卷烟引燃倾向检测模型分析

Establishing a thermophysical model to improve cigarette ignition propensity test

为提高卷烟引燃倾向检测结果的通过率和稳定性,基于对燃烧锥与滤纸间有效接触面积的计算,采用Comsol Multiphysics软件建立传热模型并结合实验验证,分析了传热过程和阻燃条位置对测试结果的综合影响。结果表明:①燃烧锥与滤纸接触的前6 mm内,由于传热量大,熄灭的概率高,若该区域内含有部分阻燃条,则一般不会发生全长燃烧(Full Length Burn,FLB)行为,且熄灭容易发生在该区域内,而发生FLB行为的低引燃倾向(Lower Ignition Propensity,LIP)卷烟一般在该区域内不含阻燃条;②卷烟在滤纸表面阴燃时,燃烧锥会向上弯曲,在燃烧锥下部与滤纸间产生的空间为卷烟的持续燃烧起到了促进作用,进而使检测到的卷烟引燃能力比实际大,一定程度上影响了ISO 12863方法测试结果的稳定性;③通过每隔一定时间将卷烟迅速旋转180度的方法可以有效解决卷烟在滤纸表面阴燃过程中的燃烧锥弯曲过大问题。

In order to improving the pass rate and stability of test results for cigarette ignition propensity tests,the effects of heat transfer process and burn retardant band positions on the test results were analyzed via calculating the effective contact area between the burning cone and substrate filter paper,adopting the software Comsol Multiphysics to describe the heat transfer model and subsequent experimental verification.The results showed that:(1)Due to the larger heat transfer within the first 6 mm contact between the burning cone and the substrate filter paper,the probability of extinguishment was higher.If there was a part of the burn retardant band in that contact area,the full length burn(FLB)would not happen generally,and the extinguishment was easier to occur.In general,the low ignition propensity cigarette displaying a FLB behavior had no burn retardant band in that area.(2)When the cigarette smoldered on the surface of the filter paper,a space was created between the lower part of the burning cone and the filter paper due to the upward bending of the burning cone.That space promoted the continuous smoldering of the cigarette and made the detected cigarette ignition ability larger than the actual one,which affected the stability of the test results of ISO 12863 method to a certain extent.(3)Through rapidly rotating the test cigarette by 180 degrees at a regular interval,the excessive bending of the burning cone during smoldering on the filter paper surface could be effectively avoided.