A two-phase closed thermosyphon with an adiabatic section using a flexible hose and R-134a filling

• The adiabatic section of the R-134a thermosyphon was constructed of a Teflon hose.
• Bending positions of the hose had an effect on heat transfer characteristics.
• Bending at both ends would result in the lowest TS performance.

This research aimed to investigate the effects of bending and tilting in a flexible hose thermosyphon (TS) on thermal performance. The adiabatic section of the TS was constructed of a Teflon hose with an inner diameter of 12.7 mm, while the evaporator and condenser were made of straight copper tubing with an identical diameter of 17.4 mm. The proposed TS was charged with R-134a refrigerant. The effects of bending positions and tilt angles on evaporator temperature, flow resistance, overall thermal resistance and heat transfer characteristics (Q/Q90) were tested in comparison with a TS that is vertically oriented. At the same tilt angle, bending at the upper end of the flexible hose would decrease TS performance more than bending at the lower end. Bending at both ends would result in the lowest TS performance. The optimum tilt angle for most cases was 45°, except for the case with bending at both ends, which was 60°.

This research aimed to investigate the effects of bending and tilting in a flexible hose thermosyphon (TS) on the thermal performance. At the same tilt angle, bending at the upper end of the flexible hose would decrease TS performance more than bending at the lower end. In comparison to the vertical orientation, the bending pipe at one end (upper or lower) have a high performance.Figure optionsDownload as PowerPoint slide