基于暖体假人的消防员降温背心热传递及降温性能分析

Assessment of the heat transfer characteristics and cooling performance of firefighter cooling vests using thermal manikins

为降低消防员热应激水平,该文开展降温背心综合性能评价,研究降温背心传热规律以及高温辐射环境、不同劳动强度对降温背心性能的影响。通过环境舱和暖体假人系统评估3个型号的消防员降温背心的降温性能,分别在不同温度(35、40和45℃)、不同定向热辐射(1.5和2.5 kW/m^(2))和不同劳动强度(低、中等和高)下开展实验。实验结果表明:降温背心可以有效降低消防服内部微环境温度,在200 min后消防服内外层温差仍有6.6℃,辐射直射部位中降温背心对腹部冷却作用最明显;3个型号的降温背心均有不同程度的降温效果,其中降温背心1的降温性能最佳,散热降温功率为4.097 W,散热降温时间超过2 h,降温背心3的降温性能相对最差,散热降温功率为0.753 W,散热降温时间为90 min;随着劳动强度的增大,降温背心的冷却效果下降,其中假人腹部在劳动强度65、110和165 W/m^(2)时温度变化曲线线性拟合直线斜率分别为0.1068、0.2734和0.5086;降温背心的降温性能随环境温度升高而衰减,在环境温度45℃时,假人胸部、肩部、腹部和背部的温度上升梯度与35℃时相比分别增大50.0%、40.6%、60.0%和50.0%;定向热辐射对降温背心的降温性能影响明显,2.5 kW/m^(2)时假人胸部位置仅7 min温度就达到35.69℃。

[Objective]Firefighting suits worn by firefighters in high-temperature radiation environments,coupled with moderate physical exertion,can lead to body heat accumulation and increased microenvironment temperature inside the suits,which triggers adverse physiological reactions due to severe heat stress,resulting in decreased work efficiency,heat cramps,and other harms.Hence,cooling vests are widely used by firefighters to effectively alleviate heat stress in firefighting scenarios.However,most contemporary cooling vests encounter issues such as severe cold stress,short cooling duration,and poor comfort.Therefore,it is necessary to conduct research on the cooling performance of these vests.[Methods]The cooling effectiveness of three types of firefighter cooling vests was assessed using a thermal manikin system in an environmental chamber under the following conditions:temperatures of 35℃,40℃,and 45℃and directed thermal radiation of 1.5 and 2.5 kW/m^(2),with low,moderate,and high levels of physical exertion.D1922L temperature sensors were deployed on the thermal manikin system to measure the temperatures of the outer,insulation,comfort,and inner layers of the cooling vest as well as the temperatures of the inner and outer layers of the firefighting suit.[Results]The experiments reveal that the cooling vests effectively reduce the microenvironmental temperature inside the firefighting suit,with a temperature difference of 6.6℃between the inner and outer layers of the firefighting suit after 200 min of exposure.The cooling effect is most pronounced in the abdominal area with direct radiation.Among the three types of cooling vests assessed,Cooling Vest 1 exhibits the best performance,achieving a cooling power of 4.097 W and a cooling duration exceeding 2 h.Meanwhile,Cooling Vest 3 has a relatively poor cooling performance,with a cooling power of 0.753 W and a cooling duration of 90 min.As the physical exertion levels increase,the cooling effect of the vests is less pronounced.The linear fitting slopes of the temperature variation curves for the manikin's abdominal areas at 65,110,and 165 W/m^(2) are 0.1068,0.2734,and 0.5086,respectively.Furthermore,the cooling performance of the vests diminishes with increasing environmental temperatures.At an environmental temperature of 45℃,the temperature gradients in the manikin's chest,shoulders,abdomen,and back areas increase by 50.0%,40.6%,60.0%,and 50.0%,respectively.Moreover,the directed thermal radiation has a significant impact on the cooling performance of the vests.The temperature of the manikin's chest area reaches 35.69℃within only 7 min with a directed thermal radiation of 2.5 kW/m^(2).[Conclusions]These research findings are anticipated to serve as the preliminary data to enable the determination of rational work durations and intensity.In real fire rescue scenarios,the distribution of phase change materials for heat storage over the chest area and the duration of high-intensity work should be carefully considered.Additionally,these findings provide technical support for the development,testing,and evaluation of personal thermal protective equipment.