Refinement of vehicle emission factor estimation in tunnel experiments using CFD and field measurement

IF 7.6 2区环境科学与生态学 Q1 ENVIRONMENTAL SCIENCES

Environmental Pollution Pub Date : 2025-07-16 DOI:10.1016/j.envpol.2025.126835

Xiaoyu Liang, Jianfei Peng, Yan Liu, Jinsheng Zhang, Lin Wu, Hongjun Mao

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Abstract

Tunnel experiments are widely used to determine fleet-average vehicle emission factors (EFs) under real-world conditions. However, limited sampling locations often lead to inaccuracies due to spatial heterogeneity in wind and pollutant dispersion. This study integrates CFD modeling with tunnel measurements to quantify and correct such errors. Simulations reveal that EFs derived from field measurements alone can be underestimated by up to 40 %, particularly under low traffic density and weak natural wind conditions. The estimated correction schemes for EFs were evaluated and validated using practical case studies. The results showed that the average EFs of NOx, CO, and PM_2.5 for the tunnel fleet were underestimated by approximately 24.50, 161.66, and 3.33 mg km⁻¹·veh⁻¹, respectively. Although the corrected EFs for diesel vehicles remain significantly higher than those for petrol vehicles, their relative contribution to the fleet-average EFs is notably reduced. The CFD analysis also highlights that external atmospheric conditions strongly influence internal tunnel flows, especially within 200 m of the entrance, offering valuable guidance for tunnel siting and sampling strategies. This study enhances the reliability of tunnel-derived EFs and supports the standardization of tunnel experiment protocols, contributing to more accurate emission inventories and targeted air quality management policies.

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基于CFD和现场测量的隧道试验中车辆排放因子估算的改进

隧道试验被广泛用于确定现实条件下车队平均车辆排放因子。然而，由于风和污染物扩散的空间异质性，有限的采样位置往往导致不准确。该研究将CFD建模与隧道测量相结合，以量化和纠正这些误差。模拟表明，仅从现场测量中得出的电场值可能被低估高达40%，特别是在低交通密度和弱自然风条件下。利用实际案例研究对电磁场的估计校正方案进行了评估和验证。结果表明，隧道车队NOx、CO和PM2.5的平均EFs分别被低估约24.50、161.66和3.33 mg·km-1·veh-1。虽然经校正后的柴油车辆废气排放仍明显高于汽油车辆废气排放，但柴油车辆废气排放在车队平均废气排放中所占的比例已明显下降。CFD分析还强调了外部大气条件对隧道内部流动的强烈影响，特别是在入口200 m范围内，为隧道选址和采样策略提供了有价值的指导。该研究提高了隧道衍生EFs的可靠性，支持隧道实验协议的标准化，有助于更准确的排放清单和有针对性的空气质量管理政策。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Environmental Pollution 环境科学-环境科学

CiteScore

16.00

自引率

6.70%

发文量

2082

审稿时长

2.9 months

期刊介绍： Environmental Pollution is an international peer-reviewed journal that publishes high-quality research papers and review articles covering all aspects of environmental pollution and its impacts on ecosystems and human health. Subject areas include, but are not limited to: • Sources and occurrences of pollutants that are clearly defined and measured in environmental compartments, food and food-related items, and human bodies; • Interlinks between contaminant exposure and biological, ecological, and human health effects, including those of climate change; • Contaminants of emerging concerns (including but not limited to antibiotic resistant microorganisms or genes, microplastics/nanoplastics, electronic wastes, light, and noise) and/or their biological, ecological, or human health effects; • Laboratory and field studies on the remediation/mitigation of environmental pollution via new techniques and with clear links to biological, ecological, or human health effects; • Modeling of pollution processes, patterns, or trends that is of clear environmental and/or human health interest; • New techniques that measure and examine environmental occurrences, transport, behavior, and effects of pollutants within the environment or the laboratory, provided that they can be clearly used to address problems within regional or global environmental compartments.