Effect of Inlet Air Humidity and Temperature on Diesel Exhaust Emissions

Krause, Sven; Merrion, David F.; Green, G. L.

doi:10.4271/730213

Cited by 15 publications

(4 citation statements)

References 3 publications

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“…Higher humidity may cause a decrease in N O 2 concentration in exhaust gases 65,66 ; we have found that such an effect takes place with 5 to 6 hours of delay.…”

Section: Discussionmentioning

confidence: 57%

“…This is probably due to the distance between the intersection and the meteorological station; the average wind speed of 3 m s −1 and the roughness of terrain explain the amount of the delay. • • Higher humidity may cause a decrease in NO 2 concentration in exhaust gases 65,66 ; we have found that such an effect takes place with 5 to 6 hours of delay. • • High solar duration and high temperature favor the transformation of nitrogen oxides into secondary pollutants, which include ozone, and this implies a decrease in NO x concentration; even more important is sunlight, which acts as a catalyst, which explains the negative coefficient and the delay for sunlight duration.…”

Section: • • Wind Always Affects Concentration In a Negative Waymentioning

confidence: 70%

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Temporal Aspects in Air Quality Modeling—A Case Study in Wrocław

Kamińska

Lucena-Sánchez

Sciavicco

2020

Air, Soil and Water Research

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Anthropogenic environmental pollution is a known and indisputable issue, and the importance of searching for reliable mathematical models that help understanding the underlying process is witnessed by the extensive literature on the topic. In this article, we focus on the temporal aspects of the processes that govern the concentration of pollutants using typical explanatory variables, such as meteorological values and traffic flows. We develop a novel technique based on multiobjective optimization and linear regression to find optimal delays for each variable, and then we apply such delays to our data to evaluate the improvement that can be obtained with respect to learning an explanatory model with standard techniques. We found that optimizing delays can, in some cases, improve the accuracy of the final model up to 15%.

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“…Higher humidity may cause a decrease in N O 2 concentration in exhaust gases 65,66 ; we have found that such an effect takes place with 5 to 6 hours of delay.…”

Section: Discussionmentioning

confidence: 57%

Section: • • Wind Always Affects Concentration In a Negative Waymentioning

confidence: 70%

Temporal Aspects in Air Quality Modeling—A Case Study in Wrocław

Kamińska

Lucena-Sánchez

Sciavicco

2020

Air, Soil and Water Research

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“…On the other hand, as the NOx emission depends on ambient air conditions, the NOx concentration shall be corrected for ambient air temperature and humidity before analyzing the deterioration of engine out NOx emissions by using the data from the on-board NOx sensors (Krause et al, 1974;Hiromi et al, 1991;Pekula et al, 2003;Asad et al, 2012;Liu et al, 2015;Wang et al, 2018;Wang et al, 2019). Since few in-use vehicles were equipped with ambient humidity sensor，almost no study takes advantage of vehicle operation data to analyze the influence of ambient factors on engine out NOx emission.…”

Section: Introductionmentioning

confidence: 99%

Research on a China 6b Heavy-duty Diesel Vehicle Real-world Engine out NOx Emission Deterioration and NOx Correction for Humidity and Temperature using On-board Sensors and Big Data Approach

Peng

Lin

2021

Preprint

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China VI standard proposed higher requirements for durability of heavy-duty diesel vehicles emissions. Previous research which took advantages of both on-board sensors and big data approach to get the NOx deterioration factor was rather scarce. This paper used big data approach to study the deterioration of engine out NOx emission based on 254,622 km operation data getting from the on-board sensors or ECUs. Meanwhile, a formula for on-board NOx correction for ambient humidity and temperature had been fitted. The analyses revealed that engine out NOx would not be deteriorated during the useful life or even longer (deterioration factor was 1.014 @700,000km). For a steady working condition, the engine out NOx mass flow (g/h) is negatively linearly correlated with absolute humidity (R2 = 0.997). If Ha was lower than 12g/kg, Ha almost had no effect on engine out NOx concentration (ppm). Otherwise, there was also a negatively linear relationship between them (R2 = 0.978). It is hoped that the methods and conclusions of this paper could provide some enlightenment for future NOx emission deterioration research.

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“…It has been shown in several studies [56,88] that the NOx emissions from a heavy-duty diesel engine are influenced by the intake air humidity leading to lower NOx with higher humidity in the intake air, and vice versa. Therefore, in order to normalize the NOx emissions measured from engines operating at different ambient conditions, it is mandated to correct the measured emissions to standard intake air humidity value, which is fixed at 10.…”

Section: Correction Of Nox Emissions For Intake Air Humiditymentioning

confidence: 99%

Development of a Reference Dataset to Evaluate PEMS Post-Processing Software

Kappanna¹

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Since the implementation of in-use emissions standards, an outcome of the consent decree between heavy-duty diesel engine manufacturers and the Environmental Protection Agency (EPA), there has been an increased interest in the research and development of portable emissions measurement systems (PEMS) that are capable of analyzing exhaust emissions continuously while a vehicle or equipment powered by an internal combustion engine is performing its intended vocation. Ultimately for an engine to pass in-use emissions requirements, the brake specific emissions of regulated pollutants measured over valid Not-to-Exceed (NTE) events must be less than or equal to 1.25 or 1.5 times the engine emission certification standards, based on the engine model year (MY), plus an additional margin known as in-use measurement allowance. The vehicle has to satisfy the in-use emissions standard for 90% of the NTE events provided the brake specific emissions over the rest of the events are less than two times the certification level to comply with in-use emission regulations. As in-use emissions measurement and regulation together form a requirement since 2004 for certification of engines, it is imperative to develop procedures of oversight similar to ones that exist for laboratory-based engine certification. Therefore, a reference data set that incorporates all the in-use emissions regulations used to quantify the measured emissions over an NTE event, including the conditions used to validate an NTE event is developed in the direction of providing a means to validate commercial PEMS data analysis software. A reference data set was designed and used to evaluate the post-processing software of two commercial PEMS devices. A black box testing methodology was implemented to evaluate the performance of the post-processing software. Specifically, the input data set was developed to execute different sections of the program based on logical conditions required to branch into a particular section therefore verifying the truth in executing a logical condition and the interpretation of in-use emissions regulation. Also, the brake specific emissions results to be expected from the given input data set were known a priori to verify the accuracy of the equations used in calculating the final emissions results. The dataset was also used to evaluate PEMS data post-processing software developed at WVU. The test results indicated that definition of NTE emissions performance was not in agreement for the post-processing software evaluated. Being that compliance is required for manufacturers to sell engines without penalty, it is critical that the metric by which compliance is assessed must be accurate and robust. As such, the reference data set developed will serve in identifying interpretation errors of inuse emissions regulations as well as calculation error and reduce the chances of triggering false positives and negatives that could prove costly to engine manufacturers as well as air quality regulating agencies. This reference data set will also serv...

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Effect of Inlet Air Humidity and Temperature on Diesel Exhaust Emissions

Cited by 15 publications

References 3 publications

Temporal Aspects in Air Quality Modeling—A Case Study in Wrocław

Temporal Aspects in Air Quality Modeling—A Case Study in Wrocław

Research on a China 6b Heavy-duty Diesel Vehicle Real-world Engine out NOx Emission Deterioration and NOx Correction for Humidity and Temperature using On-board Sensors and Big Data Approach

Development of a Reference Dataset to Evaluate PEMS Post-Processing Software

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