密閉形円管熱サイホンの流動様式と伝熱機構

概要

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Measurements of the heat transfer and the visualization of the flow are carried out on vertical closed and open thermosyphons using water and ethylene glycol as a working fluid. The sizes of the closed thermosyphons are 10 and 20 mm in radius and 300 mm in length, and that of the open thermosyphon is 20 mm in radius and 150 mm in length. The present Nusselt number and flow pattern of the closed thermosyphons are compared with those of the open thermosyphon and the experimental and theoretical Nusselt numbers of the closed thermosyphon by Bayley et al.. The Nusselt number of the closed thermosyphons significantly decreases for the predominant flow of the conduction mode and the weak flow of the convection mode in the coupling region. The fraction of the flow of the convection mode is usually small and sensitively varied with the change of the tube diameter and the Rayleigh number for the range of diameter from 20 to 50 mm. This is the reason that the present Nusselt number of the closed thermosyphons is quite small, as compared with that of an open thermosyphon, and smaller than the other sources of data.
一般社団法人日本機械学会の論文
1988-03-25