Workers in underground coal mines are always at risk of heat shock due to high temperatures and narrow spaces. To reduce the temperature in the longwall faces, some mines have used air conditioners to increase the cooling capacity, creating a better working environment for miners

Several experiments were conducted in a drying chamber, with Natto as the test material. These experiments involved varying the number of trays and the angle of the trays to determine the most appropriate configuration, verify the uniformity of air distribution in the equipment, and evaluate the uniformity of the average moisture reduction of Natto seeds in each batch compared to the established theory in the previous study.

This study evaluates the effect of the air gap size (d) on the air uniformity in the chamber dryer with the most appropriate air blade angle value inherited from the previous study. Furthermore, several cases of tray and equipment length are also tested, and they also affect the air distribution.