Stephen Samuel

Automotive test drive cycles for emission measurement and real-world emission levels-a review

Abstract The emission levels produced by any vehicle are dependent on the mode of operation of the vehicle and technology behind the vehicle design. The test drive cycles employed to measure the emissions produced by vehicles should adequately represent the real-world driving pattern of the vehicle to provide the most realistic estimation of these levels. However, there is increasing concern about the representative drive cycles used by the various vehicle certification and regulatory authorities. This paper reviews the various drive cycles used for gasoline engine vehicles in Europe and the United States, and the impact of various factors and their influence on real-world emission levels. The proposed new drive cycles of the United States and Europe are considered. From the work reviewed, it can be concluded that the amount of pollutant levels from automotive vehicles are underestimated because of the characteristics of the existing drive cycles. While much work remains to be done with the development of new drive cycles to represent real-world driving patterns, some useful conclusions can be drawn regarding the impacts of the factors reviewed here. The impacts of the factors reviewed in this paper can be characterized to improve estimations and simulations of the real-world emission levels of the vehicle.

Real-world fuel economy and emission levels of a typical EURO-IV passenger vehicle

This paper presents the findings of research into real-world emission levels of a typical EURO-IV passenger car in the United Kingdom (UK). Four real-world drive cycles representing typical urban driving in the UK were used for the experiments. The work identified that the real-world emission levels of a EURO-IV vehicle in the UK are significantly higher than the certified legislative emission levels. The present work also identified that tailpipe-out carbon monoxide is the most affected emission specie in a gasoline-powered vehicle for real-world driving conditions.

The Effect of a Three-Way Catalytic Converter on Particulate Matter from a Gasoline Direct-Injection Engine During Cold-Start

This work investigates the effect of a three-way catalytic converter and sampling dilution ratio on nano-scale exhaust particulate matter emissions from a gasoline direct-injection engine during cold-start and warm-up transients. Experimental results are presented from a four cylinder in-line, four stroke, wall-guided direct-injection, turbo-charged and inter-cooled 1.6 l gasoline engine. A fast-response particulate spectrometer for exhaust nano-particle measurement up to 1000 nm was utilised. It was observed that the three-way catalytic converter had a significant effect on particle number density, reducing the total particle number by up to 65 % over the duration of the cold-start test. The greatest change in particle number density occurred for particles less than 23 nm diameter, with reductions of up to 95 % being observed, whilst the number density for particles above 50 nm diameter exhibited a significant increase. The exhaust temperature plays a significant role on the influence of the catalytic converter on the nano-scale particulate matter. It is evident that the dilution ratio of the exhaust sample has a distinct effect on the particulate matter number and size distribution, influencing the engine-out PM more significantly than the tailpipe-out PM during cold-start engine operation. The catalytic converter also has a considerable effect on the estimated total particle mass.

The Most Significant Vehicle Operating Parameter for Real-World Emission Levels

The present work investigated the real-world emission performance of a typical light-duty gasoline vehicle to identify the most significant vehicle operating parameter responsible for excessive real-world emission levels. Based upon tailpipe-out emission levels, two distinct portions in the engine maps could be identified; a clean portion of the map, which covers the engine operating points within the European legislative drive cycle, and an unclean portion of the map that is outside the legislative testing. A systematic investigation of the tailpipe-out emission levels for the real-world drive cycle showed that the levels of vehicle speed and acceleration are immaterial if the vehicle operating points remain within the cleaner zone of the engine map. The methodical approach followed to identify the most significant vehicle operating parameter responsible for the real-world emission levels is given in this paper.

Real-world performance of catalytic converters

This paper investigates experimentally the performance of a three-way catalytic (TWC) converter for real-world passenger car driving in the United Kingdom. A systematic approach is followed for the analysis using a Euro-IV vehicle coupled with a TWC converter. The analysis shows that the real-world performance of TWC converters is significantly different from the performance established on legislative test cycles. It is identified that a light-duty passenger vehicle certified for Euro-IV emissions reaches the gross polluting threshold limits during real-world driving conditions. This result is shown to have implications for overall emission levels and the use of remote emissions sensing and on-board diagnostics (OBD) systems.

Numerical Investigation of Real-World Gasoline Car Drive-Cycle Fuel Economy and Emissions

This paper investigates an approach to modelling real-world drive cycles for the prediction of fuel economy and emission levels. It demonstrates that a steady-state engine performance data based modelling approach can be used for real-world drive cycle simulation. It identifies and demonstrates that a steady-state performance data-based approach is the only current viable approach for real-world tailpipe-out CO level predictions. It also identifies quantitatively the difference between the modal emission measurements and constant volume sampling (CVS) bag values for emission modelling validation. A systematic validation and sensitivity analysis of the modelling approach is also described.

Deriving on-road spatial vehicle emission profiles from chassis dynamometer experiments

Abstract A method has been derived for the identification of spatial emission hot-spots on vehicle road routes using chassis dynamometer data. The work presented here uses tailpipe-out carbon monoxide (CO) levels to demonstrate the application of the method. The approach is used to analyse critically methods used by legislators that derive road-side emission levels from the vehicle emission inventory and legislative emission levels. The work presented in this paper demonstrates that the generic approach using vehicle speed, gear change patterns, spatial geographical data, and route geometric information is sufficient for the identification of the location of emission hot-spots in any journey route of interest.

Route selection strategy for hybrid vehicles based on energy management and real time drive cycles

Air pollution levels in an urban environment is a major concern for developed and developing countries alike. Governments around the world are constantly trying to control and reduce air pollution levels through regulations. Low emission zones are being designated in cities worldwide in order to reduce the level of pollutants in big cities. The automotive industry is affected by those regulations and they are becoming more demanding over the years. Present work is aimed at developing a control strategy for a hybrid vehicle in order to optimize the fuel economy and emission levels based on GPS information, driver specific driving characteristics and weather forecast data for a given route. It uses powertrain model of a hybrid vehicle for developing route and driver specific control strategy. The full vehicle model has two sub-models: a route selector and a powertrain optimization model. The route selector selects the optimum route for the vehicle based on energy consumption considering possible routes for reaching the destination. Then the performance is optimized for the selected route using a cost function, which considers route segments which include low emission zone and available data for the headwind during the journey. The results identified the option for choosing strategy for improving both fuel economy and emission levels for a given route.

Numerical Simulation of a 2018 F1 Car Cooling System for Silverstone Circuit

The thermal management of a Formula 1 car is a challenging task as it involves multiple components, systems and multiple sources of thermal energy. The present work attempts to model a representative F1 car following 2018 F1 regulations directly linked to the cooling systems requirements and performance. The main purpose of this work is to simulate the steady and transient behaviour of the cooling system when the vehicle is in a qualifying lap, and during the entire race, including the wait in the starting grid and the pit stops. This model includes the sub-models representing internal combustion engine, hybrid powertrain, vehicle, driver and an appropriate cooling system composed of radiators, pumps and expansion tanks. This work validates the cooling system of a representative 2018 F1 car for the Silverstone Circuit. This model is capable of simulating the overall thermal performance of the F1 car for sizing the cooling system for most of the F1 circuits. This paper presents a systematic approach followed for modelling a representative F1 car based on 2018 regulations, methods used for deriving appropriate data from various sources, approach used for validating the model and finally the strengths of the validated model for sizing the cooling system.

Modelling the capture of gasoline engine exhaust particulate matter in three-way catalytic converters

The aim of this work was to numerically model the effect of a three-way catalytic converter on nano-scale particulate matter from a gasoline direct injection engine. The work used a deep bed filtration model to simulate and validate experimental findings. A 1.6L, gasoline direct injection, spark ignition, turbocharged and intercooled Euro IV engine was used for experimentation. The capture efficiency was experimentally determined by measuring pre and post-catalyst particulate matter numbers using a DMS-500 differential mobility spectrometer at different dilution ratio settings. Despite variable experimental results at lower engine speeds and loads, the model was capable of predicting catalytic converter particle capture efficiency in the majority of cases. This indicates that deep bed filtration theory can indeed be used to explain nano-scale particle capture within three-way catalytic converters. The results also suggest that there is no significant agglomeration of particles within the catalytic converter. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.