Volume 6, Issue 2 (February 2009)

    Gas-Cooling of Multiple Short Inline Disks in Flow Along Their Axis

    (Received 30 April 2008; accepted 25 November 2008)

    Published Online: 2008

    CODEN: JAIOAD

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    Abstract

    To learn about cooling of gas quenched batches, this paper reports on numerical predictions of local and average convective heat transfer coefficients, and overall pressure drops, on batches of five axially aligned, constant temperature, short cylindrical disks (25 cm diameter, 5 cm thickness) with and without a concentric hole, with interdisk spacings of 5–20 cm, in axial turbulent flows of 20 bar nitrogen gas at inlet speeds from 10 m/s to 100 m/s, corresponding to Reynolds numbers (Re) between 3.27×106 and 32.7×106. The heat transfer coefficients along the disk surfaces vary strongly up to a worse case of two orders of magnitude for the upstream disk. This nonuniformity is much lower for the disks downstream, especially after spacing is increased beyond 0.1 m. As expected, the upstream disk exhibited rather different heat transfer coefficients than the ones downstream, the magnitude of the heat transfer coefficient and its uniformity increased with the interdisk spacing, and varied by a factor of about 4–5 along the surfaces. The average heat transfer coefficient (Nusselt number, Nu) on the disks increased approximately with Reynolds number as Re0.85. Re did not have much influence on the nonuniformity of Nu on the disk surfaces. The overall pressure drop along the flow increases with the interdisk spacing, rising by about 60 % as the spacing is increased from 0.05 m to 0.20 m. The presence of a hole increases the heat transfer coefficient in all cases. Some suggestions for reducing the heat transfer coefficient nonuniformity are made.


    Author Information:

    Lior, Noam
    Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA

    Papadopoulos, Dimitrios
    Faxénlaboratoriet, KTH, Stockholm,


    Stock #: JAI101849

    ISSN: 1546-962X

    DOI: 10.1520/JAI101849

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    Author
    Title Gas-Cooling of Multiple Short Inline Disks in Flow Along Their Axis
    Symposium , 0000-00-00
    Committee G04