Garment size effect of thermal protective clothing on global and local evaporative cooling of walking manikin in a hot environment

Evaporative cooling is the critical heat dissipation mechanism for working individuals wearing thermal protective clothing in hot environments. However, until now, there is no knowledge on garment size design for evaporative cooling optimization, especially when the human body is in movements. In this study, to understand the dynamic effect of garment size on evaporative cooling, we performed experiments on a sweating thermal manikin with seven garment sizes and three walking speeds. The evaporative cooling of global and local manikin body with this wide range garment sizes was present. Results demonstrated that the effect of garment size on evaporative cooling depended on the walking speed. At lower walking speeds, the global evaporative cooling tended to decrease with greater garment size, while at higher walking speeds, the global evaporative cooling tended to increase with greater garment size. Similarly, according to effects of garment size on local evaporative cooling, body segments could be divided into three categories for evaporative cooling optimization. Further, we analyzed factors which influenced the positive effect of walking speed on the evaporative cooling. Results showed that, for most cases, the increase of evaporative cooling caused by walking showed positive linear relationship with the garment size. Further increase of walking speed led to a greater increase rate of evaporative heat loss for body segments with the small air gap. This study provides insights into clothing local characteristics of evaporative cooling with different garment sizes under dynamic conditions and may help clothing design to optimize the evaporative cooling of working individuals in hot environments.