Abstract: In order to improve the performance of air conditioning, the material selection of the expansion tube in the two units is mostly copper, with the rapid development of air conditioners and the continuous rise of international copper prices, the heat exchangers used in the refrigeration and air conditioning industry are gradually developing in the direction of high energy efficiency, small volume and low cost. The use of smaller pipe diameter copper pipe or directly reduce the number of copper pipe can meet the above needs. Taking the 2 P ceiling machine as the research object, the evaporator uses D5 copper tube, and the upwind heat exchange area and the constant number of copper tubes are controlled to be unchanged. The temperature difference at the outlet of each branch is controlled within 3 ℃ by adjusting the evaporator shunt capillary tube and adjusting the shunt, and the APF before adjustment is 3.37. After adjustment by two ways, the APF is 3.57 and 3.6, respectively, with an increase of 5.9% and 6.8%, through the final result comparison, it can be concluded that the flow path uniformity has a great impact on the overall performance and energy efficiency of the ceiling machine.

Key words: Ceiling machine, Evaporator, Flow path, Property