Experimental study of the heat transfer coefficient deterioration during Density Wave Oscillations

•Study of heat transfer deterioration during Density Wave Oscillations.•Density Wave Oscillations can deteriorate the heat transfer coefficient.•The impact is more severe for low pressure, mass flux and inlet temperature.

The effect of the Density Wave Oscillations (DWO) on the heat transfer is studied experimentally. A horizontal test section of 5 mm I.D. with R134a as working fluid was used for the experiments. The time averaged boiling heat transfer was found to be different under DWO conditions than under steady-state flow. Four different cases were studied considering different inlet pressure, temperature and mass flow rate. It was observed that the occurrence of the DWO can result in a premature dry-out and that the impact of the DWO on the heat transfer depends on the particular conditions. However for the studied cases the impact on the heat transfer was not severe.