Increasing Engine Load Research Articles

Experimental investigation of vibrations and noise characterization for spark ignition engine

An experimental study was carried out for measuring vibrations, noise and combustion characteristics associated correlations using a four-cylinder spark ignition engine. This study aims to investigate the effects of vibrations and noise on spark-polishing machines that are triggered by pure gasoline. This test runs at 15% engine load and 20% with engine speed 1000-2200 rpm at intervals of 300 rpm. The measurement of engine vibration in pistonic uses PCB Piezotronics ICP® Accelerometer (352C22). Overall tests that have been carried out for 20% loads at 1900 and 2200 maximum vibrations, the velocity is 0.214 and 0.234, compared to 0.617 and 0.562 for 15% loads. From the results of engine vibration analysis, it can be reported that increasing engine speed and the load is given engine vibration can significantly decrease. Generally, noise increases for all samples tested; however, reduced noise is recorded when speed and engine load increase. This observation is also consistent with other observations related to vibration and combustion noise, heat release rates, and ignition delays.

Performance, emission, energy, and exergy analysis of CI engine using Kaner seed pyrolysis oil blended diesel

AbstractThis work reports the engine performance, emission parameters, and energy‐exergy characteristics of a twin cylinder four‐stroke CI engine fueled with Diesel blended Kaner seed pyrolysis oil (KSPO). KSPO is obtained by the thermal pyrolysis of Kaner (Thevetia peruviana) seed at 600°C in a batch reactor and mixed with diesel in the ratio of 5, 10, 15, and 20%, to use in the engine. Brake thermal efficiency is marginally higher and brake specific fuel consumption is comparatively lower for KSPO‐diesel blend as compared to pure diesel fuel operation. Low carbon monoxide emission and high hydrocarbon, oxides of nitrogen and smoke emission is observed with KSPO—diesel blend. In addition, energy and exergy values of KSPO‐diesel with different blends at different loads are evaluated. Fuel exergy rate of the blended fuel is higher than pure diesel fuel where as exergetic efficiency of the blended fuel found is lower than pure diesel fuel. Moreover, the exergetic efficiency is increased with increasing engine load.

Influences of biodiesel fuels produced from highly degraded waste animal fats on the injection and emission characteristics of a CRDI diesel engine

In the current study, biodiesel fuels produced from waste chicken fat and waste fleshing oil with high free fatty acid were tested in a four stoke, four-cylinder, water-cooled, turbocharged-intercooled, common rail direct injection (CRDI) diesel engine. Their effects on the injection and exhaust emission characteristics of the test engine were determined and compared with those of petroleum-based diesel fuel (DF) as the reference fuel. Engine tests were performed at different engine loads and constant engine speed of 2000 rpm. Injection characteristics showed differences with respect to engine load and fuel type. However, the effects of biodiesel fuels on the injection profiles were more dominant for main injection characteristics such as the start of main injection, end of the main injection, injection amount and injection rate and these effects became more pronounced with increasing engine load. Compared to DF, animal fat based biodiesels had better total hydrocarbon (THC) and carbon monoxide (CO) emissions, but their carbon dioxide (CO2) and especially nitrogen oxides (NOx) emissions were higher. In addition, waste fleshing oil-based biodiesel fuel emitted lower emissions than waste chicken fat-based biodiesel.

VOCs emission characteristics in motorcycle exhaust with different emission control devices

Speciated VOCs and regulated air pollutant emissions (CO, HC and NO) of carburetor (CB) and fuel injection (FI) motorcycles were evaluated based on engine dynamometer tests. Effects of engine loads and emission control systems were evaluated. CB was equipped with oxidation catalytic converter (OCC) and secondary air system (SAS) while FI had three-way catalytic converter (TWC) and oxygen sensor (OS). Under normal operation of the control devices, the emissions of regulated pollutants and the sum of detected VOCs (ΣVOC) were higher in CB than in FI motorcycle. Alkanes and aromatics had the highest concentrations contributing approximately 90% to the ΣVOC while xylene and toluene were most abundant among the BTEX, in both motorcycles. Emissions of all regulated pollutants and ΣVOC increased with increase in engine load. The emission control devices showed differential efficiencies on different VOC groups. Average emission reduction efficiencies of OCC with SAS (CB motorcycle) were 45.4% (ΣVOC) and 48.6% (BTEX) and TWC with OS (FI motorcycle) were 74.4% (ΣVOC) and 88.0% (BTEX). Without SAS, the efficiency of OCC dropped to 30.2% (ΣVOC) and 34.9% (BTEX) in CB motorcycle. Similarly, the efficiency of TWC reduced to 69.0% (ΣVOC) and 85.2% (BTEX) when the OS was blocked in FI motorcycle. The ozone formation potentials of VOCs ranged from 500 mg-O3/m3 (FI motorcycle with TWC and OS, TO 20%) to 2218 mg-O3/m3 (CB motorcycle without control system, TO 30%).

Analysis and Optimization of Coupled Thermal Management Systems Used in Vehicles

About 2/3 of the combustion energy of internal combustion engine (ICE) is lost through the exhaust and cooling systems during its operation. Besides, automobile accessories like the air conditioning system and the radiator fan will bring additional power consumption. To improve the ICE efficiency, this paper designs some coupled thermal management systems with different structures which include the air conditioning subsystem, the waste heat recovery subsystem, engine and coolant subsystem. CO2 is chosen as the working fluid for both the air conditioning subsystem and the waste heat recovery subsystem. After conducting experimental studies and a performance analysis for the subsystems, the coupled thermal management system is evaluated at different environmental temperatures and engine working conditions to choose the best structure. The optimal pump speed increases with the increase of environmental temperature and the decrease of engine load. The optimal coolant utilization rate decreases with the increase of engine load and environmental temperature, and the value is between 38% and 52%. While considering the effect of environmental temperature and road conditions of real driving and the energy consumption of all accessories of the thermal management system, the optimal thermal management system provides a net power of 4.2 kW, improving the ICE fuel economy by 1.2%.

Combustion and emissions behaviour assessment of a partially premixed charge compression ignition (PCCI) engine with diesel and fumigated ethanol

The study is aimed to evaluate the combustion and emission characteristics of a partially premixed charge compression ignition (PCCI) engine with diesel and ethanol fuels. Ethanol was fumigated with preheated intake air at 40°C and inducted into the intake manifold of the test engine. Experimental tests were carried out with varying proportions of premixed ethanol at different engine loading conditions of 1, 2, 3, and 4 bar brake mean effective pressures (BMEP). It was explored that at lower BMEP, oxides of nitrogen (NOx) were decreased with an increment of premixed ethanol, however, at higher BMEP, the emissions increased. At all loads, smoke opacity decreased exceedingly with increasing premixed ethanol share. At part loads, hydrocarbon (HC) and carbon monoxide (CO) emissions were increased because of the high latent heat of vaporization of ethanol. Net heat release rate and in-cylinder pressure rise were found to be increased with an increasing engine load. Overall, it could be determined that the performance of the PCCI engine with ethanol fumigation is comparable with the conventional diesel fuel operation.

Soot Particulate Emission from A Single Cylinder Direct Injection Diesel Engine

Soot formation, which occurs mainly because of imperfect combustion, affects engine. Engine components tend to wear hence reduce engine performance. In the present study, soot particle collection and analysis was carried out in a relatively simple and low-cost method. The first objective is to identify the level of opacity percentage of the soot at different engine speeds and loads. The second objective is to obtain the mass of soot using Alkidas theory. The last objective is to measure and obtain the size of soot particles. The opacity was measured using a Bosch Gas Analyser and soot particles from the engine were simultaneously collected using TEM grids inserted into the exhaust manifold. Alkidas’s correlation was used to convert soot opacity to soot mass. The TEM instrument was used to produce images of the collected soot particles and at once, enable the measurement of the size of the particles. The results from this study shows that, soot opacity and mass emitted increase as the engine speed and load increase. It was observed that soot particle size become smaller at higher engine speeds and loads. From TEM image analyses, the range of size of soot obtained is 26 nm to 84 nm.Â

N-Butanol reactivity modulation with early fuel injections for low NOx compression ignition combustion

This paper investigates pilot injection strategies to improve the combustion controllability of a premixed n-butanol cylinder charge while achieving ultra-low NOx emissions comparable to homogenous charge compression ignition (HCCI). Detailed insights are given for the ignition processes controlled by fuel and reactivity stratification. The n-butanol port injection is applied to form a homogeneous cylinder charge, an early pilot direct injection of either n-butanol or diesel is generated to control the ignition and combustion. In dual-fuel reactivity stratification combustion (RSC) strategy with an early diesel pilot injection, the prompt control of combustion phasing relies on fuel energy ratio adjustment. Under heavy EGR, the RSC can lower the NOx emissions to the level of 10 ppm and retain the combustion completeness, however, at the cost of increased pressure rise rate. EGR plays a key role in suppressing the pressure rise rate for load extension of RSC combustion. In order to maintain a moderate pressure rise rate when the engine load increases, the combustion phasing must be retarded through heavy EGR together with increased PFI n-butanol energy ratio, which leads to an efficiency penalty. In the single-fuel strategy, the early pilot injection of n-butanol results in fuel stratification in the cylinder which is responsible for the combustion initiation. The single-fuel strategy retains effective ignition controllability although the start of combustion manifests less sensitivity to the n-butanol pilot injection timing. In the tested low to medium engine load range, the single-fuel strategy can achieve NOx emissions level same to HCCI combustion, while the NOx emissions of dual-fuel RSC strategy are slightly higher because of the reactivity gradient and more advanced combustion phasing.

Experimental investigation on engine characteristics fueled with waste HDPE oil and study on NO x emission variation using thermal imager.

For heavy duty applications like power generation and transportation, the best option is the compression ignition engines, but the major concerns are the rising prices and environmental issues due to the rapid depleting sources of conventional fossil fuels. The present investigation is to study the performance and emission characteristics of a single cylinder four-stroke, air-cooled direct injection diesel engine runs with an alternate fuel as waste high density polyethylene plastic oil (HDPE) obtained by catalytic pyrolysis. At constant speed, test fuels have been experimented successfully to determine the engine performance such as brake thermal efficiency, brake specific energy consumption, and exhaust gas emissions such as carbon monoxide, carbon dioxide, oxides of nitrogen, and unburned hydrocarbons. The result shows that the brake thermal efficiency is lower at all load conditions when compared to diesel fuel whereas the brake specific energy consumption decreases with increase in engine load and increases with increase in waste plastic oil blend ratio. CO emission increases and NOx emission level decreases with enhancement in engine load whereas the NOx emission and CO emission augments with increase in waste plastic oil blend percentage. But in case of NOx emission increase in concentration of waste plastic oil with diesel leads to raise in emission level. By using thermal imager, the link between in-cylinder temperature and NOx emission has been fixed. With the help of this course of action, it has been observed that in-cylinder temperature plays the major role in NOx concentration.

A comparative analysis of engine characteristics from various biodiesels: Numerical study

The present study involves the numerical simulation of the diesel engine by means of Diesel-RK, tool for determining engine characteristics for diesel, vegetable oil, animal fats, waste oils and alcohols respectively. Simulation results are verified with experimental results and exhibits a good agreement for diesel fuel. The tool also delivers a reasonably accurate prediction of in-cylinder pressure, in-cylinder heat rate, and fuel consumption in combustion and NOX emission level. The study shows maximum power and cylinder peak pressure obtained were of 17.65% for coconut oil and 1.5%, 0.77%, 2.3%, and 17.8% for rapeseed oil, fish oil and veal oil, waste frying oil and propanol biodiesel respectively. On the other hand, the ignition delay was found to be lower than diesel for biodiesel and even decreased with an increase in engine load. The combustion duration obtained to be higher for biodiesels compared to diesel fuel. Simulation results are conducted under different engine loads, constant speed (1500 rpm) and advanced injection timing 23.0° b TDC with higher injection pressure.

Production of waste tyre oil and experimental investigation on combustion, engine performance and exhaust emissions

In this study, waste tyre was pyrolyzed at different conditions such as temperature, heating rate and inert purging gas (N2) flow rate. Pyrolysis parameters were optimized. Optimum parameters were determined. The main objective of this study was to investigate combustion, performance and emissions of diesel and waste tyre oil fuel blend. Experimental investigation was performed in a single cylinder, direct injection, air cooled diesel engine at maximum engine torque speed of 2200 rpm and four different engine load including 3.75, 7.5, 11.25 and 15 Nm. The effects of waste tyre oil on combustion characteristics such as cylinder pressure, heat release rate, ignition delay (ID), combustion duration, engine performance were investigated. In-cylinder pressure and heat release rate increased with waste tyre oil fuel blend (W10) with the increase of engine load. In addition, ID was shortened with the increase of engine load for test fuels but it increased with the addition of waste tyre oil. Lower imep values were obtained because of the lower calorific value of waste tyre oil fuels. Maximum thermal efficiencies were determined as 28.27% and %25.12 with diesel and W10 respectively at 11.25 Nm engine load. When test results were examined, it was seen that waste tyre oil highly affected combustion characteristics, performance and emissions.

Effect of sulphur and vanadium spiked fuels on particle characteristics and engine performance of auxiliary diesel engines

Particle emission characteristics and engine performance were investigated from an auxiliary, heavy duty, six-cylinder, turbocharged and after-cooled diesel engine with a common rail injection system using spiked fuels with different combinations of sulphur (S) and vanadium (V) spiking. The effect of fuel S content on both particle number (PN) and mass (PM) was clearly observed in this study. Higher PN and PM were observed for fuels with higher S contents at all engine load conditions. This study also found a correlation between fuel S content and nucleation mode particle number concentration which have more harmful impact on human health than larger particles. The highest PN and PM were observed at partial load conditions. In addition, S in fuel resulted in higher viscosity of spiked fuels, which led to lower engine blow-by. Fuel V content was observed in this study, evidencing that it had no clear effect on engine performance and emissions. Increased engine load also resulted in higher engine blow-by. The lower peak of in-cylinder pressure observed at both pre-mixed and diffusion combustion phases with the spiked fuels may be associated with the lower energy content in the fuel blends compared to diesel fuel.

Technical note: Use of an atmospheric simulation chamber to investigate the effect of different engine conditions on unregulated VOC-IVOC diesel exhaust emissions

Abstract. Diesel exhaust emissions were introduced into an atmospheric simulation chamber and measured using thermal desorption (TD) comprehensive two-dimensional gas chromatography coupled to a flame ionisation detector (GC × GC-FID). An extensive set of measurements were performed to investigate the effect of different engine conditions (i.e. load, speed, “driving scenarios”) and emission control devices (with or without diesel oxidative catalyst, DOC) on the composition and abundance of unregulated exhaust gas emissions from a light-duty diesel engine, fuelled with ultra-low sulfur diesel (ULSD). A range of exhaust dilution ratios were investigated (range = 1 : 60 to 1 : 1158), simulating the chemical and physical transformations of the exhaust gas from near to downwind of an emission source. In total, 16 individual and 8 groups of compounds (aliphatics and single-ring aromatics) were measured in the exhaust gas ranging from volatile to intermediate volatility (VOC-IVOC), providing both detailed chemical speciation and groupings of compounds based on their structure and functionality. Measured VOC-IVOC emission rates displayed excellent reproducibility from replicate experiments using similar exhaust dilution ratios. However, at the extremes of the investigated exhaust dilution ratios (comparison of 1 : 60 and 1 : 1158), measured VOC-IVOC emission rates displayed some disagreement owing to poor reproducibility and highlighted the importance of replicate sample measurements. The investigated DOC was found to remove 43±10 % (arithmetic mean ± experimental uncertainty) of the total speciated VOC-IVOC (∑SpVOC-IVOC) emissions. The compound class-dependant removal efficiencies for the investigated DOC were 39±12 % and 83±3 % for the aliphatics and single-ring aromatics, respectively. The DOC aliphatic removal efficiency generally decreased with increasing carbon chain length. The ∑SpVOC-IVOC emission rates varied significantly with different engine conditions, ranging from 70 to 9268 mg kg−1 (milligrams of mass emitted per kilogram of fuel burnt). ∑SpVOC-IVOC emission rates generally decreased with increasing engine load and temperature, and to a lesser degree, engine speed. The exhaust gas composition changed considerably as a result of two influencing factors: engine combustion and DOC hydrocarbon (HC) removal efficiency. Increased engine combustion efficiency resulted in a greater percentage contribution of the C7 to C12 n-alkanes to the ∑SpVOC-IVOC emission rate. Conversely, increased DOC HC removal efficiency resulted in a greater percentage contribution of the C7 to C12 branched aliphatics to the ∑SpVOC-IVOC emission rate. At low engine temperatures (<150 ∘C, below the working temperature of the DOC), the contribution of n-alkanes in the exhaust gas increased with increasing combustion efficiency and may be important in urban environments, as n-alkanes are more efficient at producing secondary organic aerosol (SOA) than their branched counterparts. At very high engine temperatures (maximum applied engine speed and load, engine temperature = 700 ∘C), the n-alkane contribution increased by a factor of 1.6 times greater than that observed in the cold-start experiment (most similar to unburnt fuel) and may suggest liquid-fuel-based estimates of SOA yields may be inconsistent with exhaust SOA yields, particularly at high engine speeds and loads (i.e. high engine temperatures). Emission rates were found to be 65 times greater from a cold-start experiment than at maximum applied engine speed and load. To our knowledge, this is the first study which uses an atmospheric simulation chamber to separate the effects of the DOC and combustion efficiency on the exhaust gas composition.

Reduction of smoke, PM2.5, and NOX of a diesel engine integrated with methanol steam reformer recovering waste heat and cooled EGR

Over recent years, combustion engines are effectively equipped with a waste heat recovery (WHR) system to produce power or hydrogen at less additional energy input. The WHR system in this study is partially utilized to heat reforming gas in a methanol steam reformer integrated with a diesel engine and a cooled EGR (Exhaust Gas Recirculation) device to reduce smoke, PM2.5, and NOX emissions. The test items are such as the gas pressure of cylinder, crank angle, diesel consumption rate, hydrogen-rich gas flow rate, air flow rate, and smoke, PM2.5, NOX, HC and CO emissions and the molar analysis of hydrogen-rich gas. The authors analyze how the hydrogen-rich gas addition with EGR influences smoke, PM2.5, NOX, HC and CO emissions and combustion performance. The results show that the maximum increase rate of heat recovery efficiency with respect to reaction temperature is 17.5%. The heat recovery efficiency of the reformer rises with increasing engine load up to 24.8%. Adding hydrogen-rich gas with appropriate proportion of EGR helps reduce smoke, PM2.5 and NOX from a diesel engine. In addition, the engine body is rarely changed, and it is effectively to save energy and decrease pollutants.

Emission factors of particulate and gaseous compounds from a large cargo vessel operated under real-world conditions

On-board emissions measurements were performed on a Handysize-class bulk carrier operating under real-world conditions. Emission factors (EFs) were determined for criteria pollutants such as NOx, CO, total hydrocarbons (THC), and PM; PM composition, including organic and elemental carbon (OC and EC), inorganic species, and a variety of organic compounds and VOC species (including alkanes, alkenes, single-ring aromatics, and oxygenated VOCs) were also analyzed. To investigate the impacts of engine type, fuel, and operating conditions on emissions, measurements were conducted on one main and one auxiliary engines using low- and high-sulfur fuels (LSF and HSF) under actual operating conditions, including at-berth, maneuvering, and cruising at different engine loads. OC was the most abundant PM component (contributing 45–65%), followed by sulfate (2–15%) and EC (1–20%). Compounds with 3 or 4 aromatic rings, including phenanthrene, fluoranthene, pyrene, and benzo[b+k]fluoranthene, dominated the particulate polycyclic aromatic hydrocarbons (PAHs) emitted from the ship, accounting for 69–89% of the total PAHs. Single-ring aromatics constituted 50–78% of the emitted VOCs and were dominated by toluene. In this study, switching from HSF (1.12% S) to LSF (0.38% S) reduced emitted PM by 12%, OC by 20%, sulfate by 71%, and particulate PAHs by 94%, but caused an increase in single-ring aromatics. The power-based EFs generally decreased with increasing engine loads. However, decreasing the ship engine load also reduced the vessel speed and, thus, decreased emissions over a given voyage distance. Herein, a Vessel Speed Reduction (VSR) from 11 to 8–9 knots decreased NOx and PM emissions by approximately 33% and 36%, respectively, and OC, EC, sulfate, and particulate PAHs in PM emissions by 34%, 83%, 29%, and 11%. These data can be used to minimize uncertainty in the emission factors used in ship emissions calculations.

Comparison of Diesel Engine Efficiency and Combustion Characteristics Between Different Bore Engines

This study investigates the effects of engine bore size on diesel engine performance and combustion characteristics, including in-cylinder pressure, ignition delay, burn duration, and fuel conversion efficiency, using experiments between two diesel engines of different bore sizes. This study is part of a larger effort to discover how fuel property effects on combustion, engine efficiency, and emissions may change for differently sized engines. For this specific study, which is centered only on diagnosing the role of engine bore size on engine efficiency for a typical fuel, the engine and combustion characteristics are investigated at various injection timings between two differently sized engines. The two engines are nearly identical, except bore size, stroke length, and consequently displacement. Although most of this diagnosis is done with experimental results, a one-dimensional model is also used to calculate turbulence intensities with respect to geometric factors; these results help to explain observed differences in heat transfer characteristics of the two engines. The results are compared at the same brake mean effective pressure (BMEP) and show that engine bore size has a significant impact on the indicated efficiency. It is found that the larger bore engine has a higher indicated efficiency than the smaller displaced engine. Although the larger engine has higher turbulence intensities, longer burn durations, and higher exhaust temperature, the lower surface area to volume ratio and lower reaction temperature leads to lower heat losses to the cylinder walls. The difference in the heat loss to the cylinder walls between the two engines is found to increase with increasing engine load. In addition, due to the smaller volume-normalized friction loss, the larger sized engine also has higher mechanical efficiency. In the net, since the brake efficiency is a function of indicated efficiency and mechanical efficiency, the larger sized engine has higher brake efficiency with the difference in brake efficiency between the two engines increasing with increasing engine load. In the interest of efficiency, larger bore designs for a given displacement (i.e., shorter strokes or few number of cylinders) could be a means for future efficiency gains.

Emission and Performance Characteristics of Waste Cooking Oil Biodiesel Blends in a Single Direct Injection Diesel Engine

The use of Waste Cooking Oil (WCO) as feedstock, and microwave heating technology are favored to reduce the cost of biodiesel. In order to identify the effect of using biodiesel from WCO Methyl Ester (WCOME) blends on diesel engine emissions and performance, WCOME blends were tested in a single-cylinder Direct Injection (DI) diesel engine at a constant speed of 2500 rpm and with five loads. For comparison, commercial diesel fuel, Petron Diesel Max (PDM), and biodiesel mixture from palm oil (POME) were also used. The performance and emission test results of the five test fuels: PDM, BP10, BP20, BW10, and BW20 were then compared with simulation results created by using GT-Power software. The experimental results indicated that using POME and WCOME blends led to increments in Brake Specific Fuel Consumption (BSFC) of up to 5.9% and reduction in Brake Thermal Efficiency (BTE) of up to 29.3% compare to PDM. These biodiesel blends also increased nitrogen oxide emissions and decreased carbon dioxide, carbon monoxide and hydrocarbon emissions for all engine loads at a constant speed of 2500 rpm. The experimental testing of the cylinder peak pressure demonstrates significant increase with the increase of engine load for the four test fuels. All the simulation graphs show similar trends.

Analysis of Particulate Matter (PM) Emissions in Diesel Engines Using Palm Oil Biodiesel Blended with Diesel Fuel

This study has focused on the PM emissions of diesel engines. Diesel engines are attractive power units that are used widely in many fields and have become one of the larger contributors of total petroleum consumption. However, diesel engines are among the main contributors of emissions into the air, especially particulate matter (PM) and nitrogen oxides (NOx). PM is one of the major pollutants emitted by diesel engines and has adverse effects on human health. Accordingly, many studies have been conducted to find alternative fuels that are clean and efficient. Biodiesel, which produces less PM than diesel fuel, is preferred as an alternative source for diesel engines. Therefore, using palm oil methyl ester (POME) for diesel engines would be a more economical and sustainable solution. This study has focused on the PM emissions of diesel engines fuelled by a diesel and POME blend (B5, B10, B20, and B100). A comparison between diesel and the POME blend has been made which involves PM mass concentration and its components (soluble organic fraction (SOF) and dry soot (DS)). Combustion characteristics, such as in-cylinder pressure and rate of heat release of the engine, as well as gaseous emissions, have also been observed at different operating engine loads (0.05 MPa 20%, 0.4 MPa 40%, and 0.7 MPa 60%). The results show that PM emissions of B100 are lower than those of diesel fuel owing to the oxygen content of POME. With regard to the SOF concentration, B100 has a higher SOF value than diesel fuel at all engine loads. Meanwhile, the DS for B100 is lower than that of diesel fuel. Moreover, as the engine load increased, PM and SOF concentrations increased, while DS concentration decreased. The observation of in-cylinder pressure showed that the increment of pressure with the increasing POME blend, as well as the increasing engine load due to the high cetane number for B100, led to a short ignition delay. The engine brake thermal efficiency between the POME blend and mineral diesel was comparable. Furthermore, B100 fuels showed lower engine power at higher brake-specific fuel consumption compared to other tested fuels. In terms of gaseous emissions, increasing POME blends led to an increase in NOx emissions. Meanwhile, as the engine load increased, NOx also continued to increase. The effect of the POME blend on the PM-NOx trade-off observation showed that B100 simultaneously increased the NOx and decreased the PM emissions. It can be concluded that POME creates a lower PM concentration while giving some negative feedback to NOx.

Experimental Investigation of Impacts of Injection Timing and Pressure on Combustion and Particulate Matter Emission in a Spray-Guided GDI Engine

A detailed investigation of the impact of injection timing and injection pressure on combustion and particles of a spray-guided GDI engine was conducted, under different engine operating conditions. The results indicated that, more proportion of large particles were emitted when increasing engine load, and the peak of accumulation mode particles moved toward smaller size when rising engine speed. With retarding the injection timing, the in-cylinder pressure and heat release rate rose first and then dropped at 2000 rpm, but they continuously rose at lower or higher speed conditions. The total particles concentration curves at all cases showed a trend of U-shape, and the corresponding timing of the lowest particles concentration advanced as the engine speed or load increased. The minimum value of emitted particles first rose and then fell when increasing load at 2000 rpm conditions, and it continuously rose when increasing speed at 40 Nm conditions. Generally, injection pressure did no sensitively affect combustion process except that it showed a relatively strong impact at low load conditions. However, particulate matter could be effectively inhibited by elevating fuel pressure from 5.5 to 11.5 MPa at all cases. In detail, the total particles concentration continuously fell at low speed and mid speed-high load cases, but it showed a rose trend when further increase fuel injection pressure at mid speed-low load and high-speed conditions.

Investigation of Particle Number Emission Characteristics in a Heavy-Duty Compression Ignition Engine Fueled with Hydrotreated Vegetable Oil (HVO)

Diesel engines are one of the most important power generating units these days. Increasing greenhouse gas emissions level and the need for energy security has prompted increasing research into alternative fuels for diesel engines. Biodiesel is the most popular amongst the alternatives for diesel fuel as it is biodegradable, renewable and can be produced domestically from vegetable oils. In recent years, hydro-treated vegetable oil (HVO) has also gained popularity due to some of its advantages over biodiesel such as higher cetane number, lower deposit formation, storage stability etc. HVO is a renewable, paraffinic biobased alternative fuel for diesel engines similar to biodiesel. Unlike biodiesel, the production process for HVO involves hydrogen as catalyst instead of methanol which removes oxygen content from vegetable oil. A modified 6-cylinder heavy-duty diesel engine (modified for operation with single cylinder) was used for studying particle number emission characteristics for HVO fuel. The investigation was performed for varying fuel injection pressure at various engine operating loads (6, 8, 10, 12 and 14 bar IMEP). Five rail pressures were chosen from 800 to 2000 bar at a step of 300 bar. The results show that increase in rail pressure tends to increase nucleation mode particle number concentration (quantify the increase) while increase in engine load results in higher total particle number concentration. No significant differences were observed in soot and oxides of nitrogen (NOx) emission for HVO compared to mineral diesel. The fraction of emitted particles in the nucleation mode was observed to increase with increasing fuel injection pressure. (Less)