Effect of By-Pass on the Heat Transfer Coefficient During Density Wave Oscillations in a Horizontal Mini-Channel

Two phase flow instabilities and in particular density wave oscillations, DWO, are strongly dependent on the internal and external characteristics of the system. Although significant work has been done investigating the characteristics of the stability of the oscillations, the effect of the oscillations on the heat transfer coefficient demands further research. In this work, the influence of a parallel bypass to the test section on the heat transfer coefficient during density wave oscillations is studied. It is observed that in the case of small amplitude DWO the influence of the bypass is negligible, while for the case of large amplitude DWO that reach conditions of flow reversal the heat transfer coefficient can be enhanced. This fact is attributed to cold liquid entering at the outlet of the test section from the bypass preventing the dryout of the wall at high qualities.