Exhaust emissions and energy conversion of hybrid and conventional CNG buses

IF 7.3 1区工程技术 Q1 ENVIRONMENTAL STUDIES

Transportation Research Part D-transport and Environment Pub Date : 2024-09-06 DOI:10.1016/j.trd.2024.104405

Rui Hu , Xinyi Chen , Li Li , Fanling Kong , Yonghong Liu

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Abstract

The real-driving emission (RDE) test was employed involving a conventional compressed natural gas (CNG) bus and its hybrid counterpart powered by the same engine type along the same route. By calculating the energy balance of engine and vehicle, hybrid bus saves energy in three ways: engine efficiency increase (30 %), regenerative braking (21 %) and without idling (7 %). But the higher curb weight offset 32 % of the benefits, resulting in 24 % improvement in comprehensive efficiency. The NOx and particulate number (PN) emissions of the hybrid bus could be reduced by 46 % and 39 %, respectively. The emission causes of all pollutants were further classified into: cold-start, restart and hot running. Restart accounts for 52 % of CO emission and hot running for 55 % of NOx emission. Frequent engine restart and short engine running durations (<50 s) impair efficiency and emissions. The findings can help policymakers assess the environmental impact of transport electrification.

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混合动力和传统 CNG 公共汽车的废气排放和能量转换

实际驾驶排放（RDE）测试采用了传统压缩天然气（CNG）公交车和由相同型号发动机驱动的混合动力公交车在相同路线上行驶的情况。通过计算发动机和车辆的能量平衡，混合动力公交车通过三种方式节能：提高发动机效率（30%）、再生制动（21%）和不空转（7%）。但较高的整备质量抵消了 32% 的效益，使综合效率提高了 24%。混合动力公交车的氮氧化物和颗粒物排放量分别减少了 46% 和 39%。所有污染物的排放原因进一步分为：冷启动、重新启动和热运行。重新启动占一氧化碳排放量的 52%，热运行占氮氧化物排放量的 55%。发动机频繁重启和短时间运行（50 秒）会影响效率和排放。研究结果有助于决策者评估交通电气化对环境的影响。

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

Transportation Research Part D-transport and Environment 工程技术-运输科技

CiteScore

14.40

自引率

9.20%

发文量

314

审稿时长

39 days

期刊介绍： Transportation Research Part D: Transport and Environment focuses on original research exploring the environmental impacts of transportation, policy responses to these impacts, and their implications for transportation system design, planning, and management. The journal comprehensively covers the interaction between transportation and the environment, ranging from local effects on specific geographical areas to global implications such as natural resource depletion and atmospheric pollution. We welcome research papers across all transportation modes, including maritime, air, and land transportation, assessing their environmental impacts broadly. Papers addressing both mobile aspects and transportation infrastructure are considered. The journal prioritizes empirical findings and policy responses of regulatory, planning, technical, or fiscal nature. Articles are policy-driven, accessible, and applicable to readers from diverse disciplines, emphasizing relevance and practicality. We encourage interdisciplinary submissions and welcome contributions from economically developing and advanced countries alike, reflecting our international orientation.