In this study

a swing absorption refrigeration system with 2

2

2-trifluoroethanol/tetraethylene glycol dimethyl ether (TFE-TEGDME) solution as the refrigerant pair was built to observe the vertical tube falling film absorber. Experiments in the stationary state showed that when the mass flow rate was 0.1–0.2 kg/min

the liquid film was in a laminar and monochromatic wave state; when the mass flow rate was 0.5 kg/min and 0.8 kg/min

the liquid film appeared to be a quasi-sine wave and merging wave flow

respectively; when the mass flow rate was 1.2 kg/min

the liquid film partly fell off. The absorption effect depends heavily on the surface wave type. The experimental results in the swing state showed that the perturbation on the liquid film will increase with increasing swing amplitude or a decreasing swing period. When the swing amplitude is 15° or the period is 4 s

the liquid film appears to be a merging wave or falls off from the wall of the tube. Under a fixed swing amplitude and period

the perturbation on the film is greater at the edge of the swing

whereas the flow is smoother at the middle of the swing. When the mass flow rate is 0.28 kg/min

the coefficient of performance (COP) of the system reaches the maximum at the swing amplitude of 8° or a period of 10 s. However

the COP will reach the maximum at a swing amplitude of 10° or a period of 8 s when the mass flow rate is 0.14 kg/min. The results also showed that when the flow rate is higher

the perturbation of the swing is greater.