In this study, artificial snow is produced under natural conditions using a snowmaking machine, and the microscopic morphology of the snow crystals is obtained. The sizes of snow particles and the factors that influence them under various working conditions are subsequently analyzed, and the formation of artificial snow is deduced. The results show that the falling position, environmental temperature and humidity, and nozzle atomization particle size are important factors affecting snow particle diameter. Lower environmental temperature and humidity, as well as a smaller nozzle diameter, facilitate the formation of larger snow particles. When the snowmaker operates stably, the distribution of snow particle diameter is more non-uniform in distant areas than at the edges and middle regions. The measured snow particle size is approximately 0.3 mm, which is significantly larger than the atomization particle size of the nozzle (0.12 mm). This result indicates that snow particles collide during flight. Overall, this study is important for understanding the mechanisms of snow formation and the regulation of snow quality.

An experimental platform was built to evaluate the thermal switching performance of a parallel pulsating multi-channel heat pipe using fluoroether HFE-7100 as the working fluid with a liquid filling ratio of 80%. The heating and cooling temperatures of the pulsating heat pipe were controlled using water baths for heating and cooling. The thermal switching characteristics of the pulsating heat pipe at different cooling temperatures were investigated experimentally. The results showed that after the complete start-up of the multi-channel parallel pulsating heat pipe, the average temperature of the evaporation section decreased, the average temperature of the condensation section increased, the thermal resistance decreased, and the heat transfer performance improved rapidly. The temperature and thermal resistance transient processes exhibited a sudden step change, which can be used as a thermal switch. As the cooling temperature increased, the closing time of the thermal switch and the switch temperature increased. At a cooling temperature of 10 ℃, the closing time of the thermal switch was 12 s, and the switch temperature was 59.3 ℃. At higher cooling temperatures, the thermal switch performed better, characterized by a greater increase in the switch ratio and heat transfer rate. When the cooling temperature was 30 ℃, the heat transfer rate increased by 26.8 W following the closure of the thermal switch, with a switch ratio of 5.05.