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Non-parametric statistical evaluation of biodiesel emissions from transit buses.

机译：公交公交车生物柴油排放量的非参数统计评估。

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摘要

Research on biodiesel emissions has been triggered by depleting fossil fuel resources and environmental protection concerns. However, vehicular emissions are inadequately understood and quantified because of large variations in individual vehicle emissions with changing operating conditions, engines and fuels. More research is needed to evaluate biodiesel emissions especially from heavy duty vehicles which include transit buses. Past research findings have been contradictory mostly in case of NOx emissions. These make it essential to carry out further research especially with the help of on-road measurement devices which can capture the real-time variation in operating conditions, unlike dynamometers and remote sensing devices.;Emissions data were collected using a portable emission measurement system (PEMS) from three transit buses fueled with regular diesel (B0), 10% biodiesel (B10) and 20% biodiesel (B20). At an interval of one second, NOx, HC, CO, CO2 and particulate matter (PM) were recorded along with speed, acceleration, other engine parameters, and number of passengers for all the nine bus-fuel combinations. Emissions were found to exhibit auto-correlation and non-normal distributions, which necessitated a binning-based approach and the use of non-parametric statistics respectively for data analysis. Emission rates were not proportional to percentage of biodiesel. This was also seen when the same batch of biodiesel was tested using a dynamometer. Therefore, B10 and B20 were evaluated separately. The commonly used VSP formula was modified to account for passenger weight and load imparted by the use of air-conditioning. Emissions from each fuel were binned by speed and vehicle specific power (VSP). Emissions from each fuel were grouped by VSP into three bins. Emissions varied monotonically with VSP. Further, no significant change in result was obtained upon using the new formula. Statistical tests were performed to compare emissions from B10 and B20 to B0.;Evaluation of B10 revealed that NOx, HC, CO, and CO2 emission rates decreased for Tier-1 buses. For Tier-2 bus, NO x, HC, CO2 and PM emission rates increased while CO emission rates decreased. With B20, HC and PM emission rates decreased for all the buses. NOx and CO, CO2 results were contradictory. Decrease in PM emissions is very significant particularly for heavy duty vehicles in terms of freight demand. Decrease in HC is not significant for diesel engines. Likewise, inconsistency in CO emissions is also immaterial while inconsistency in NO x emissions supports previous researches.;Keywords: biodiesel, data binning, diesel, emissions, on-road testing, non-parametric statistical tests, VSP.
机译：消耗化石燃料资源和环境保护问题引发了对生物柴油排放的研究。然而，由于随着操作条件，发动机和燃料的变化，单个车辆的排放量有很大的变化，因此对车辆的排放量没有充分的理解和量化。需要更多的研究来评估生物柴油的排放，尤其是包括公交车在内的重型车辆的生物柴油排放。过去的研究结果主要在氮氧化物排放的情况下是矛盾的。这些使得进行进一步的研究至关重要，尤其是借助公路测量设备，该设备可以捕获运行状况的实时变化，这与测功机和遥感设备不同。;排放数据是使用便携式排放测量系统收集的（ PEMS）来自三辆使用常规柴油（B0），10％生物柴油（B10）和20％生物柴油（B20）燃料的公交车。每隔一秒钟，会记录所有九种公交车燃料组合的NOx，HC，CO，CO2和颗粒物（PM）以及速度，加速度，其他发动机参数和乘客人数。发现排放物表现出自相关和非正态分布，这需要基于分类的方法和分别使用非参数统计进行数据分析。排放率与生物柴油的百分比不成比例。当使用测力计测试同一批生物柴油时，也可以看到这一点。因此，B10和B20分别进行了评估。修改了常用的VSP公式，以考虑使用空调带来的乘客重量和负载。每种燃料的排放按速度和车辆特定功率（VSP）进行分类。 VSP将每种燃料的排放分为三个箱。排放随VSP单调变化。此外，使用新配方后结果没有明显变化。进行了统计测试，以比较B10和B20与B0的排放量；对B10的评估显示，一级巴士的NOx，HC，CO和CO2排放率降低了。对于2级公交车，NOx，HC，CO2和PM排放速率增加，而CO排放速率降低。使用B20，所有公交车的HC和PM排放率均降低。 NOx与CO，CO2结果矛盾。就货运需求而言，尤其对于重型车辆而言，PM排放量的减少非常重要。 HC的减少对于柴油发动机而言并不重要。同样，CO排放的不一致也无关紧要，而NOx排放的不一致则支持以前的研究。关键词：生物柴油，数据分箱，柴油，排放，道路测试，非参数统计测试，VSP。

著录项

  • 作者

    Mudgal, Abhisek.;

  • 作者单位

    Iowa State University.;

  • 授予单位 Iowa State University.;
  • 学科 Engineering Civil.;Transportation.
  • 学位 M.S.
  • 年度 2009
  • 页码 108 p.
  • 总页数 108
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 建筑科学;综合运输;
  • 关键词

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