1993 Fiscal Year Final Research Report Summary
A study of Heat and Mass Transfer in Porous Media with Phase Change
| Project/Area Number |
03650197
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Thermal engineering
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| Research Institution | Akita National College of Technology |
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Principal Investigator |
SASAKI Akira Akita National College of Technology, Mechanical Engineering, Associate Professor, 機械工学科, 助教授 (00099772)
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| Project Period (FY) |
1991 – 1993
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| Keywords | Melting Heat Transfer / Natural Convection / Porous Media / Thermal Energy / Phase Change |
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| Research Abstract |
In recent years, from the view point of effective use of energy, the utilization of cold energy has been attempted in cold regions. Therefore it is important to know the melting characteristics.
In this study, the effects of the bead diameter and the physical properties of porous materials on melting heat transfer is analytically and experimentally examined in frozen porous media with a vertical heating wall.
The following conclusions can be drawn within the limits of this study.
(1) In the case that the diameter of bead is large and the temperature of heating wall is high, the effect of natural convection is observed in the melting region. The shape of melting front is determined from the large clockwise fluid flow occurred in the melting region.
(2) Nusselt number is in good agreement with the heat conduction solution when the heating began. The melting process is dominated by a conduction heat transfer. With time, the heat transfer mode is transformed from a conduction to a convection heat transfer. Nusselt number shows the minimum value in the case that the bead diameter is large and the temperature of heating wall is high.
(3) With the increase of the temperature of heating wall, Nusselt number and the increasing rate of melting volume increase. In the case that bead diameter is large, the effect of the density inversion is observed. Nusselt number for the case that the temperature of heating wall is 4ﾟC is larger than that of 8ﾟC
(4) The time that the heat transfer mode is transformed from a conduction to a convection heat transfer decreases with the increase of the bead diameter and the increase of the temperature of heating wall.
(5) The temperature of heating wall that the natural convection occurs in the melting region decreases with the increase of the bead diameter.
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