In-vehicle air pollution has become a public health priority worldwide, especially for volatile organic compounds (VOCs) emitted from the vehicle interiors. Although existing literature shows VOCs emission is temperature-dependent, the impact of solar radiation on VOCs distribution in enclosed cabin space is not well understood. Here we made an early effort to investigate the VOCs levels in vehicle microenvironments using numerical modeling. We evaluated the model performance using a number of turbulence and radiation model combinations to predict heat transfer coupled with natural convection, heat conduction and radiation with a laboratory airship. The Shear–Stress Transport (SST) k-ω model, Surface-to-surface (S2S) model and solar load model were employed to investigate the thermal environment of a closed automobile cabin under solar radiation in the summer. A VOCs emission model was employed to simulate the spatial distribution of VOCs. Our finding shows that solar radiation plays a critical role in determining the temperature distribution in the cabin, which can increase by 30 °C for directly exposed cabin surfaces and 10 °C for shaded ones, respectively. Ignoring the thermal radiation reduced the accuracy of temperature and airflow prediction. Due to the strong temperature dependence, the hotter interiors such as the dashboard and rear board released more VOCs per unit time and area. A VOC plume rose from the interior sources as a result of the thermal buoyancy flow. A total of 19 mg of VOCs was released from the interiors within two simulated hours from 10:00 am to noon. The findings, such as modeled spatial distributions of VOCs, provide a key reference to automakers, who are paying increasing attention to cabin environment and the health of drivers and passengers.

中文翻译：

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模拟太阳辐射下车厢内表面的车内 VOC 分布

车内空气污染已成为全球公共卫生的重点，尤其是从车辆内部排放的挥发性有机化合物 (VOC)。尽管现有文献表明 VOCs 排放与温度有关，但太阳辐射对封闭机舱空间中 VOCs 分布的影响尚不清楚。在这里，我们早期努力使用数值建模研究车辆微环境中的 VOC 水平。我们使用许多湍流和辐射模型组合来评估模型性能，以预测与实验室飞艇结合的自然对流、热传导和辐射的热传递。剪切应力传递 (SST) k-ω 模型，采用表面对表面（S2S）模型和太阳负荷模型研究夏季太阳辐射下封闭式汽车车厢的热环境。VOCs排放模型被用来模拟VOCs的空间分布。我们的研究结果表明，太阳辐射在确定机舱内的温度分布方面起着至关重要的作用，直接暴露的机舱表面可以分别增加 30°C，阴影部分可以分别增加 10°C。忽略热辐射会降低温度和气流预测的准确性。由于强烈的温度依赖性，仪表板和后板等较热的内饰在单位时间和面积上释放出更多的 VOC。由于热浮力流，VOC 羽流从内部来源上升。从上午 10:00 到中午的两个模拟小时内，总共从内部释放了 19 毫克的 VOC。研究结果，例如模拟的 VOC 空间分布，为越来越关注机舱环境以及驾驶员和乘客健康的汽车制造商提供了重要参考。