Search Results

Air pollution remains to be one of the leading causes of premature death worldwide, with significant share attributed to particulate matter and reactive nitrogen compounds from mobile sources. Due to discrepancies between legislative metrics and health effects, and between laboratory tests and real driving, health-relevant metric applicable to real driving conditions are sought to evaluate the effects of emerging legislation, technologies and fuels. Models of human lung air-liquid interface have been recently explored to simulate effects of exposure to the whole exhaust. In this study, a compact exposure system, utilizing commercially available inserts with 3D in-vitro model of human lung cells, has been designed and fabricated in-house with the vision of mobile use, minimizing size and power consumption. Preliminary tests were done on a Euro 6 direct injection spark ignition engine operating at speeds and throttle positions corresponding to the WLTC cycle.

In this study, the combustion of butanol, neat and mixed with gasoline, was investigated on a 0.6 liter two-cylinder spark ignition engine with fully adjustable fuel injection and spark timing, coupled with an eddy current dynamometer. Two isomers of butanol, n-butanol and iso-butanol, were examined. This basic parameter study gives information about potential requirements of engine control systems for butanol FFV. Compared to the traditionally used ethanol, butanol does not exhibit hygroscopic behaviour, is chemically less aggressive and has higher energy density. On other hand, different laminar burning velocity and higher boiling temperature of butanol, compared to gasoline, requires some countermeasures to keep the engine operation reliable and efficient.

N-butanol and isobutanol are alcohols that can be produced from biomass by fermentation and are possibly more compatible with existing engines than ethanol. This work reports on the effects of these two isomers on exhaust emissions of an unmodified direct injection spark ignition (DISI) engine. A Ford Focus car with a 1.0-liter Euro 6 Ecoboost DISI engine has been tested on a chassis dynamometer using WLTP and Artemis driving cycles, and on the road on a one-hour test loop containing urban, rural and motorway driving. Two isomers of butanol, 1-butanol and 2-methyl-propanol, were each blended with gasoline at 25% volume. Non-oxygenated gasoline and 15% ethanol in gasoline (E15) were used as reference fuels. The vehicle performed well in terms of cold start, drivability, general performance, and off-cycle particle emissions, staying within several mg of particle mass and about 2×1012 particles (per PMP procedure) per km during laboratory tests.

Butanol, which can be produced from biomass, has been suggested as an alternative to ethanol, due to its higher energy density, lower oxygen content and more favorable hygroscopic and corrosive properties. In the Czech Republic, E85 is widely sold at fuel stations and used in ordinary vehicles, both with and without aftermarket control units. This work investigates the potential of ordinary automobiles to run on butanol, and the associated effects on exhaust emissions under real driving conditions. A Škoda Felicia car with a throttle body injection and a Škoda Fabia car with a multi-point port injection have been run on gasoline and its mixtures with up to 85% volume of ethanol, of n-butanol, and of isobutanol (2-methyl-1-propanol). An auxiliary control unit has been used with higher alcohol content. On each fuel, each car was driven 5-6 times along a local test route.

An ordinary, unmodified port fuel injection spark ignition automobile engine with closed-loop air-fuel ratio control and a three-way catalyst was operated on two butanol isomers, n-butanol and iso-butanol, and their blends with gasoline at steady-state operating points covering both common and potentially problematic regimes. The engine control unit was able to maintain the air-fuel ratio while running on both butanol isomers and their blends with gasoline. Only small changes in the heat release rates, small and insignificant decrease in exhaust gas temperatures, and no excessive increase in emissions were observed. Under commanded enrichment operation, the maximum torque, air-fuel ratio and exhaust emissions were comparable among nearly all fuels tested. The exhaust gas temperatures were comparable among fuels, with a moderate increase observed in some regimes during operation with high share of n-butanol in fuel.

The paper focuses on portable “on-board” instrumentation and methods for evaluation of exhaust emissions from scooters and various small machinery under real-world driving conditions. Two approaches are investigated here. In one, a miniature on-board system mounted on the equipment itself performs online measurements of the concentrations of the pollutants of interest (HC, CO, CO2, NOx, some property of particulate matter), and measurement or computation of the intake air flow. This approach has been used on a 50 cm3 scooter fitted with a 14-kg on-board system and driven on local routes. Measured concentrations of gaseous compounds, particle mass and total particle length were multiplied with the corresponding intake air flow computed from measured engine rpm, intake air manifold pressure and temperature. In the second approach, a full-flow dilution tunnel, gas analyzers and particle measurement or sampling devices are mounted on an accompanying hand cart or vehicle.

Bioethanol, produced from renewable sources, is promoted as a fuel in higher concentrations in newer flexible fuel engines, and in lower concentrations in the general fleet. Introduction of a blend of 85% ethanol with gasoline (E85) at a competitive price in the Czech Republic has, however, spontaneously resulted in this fuel being used in “ordinary” engines not adapted for this fuel. This study investigates the operation of a typical gasoline car with fuel injection and three-way catalyst on gasoline, E85, and additionally on a blend of 85% n-butanol with gasoline, as butanol features better material compatibility than ethanol. The car was equipped with a portable, on-board emissions monitoring system and driven along a route comprising city and rural roads, including hills. Multiple runs were made on each fuel to verify test-to-test repeatability.

Traditional smoke opacity measurement, performed on diesel engines during regular emissions inspections, sensitive primarily to larger particles of elemental carbon, is very little sensitive to nanoparticles and to semi-volatile “organic carbon” particles. For this reason, it no longer suffices as a high emitter detection tool for modern vehicles with a particle filter or for advanced low-emissions technology where semi-volatile organic particles are the dominant fraction of particulate matter. This paper investigates the potential of common low-cost ionization type smoke detectors, produced in mass quantities for fire detection in buildings, as a tool to measure particle emissions in vehicular exhaust. Two ionization chambers were used to measure both raw and diluted exhaust of various engines powered by diesel fuel and biofuels under laboratory conditions as well as on the road.

This paper describes attempts to determine stabilized emissions of non-road engines without waiting for stable emissions values to be reached, with the goal to shorten laboratory testing time and/or to use real-world, in-service data featuring limited segments of steady-state operating conditions. The emissions from non-road engines are often evaluated and reported in steady-state operating conditions. Many larger engines are tested in the field, due to impracticality of dynamometer testing, resulting in practical limits for testing time at constant operating conditions. With lower fractions of elemental carbon (black soot) in the particulate matter and increased deployment of catalytic aftertreatment devices, longer times are required for reaching stable values. This work seeks to infer stabilized emissions values from limited length segments of unsteady but converging data.

To reduce exhaust emissions and dependency on petroleum-based fuels, various alcohols have been considered as gasoline substitutes for spark ignition engines. In the existing vehicle fleet, the use of ethanol, the most widely used alcohol, is practically limited to blends in relatively small concentrations with gasoline, due to its hygroscopicity, aggressivity, substantially lower heat content, and high latent heat. Butanol has relatively low toxicity, can be produced from biomass, and has higher energy density, lower latent heat, lower hygroscopicity and lower aggressivity than ethanol. In this study, the effects of blends of 30% and 50% of n-butanol (1-butanol) with gasoline on combustion process, engine control unit adaptation and exhaust emissions before and after a three-way catalyst were examined on a 1.2-liter, three-cylinder, four-valves-per-cylinder, naturally aspirated port-fuel-injected Skoda 1.2 HTP spark ignition engine coupled to an engine dynamometer.

Neat, non-esterified vegetable oils are often used as alternative, renewable, locally produced, low greenhouse gas emissions fuel for diesel engines, which are typically fitted with a heated secondary fuel system, and are started, warmed up, and shut down on diesel fuel. This paper addresses the question of the temperature to which the fuel should be, can be, and is heated. Experiments done on a tractor engine with a mechanical inline injection pump revealed that at sustained higher loads, the fuel can be heated by engine coolant nearly to the thermostat opening temperatures prior to the injection pump inlet, with additional heating taking place before the fuel reaches the injector inlet. While vegetable oil heating to at least about 40-50°C was beneficial to prevent large power loss on a common-rail type engine tested, excessive heating decreased the maximum engine torque on the engine with an inline injection pump, and accelerated degradation of the fuel.

Neat, non-esterified vegetable oils, alternative, locally produced, renewable fuels for diesel engines, have considerably higher viscosity than diesel fuel, even when heated. While mechanical injection pumps with volumetric fuel metering compensate for higher viscosity of the fuel by an increased injection pressure, and possibly longer ignition delay is on some engines compensated by an earlier injection due to higher density and bulk modulus of vegetable oils, newer common-rail type systems do not have such mechanism, and inject vegetable oils and diesel fuel at comparable timing and pressures. The complexity of the newer injection systems also raises the issue of the effects of varying fuel properties. This paper reports on laboratory experiments carried on a four-cylinder, 4.5-liter Cummins ISBe4 engine with a Bosch Common Rail injection system, fitted with an auxiliary heated secondary fueling system, and operated on fuel-grade rapeseed oil heated to 50-60°C.

Vegetable oils, commonly used as a feedstock for the production of biodiesel, are also combusted directly as a diesel engine fuel in their neat, non-esterified form. A review of literature and experimental research conducted by this group and presented here shows that the combustion of vegetable oils, generally favorable at moderate and high loads, is problematic mostly at low engine loads and temperatures, characterized by a large increase in particulate matter emissions, penetration of the fuel into the engine lubricating oil, and deposition of liquid fuel within the engine and the exhaust system. Increase of the overall engine load, avoidance of low-load regions, and control of engine operating point, all typical for a hybrid-electric system, could resolve many of the drawbacks of neat, non-esterified vegetable oils, which can be a local, renewable fuel, with considerable benefits in terms of the very low "excess" CO₂ emissions.

This paper investigates the emissions performance of modern European light-duty passenger vehicles with turbodiesel engines during real-world driving, notably during two extreme but not uncommon operating regimes: congested urban traffic and high-speed and performance driving. Four cars and one van were tested on a chassis dynamometer and/or on the road with a portable, on-board emissions monitoring system capable of online measurements of particulate and gaseous emissions. On all cars, operation at speeds and acceleration rates in excess to those within the applicable certification NEDC cycle resulted in higher concentrations of nitrogen oxide (NO) and particulate matter (PM). High-speed driving in excess of 120 km/h resulted in a marked increase in NO and PM concentrations, with further increases past 130-140 km/h. In urban driving, highest PM concentrations occurred at the onset of and during accelerations from low rpm.

One of the fundamental problems associated with combustion of vegetable oils in diesel engines is their poor combustion at low engine speeds and loads. As a possible remedy to this problem, co-firing of small amount of gaseous hydrogen introduced into the intake air was investigated on a mechanically controlled direct injection turbodiesel tractor engine. The engine was operated at idle and several low-rpm, low-load points on fuel-grade rapeseed oil heated to 60–70°C, with up to 5.5% of hydrogen by volume (600 g/h) injected into the intake air. Emissions of HC, CO, and NOx have all markedly decreased with increasing hydrogen concentrations. At higher hydrogen concentrations the onset of the combustion became noticeably delayed and the peak combustion pressure has decreased.

This paper reports on the experimental investigation of the combustion of heated rapeseed oil in a typical tractor engine, which was operated alternately on heated rapeseed oil and diesel fuel without any adjustments of the injection pump. At intermediate to high engine rpm and loads, onset of combustion occurred earlier on rapeseed oil. This was correlated with increased emissions of nitrogen oxide and earlier onset of pressure rise in the injector, and independent of fuel temperature. At low rpm and loads, the onset of the combustion occurred later on rapeseed oil and was correlated with elevated emissions of hydrocarbons; this deterioration was exacerbated by prolonged low-load operation and by low fuel temperatures.

This paper reports on particulate matter (PM) emissions measurement on a turbocharged direct injection tractor diesel engine with a mechanically controlled injection pump operated alternately on diesel fuel and fuel-grade rapeseed oil heated to 70-90°C. PM emissions were measured using standard gravimetric method, with supplemental online measurements with a semi-condensing integrating forward laser beam scattering detector and a measuring ionization chamber. All three measurements were in good agreement and show that the operation on heated rapeseed oil results, compared to operation on diesel fuel, in moderate decreases in PM emissions at moderate and higher speeds and loads, and substantial increases in PM at low speeds and loads. Low-speed, low-load operation on vegetable oil therefore needs to be addressed even if the engine appears to produce acceptable emissions during standard tests.

In an effort to demonstrate the ability of portable, on-board emissions monitoring systems to collect data on a large number of vehicles in a short period of time, 40 heavy-duty diesel trucks were tested in 2.5 days using a portable, on-board system. The trucks were randomly recruited at a Tulare, CA rest area, and subjected to idling and opacity tests. 21 of these trucks were also tested on the road. The equipment was well received by the drivers. Average NOx emissions were 157-188 grams per gallon of fuel during idle and 112 g/gallon during cruise. At least one case suggesting a NOx “defeat” strategy was observed. Elevated PM emissions during deceleration, attributed to the use of engine brake, were observed on one third of the trucks. Results show that stationary idle data can be used to identify trucks with high NOx during acceleration, but not necessarily all the trucks with high NOx during cruise could be identified using idle measurements.

To complement laboratory emissions tests and to obtain emissions data for events that are difficult to simulate, a portable, on-board mass exhaust emissions monitoring system has been developed. The system utilizes NDIR for CO and CO2, an electrochemical cell for NOx and laser light scattering detectors for PM real-time concentrations measurements. Exhaust flow is determined computationally from engine operating data using mass balance equations. The system is designed to easily and quickly install on a large variety of vehicles, including buses with passengers on board, and to produce a wealth of on-road data with minimal downtime and travel of the vehicle tested.