抄録
An experiment was carried out to elucidate operating limit of a two-phase bottom heated thermosyphon at atmospheric pressure. The operating limit is defined as a heat flux (q_f) at onset of heated surface temperature fluctuation. The thermosyphon employs water and has an adiabatic tube of inner diameter from D_p=2 to 8 mm and of its length of L=500 and 1000 mm. A feature of bubbles at the end of the tube was photographed to relate the temperature fluctuation and the effect of D_p and L on q_f was clarified. The characteristics of the temperature fluctuation and flow are changed at D_p=4 mm. The onset of the temperature fluctuation can be predicted by the Wallis equation with Cw=0.7 for 4<D_p≦8 mm.
