Experimental investigation of droplet parameters in a 2?2 rod bundle under air-water annular-mist flow

An experimental study was conducted to investigate the local droplet parameters for annular-mist airwater flow in a 2 x 2 rod bundle. It covered a flow condition of a superficial gas velocity ( j g ) range of 25-35 m/s (gas Reynold number ( Re g ) range of 39,132-54,785) and a superficial liquid velocity ( j l ) range of 0.015-0.040 m/s (liquid Reynold number ( Re l ) range of 432-1153) in an atmospheric pressure. From the test, the distributions of the local droplet parameters such as the droplet fraction, velocity, and diameter were measured by using a double sensor optical fiber probe (OFP). The effect of the superficial gas and liquid velocities on the local droplet parameters have been identified. Furthermore, the droplet mass flux over the measurement cross-section was obtained from the local droplet parameters distributions. It was found that the droplet mass flux has a decreasing trend with the superficial gas velocity and an increasing trend with superficial liquid velocity. That was attributed to the significant effect of the liquid film on the measured droplet mass flux and its trends. Moreover, the present droplet mass flux data were compared with the prediction of three existing droplet entrainment and deposition models. Finally, new entrainment and deposition rate models for predicting the droplet mass flux of a rod bundle were proposed and validated. The applicability of the proposed models is within the present experimental flow conditions range with a mean absolute percentage error (MAPE) of 10.34%. (c) 2022 Elsevier Ltd. All rights reserved.