Abstract: As important equipment for air conditioning, the noise control level of the air conditioning system is one of the key factors in evaluating its quality. Therefore, in-depth research on the noise problem of air conditioning systems is particularly important. The noise, airflow, and whistling sounds that occur during the cooling and heating process of heat pump heating mechanisms are focused on by this article. Through experimental analysis, the problem is identified and optimization solutions are proposed. The results indicate that the three-way variable diameter at the subcooled outlet and the structure of the electronic expansion valve is the main causes of airflow and whistling sounds; The main valve adopts a straight through type, and adjusting the diameter of the subcooled outlet main pipe to the same diameter as the three-way valve (diameter 7) can significantly reduce the occurrence of airflow and whistling sounds. This study has certain reference value for solving problems such as airflow noise and whistling sound in air conditioning systems, as well as optimizing noise reduction design in air conditioning systems.

Key words: Air conditioning system, Heat pump, Heating machine, Noise