Measurement of number and size distribution of particles emitted from a mid-sized transportation multipoint port fuel injection gasoline engine

This study was carried out to characterize the engine-exhaust particulate emissions from a typical multipoint port fuel injection gasoline engine used in transportation sector. Though gasoline engine showed no visible tail pipe emissions yet its particle concentrations were comparable to mineral diesel, particularly at high engine loads. Average sizes of particles emitted in gasoline exhaust are found to be way smaller than particles emitted in diesel exhaust under similar operating conditions. The peak particle concentrations for mineral diesel never go below 40 nm size however for gasoline engine, it was as low as 20 nm for most engine operating conditions. Within a very limited operating range, gasoline engine performance was superior to its diesel counterparts in terms of particulate size and number distribution however it deteriorates very quickly as soon as the fuel-air mixture becomes closer to stoichiometric ratio, typically under high engine load and speed conditions.     

Reduction of diesel smoke opacity from vegetable oil methyl esters during transient operation

This work is focused on the measurement and analysis of the smoke opacity resulting from a Diesel engine fuelled with conventional fuel and biofuels under transient conditions. Methyl esters obtained from used cooking and unused vegetable oils were tested as diesel fuels, pure and blended with 30% and 70% of a commercial diesel fuel which was also used pure. A commercial engine was mounted in a test bench prepared for operating in different transient conditions. A smoke meter AVL 439 allowed for the study of the effect of these fuels on the smoke opacity under varied operating conditions. The thermo chemical properties of the test fuels and the engine parameters, such as fuel/air ratio or exhaust gas recirculation (EGR) ratio, were used for the analysis and interpretation of the results. The engine transient processes studied were (a) engine start, (b) load increase at constant engine speed and (c) engine speed decrease at constant torque. These results suggested that the use of the diesel blends containing vegetable esters is an interesting alternative for a significant reduction in smoke opacity not only in steady conditions but also in transient engine operation, the latter being the most usual condition in passenger vehicles.     

Influences on the Particle Size Distribution of Diesel Particulate Emissions

Particulates give great concern for mankind health. Especially the nano size particles are under discussion. Therefore, the particle size distribution from the combustion chamber to tail pipe emissions are of great interest. With the aim of scanning mobility particle sizer the number weighted particle size distributions were measured in the combustion chamber as well as in the exhaust gas up and downstream of aftertreatment systems. Using the identical particle measurement technique results can be compared without changing the particle size definition. The particles in the cylinder of a modern serious DI diesel engine were sampled with a time resolved fast gas sampling valve. The Soot particles formed in the cylinder during the early combustion phase are oxidized by about 99% in the late combustion/early expansion phase, whereas the soot particle sizes distribution in the cylinder at the end of the expansion phase are equal to that in the tail pipe. DI diesel engines with high pressure injection system emit less numbers of particle with in tendency greater sizes compared to IDI diesel engines. Oxidation catalysts do not influence particle size distribution but particulate traps reduce particle number by up to two orders of magnitude. Detail analysis shows that an increase of nano size particle number downstream of an aftertreatment device results from artifacts.     

Emissions from large-scale medium-speed diesel engines: 1. Influence of engine operation mode and turbocharger

The operation of four – stroke diesel engines in either propulsion or generator mode application has a strong influence on gaseous, smoke (soot) and particulates emissions. Tests were made with a supercharged after-cooled large-scale diesel engine (mean speed  500 rpm, power per cylinder  1 MW) burning mainly heavy fuel oil. Gaseous emissions (NOx, CO, HC) were measured according to the IMO technical code, smoke (soot) emissions were determined optically and particulate matter (PM) was measured using a gravimetric impactor for five size fractions. Impact on gaseous emissions, smoke (soot) and PM was found when analysing the effects of the engine operating mode, fuel nozzle, start of injection (SOI), and load (speed). Results show that the exhaust emission was also highly dependent on the engine turbocharger system, especially the by-pass control, but was not affected by waste gate control. The gaseous and soot emissions were less for the generator mode in the total load region, decreasing with the load. PM emissions were found to decrease with the load for the propulsion mode, while showing an increase with the load for the generator mode.     

Performance of compression ignition engine with mahua (Madhuca indica) biodiesel

The performance of biodiesel obtained from mahua oil and its blend with high speed diesel in a Ricardo E6 engine has been presented in this paper together with some of its fuel properties. These properties were found to be comparable to diesel and confirming to both the American and European standards. Engine performance (brake specific fuel consumption, brake thermal efficiency and exhaust gas temperature) and emissions (CO, smoke density and NO_x) were measured to evaluate and compute the behaviour of the diesel engine running on biodiesel. The reductions in exhaust emissions and brake specific fuel consumption together with increase brake power, brake thermal efficiency made the blend of biodiesel (B20) a suitable alternative fuel for diesel and thus could help in controlling air pollution.     

Influence of waste cooking oil biodiesel on the nanostructure and volatility of particles emitted by a direct-injection diesel engine

To reduce air pollution and the reliance on fossil fuel, biodiesel has been widely investigated as an alternative fuel for diesel engines. The purpose of this study is to investigate the influence of waste cooking oil (WCO) biodiesel on the physical properties and the oxidation reactivity of the particles emitted by a diesel engine operating on WCO biodiesel as the main fuel. Experiments were conducted on a direct-injection diesel engine fueled with biodiesel, B75 (75% biodiesel and 25% diesel on volume basis, v/v), B50, B20, and diesel fuel, at five engine loads and at an engine speed of 1920 rev/min. Particulate samples were collected to analyze the particulate nanostructure, volatility, and oxidation characteristics. Biodiesel or low-load operation leads to smaller primary particles and more disordered nanostructures having shorter and more curved graphene layers. It can be found that particles from biodiesel, blended fuels, or low-load operation have higher volatile mass fractions and faster oxidation reaction rates than particles from diesel or heavy-load operation. The higher oxidation reaction rates are due mainly to the smaller particle size, the more disordered nanostructure, and the higher volatile mass fraction. It is also found that changes in primary particle size and particulate nanostructure are not directly proportional to the biodiesel content, while changes in particulate volatility and particulate oxidation reactivity are proportional to the biodiesel content. The use of biodiesel can enhance particulate oxidation reactivity and the regeneration of soot particles in an after-treatment device.

Copyright © 2016 American Association for Aerosol Research     

Characterization of Soot Particles Produced in a Transparent Research CR DI Diesel Engine Operating with Conventional and Advanced Combustion Strategies

The effect of the combustion mode on particle emission was analyzed both in the cylinder and at the exhaust of a direct injection (DI) Common Rail (CR) transparent research diesel engine by means of spectroscopic and conventional methods. The engine was equipped with a flexible electronic control unit (ECU) capable of operating up to 5 injections per cycle with different start of injection and dwell time allowing performing different combustion modes. The conventional diesel combustion, the homogeneous charge compression ignition (HCCI), and the low temperature combustion (LTC) modes were analyzed. In-cylinder broadband UV–visible scattering and extinction measurements were carried out to follow the particle formation and oxidation processes as well as to have information about their chemical nature and size distribution. The characterization of the particulate emission at the exhaust was performed by means of an electrical low pressure impactor (ELPI), for the counting and the sizing of the particles, and an opacimeter, for measuring the smoke opacity. The in-cylinder measurements highlighted that particles ranged from 3 to 100 nm whatever was the combustion mode. Nevertheless, particles produced by a conventional diesel combustion process principally consist of soot. Whereas particles formed during HCCI and LTC modes are composed mainly of organic compounds. The exhaust particle emissions depend on the combustion mode both in terms of size and number. A larger amount of particles smaller than 100 nm was emitted during HCCI and LTC modes with respect to the conventional one. Moreover, HCCI mode showed a strong accumulation mode.

Copyright 2012 American Association for Aerosol Research     

Effect of Waste Cooking Oil Biodiesel on the Properties of Particulate from a DI Diesel Engine

The present work focuses on the effect of waste cooking oil biodiesel on the particulate mass, number concentration, nanostructure, and oxidative reactivity under different engine speeds and engine loads. Particulate samples were collected from the diluted exhaust of a medium-duty direct injection diesel engine and were used to analyze the physico-chemical properties via the transmission electron microscope (TEM) and the thermogravimetric analyzer/differential scanning calorimeter (TGA/DSC). The TEM images reveal that smaller primary particles are formed at higher engine speed, lower engine load, or using biodiesel. Quantitative analysis of the nanostructures indicates more soot with more disordered configuration, in which shorter and more curved graphene layer is prevailing at lower engine load or when using biodiesel. Furthermore, the TGA results infer that the soot oxidative reactivity is closely related to the nanostructure properties and the effect of engine load is more pronounced than the effect of engine speed. Also biodiesel soot has faster oxidative reactivity than diesel soot. Moreover, results obtained for B30 (30% biodiesel and 70% diesel fuel) lie in between those for biodiesel and diesel fuel.

Copyright 2015 American Association for Aerosol Research     

Fundamentals‐based low‐dimensional combustion modeling of spark‐ignited internal combustion engines

A four‐mode low‐dimensional model for the in‐cylinder combustion process in an internal combustion engine is developed. The lumped parameter ordinary differential equation model is based on two mixing times that capture the reactant mixing limitations inside the cylinder and mixing limitations caused by the input and exit stream distribution. For a given inlet and operating conditions, the model predicts the exhaust composition of regulated gases (total unburned HCs, CO, and NO_x) as well as the in‐cylinder pressure and temperature. The model is able to capture the qualitative trends observed with change in fuel composition (gasoline and ethanol blending), air/fuel ratio, spark timing, engine load, and speed. The results show good qualitative and fair quantitative agreement with the experimental results published in the literature and demonstrate the possibility of such low‐dimensional model for real‐time control. Improvements and extensions to the model are discussed. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

The influence of n-butanol/diesel fuel blends utilization on a small diesel engine performance and emissions

Nitrogen oxides and smoke emissions are the most significant emissions for the diesel engines. Especially, fuels containing high-level oxygen content can have potential to reduce smoke emissions significantly. The aim of the present study is to evaluate the influence of n-butanol/diesel fuel blends (as an oxygenation additive for the diesel fuel) on engine performance and exhaust emissions in a small diesel engine. For this aim five-test fuels, B5 (contains 5% n-butanol and 95% diesel fuel in volume basis), B10, B15, B20 and neat diesel fuel, were prepared to test in a diesel engine. Tests were performed in a single cylinder, four stroke, unmodified, and naturally aspirated DI high speed diesel engine at constant engine speed (2600 rpm) and four different engine loads by using five-test fuels. The experimental test results showed that smoke opacity, nitrogen oxides, and carbon monoxide emissions reduced while hydrocarbon emissions increased with the increasing n-butanol content in the fuel blends. In addition, there is an increase in the brake specific fuel consumption and in the brake thermal efficiency with increasing n-butanol content in fuel blends. Also, exhaust gas temperature decreased with increasing n-butanol content in the fuel blends.     

基于粒子群算法的车用柴油机有机朗肯循环系统运行参数优化

为了有效回收柴油机排气余热能,通过实验研究了一台车用柴油机排气能量变化规律,进而设计有机朗肯循环(ORC)系统回收该柴油机的排气余热能,并基于粒子群算法,以净输出功率和(火用)效率为目标函数,选取蒸发压力、过热度和膨胀机膨胀比为优化变量,对ORC系统的运行参数进行了优化研究。优化结果表明,在柴油机不同运行工况条件下,存在最佳的蒸发压力、过热度和膨胀机膨胀比,从而使ORC系统的净输出功率和(火用)效率最优。根据运行参数优化结果,分析了ORC系统和车用柴油机-ORC联合系统(联合系统)的性能。研究结果表明,当柴油机转速为2200 r·min^-1,转矩为1215 N·m时,ORC系统的净输出功率可达30.61 kW,联合系统的有效输出功提升率(POIR)可达9.86%;当柴油机转速为1200 r·min^-1,转矩为1131 N·m时,联合系统的有效燃油消耗率(BSFC)为175.0 g·(kW·h)^-1。     

AEROSOL CHARACTERISATION IN MEDIUM-SPEED DIESEL ENGINES OPERATING WITH HEAVY FUEL OILS

Aerosol measurements were carried out in medium-speed diesel engines to determine the aerosol characteristics and formation in four-stroke diesel engines equipped with turbocharger(s) burning heavy fuel and high ash-content heavy fuel oil. The mass size distributions are bimodal with a main mode at 60–90 nm and a second mode at 7–10 μm. The small mode particles are formed by nucleation of volatilized fuel oil ash species, which further grow by condensation and agglomeration. The large mode particles are mainly agglomerates of different sizes consisting of the small particles. The number size distributions peak at 40–60 nm, as also observed in the SEM micrographs. Agglomerates consisting of these primary spherical particles are also found. The TEM micrographs reveal that these particles consist of even smaller structures. Based on the mass and elemental size distributions evidence of high volatility of the fuel oil ash was found. The main effect on the aerosol size distributions was caused by the engine type and fuel oil properties.     

Particulate emissions from large-scale medium-speed diesel engines: 1. Particle size distribution

This paper addresses particulate matter (PM) size distributions in large-scale diesel engine exhaust. The test engines were multivariable large-scale turbo-charged, after-cooled medium speed (~ 500 rpm, ~ 1 MW power per cylinder) direct injection diesel engines. Emissions measurements were carried out while burning heavy fuel (HFO) and light fuel (LFO) oils. Test modes for investigation were propulsion mode (marine) and generator mode (power plant), with load varying from 25 to 100%. PM was measured using a gravimetric impactor with four impactor stages plus a filter, classifying particles between 0.005 and 2.5 μm (aerodynamic diameter). The results show that HFO firing produces significantly higher PM emissions (more than factor of ~three on mass bases for high load operation) compared to LFO, especially for particles smaller than 0.5 μm. This is mainly due to higher ash-forming elements and sulphur content of HFO. For HFO, the fraction of the finest particles increases with load, more strongly for generator mode than for propulsion mode, with generator mode giving ~ 50% higher PM emissions than propulsion mode. With LFO firing, the largest amount of fine PM was emitted at the lowest load, for propulsion mode being lower and almost independent of load at higher loads, while for generator mode a steady decrease in emissions with increasing load is seen for all PM size classes measured.     

Experimental investigation on dual fuel operation of acetylene in a DI diesel engine

Depletion of fossils fuels and environmental degradation have prompted researchers throughout the world to search for a suitable alternative fuel for diesel engine. One such step is to utilize renewable fuels in diesel engines by partial or total replacement of diesel in dual fuel mode. In this study, acetylene gas has been considered as an alternative fuel for compression ignition engine, which has excellent combustion properties.Investigation has been carried out on a single cylinder, air cooled, direct injection (DI), compression ignition engine designed to develop the rated power output of 4.4 kW at 1500 rpm under variable load conditions, run on dual fuel mode with diesel as injected primary fuel and acetylene inducted as secondary gaseous fuel at various flow rates. Acetylene aspiration resulted in lower thermal efficiency. Smoke, HC and CO emissions reduced, when compared with baseline diesel operation. With acetylene induction, due to high combustion rates, NO_x emission significantly increased. Peak pressure and maximum rate of pressure rise also increased in the dual fuel mode of operation due to higher flame speed. It is concluded that induction of acetylene can significantly reduce smoke, CO and HC emissions with a small penalty on efficiency.     

Experimental investigation of diesel engine performance and emission characteristics using jojoba/diesel blend and sunflower oil

Experimental study has been carried out to investigate performance parameters, emissions, cylinder pressure, exhaust gas temperature (T_exhaust) and engine wall temperatures (T_wall) for direct injection diesel engine. Tests were conducted for sunflower oil (S100) and 20% jojoba oil + 80% pure diesel fuel (B20) in comparison to pure diesel fuel with different engine speeds. S100 and B20 were selected for the study because of its being widely used in Egypt and in the world. Also, series of tests are conducted at same previous conditions with different percentage of exhaust gas recirculation (EGR) from 0% to 12% of inlet mass of air fresh charge. Results indicate that S100 or B20 gives lower brake thermal efficiency (η_B), brake power (BP), brake mean effective pressure (BMEP), and higher brake specific fuel consumption (BSFC) due to lower heating value compared to pure diesel fuel. S100 or B20 gives lower NO_X concentration due to lower gas temperature. S100 or B20 gives higher T_wall and T_exhaust due to incomplete combustion inside engine cylinder. S100 or B20 gives higher CO and CO₂ concentrations due to higher carbon/hydrogen ratio. The position of maximum pressure (P_max) change for pure diesel fuel is earlier than for S100 or B20. The results show that S100 or B20 are promising as alternative fuel for diesel engine. The utilization of vegetable oils does not require a significant modification of existing engines. This can be seen as the main advantage of vegetable oils. The main disadvantages of biodiesel fuels are high viscosity, drying with time, thickening in cold conditions, flow and atomization characteristics.     

Effect of engine parameters and gaseous fuel type on the cyclic variability of dual fuel engines

This paper presents an analysis of the cycle-to-cycle combustion variation as reflected in the combustion pressure data of a single cylinder, naturally aspirated, four stroke, Ricardo E6 engine converted to run as dual fuel engine on diesel and gaseous fuel of LPG or methane. A measuring set-up consisting of a piezo-electric pressure transducer with charge amplifier and fast data acquisition card installed on an IBM microcomputer was used to gather the data of up to 1200 consecutive combustion cycles of the cylinder under various combination of engine operating and design parameters. These parameters included type of gaseous fuel, engine load, compression ratio, pilot fuel injection timing, pilot fuel mass, and engine speed. The data for each operating conditions were analyzed for the maximum pressure, the maximum rate of pressure rise—representing the combustion noise, and indicated mean effective pressure. The cycle-to-cycle variation is expressed as the mean value, standard deviation, and coefficient of variation of these three parameters. It was found that the type of gaseous fuel and engine operating and design parameters affected the combustion noise and its cyclic variation and these effects have been presented.     

Characterization of Particulate Matter Morphology and Volatility from a Compression-Ignition Natural-Gas Direct-Injection Engine

The particulate matter (PM) emitted from a single-cylinder compression-ignition, natural-gas engine fitted with a High-Pressure Direct-Injection (HPDI) system distinctly different from a duel fuel engine was investigated, and characterized by size distribution, morphology, mass-mobility exponent, effective density, volatility, mixing state, and primary particle size using transmission electron microscopy (TEM), and tandem measurements from differential mobility analyzers (DMA) and a centrifugal particle mass analyzer (CPMA). Six engine conditions were selected with varying load, speed, exhaust gas recirculation (EGR) fraction, and fuel delivery strategy. An increase in engine load increased both the number concentration and the geometric mean diameter of the particulate. The fraction of the number of purely volatile particles to total number of particles (number volatile fraction, NVF) was found to decrease as load increased, although at the lower speed, partially premixed mode, the lowest NVF. All size distributions were also found to be unimodal. The size-segregated ratio of the mass of internally mixed volatile material to total particle mass (mass volatile fraction, MVF) decreased with load and with particle mobility-equivalent diameter. A roughly constant amount of volatile material is likely produced at each engine mode, and the decrease in MVF is due to the increase in PM number with load. Effective density and mass-mobility exponent of the non-volatile soot at the different engine loads were the same or slightly higher than soot from traditional diesel engines. Denuded effective density trends were observed to collapse to approximately the same line, although engine modes with higher MVFs had slightly higher effective densities suggesting that the soot structures have collapsed into more dense shapes—a suspicion that is confirmed with TEM images. TEM results also indicated that primary particle size first decreases from low to medium load, then increases from medium to high load. An increase in EGR was also seen to increase primary particle size. Coefficients were determined for a relation that gives primary particle diameter as a function of projected area equivalent diameter. A decrease in load or speed results in a stronger correlation.

Copyright 2015 American Association for Aerosol Research     

Investigation of the performance and emissions of bus engine operating on butanol/diesel fuel blends

An experimental investigation is conducted to evaluate the effects of using blends of n-butanol (normal butanol) with conventional diesel fuel, with 8% and 16% (by vol.) n-butanol, on the performance and exhaust emissions of a fully instrumented, six-cylinder, water-cooled, turbocharged and after-cooled, heavy duty, direct injection (DI), Mercedes-Benz engine, installed at the authors’ laboratory, which is used to power the mini-bus diesel engines of the Athens Urban Transport Organization sub-fleet. The tests are conducted using each of the above fuel blends, with the engine working at two speeds and three loads. Fuel consumption, exhaust smokiness and exhaust regulated gas emissions such as nitrogen oxides, carbon monoxide and total unburned hydrocarbons are measured. The differences in the measured performance and exhaust emissions of the two butanol/diesel fuel blends from the baseline operation of the engine, i.e. when working with neat diesel fuel, are determined and compared. It is revealed that this fuel, which can be produced from biomass (bio-butanol), is a very promising bio-fuel for diesel engines. The differing physical and chemical properties of n-butanol against those for the diesel fuel, aided by sample cylinder pressure and heat release rate diagrams, are used to interpret the observed engine behavior.     

Biodiesel development from high acid value polanga seed oil and performance evaluation in a CI engine

Non-edible filtered high viscous (72 cSt at 40 °C) and high acid value (44 mg KOH/gm) polanga (Calophyllum inophyllum L.) oil based mono esters (biodiesel) produced by triple stage transesterification process and blended with high speed diesel (HSD) were tested for their use as a substitute fuel of diesel in a single cylinder diesel engine. HSD and polanga oil methyl ester (POME) fuel blends (20%, 40%, 60%, 80%, and 100%) were used for conducting the short-term engine performance tests at varying loads (0%, 20%, 40%, 60%, 80%, and 100%). Tests were carried out over entire range of engine operation at varying conditions of speed and load. The brake specific fuel consumption (BSFC) and brake thermal efficiency (BTE) were calculated from the recorded data. The engine performance parameters such as fuel consumption, thermal efficiency, exhaust gas temperature and exhaust emissions (CO, CO₂, HC, NO_x, and O₂) were recorded. The optimum engine operating condition based on lower brake specific fuel consumption and higher brake thermal efficiency was observed at 100% load for neat biodiesel. From emission point of view the neat POME was found to be the best fuel as it showed lesser exhaust emission as compared to HSD.