辐射制冷技术在安全帽上的应用研究*

为缓解夏季配戴安全帽导致的头部高温不适，采用具有光谱选择特性的辐射降温涂料对安全帽表面光学性能进行改性，经光学测试，安全帽的太阳辐射反射率由45%提升至89%，大气窗口发射率由92%提升至95%。对安全帽进行降温效果测试，并基于测试结果建立热力学模型。结果表明:在阳光直射下，改性安全帽内部温度低于普通白色安全帽，温差最大12.2 ℃；在热力学模型中，即使在夏季最热时间段（12∶00～14∶00），改性安全帽内部温度仍可比普通安全帽低8 ℃，预测平均评价值由普通安全帽的3.5降低至1.0，预测不满意百分比从100%降低至20%。

Application research of radiative cooling technology on safety helmet

In order to relieve the head high temperature discomfort caused by wearing the safety helmet in summer,the surface optical performance of safety helmet was optimized by using the radiative cooling coating with the spectral selection characteristics.Through the optical testing,the solar radiation reflectivity of safety helmet increased from 45% to 89% and the atmospheric window emissivity increased from 92% to 95%.The cooling effect tests were conducted on the safety helmet,and a thermodynamic model was established on the basis of the testing results.It showed that under the direct sunlight,the internal temperature of the optimized safety helmet was lower than that of the common white safety helmet,and the maximum temperature difference was 12.2 ℃.In the thermodynamic model,even at 12∶00-14∶00 in the hottest day of summer,the internal temperature of the optimized safety helmet was still lower than that of the common safety helmet,with the temperature difference of 8 ℃.The predicted mean vote (PMV) decreased from 3.5 of common safety helmet to 1.0,and the predicted percent dissatisfied (PPD) decreased from 100% to 20%.