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The current targets to decrease greenhouse gases production, to reduce fossil fuel dependency and to gain energy security and sustainability are driving demand on combustion engine fuels from renewable sources. This effort resulted in utilization of first generation biofuels. Unfortunately, these fuels brought new dilemmas and challenges in general, such as food production competition and land use and, in case of fatty acid methyl esters for compression ignition engines, also technical challenges such as storage stability and deposit formation. Utilization of particle filters and sensitive fuel systems are driving effort to develop compatible renewable biofuels which can be utilized at higher than current shares. Hydrotreated vegetable oils (HVO), as industrially produced biofuels, exhibit some beneficial properties compared to traditional fatty-acid methyl esters especially in terms of oxidation stability, injector fouling, energy content and cetane number.

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 the general efforts to replace the fossil fuels in transportation by renewable fuels the bioalcohols are an important alternative. The global share of Bioethanol used for transportation is continuously increasing. Butanol, a four-carbon alcohol, is considered in the last years as an interesting alternative fuel, both for Diesel and for Gasoline application. Its advantages for engine operation are: good miscibility with gasoline and diesel fuels, higher calorific value than Ethanol, lower hygroscopicity, lower corrosivity and possibility of replacing aviation fuels. In the present work research with different nButanol portions in gasoline (BuXX)* was performed on the 2-cylinder SI engine with variations of several parameters on engine dynamometer. At different steady state operating points were varied: spark timing (αz), air excess factor (λ) and EGR-rate. Furthermore, the conversion rates and light-off of a 3-way-catalyst were investigated.

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.

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.