The gas–liquid two-phase flow characteristics in the riser of the bubble pump directly affects its working substance lifting performance. A high-speed camera system was set-up to visualize the lifting process of multiple tube bubble pump under different heating power values (400

600

800

1000

1 200

1 400 W)

and the liquid lifting process of the multiple tube bubble pump was compared with that of the single-tube bubble pump. The research results indicated that multiple tube bubble pumps exhibit an increase in total lifting capacity and liquid lifting rate as heating power increases. When the heating power was 1400 W

the total lifting capacity increased by 15.16 kg and liquid lifting rate increased by 5.08 g/s when compared to that under a heating power of 1200 W. The lifting effect was optimal when the number of bubbles in the lifting tube at the center of the multi-tube bubble pump was higher. With respect to single-tube bubble pumps

when the heating power was 400 W

the increase in the number of riser tubes could not improve the liquid lifting performance of the bubble pump when compared with that of multiple tube bubble pumps. When the heating power was 400 W

the increase in the number of riser tubes could not improve the liquid lifting performance of the bubble pump. Furthermore

when the heating power was 600–800 W

the single-tube bubble pump liquid lifting performance was approximately similar to that of multiple tube bubble pump. When the heating power was 1000–1400 W

the total lifting capacity

maximum lifting rate

and pump efficiency of the multiple tube bubble pump were significantly improved when compared with the corresponding performance of a single-tube bubble pump.