Simulation of bubbles motion side by side in lifting pipe of two-stage bubbles pump

Bubble pump was proposed to replace the traditional mechanical solution pump in the lithium bromide absorption chiller, for its advantageous feature that can be driven by industrial waste heat or solar energy or other low-grade energy. In two-stage bubble pump lithium bromide absorption refrigeration system, different flow patterns in lifting pipe have large relations with the performance of bubble pump. In this paper, a numerical simulation was performed to investigate the interaction of bubbles rising side by side in lithium bromide solution using the lattice Boltzmann method. The rising of bubbles with different configurations, including horizontal alignment and oblique alignment, was simulated. The results show that: the rising process of two side by side bubbles with horizontal alignment has two stages: close to the first, and then separated. The rising speed decreased with two bubbles close and increased with bubbles separate. For two different size rising bubbles with horizontal configuration, the bigger one has an attractive force on the little one, and the velocity of bigger bubble is much larger than the little one too.