SIMULATION OF DROPLET SIZE DISTRIBUTION DURING JUMPING-DROPLET CONDENSATION

High-flux condensation heat transfer is crucial to the enhanced efficiency and the safety of nuclear power plants. During the last decade, jumping droplet condensation has attracted extensive attention due to its significant potential to enhance heat transfer. Previous studies of coalescence-induced droplet jumping dynamics have focused on energy balance with equal-sized-droplet while ignoring size-mismatched droplet jumping, which actually markedly affects jumping behaviour during condensation. In this study, a simulation framework reproducing nucleation, droplet growth, coalescence-induced droplet jumping and re-nucleation has been developed to study jumping-droplet condensation heat transfer. The linked-list search algorithm was applied to search neighbouring droplets to enhance the computational performance. To take into account droplet size mismatch effects on the coalescence-induced droplet departure, an experiment-based jumping criterion was incorporated into the model. The simulation results were validated by previously reported droplet size distribution during jumping droplet condensation. In the transient process, the initial nucleated droplets followed the random distribution with uniform droplet size and then transitioned to bimodal distribution, with right peak value declining as condensation proceeded. Eventually, the droplet size distribution reached a steady-state exponential distribution. Our study not only presents a simulation framework of jumping droplet condensation, but also provide insights into the entire lifecycle of multiscale condensation dynamics.