The present experiments have demonstrated that water droplets (∼200-μm dia) can be lifted to substantial heights (∼50 m) by their own vapor produced in flashing over temperature differences typical of the tropical seas. The coupling between the vapor and droplets is found to be excellent. The efficiency for momentum coupling is over 90 percent, and that for energy coupling is shown to vary inversely with the slip ratio. For the conditions in the present experiments, it varies from 50 to 80 percent. The momentum transfer is correlated with an interaction parameter which is the product of the liquid fraction, the slip, and the amount of flashing. For the high vapor flow cases, the pressure difference across the lift column is found to be proportional to the interaction parameter. The relevance of the two-phase flow to a class of open-cycle ocean thermal energy conversion (OTEC) schemes is considered, and the implications of the observed strong vapor/droplet coupling to the feasibility of the mist-flow OTEC cycle are discussed.

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