Abstract: The inverted air duct machine adopts the suction system scheme. The condensation problem inside the box has become the key problem in the air conditioning design. The causes and solutions of condensation problems in the air conditioning box were analyzed. Firstly, the main mechanism of condensation formation was determined by analyzing the location and phenomenon of condensation. The temperature field inside the chamber was tested in the experiment, and it was determined that there was a problem of uneven shunt in the design of heat exchanger, which led to uneven heat transfer and the presence of hot and humid air, which became the main factor leading to condensation. Then the CFD simulation technology was used to simulate the internal flow field, and it was confirmed that there was eddy current at the bottom of the volute, and the hot and humid gas converged at the bottom of the volute to form condensation. According to the flow field in the machine, the air guide plate is formulated to alleviate the temperature field stratification phenomenon caused by the uneven heat transfer under the influence of shunt and gravity. The feasibility of the scheme is further verified through experiments, and the problem of condensation inside the box is finally solved, and it is applied to the product.

Key words: Condensation, Volute, CFD, Vertical air duct machine, Dew point temperature