On the performance limit of closed two-phase thermosyphons.

Abstract

An experiment was conducted to examine the performance limit of closed two-phase thermosy-phons, together with visual observation of flow state in the adiabatic section. The working fluids used were R 113, methanol and water. The flow state at the performance limit conditions was a violently disturbed slug type, in which the vapor plugs hold up the liquid slugs periodically to a high level, causing a local liquid circulation in the adiabatic section. This phenomenon is somewhat different from the flooding observed in open systems. Then, an equation correlating the vapor velocity at the performance limit to the rising velocity of vapor plugs in stagnant liquid columns is proposed. This correlation is in good agreement with the performance limit data covering a wide range of parameters.