Idle Conditions Research Articles

Aircraft engine particulate matter: Macro- micro- and nanostructure by HRTEM and chemistry by XPS

Carbonaceous particulate emissions from jet aircraft are a significant source of emissions from airports near urban areas. Physical structure and surface chemistry are relevant towards assessing impacts of combustion-produced soot upon the environment and assessing health impacts. In this report high-resolution electron microscopy (HRTEM) and X-ray photoelectron (XPS) data are presented for particulate emissions from a CFM-56-3 engine aboard a DC-9 aircraft, fueled by JP-8. Engine power levels were varied from 4% to 100%. Soot aggregate macrostructure, microstructure and nanostructure are discussed with respect to combustion conditions. Ultrafine particle size distributions at idle and near full power conditions are highlighted by HRTEM and compare favorably to reported scanning mobility particle sizer (SMPS) measurements. Particle composition, as inferred from the XPS ratio for sp2/sp3 carbon bonding is compared to results from thermo-optical evaluation of organic and elemental carbon analysis at selected powers with excellent agreement. Across engine power levels, these ultra-fine particles appear to be remnants of oxidized larger aggregates.

On the ignition and flame development in a spray-guided direct-injection spark-ignition engine

High-speed fuel, flow, and flame imaging are combined with spark discharge measurements to investigate the causes of rare misfires and partial burns in a spray-guided spark-ignited direct-injection (SG-SIDI) engine over a range of nitrogen dilution levels (0–26% by volume). Planar laser induced fluorescence (PLIF) of biacetyl is combined with planar particle image velocimetry (PIV) to provide quantitative measurements of equivalence ratio and flow velocity within the tumble plane of an optical engine. Mie scattering images used for PIV are also used to identify the enflamed region to resolve the flame development. Engine parameters were selected to mimic low-load idle operating conditions with stratified fuel injection, which provided stable engine performance with the occurrence of rare misfire and partial burn cycles. Nitrogen dilution was introduced into the intake air, thereby displacing the oxygen, which destabilized combustion and increased the occurrence of poor burning cycles. Spark measurements revealed that all cycles exhibited sufficient spark energy and duration for successful ignition. High-speed PLIF, PIV, and Mie scattering images were utilized to analyze the spatial and temporal evolution of the fuel distribution and flow velocity on flame kernel development to better understand the nature of poor burning cycles at each dilution level. The images revealed that all cycles exhibited a flammable mixture near the spark plug at spark timing and a flame kernel was present for all cycles, but the flame failed to develop for misfire and partial burn cycles. Improper flame development was caused by slow flame propagation which prevented the flame from consuming the bulk of the fuel mixture within the piston bowl, which was a crucial step to achieve further combustion. The mechanisms identified in this work that caused slower flame development are: (1) lean mixtures, (2) external dilution, and (3) convection velocities that impede transport of the flame into the fuel mixture.

Characterization of Lean Burn Module Air Blast Pilot Injector With Laser Techniques

For lean burn combustor development in low emission aero-engines, the pilot stage of the fuel injector plays a key role with respect to stability, operability, NOx emissions, and smoke production. Therefore it is of considerable interest to characterize the pilot module in terms of pilot zone mixing, fuel placement, flow field, and interaction with the main stage. This contribution focuses on the investigation of soot formation during pilot-only operation. Optical test methods were applied in an optically accessible single sector rig at engine idle conditions. Using planar laser-induced incandescence (LII), the distribution of soot and its dependence on air/fuel ratio, as well as geometric injector parameters, was studied. The data shows that below a certain air/fuel ratio, an increase of soot production occurs. This is in agreement with smoke number measurements in a standard single sector flame tube rig without optical access. Reaction zones were identified using chemiluminescence of OH radicals. In addition, the injector flow field was investigated with PIV. A hypothesis regarding the mechanism of pilot smoke formation was made based on these findings. This along with further investigations will form the basis for developing strategies for smoke improvement at elevated pilot-only conditions.

Investigation of engine restart stability after idle stop for a mild type HEV powertrain

Stringent regulations on exhaust emissions and fuel economy for vehicles have become major issues in the automotive industry. Hybrid electric vehicles (HEV) are one of the crucial alternative plans to current conventional vehicles, but they have drawbacks, which include increases in total hydrocarbon (THC) emission from the engine and deterioration of the combustion stability with frequent stopping and restarting of the engine. Intake port fuel film is evaporated up during the deceleration state due to the fuel-cut. The λ (relative A/F ratio) at engine restart is lean because part of injected fuel is used to form the fuel film in the intake port. This study revealed the behavior of a fuel film in engine stop with fuel-cut and in engine restart with a simulation model. To investigate the fuel film characteristics, a simulation model was applied and validated with a single-cylinder engine. The simulation result shows that λ of at least 1.2 is required for a stable engine restart. The minimum injection quantity of the first cycle for stable combustion is suggested to be at least 240% of the steady-state idle condition.

Production of palm and Calophyllum inophyllum based biodiesel and investigation of blend performance and exhaust emission in an unmodified diesel engine at high idling conditions

Rapid depletion of fossil fuels, increasing fossil-fuel price, carbon price, and the quest of low carbon fuel for cleaner environment – these are the reason researchers are looking for alternatives of fossil fuels. Renewable, non-flammable, biodegradable, and non-toxic are some reasons that are making biodiesel as a suitable candidate to replace fossil-fuel in near future. In recent years, in many countries of the world production and use of biodiesel has gained popularity. In this research, biodiesel from palm and Calophyllum inophyllum oil has been produced using the trans-esterification process. Properties of the produced biodiesels were compared with the ASTM D6751 standard: biodiesel standard and testing methods. Density, kinematic viscosity, flash point, cloud point, pour point and calorific value, these are the six main physicochemical properties that were investigated. Both palm biodiesel and Calophyllum biodiesel were within the standard limits, so they both can be used as the alternative of diesel fuel. Furthermore, engine performance and emission parameters of a diesel engine run by both palm biodiesel–diesel and Calophyllum biodiesel–diesel blends were evaluated at high idling conditions. Brake specific fuel consumption increased for both the biodiesel–diesel blends compared to pure diesel fuel; however, at highest idling condition, this increase was almost negligible. Exhaust gas temperatures decreased as blend percentages increased for both the biodiesel–diesel blends. For low blend percentages increase in NOX emission was negligible but as blend percentages increase, emission increased significantly. CO and HC emission for both biodiesel–diesel blends were lower compared to pure diesel fuel. 20% Calophyllum biodiesel–diesel blends emitted lowest HC and CO emission.

Online measurements of the emissions of intermediate-volatility and semi-volatile organic compounds from aircraft

Abstract. A detailed understanding of the climate and air quality impacts of aviation requires measurements of the emissions of intermediate-volatility and semi-volatile organic compounds (I/SVOCs) from aircraft. Currently both the amount and chemical composition of aircraft I/SVOC emissions remain poorly characterized. Here we characterize I/SVOC emissions from aircraft, using a novel instrument for the online, quantitative measurement of the mass loading and composition of low-volatility organic vapors. Emissions from the NASA DC8 aircraft were sampled on the ground 143 m downwind of the engines and characterized as a function of engine power from idle (4% maximum rated thrust) through 85% power. Results show that I/SVOC emissions are highest during engine idle operating conditions, with decreasing but non-zero I/SVOC emissions at higher engine powers. Comparison of I/SVOC emissions with total hydrocarbon (THC) measurements, VOC measurements, and an established emissions profile indicates that I/SVOCs comprise 10–20% of the total organic gas-phase emissions at idle, and an increasing fraction of the total gas-phase organic emissions at higher powers. Positive matrix factorization of online mass spectra is used to identify three distinct types of I/SVOC emissions: aliphatic, aromatic and oxygenated. The volatility and chemical composition of the emissions suggest that unburned fuel is the dominant source of I/SVOCs at idle, while pyrolysis products make up an increasing fraction of the I/SVOCs at higher powers. Oxygenated I/SVOC emissions were detected at lower engine powers (≤30%) and may be linked to cracked, partially oxidized or unburned fuel components.

대향류식 배기열 회수장치의 가솔린기관 적용 특성에 관한 연구

Abstract : The purpose of this study is to investigate the performance characteristics of the counterflow exhaust heat recovery device for the applied gasoline engines. The EHRS device is installed behind the catalyst. This study investigates the engine warm-up characteristic, the exhaust noise characteristic, the back-pressure characteristic . The engine warm-up characteristics is (load 0%, load 10%, load 20%) in (idle, 1000rpm, 1500rpm, 2000rpm, 2500rpm) conditions by measuring the time it warmed up, coolant temperature (25°C~80°C) until the performance evaluation is performed. The wide open throttle and the coast down the exhaust noise and the back-pressure characteristic experiment repeated twice. The test conditions is 950rpm~6,050rpm proceed experiment repeated 3-5 times. Load 0% idle conditions except the results improved engine warm-up characteristics. The exhaust noise obtain similar results the BASE+EHRS W/O_FRT_MUFF with BASE and back-pressure to obtain similar results BASE+EHRS W/O_FRT_ MUFF with BASE+EHRS.

Experimental Study on the Cycle-to-Cycle Combustion Variations in a Spark Ignition Engine

A cyclic variability has long been recognized as limiting the range of operating conditions of spark ignition engines, in particular, under idling conditions. The coefficient of variation (COV) in indicated mean effective pressure (IMEP) defines the cyclic variability in indicated work per cycle, and it has been found that vehicle drivability problems usually result. For analysis of the cyclic variations in spark ignition engines at idling, the results show that cyclic variability by the COV, COV of IMEP, the lowest normalized value (LNV), and burn angles can help to design the spark ignition engine.

Reaserch on an Electronic Control System of CNG/Diesel Dual Fuel Engine

In order to convert the high pressure common rail system engine to CNG/Diesel dual fuel engine, an electronically controlled system is developed. The system includes a CNG fuel supply system, the CNG electronic control unit (ECU) and its matching harness etc. During starting and idle load conditions, the engine runs under pure diesel mode, when the speed and load reached a certain set point, the diesel ECU reduces the pilot diesel quantity, meanwhile, the CNG ECU increases the natural gas quantity, then the engine runs under dual fuel mode. The engine experiment data show that in different conditions, the highest substitution rate is 90% and the average substitution rate is 83%; the average savings ratio of operation cost per hour is 26%.

엔진 냉각수 유량 단속에 의한 디젤 차량의 연비 및 배기가스 특성 연구

Abstract The use of the electromagnetic clutch water pump for internal combustion engine vehicles saves fuel and leads to a reduction in emissions. The clutch water pump allows the engine cooling system to select the optimum operation condition by using coolant flow rate on/off control. This study investigated the characteristics of fuel consumption and emissions of the diesel engine cooling system using the clutch water pump. The electromagnetic clutch operation reduced by about 49% of engine warm up period at idle condition and controlled the optimum high coolant temperature at driving condition. Therefore, fuel consumption was enhanced by about 5%, and emissions such as HC, CO and CO 2 were also reduced to a certain degree even though NOx increased a little bit, compared to those of the conventional water pump under NEDC mode which represents the real driving pattern. Key Words : Water pump, Electromagnetic clutch, Fuel consumption, Emission, Warm-up, NEDC * Corresponding Author : Sung Chul Kim(Korea Automotive Technology Institute)Tel: +82-41-559-3093 email: sckim@katech.re.krReceived February 8, 2013 Revised March 11, 2013 Accepted May 9, 2013

The Low Load Limit of Gasoline Partially Premixed Combustion Using Negative Valve Overlap

Partially premixed combustion has the potential of high efficiency and simultaneous low soot and NOx emissions. Running the engine in partially premixed combustion mode with high octane number fuels has the advantage of a longer premix period of fuel and air which reduces soot emissions, even at higher loads. The problem is the ignitability at low load and idle operating conditions. The objective is to investigate different multiple-injection strategies in order to further expand the low load limit and reduce the dependency on negative valve overlap in order to increase efficiency. The question is, what is the minimum attainable load for a given setting of negative valve overlap and fuel injection strategy. The experimental engine is a light duty diesel engine equipped with a fully flexible valve train system. The engine is run without boost at engine speed 800 rpm. The fuel is 87 RON gasoline. A turbocharger is typically used to increase the boost pressure, but at low engine speed and load the available boost is expected to be limited. The in-cylinder pressure and temperature around top-dead-center will then be too low to ignite high octane number fuels. A negative valve overlap can be used to extend the low engine speed and load operating region. But one of the problems with negative valve overlap is the decrease in gas-exchange efficiency due to heat-losses from recompression of the residual gases. Also, the potential temperature increase from the trapped hot residual gases is limited at low load due to the low exhaust gas temperature. In order to expand the low load operating region further, more advanced injection strategies are investigated.

Abnormal Noise Source Identification and Control for Automobile Transmission in the Neutral Idle Condition

Aiming at the abnormal noise of a domestically-made automobile transmission in the neutral idle condition, seriously affecting the vehicle market competitiveness and the riding comfort ability for customers, the objective of this study to reduce the noise and vibration of the automobile transmission by accurately identifying the noise source of the transmission in the neutral idle condition. For this purpose, based on the working characteristics of the transmission, modal analysis of automobile transmission housing is formulated using 3D graphics software Pro/E together with Finite Element Method. In addition, the calculation of meshing frequency of gear pair is conducted also. Finally, through comparing model analysis results to the calculation results, it is indicated that the gear meshing impact noise of the third gear pair was identified as the noise resource of the automobile transmission in neutral idle condition, which will provide the theoretic basis to analyze its dynamic characteristics of the transmission as well as its improvement to reduce vibration and noise.

Rating the dieselness of vehicle noise using different psychoacoustic methods

Modern diesel engines meet the demand for high power-engines while strict emission regulations have to be fulfilled. Therefore, diesel engines entered vehicle segments where the expectations on the sound quality are exceptionally high. Sound quality and fuel efficiency are often conflicting goals during the development of a diesel engine. The typical sound character of diesel engines, the so called Dieselness, is an indicator for the overall sound quality of the vehicle noise. Hence, it is desirable to rate the Dieselness of engine sounds. Sounds emitted by gasoline- and diesel-powered vehicles in idle condition were rated in psychoacoustic experiments using different methods. First, the method of line length was used as direct scaling procedure to get ratio ratings of the relative Dieselness of the vehicle noises. Second, a direct ranking of the noises has been done with the Random Access method where subjects had to rank the sounds according to their Dieselness. Third, in a paired-comparison test the participants had to judge which of two sounds had more Dieselness, resulting in an indirect scaling. These methods are compared regarding the time the experiments took and the resulting ranking respectively scaling. In addition, a semantic differential test with general adjective pairs was conducted.

Precise order tracking analysis of time-varying vibro-acoustic signature from rotating machines

Transient operation of rotating machines usually exhibit a large variation in rotating speed and frequencies of interest often fluctuate due to RPM variations. Order tracking is useful for the transient analysis of vibro-acoustic signal from a rotating machine. A fine resolution is required both in time and frequency domains to trace the spectral magnitude of the interested frequency in precision. In this study, characteristics of popular order tracking methods using short time Fourier transform (STFT) and Vold-Kalman filter are studied in the viewpoint of calculation time and resolution. They are compared with a new tracking method using variable frequency resolution STFT (VFR-STFT), being suggested for the sound quality analysis. For a test signal, vehicle interior noise measured in an idle run-up condition is used. Under the same signal processing conditions, time and frequency domain resolutions produced by three methods are compared. It is observed that VFR-STFT detects bandwidth of high order components of engine firing frequency precisely and it produced the finest resolution in time and frequency domain among three methods. Although VFR-STFT needs a bit more calculation time compared to the other methods, it is useful for the cases that do not require a real time analysis.

Comparison of Negative Valve Overlap (NVO) and Rebreathing Valve Strategies on a Gasoline PPC Engine at Low Load and Idle Operating Conditions

Gasoline partially premixed combustion (PPC) has the potential of high efficiency and simultaneous low soot and NOx emissions. Running the engine in PPC mode with high octane number fuels has the advantage of a longer premix period of fuel and air which reduces soot emissions. The problem is the ignitability at low load and idle operating conditions. In a previous study it was shown that it is possible to use NVO to improve combustion stability and combustion efficiency at operating conditions where available boosted air is assumed to be limited. NVO has the disadvantage of low net indicated efficiency due to heat losses from recompressions of the hot residual gases. An alternative to NVO is the rebreathing valve strategy where the exhaust valves are reopened during the intake stroke. The net indicated efficiency is expected to be higher with the rebreathing strategy but the question is if similar improvements in combustion stability can be achieved with rebreathing as with NVO. The results show that the rebreathing valve strategy has similar improvements on combustion stability as NVO when the same fuel injection strategy is used. This work also includes results with the NVO valve strategy where a fuel injection is added during the NVO. When a fuel injection is added during the NVO, an additional improvement on combustion stability can be seen which is unmatched by the rebreathing valve strategy. (Less)

Hand-Arm Vibration of Unskilled Oil Palm Motorised Cutter Operator

The portable petrol driven oil palm motorised cutter or CANTAS has been identified as a type of machine that generates hand-arm vibration. These vibrations can cause complex vascular, neurological and musculoskeletal disorder known as hand-arm vibration syndrome (HAVS) when over exposure of daily usage. The objective of this study is to investigate the vibration level at different angles during the operational of the CANTAS including idle and full throttle conditions. The CANTAS vibration experiments were carried out at a farm in Parit Raja, Batu Pahat, Johor. A student participated as the unskilled worker and was assisted by two technical staffs to conduct the vibration measurements. The measurement was taken during the operations of cutting first fronds, second fronds and a fruit bunch during idle and full throttle conditions and by varying the inclination angle. The inclinations of cutting angle were varied from 45º, 60º and 75º. The hand-arm vibration value, ahv achieved 10.93 ±1.2 m/s2 and 7.94 ± 1.0 m/s2 for unskilled user during operation of two bunches and one pruning frond for all angles at point 1 and point 2 handle respectively. Mean vibration values at both point of handles resulted in vibration values of 10.12±3.8m/s2 at 450, 9.15±3.0m/s2 at 600 and 9.03±1.8m/s2 at 750. Increasing the angle overall results in decreasing the level of vibration at both handle points.

Hand-Arm Vibration Analysis of Palm Oil Fruit Harvester Machine

The objective of this study is to determine the vibration value of Palm Oil Harvester Machine or CANTAS motorized cutter profile. The CANTAS machines have been divided into twelve nodes and hand arm vibration measurements are taken for idle and full throttle operation. Three cutting heads provided by MPOB have been measured for comparison purposes. The hand-arm vibration values for Type A Cutting head achieves (3.89±1.10) m/s2 for idle condition and (10.71±2.88) m/s2 for full throttle condition. Meanwhile Type B Cutting Head achieves (3.63±0.87) m/s2 for idle condition and (11.22±1.74) m/s2 for full throttle condition. Type C of Cutting Head yields (3.51±0.82) m/s2 for idle condition and (15.54±3.81) m/s2 for full throttle condition along the structure. The results also shows which points depicted highest vibration level during idle (no operation, ideally from tree to tree) and full throttle (overuse operation). These values present the maximum and minimum vibration levels that will be received by the user in daily usage of the machine. design in reducing vibration to the hand-arm of the user.

Driver exposure and environmental noise emission of Massey Ferguson 285 tractor during operations with different engine speeds and gears

Agricultural tractor has led to development of agriculture industry, however, same as other new technologies it produces noise pollution on fields and makes some problems for drivers and farmers as well. This is aimed to investigate the driver's exposure and noise emitted from Massey Ferguson tractor; model 285 during operation by various engine speeds and gears. For field measurements, the Massey Fergusson 285 tractor of agriculture college field was used. The noise levels at the right ear of driver and surroundings were measured in both idle and mobile conditions. Frequency analysis in both idle and mobile conditions has shown that the noise levels at low frequencies were higher compared with high frequencies. Based on the measurements at selected engine speed, noise levels at surrounding conditions were lower than ACGIH standard. Similar results were also observed at driver’s right ear by engine speed of 1000 rpm, while the noise levels for 2000 rpm was higher than standard limit of 85 dB A. The results indicate the high influence of engine speed and low impact of gear ratio on both driver's exposure and environmental noise pollution. Key words: Noise levels,engine speed, gears, surroundings, idle condition, mobile condition.

Evaluation of the use of bioethanol fuelled buses based on ambient air pollution screening and on-road measurements

Mitigation measures to reduce greenhouse gas emissions may have adverse effects on urban air quality and human exposure to harmful pollutants. The use of bioethanol fuelled vehicles is increasing worldwide and may create new undesired pollution effects. Different measurement campaigns were performed in a pilot study to contribute to the understanding of the consequences associated with the use of bioethanol blended fuel (E95) on a series of pollutants. Ambient screening measurements of NO2, O3, acetic acid, formaldehyde and acetaldehyde were performed at different urban locations, exposed and not exposed to the circulation of bioethanol buses. In addition, volatile organic compounds were measured at the exhaust pipe of a bioethanol fuelled bus, both under idling conditions (carbonyls; DNPH cartridge) and under on-road driving conditions applying online monitoring (PTR-TOF). Higher ambient acetaldehyde values were measured at locations exposed to bioethanol fuelled buses than at locations not exposed, and very high acetaldehyde and acetic acid values were measured from the exhaust pipe during driving conditions (acetaldehyde>150ppm; acetic acid≈20–30ppm) and modelled at close distance to the bioethanol bus. Human exposure to high concentration of acetaldehyde is expected, and it may involve a significantly increased chance in developing cancer. The high concentration of acetic acid will involve odour annoyance and significant material degradation or corrosion.

GRID VOLTAGE STABILITY ENHANCEMENT USING PHOTOVOLTAIC BASED STATIC SYNCHRONOUS COMPENSATOR

Today, we are mostly dependent on non renewable energy that have been and will continue to be a major cause of pollution and other environmental degradation. Because of these problems and our dwindling supply of petroleum, finding sustainable alternatives is becoming increasingly urgent. Perhaps, the greatest challenge is in devising a sustainable future, which relies on integration and control of renewable energy sources in grid distributed generation. This study presents the usage of utilizing Photovoltaic (PV) Solar Farm (SF) during idle conditions as Static Synchronous Compensator (STATCOM), to regulate the point of common coupling voltage when the wind farm supply the power to the grid. The proposed control will enable increased connections of WECS to the grid. MATLAB/Simulink based simulation results are presented for validation of the system. The PV-STATCOM increase the stability of the grid with interconnected wind farm system without any use of additional compensator.