Visual experimental research on bubble absorption in a vertical tube with R124–DMAC working pair

•The visual bubble absorption experiment in a vertical tube for R124–DMAC was done.•Three kinds of flow pattern, churn, slug and bubbly flow were observed.•The variations of operation parameters affect flow pattern and absorption height. Visual experimental investigations were carried out on a vertical co-current glass tube absorber to observe the behavior of the R124 (2-chloro-l,l,l,2,-tetrafluoroethane)–DMAC (N′,N′-dimethylacetamide) bubble absorption process and study the effects of different operating conditions on absorption performance. The results show that the refrigerant vapor flow rate, absorption solution flow rate, concentration, temperature and nozzle orifice diameter significantly affect the flow pattern and absorption height. As the vapor flow rate, absorption solution concentration and temperature, and nozzle orifice diameter increases, the absorption height increases. As the absorption solution flow rate increase, the absorption height reduces. Under the conditions of a large refrigerant vapor flow rate, high solution inlet concentration and temperature, three kinds of flow pattern, namely churn, slug and bubbly flow, can be simultaneously observed in the absorption tube.