Aerodynamic performance improvement of up-flow outdoor unit of air conditioner by redesigning the bell-mouth profile

• Aerodynamic character of up-flow outdoor units is studied by tests and simulations.
• We found vortexes near rotor tip caused blockage on through flow of the fan.
• Aerodynamic performance of outdoor units is improved using the optimized bell-mouth.
• Combinations of different bell-mouth geometries and fan blade numbers are evaluated.

To improve the aerodynamic performance of an up-flow outdoor unit in a split-type air conditioner, experimental and numerical investigations on the propeller fan system of the outdoor unit are performed. Based on the prototype analysis, the propeller fan has a complex vortical flow field near the rotor tip. The vortex structures cause blockage effect on the through flow and have influence on the aerodynamic performance of the outdoor unit. The bell-mouth configuration is redesigned to control the vortex structures. It is shown that the redesigned bell-mouth can weaken the tip vortex and reduce the blockage effect. The redesigned bell-mouth is fabricated and installed on the outdoor unit with 2-blade fan to perform experimental validation. The measured results demonstrate that the aerodynamic efficiency of the outdoor unit is improved by 1.2% with use of the redesigned bell-mouth. The 3-blade fan solution is also attempted to provide more work capacity to enhance the flow rate.