plate under long-term ring loading with 20 m diameterTsutomu KOKAWA2004 Volume 66 Issue 4 Pages 485-493
Published: July 15, 2004
Released on J-STAGE: February 05, 2010
JOURNAL FREE ACCESSBased on the viscoelastic solution in a previous paper, a numerical analysis of a 20 m span (at the base) ice dome on a floating ice plate was conducted in order to predict the creep behavior theoretically. According to the numerical simulation, which assumes 4 days as the construction period, 100 cm as the plate thickness, 100 t as the total ring load and Jellinek & Brill's experimental values for the material constants of ice, very important results have been obtained for stress relaxation and the flooding problem during 8 days including the construction period. As for the stress relaxation, the maximum creep bending stress is 1.74 kg/cm2, reduced to 60% of the elastic stress, while stress continues to decrease over time after completion under fixed load. It is predicted that the ice plate will offer adequate stability from the point of view of strength.
Meanwhile, displacement will reach about 1/10 of the plate thickness just before completion and some flooding will occur, but the rate of rise of water level will be 2 to 3cm/day, slow enough for freezing to occur through natural cooling, in fact it is expected that the gradual flooding will actually improve the dynamical performance of the ice plate. In other words, the water will freeze into good quality ice because of the low flooding speed. Therefore, it is concluded theoretically that a 20m span ice dome could be practically useful on a lake-ice plate for 2 to 3 months.View full abstractDownload PDF (6893K) -
Yusuke FUKUSHIMA, Jiro KIMOTO, Masaei HARA, Toshio KOBAYASHI, Ryuichi ...2004 Volume 66 Issue 4 Pages 495-502
Published: July 15, 2004
Released on J-STAGE: February 05, 2010
JOURNAL FREE ACCESS
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