Exhaust Hydrocarbon Emissions Research Articles

Emission Characteristics of Heavy-Duty Vehicle Diesel Engines at High Altitudes

The aim of this study was to accurately quantify the emission characteristics of pollutants at different altitudes. We used an intake and exhaust altitude simulation system that could simulate the intake and exhaust pressures of a national sixth vehicle diesel engine at different altitudes. Experimental research was conducted on the World Harmonized Transient Cycle (WHTC) and World Harmonized Steady State Cycle (WHSC) of the diesel engine. The results showed that carbon monoxide (CO) emissions increased with the altitude at full load, but their rates were significantly reduced at low speed (800 rpm), increasing by 0.0084–0.665 ppm/m. Hydrocarbon (HC) emissions showed an initial decreasing and then increasing trend, with a rise of up to 30%. Nitrogen oxides (NOx) showed a linear decreasing trend, especially at low speed. With the increase in altitude, the cycle work of the diesel engine decreased in a non-linear manner, and the decrease became more pronounced above 3000 m. The raw emission results of the WHTC and WHSC tests also revealed that CO increased exponentially, NOx decreased slightly and then increased rapidly, HC increased linearly, and the emissions of all pollutants deteriorated significantly above 3000 m. The exhaust emission results of the WHTC and WHSC tests showed that the CO emission showed an initial decreasing and then increasing trend with the elevation of the altitude, approximately 15 ± 5 mg/kWh. HC emissions showed an increasing trend, with HC emissions of 3 – 6 mg/kWh for the WHTC and 1 – 2 mg/kWh for the WHSC. NOx emissions did not follow any obvious rule, while the particulate matter (PM) tended to increase and then decrease with the elevation of the altitude. In relation to the current emission standards, the limit value margin for CO and HC exhaust emissions is greater than 95% and the limit value margin for PM emissions is greater than 88% at an altitude of 4000 m. The NOx emission limit is greater than 87% (within 3000 m), but there is a risk of exceeding the limit above 3000 m. The second sampling data from the WHTC and WHSC showed that the raw emissions of the engine were higher in the high-altitude area than in the low-altitude area, but the change law of the exhaust emissions was not obvious, and the levels of both emissions were low.

A Review on Compression-Ignition Engine Performance And Emissions With Hydrogen-Diesel Mixtures: Effect Of Operational Parameters

The combustion of conventional fuel in Compression-Ignition (CI) engines is generally understood as a primary cause of hydrocarbon exhaust emissions. Alternative fuels and hydrocarbon fuels can be mixed to lower pollution emissions while enhancing engine efficiency. Here, the various variables which impact emissions and engine efficiency are fully illustrated. Numerical work on the engine was done to examine the working and outflow patterns of a dual-fuel CI engine at various fuel combination ratios. In the test setup, diesel is used as main fuel and hydrogen and air as the controlling fuel. In order to formulate this special CI engine numerically, three-dimensional computer based analytical tools were used. For this method, n-heptane was chosen as reaction fuel and a reduced-reaction mechanism was taken into account. To investigate the soot formation rate inside the cylinder, the model by Hiroyasu-Nagel was developed. Here, a study looks into the performance effects on the variations of secondary fuel and its emissions. Presence of good amount of hydrogen during combustion results in better thermal efficiency and better performance. As the hydrogen rate increased, ignition timing was delayed as a result of a time lag in the OH component’s evolution. Meanwhile, Exhaust Gas Recirculation (EGR) and timing of the diesel incorporation strategies are also taken as important performance parameter.

Exhaust emissions from gasoline vehicles after parking events evaluated by chassis dynamometer experiment and chemical kinetic model of three-way catalytic converter

Despite the worldwide trend of introducing of zero-fuel-based vehicles to the market, the emissions of air pollutants and greenhouse gases from passenger vehicles are likely to remain a concern for the coming 20 to 30 years. In this study, exhaust emissions of gasoline engines running after varying parking durations were measured using a chassis dynamometer. The experimental results showed that exhaust emissions of hydrocarbons, nitrogen oxides, and carbon monoxide from most vehicles increased dramatically following 60 to 120 min of parking, and were higher than cold-start (1040 + min parking) emissions, indicating the impact of parking duration on atmospheric pollutant emissions. The after-treatment capacity of the three-way catalytic converter was evaluated by chemical kinetic modeling of the chemical reactions on the catalyst coupled with a time-dependent energy conservation equation. The results of the model calculation indicated that both the initial temperature of the three-way catalytic converter and the inlet engine gas temperature are critical factors impacting exhaust pollutants after parking; therefore, proper management to reduce the emissions after middle-term parking durations should be developed to mitigate air pollution.

KADAR EMISI GAS BUANG PADA SI ENGINE 4 STROKE-LPG FUEL DENGAN VARIASI BUKAAN KATUP GAS

Abstract The use of LPG fuel in spark ignition engines continues to be developed, including the use of converter kits as a conversion tool from gasoline to LPG. However, the use of converter kits is not optimal because the mixture of air and gas has not been mixed heterogeneously in the combustion chamber. Therefore, it is necessary to redesign the converter kits that speed up the mixing process between air and gas. This study aims to evaluate the use of LPG fuel in spark ignition engines with converter kits on variations in throttle valve openings on exhaust gas emissions and exhaust gas temperatures. The research method used is an experiment with variations in the throttle valve opening on the engine are 25%, 50%, 75%, and 100%. Data that will be compared on the use of gasoline and LPG fuels include carbon monoxide (CO), hydrocarbon (HC), and mean gas temperature. The results showed that the use of fuel between gasoline and LPG on exhaust gas emission levels in spark ignition engines with variations in throttle valve openings was able to reduce CO emissions by 92% on average, HC by 72%, and increase the mean average temperature by 17%. This shows that the use of converter kits at each valve opening is able to reduce levels of CO and HC exhaust emissions compared to gasoline. However, it is inversely proportional to the mean gas temperature, at each variation of the gas valve opening there is a significant increase in temperature. This is because the heating value of LPG is greater than that of gasoline.Keywords—Exhaust gas emission, spark ignition engine, throttle valve open

The effect of Jatropha seed cake producer gas flow rates on a diesel engine operated on dual fuel mode at high engine speed

Jatropha seed cake is a byproduct of biodiesel production. The seed cake can be used to make a producer gas that can be fumigated into a diesel engine operated on dual fuel mode without major modification. This paper intends to investigate the impact of Jatropha seed cake-derived producer gas mass flow rate on the performance and emission characteristics of a diesel engine operated on a dual fuel mode at a high engine speed of 3,000 rpm. The results highlight that the maximum diesel replacement rate reached 60% at a 20 kg/h gas flow rate when the engine was operated at medium engine load. An increase in gas flow rate augments the diesel substitution rate but decreases the electrical-thermal efficiency (ETE). At 70% of the full engine load, the specific diesel consumption declined from 0.337 to 0.185 kg/kWh when the gas was increased from zero to 20 kg/h. At this engine load, the ETE sharply fell off from 25% to 10.6% and 6.6% when the gas flow rate increased from zero to 10 kg/h and 20 kg/h, respectively. The electrical specific fuel consumption and electrical specific energy consumption, exhaust hydrocarbon (HC), carbon monoxide (CO), and carbon dioxide (CO2) emissions were found to be higher with an increase in gas flow rate. Unlike dual fuel engine operation at medium speed, the nitrogen oxides (NOX) emissions were consistent with an increase in gas flow rate. Based on the empirical findings, the dual producer gas-diesel engine should be operated at high engine load but not at a high engine speed of 3,000 rpm with a maximum gas flow rate of 20 kg/h.

Influence of operating parameters on performance and emissions for a compression-ignition engine fueled by hydrogen/diesel mixtures

Abstract Hydrocarbon exhaust emissions are mainly recognized as a consequent of carbon-based fuel combustion in compression ignition (CI) engines. Alternative fuels can be coupled with hydrocarbon fuels to control the pollutant emissions and improve the engine performance. In this study, different parameters that influence the engine performance and emissions are illustrated with more details. This numerical work was carried out on a dual-fuel CI engine to study its performance and emission characteristics at different hydrogen energy ratios. The simulation model was run with diesel as injected fuel and hydrogen, along with air, as inducted fuel. Three-dimensional CFD software for numerical simulations was implemented to simulate the direct-injection CI engine. A reduced-reaction mechanism for n-heptane was considered in this work instead of diesel. The Hiroyasu-Nagel model was presented to examine the rate of soot formation inside the cylinder. This work investigates the effect of hydrogen variation on output efficiency, ignition delay, and emissions. More hydrogen present inside the engine cylinder led to lower soot emissions, higher thermal efficiency, and higher NOx emissions. Ignition timing delayed as the hydrogen rate increased, due to a delay in OH radical formation. Strategies such as an exhaust gas recirculation (EGR) method and diesel injection timing were considered as well, due to their potential effects on the engine outputs. The relationship among the engine outputs and the operation conditions were also considered.

Utilization of natural compounds (chlorophyll and carotene extracts) as an octane-boosting additive ingasoline

Natural materials should be substituted for organometallic and oxygenated compounds in octane-boosting additives for gasoline because of environmental considerations. Chlorophyll and carotene extracts can be used as octane-boosting additives in gasoline. Maceration and adsorption methods are used to extract them. In this work, chlorophyll and carotene extracts were mixed with fatty acid methyl esters (FAMEs) and a solvent (xylene and gasoline) in a particular composition. The extracted pigment was characterized using ultraviolet-visible (UV−Vis) spectrophotometry. Three different additive formulations with chlorophyll/carotene extract ratios of 0 : 1, 3 : 1, and 2 : 3 were investigated. Additive performance tests included measurements of physical properties, octane number, exhaust hydrocarbon (HC) and carbon monoxide (CO) emissions. The results showed that additives with a chlorophyll/carotene extract ratio of 2 : 3, when added to premium-grade gasoline, increased the octane number by 0.3%. The increase of the octane number was further demonstrated by analysis of the HC composition of the gasoline, where the additive with a 2 : 3 ratio resulted in the greatest increase in the olefin content (22.9%), and the emission tests showed that it could reduce HC emissions by 30.9%.

Investigation of First and Second Law forAutomobile Waste Heat Recovery Vapour Refrigeration Cycle

AliBr-H2O absorption refrigeration cycle has been analysed. Energy and exergy analyses have been performed on this conceptual cycle. The analysis involves the determination of effects of generator, absorber and evaporator temperatures on the energetic and exergetic performance of these systems. The calculated exhaust gas energy availability suggests the cooling capacity can be highly improved for a dedicated system. Exhaust hydrocarbon emissions were higher when the refrigeration system was installed in the engine exhaust, but carbon monoxide emissions were reduced, while carbon dioxide concentration remained practically unaltered. Through the study and by analysing the obtained results it is evident that the waste heat based refrigeration system is economic, ecofriendly with zero CO2 emissions.

Study on the combustion and hydrocarbon emission characteristics of direct injection spark-ignition engines during the direct-start process

This study was conducted to investigate the combustion and emissions characteristics of the first-combustion cylinder in a direct-start process. The explosive energy of the first combustion is important for the success of a direct start, but this combustion was rarely addressed in recent research. For a 2.0L direct-injection spark-ignition engine, the in-cylinder mixture concentration, cylinder pressure, engine speed and exhaust hydrocarbon concentration were detected to analyze the fuel evaporation, combustion, engine movement and engine emissions, respectively. In the first-combustion cylinder of the direct-start process, the injected fuel was often enriched to ensure that an appropriate mixture concentration was obtained for ignition without misfiring. Approximately one-third of the injected fuel would not participate in the combustion process and would therefore reduce the exhaust hydrocarbon emissions. The start position determined the amount of the total explosive energy in the first-combustion cylinder, and an optimal start position for a direct start was found to be at a 70–80° crank angle before the top dead center to obtain a better combustion performance and lower emissions. A lower coolant temperature increased the maximum explosion energy of the first combustion, but additional hydrocarbon emissions were generated. Because there was almost no problem in the direct-start capability with different coolant temperatures after an idling stop, it was necessary to maintain the coolant temperature when the engine was stopped.

Particulate associated polycyclic aromatic hydrocarbon exhaust emissions from a portable power generator fueled with three different fuels – A comparison between petroleum diesel and two biodiesels

The fuel impact on the emission of more than 40 particulate associated polycyclic aromatic hydrocarbons (PAHs) in the molecular weight range 178–302Da were investigated. The fuels; neat diesel (EN 590), rape seed methyl ester (B100) and a 30% w/w blend thereof (B30) were tested on a portable power generator without any exhaust aftertreatment. Gaseous emissions of carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOx) were measured along with particulate emissions and its size distribution for the different fuels. Collected diesel particles were extracted using pressurized fluid extraction and analyzed using an online hyphenated liquid chromatography–gas chromatography–mass spectrometry system.The neat B100 and the B30 fuel produced less CO and total PAHs while the emissions of NOx and particulate matter increased compared with petroleum diesel fuel per kWh. The reduction of PAH emissions of the alternative diesel fuels were 36% and 70% for B30 and B100 respectively. While the PAH profiles for the neat diesel fuel and B30 were similar, the profile of B100 differed in the sense that the emission contained a higher percentage of PAHs with higher molecular weights. The emission of these PAHs was however larger using the neat diesel fuel with the exception for some of these higher molecular weight PAHs of which there was an increased emission using B100. Thermogravimetric analysis revealed that the collected particles from B100 contained a substantial amount of volatile components. A mass spectrometric full scan analysis suggests that these volatile components are in fact unburned or partially-burned fuel constituents.It is concluded that the particles originating from biodiesel combustion might be very different from those originating from petroleum diesel combustion which places new demands on the development of measurement methodologies originally developed for particulate emissions from petroleum-based fuels.

Cold start emissions of an ethanol-fuelled engine with heated intake air and fuel

This works presents the exhaust emission levels from a flexible fuel engine with heated intake air and fuel during cold start operation. A vehicle powered by an ethanol-fuelled flexible fuel engine was used in the experiments, following the US FTP-75 test schedule. The conventional gasoline injection system for cold start assistance was removed. Heating of intake air and fuel was provided by electric resistances. The results demonstrate that intake air and fuel heating can attend cold start expectations and simultaneously reduce exhaust hydrocarbon and carbon monoxide emissions.

Lubricating oil influence on exhaust hydrocarbon emissions from a gasoline fueled engine

Engine exhaust hydrocarbon emissions have been investigated for different lubricating oils, using gasoline as fuel. Six samples of lubricants have been tested: synthetic SAE 5W30 and SAE 5W40, semi-synthetic SAE 15W40 and SAE 20W50, and mineral SAE 15W40 and SAE 20W50. Experiments were carried out in a production engine mounted on a bench test dynamometer, varying engine load and speed in the range from 1500 to 6000 rev/min. The results demonstrate the influence of lubricant viscosity and base oil on hydrocarbon emissions. The synthetic oils showed the lowest hydrocarbon emission levels, especially in the low engine speed range.

Using engine exhaust gas as energy source for an absorption refrigeration system

This work presents an experimental study of an ammonia–water absorption refrigeration system using the exhaust of an internal combustion engine as energy source. The exhaust gas energy availability and the impact of the absorption refrigeration system on engine performance, exhaust emissions, and power economy are evaluated. A production automotive engine was tested in a bench test dynamometer, with the absorption refrigeration system adapted to the exhaust pipe. The engine was tested for 25%, 50%, 75% and wide-open throttle valve. The refrigerator reached a steady state temperature between 4 and 13 °C about 3 h after system start up, depending on engine throttle valve opening. The calculated exhaust gas energy availability suggests the cooling capacity can be highly improved for a dedicated system. Exhaust hydrocarbon emissions were higher when the refrigeration system was installed in the engine exhaust, but carbon monoxide emissions were reduced, while carbon dioxide concentration remained practically unaltered.

Polycyclic aromatic hydrocarbon exhaust emissions from different reformulated diesel fuels and engine operating conditions

The study of light-duty diesel engine exhaust emissions is important due to their impact on atmospheric chemistry and air pollution. In this study, both the gas and the particulate phase of fuel exhaust were analyzed to investigate the effects of diesel reformulation and engine operating parameters. The research was focused on polycyclic aromatic hydrocarbon (PAH) compounds on particulate phase due to their high toxicity. These were analyzed using a gas chromatography–mass spectrometry (GC–MS) methodology. Although PAH profiles changed for diesel fuels with low-sulfur content and different percentages of aromatic hydrocarbons (5–25%), no significant differences for total PAH concentrations were detected. However, rape oil methyl ester biodiesel showed a greater number of PAH compounds, but in lower concentrations (close to 50%) than the reformulated diesel fuels. In addition, four engine operating conditions were evaluated, and the results showed that, during cold start, higher concentrations were observed for high molecular weight PAHs than during idling cycle and that the acceleration cycles provided higher concentrations than the steady-state conditions. Correlations between particulate PAHs and gas phase products were also observed. The emission of PAH compounds from the incomplete combustion of diesel fuel depended greatly on the source of the fuel and the driving patterns.

Effect of the compression ratio on the performance and combustion of a natural-gas direct-injection engine

An experimental study on the combustion and emissions of a natural-gas direct-injection spark ignition engine under different compression ratios was carried out. The results show that the compression ratio has a large influence on the engine performance, combustion, and emissions. The penetration distance of the natural-gas jet is decreased and relatively strong mixture stratification is formed as the compression ratio is increased, giving a fast burning rate and a high thermal efficiency, especially at low and medium engine loads. However, the brake thermal efficiency is increased with a compression ratio up to a limit of 12 at high engine loads. The maximum cylinder gas pressure is increased with increase in the compression ratio. The flame development duration is decreased with increase in the compression ratio and this behaviour becomes more obvious with increase in the compression ratio at low loads or for lean mixture combustion. This indicates that the compression ratio has a significant influence on the combustion duration at lean combustion. The exhaust hydrocarbon (HC) and carbon monoxide emissions decreased with increase in the compression ratio, while the exhaust nitrogen oxide emission is increased with increase in the compression ratio. The exhaust HC emission tends to increase at high compression ratios. Experiments showed that a compression ratio of 12 is a reasonable value for a compressed-natural-gas direct-injection engine to obtain a better thermal efficiency without a large penalty of emissions.

Evaluating Inspection and Maintenance Programs: A Policy-Making Framework

This article presents a new analysis approach to design and evaluate motor vehicle inspection and maintenance (I/M) programs. The new approach, called I/M-Design, uses real-world data to provide two resources not previously available: (1) a transparent framework to quantitatively illustrate the range of emission reductions available from I/M, and (2) a sensitivity analysis tool to evaluate how key variables affect I/M performance. In addition, the approach satisfies a policy-making information need—how to convey, in a logical and straightforward manner, the expected benefits from I/M without relying on modeling tools inaccessible to those outside the air quality field. The material presented in this article illustrates the new approach by estimating hydrocarbon (HC) emission reduction benefits available from enhanced I/M in southern California’s South Coast Air Basin. I/M-Design estimates that enhanced I/M results in a 14–28% reduction in light-duty motor vehicle HC exhaust emissions; this estimate compares well to other California I/M program evaluations. Even more importantly, I/M-Design sensitivity analyses illustrate how I/M programs that implement stringent failure thresholds, motivate pre-test repair work, and improve repair effectiveness can provide emission reductions that substantially exceed the performance of existing programs.

Effect of synchronized secondary air injection on exhaust hydrocarbon emission in a spark ignition engine

A synchronized secondary air injection (SAI) method has been proposed to reduce hydro- carbon (HC) emission by injecting secondary air intermittently into the exhaust port. The method has been tested in a single-cylinder spark ignition engine operating at cold-steady/cold-start conditions. HC concentration and exhaust gas temperature were monitored with a fast-response flame ionization detector and with thermocouples respectively. Effects of exhaust air-fuel ratio (A/F), engine A/F, spark timing and air injection timing have been investigated and the results are compared with a continuous SAI method and the baseline condition. Results show that HC reduction rate and exhaust gas temperature are sensitive to the timing of synchronized SAI. Two optimum SAI timings are observed which are at 100° crank angle (CA) after top dead centre (ATDC) and 230° CA ATDC depending on spark timing. At the cold-steady condition, the synchronized SAI is found to be more effective in HC reduction and also has much higher exhaust gas temperature than either the continuous SAI or the baseline condition. At the cold-start condition when a catalyst is not used, the accumulated HC emission during the first 120 s decreases by about 55 per cent with the synchronized SAI compared with that of the baseline condition, while the result with the continuous SAI is comparable with the baseline condition.

Technical Note: Combustion characteristics and hydrocarbon emissions of a spark ignition engine fuelled with gasoline-oxygenate blends

Combustion characteristics and hydrocarbon emissions in a spark ignition engine operating on oxygenated fuel blends are studied, and the mass fraction burned and engine hydrocarbon emissions are analysed. Calculation results, based on the recorded pressure diagram, show that the flame development and rapid burn angles of gasoline-ether blends generally decrease and the maximum cylinder pressure increases as compared with those of gasoline. The flame development angle and rapid burn angle decrease when the fraction of alcohol fuels in gasoline is small, whereas they increase when the fraction of alcohol fuels is large. The experimental results show that engine exhaust hydrocarbon emissions can be reduced by blending oxygenated fuels in gasoline rather than operating on neat gasoline. Operating on gasoline-ether blends rather than on gasoline-alcohol fuel blends and neat gasoline greatly reduces hydrocarbon emissions.

The Effect of Using 30% Iso-Butanol-Gasoline Blend on Hydrocarbon Emissions from a Spark-Ignition Engine

The level of hydrocarbon (HC) emissions, from a spark-ignition engine using a 30 % iso-butanol-gasoline blend was experimentally investigated. Experiments were conducted on a Hydra single-cylinder, spark-ignition, fuel-injection engine. HC emissions were measured as a function of fuel air equivalence ratio, ignition timing and engine speed. The effect of varying the temperature of cooling water on HC emissions was also investigated under three fuel air equivalence ratios (lean, stoichiometric, and rich). Results show that retarding ignition timing with respect to maximum break torque (MBT) has a great effect on HC emissions reduction, where for lean mixture, Phi 0.85, retarding ignition timing by 6 degrees from MBT reduces the exhaust HC emissions by 12 %. The level of HC emissions is also reduced by 30 % at MBT, as the cooling water temperature increase from 55 to 90 C. It is noticed that as the engine speed increases, the level of HC emissions decrease.

Fast-spec: An infrared spectroscopic diagnostic to measure time-resolved exhaust hydrocarbon emissions from S.I. engines

An infrared spectroscopy-based system has been developed that attaches to the exhaust port of an S.I. engine and is used to make time-resolved measurements of unburned hydrocarbon emissions. Radiation from a miniaturized infrared source was coupled into modified white cell optics through sapphire windows sealing a transmission cell integrated into the exhaust manifold. The radiation absorption from the 3.4-μm vibrational stretch band common to all hydrocarbons is used to quantify the hydrocarbon concentration fluctuations throughout the exhaust process. The diagnostic system was tested in a CFR engine operated at 600 rpm using propane fuel. It measured the hydrocarbon concentration spatially averaged across the exhaust manifold. The temporal resolution of the measurements was 830 μs (3.0 crank-angle degrees). Four fuel/air equivalence ratios were examined. The peak in hydrocarbon exhaust concentration that occurs shortly after exhaust valve opening was found to have a much large magnitude and shorter duration than has been seen previously with fast flame ionization detector (fast-FID) measurements. Reasonably good agreement was found between the mass integrated HC concentrations and those measured using an FID; however, more work is needed to better quantify the accuracy of the technique. The sensitivity and signal-to-noise ratio of the system were very high with fluctuations of approximately 15 ppm c3 resolvable.