Experimental investigations on the pumping performance of bubble pumps with organic solutions

• Pumping performance of bubble pumps with R134a-DMF solutions was tested.
• Bubble pumps with lifting tubes of inner diameters (6, 8, 10) mm were selected.
• The pumping performance of the bubble pump with 6 mm lifting tube was the worst.
• Pumping performances of bubble pumps with 8 mm and 10 mm lifting tubes were similar.
• Mass fraction of R134a in solutions affected little on the bubble pump performance.

The pumping performances of bubble pumps for the diffusion absorption refrigerators were investigated on the purpose made experimental setup. The R134a-DMF (N, N-dimethylformamide) solution was used as the working fluids and R134a mass fractions of 20%, 25%, 30% and 35% were selected for three lifting tubes of different inner diameters (6 mm, 8 mm and 10 mm). The results showed that: (1) The pumping ratio of the bubble pump with the lifting tube of 6 mm inner diameter was the smallest while those of 8 mm and 10 mm lifting tubes were similar. (2) The pumping ratio decreased with the increase of the gas flow rate but increased with the increase of the concentration of R134a. (3) The generating temperature increased approximately linearly with the increase of the heat input, decreased little with the increase of the concentration of R134a and decreased obviously with the increase of the inner diameter of lifting tube. (4) The system pressure increased slightly with the increase of heat input but increased obviously with the increase of the concentration of R134a. The results will be helpful to the design of bubble pumps for the diffusion absorption refrigerators.