Effect of inlet pressure and temperature on density wave oscillations in a horizontal channel

The period of Density Wave Oscillations (DWOs) in an uniformly heated horizontal test section is experimentally investigated. The test section consists of a 5 mm I.D. pipe where R134a is used as working fluid. The experiment is performed for a range of inlet pressures Pi [500-1200 kPa], inlet sub-cooling [10 and 20 K], maintaining constant heat fluxes q″ [38 kW/m2] and mass flux G [300 kg/m2s]. The effect of the system parameters on the period of the DWOs is studied. It is observed that the period of the DWOs increases as inlet pressure and inlet sub-cooling temperature increase. Furthermore it is observed changes in the period which might be connected to the changes in the flow regime distribution inside the pipe.