Indoor Air Quality Program, Environmental Health Laboratory, California Department of Public Health, Richmond, CA, United States of America.
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka, Japan.
PLoS One. 2018 Apr 19;13(4):e0195925. doi: 10.1371/journal.pone.0195925. eCollection 2018.
To determine the effect of applied power settings, coil wetness conditions, and e-liquid compositions on the coil heating temperature for e-cigarettes with a "top-coil" clearomizer, and to make associations of coil conditions with emission of toxic carbonyl compounds by combining results herein with the literature.
The coil temperature of a second generation e-cigarette was measured at various applied power levels, coil conditions, and e-liquid compositions, including (1) measurements by thermocouple at three e-liquid fill levels (dry, wet-through-wick, and full-wet), three coil resistances (low, standard, and high), and four voltage settings (3-6 V) for multiple coils using propylene glycol (PG) as a test liquid; (2) measurements by thermocouple at additional degrees of coil wetness for a high resistance coil using PG; and (3) measurements by both thermocouple and infrared (IR) camera for high resistance coils using PG alone and a 1:1 (wt/wt) mixture of PG and glycerol (PG/GL).
For single point thermocouple measurements with PG, coil temperatures ranged from 322 ‒ 1008°C, 145 ‒ 334°C, and 110 ‒ 185°C under dry, wet-through-wick, and full-wet conditions, respectively, for the total of 13 replaceable coil heads. For conditions measured with both a thermocouple and an IR camera, all thermocouple measurements were between the minimum and maximum across-coil IR camera measurements and equal to 74% ‒ 115% of the across-coil mean, depending on test conditions. The IR camera showed details of the non-uniform temperature distribution across heating coils. The large temperature variations under wet-through-wick conditions may explain the large variations in formaldehyde formation rate reported in the literature for such "top-coil" clearomizers.
This study established a simple and straight-forward protocol to systematically measure e-cigarette coil heating temperature under dry, wet-through-wick, and full-wet conditions. In addition to applied power, the composition of e-liquid, and the devices' ability to efficiently deliver e-liquid to the heating coil are important product design factors effecting coil operating temperature. Precautionary temperature checks on e-cigarettes under manufacturer-recommended normal use conditions may help to reduce the health risks from exposure to toxic carbonyl emissions associated with coil overheating.
确定电子烟“顶置线圈”雾化器在不同外加功率设定、线圈湿润状态和烟液成分条件下的线圈加热温度，并结合本文和文献中的结果，对线圈状态与有毒羰基化合物排放之间的关联进行评估。
使用热电偶测量第二代电子烟的线圈温度，在不同的外加功率水平、线圈状态和烟液成分下进行测量，包括：（1）使用丙二醇（PG）作为测试液，在三个烟液填充水平（干、湿透芯、全湿）、三个线圈电阻（低、标准、高）和四个电压设置（3-6 V）下，对多个线圈进行测量；（2）在高电阻线圈上使用 PG 进一步测量线圈湿润程度的热电偶测量；（3）仅使用 PG 和丙二醇/甘油（PG/GL）的 1:1（wt/wt）混合物，使用热电偶和红外（IR）相机对高电阻线圈进行测量。
对于使用 PG 的单点热电偶测量，在 13 个可更换线圈头中，干燥、湿透芯和全湿条件下的线圈温度分别为 322-1008°C、145-334°C 和 110-185°C。对于使用热电偶和 IR 相机测量的条件，所有热电偶测量值都在跨线圈 IR 相机测量值的最小值和最大值之间，并且取决于测试条件，等于跨线圈平均温度的 74%-115%。IR 相机显示了加热线圈不均匀温度分布的细节。湿透芯条件下的大温度变化可能解释了文献中报道的此类“顶置线圈”雾化器甲醛生成率的巨大变化。
本研究建立了一种简单直接的方案，可在干燥、湿透芯和全湿条件下系统地测量电子烟线圈的加热温度。除外加功率外，烟液成分和设备将烟液有效输送到加热线圈的能力也是影响线圈工作温度的重要产品设计因素。在制造商推荐的正常使用条件下对电子烟进行预防性温度检查，可能有助于降低因线圈过热导致接触有毒羰基化合物排放物而产生的健康风险。
