Common Rail Direct Injection Diesel Research Articles

Effect Of n-amyl alcohol/biodiesel blended nano additives on the performance, combustion and emission characteristics of CRDi diesel engine.

This paper deals with the study on the influence of the effects of iron oxide nanoparticle additives when added to ternary fuel (diesel + mahua methyl ester + pentanol) on the emission, combustion, and performance characteristics of a four stroke, single cylinder, common rail direct injection diesel engine working at a constant speed and varying operating scenarios. Doping is done in various proportions to the nanoparticle additives with the help of a homogenizer and ultrasonicator where the cationic surfactant used is CTAB (cetyl trimethyl ammonium bromide). Iron oxide nanoparticles were used as additives in fuel in the dosages of 40 ppm, 80 ppm, and 120 ppm respectively and TF (ternary fuel) is obtained by mixing 10% pentanol, 20% mahua, and 70% diesel together is used for the experimental study. The experimental study revealed that while using the nanoparticle additives blended ternary fuel (i.e., TF80), the number of harmful pollutants like smoke (5.38%), HC (6.39%), carbon monoxide (10.24%), and NOx has reduced to a considerable extent and there was a commendable improvement in the BTE by 8.8%. So, we can summarize that when ternary fuel and nano additives are blended together the combustion and performance of the engine was improved considerably and pollutant emissions were decreased.

Influence of compressed natural gas dual fuel operation with biodiesel and low cetane alcohol as pilot fuels on performance and emission characteristics of a CRDI engine: a novel trade-off investigations

ABSTRACT This paper deals with the study of compressed natural gas (CNG) and Schleicher oleosa oil methyl ester (SOME) with diesel as pilot fuel and triacetin as an additive on the emission, combustion, and performance characteristics of a four stroke, single cylinder, common rail direct injection diesel engine working at a constant speed and varying operating scenarios. Majority of the input energy is provided by CNG when triacetin is used in pilot operation rather than diesel. The experimental study revealed that, as compared to traditional CNG + diesel (dual fuel), CNG + triacetin combination the number of harmful pollutants like smoke (5.38%), HC (6.39%), carbon monoxide (10.24%) and NOx, has reduced to a considerable extent and there was a commendable improvement in the BTE by 8.8%. A trade-off study conducted concludes that the low emission high-performance paradox can be resolved through the dual-fuel operation with CNG+ triacetin blend. So, we can summarize that when CNG and triacetin additives are blended together the combustion and performance of the engine was improved considerably and pollutant emissions were decreased.

Experimental study of using biodiesel and low cetane alcohol as the pilot fuel on the performance and emission trade-off study in the diesel/compressed natural gas dual fuel combustion mode

Increasing demand for fast depleting diesel in various transport applications with a rise in vehicular exhaust emissions led many countries to research on alternative economic fuels. This paper deals with the study of compressed natural gas (CNG) and Schleicher oleosa oil methyl ester (SOME) with diesel as pilot fuel and triacetin as an additive on the emission, combustion and performance characteristics of a four stroke, single cylinder, common rail direct injection diesel engine working at a constant speed and varying operating scenarios. Majority of the input energy is provided by CNG when triacetin is used in pilot operation rather than diesel. The experimental study revealed that, as compared to traditional CNG + diesel (dual fuel), CNG + triacetin combination the number of harmful pollutants like smoke (5.38%), hydrocarbon (6.39%), carbon monoxide (10.24%) and oxides of nitrogen, has reduced to a considerable extent and there was a commendable improvement in the brake thermal efficiency by 8.8%. A trade-off study conducted concludes that the low emission high-performance paradox can be resolved through the dual-fuel operation with CNG + triacetin blend. So, we can summarize that when CNG and triacetin additives are blended together the combustion and performance of the engine was improved considerably and pollutant emissions were decreased.

Influence of the effect of nanoparticle additives blended with mahua methyl ester on performance, combustion, and emission characteristics of CRDI diesel engine.

This research work aims to investigate the effect of fuel-borne additives when added to mahua methyl ester (MME) blend operated on common rail direct injection diesel engine. Nanoparticles (Al2O3 and Fe2O3) were chosen with the help of a homogenizer and ultrasonicator as fuel additives at dosing levels of 40, 80, and 120 ppm, respectively, and the biodiesel is prepared by blending 80% diesel and 20% MME. The performance, emission, and combustion characteristics were considered for analysis. The experimental study revealed that while using the Al2O3 nanoparticle additives' blended biodiesel (MME20+AONP120), the number of harmful pollutants like smoke (5.38%), HC (6.39%), carbon monoxide (10.24%), NOx, etc. has reduced to a considerable extent and there was a commendable improvement in the BTE by 8.8% in comparison with MME20. Moreover, MME20+AONP120 blend resulted in high in-cylinder pressure, HRR of about 58.4 bar, and 118 J/0CA, respectively, which are higher than diesel and MME20. So, it can be summarized that when biodiesel and nano additives are blended together, the combustion and performance of the engine were improved considerably and pollutant emissions were decreased.

Experimental study on spray characteristics, combustion stability, and emission performance of a CRDI diesel engine operated with biodiesel–ethanol blends

Biodiesel is a promising alternative fuel for diesel engines, but its high viscosity and low volatility have limitations in decreasing emissions. As a renewable alternative fuel with a high oxygen content, ethanol blended with biodiesel can decrease kinematic viscosity and improve fuel evaporation. In this study, the effects of the ethanol addition ratio on the spray, combustion, and emission performances of a diesel engine fuelled with biodiesel were investigated. The spray characteristics were measured using a high-speed camera and Malvern laser analysis, whereas the combustion and emission performances were tested on a turbocharged common rail direct injection (CRDI) diesel engine. The results show that adding ethanol to biodiesel enlarges the spray cone angle (SCA) and shortens spray tip penetration (STP). In addition, the curves of the size–volume distribution (SVD) of the atomized fuel droplets move toward a smaller diameter, and the Sauter mean diameter (SMD) of the biodiesel–ethanol (BE) blends gradually decreases with increasing ethanol proportion. At low loads, the fuel injection strategy is multi-injection, and the peak cylinder pressures (PCPs) of BE blends are 0.77–1.96% higher than that of diesel at different ethanol blending ratios. However, the peak heat release rates (PHRRs) of BE blends are 9.3–11.5% higher than that of diesel owing to a faster combustion rate, longer main-injection duration, and more hydroxyl radicals generated in the pilot-injection stage. At medium–high loads, the injection strategy changes to single injection, the PCPs of BE blends are roughly equivalent to that of diesel, and the PHRRs of BE blends for different ethanol blending ratios are 9.76–11.91% lower than that of diesel. This is because of the lower diffusion combustion ratio, lower heat value, and change of injection duration corresponding to the variation in fuel properties. In addition, the results of the peak pressure rise rate and the cyclic variation indicate that the higher ethanol addition ratio increases the combustion noise and decreases the combustion stability. In terms of exhaust emissions, compared with biodiesel, with increasing ethanol blending ratio, the soot emissions for different BE blends decrease by 11.28–47.23%, the NOx emissions increase by 2.68–7.04%, and the HC emissions increase by 9.99–21.47%. Considering the engine performance comprehensively, a 20% ethanol blending ratio in biodiesel is recommended.

Effect of fuel injection pressure and EGR techniques on various engine performance and emission characteristics on a CRDI diesel engine when run with linseed oil methyl ester

Nowadays, owing to the reduction in petroleum supplies due to the growing oil demand, the search for alternate fuels has intensified. However, as alternate fuel choice grows, checking whether alternative fuels are suitable for use in engines has become time-consuming and expensive. Therefore, the usage of Linseed oil methyl ester (linseed biodiesel) in the common rail direct injection (CRDI) diesel engine was optimized for a smaller number of trials in this research. Response surface methodology (RSM) was employed for optimization. Input variables were chosen for LOME content in the blend, fuel injection pressure (FIP), exhaust gas recirculation (EGR) rates, and engine load while output parameters were selected for like indicated power (IP), indicated thermal efficiency (η(I)), indicated mean effective pressure (IMEP), hydrocarbon (HC), and NOx (Oxide of Nitrogen).The model layout employed in the analysis is focused on the matrix of the CCRD (central composite rotating design). The optimal input variables configuration is estimated at 5.45% LOME blend, 57.77 MPa FIP, 6.50% EGR, and 6.909 kg engine load leading to better efficiency together with reduced emissions. The optimized output of the engine at this input configurations are as IP 4.878 kW, IMEP 0.5886 MPa, indicated thermal efficiency 48.36%, HC 23.43 ppm vol., and NOx 533.15 ppm vol. Testing and optimum output response results are measured at acceptable input parameters and are considered to be within an acceptable error range. The findings of this analysis have shown that RSM is an appropriate technique for optimizing CRDI diesel engines.

Soot Particle Size Distribution, Regulated and Unregulated Emissions of a Diesel Engine Fueled with Palm Oil Biodiesel Blends

In this study, five fuels including pure diesel (B0), pure palm oil biodiesel (B100), and their blends (B10, B20, and B30) were investigated in relation to soot particle distribution and regulated and unregulated emission characteristics in a common rail direct injection (CRDI) diesel engine. The results indicated that CO, hydrocarbon (HC), and particulate matter (PM) regulated emissions were effectively controlled to a very low level by combining the addition of palm oil biodiesel (POB) to diesel with optimized engine operating conditions. Paper filters and TEM grids were used to capture the diesel particles. All the PM primary particles were less than 100 nm in diameter observed by TEM, and the average diameters of the PM primary particles for the biodiesel blends were distributed between 20 and 26 nm. Unregulated emissions such as trace metals including Pb, Mn, and Ba were found in the PM particles, and the xylene, toluene, and benzene unregulated emissions of B100 were reduced by 55.68%, 21.56%, and 18.32%, respectively, compared to those of B0. Therefore, POB is an excellent alternative fuel for diesel engines and has great application potential to solve the current pollution problems of regulated and unregulated emissions.

Effect of Sr@ZnO nanoparticles and Ricinus communis biodiesel-diesel fuel blends on modified CRDI diesel engine characteristics

The current study aims to evaluate the performance and emission characteristics of a modified common rail direct injection (CRDI) diesel engine fueled by Ricinus communis biodiesel (RCME20), diesel (80%), and their blends with strontium-zinc oxide (Sr@ZnO) nanoparticle additives. The Sr@ZnO nanoparticles were synthesized using aqueous precipitation of zinc acetate dehydrate and strontium nitrate. Several characterization tests were performed to study the morphology and content of synthesized Sr@ZnO nanoparticles. The Sr@ZnO nanoparticles were steadily blended with RCME20-diesel fuel blend in mass fractions of 30, 60 and 90 ppm using a magnetic stirrer and ultrasonication process. For a long term stability of nanoparticles, Cetyl trimethylammonium bromide (CTAB) surfactant was added. The physicochemical properties of the fuel blends were measured using ASTM standards. The CRDI engine was operated at two compression ratios 17.5 and 19.5, 1000 bar injection pressure, 23.5°BTDC injection timing and constant speed. For enhanced swirl and turbulence, and improved spray quality lateral swirl combustion chamber and 6-hole fuel injector were used. The compression ratio of 19.5 and 60 ppm of Sr@ZnO nano-additives showed overall enhancement in engine characteristics compared to RCME20 fuel. The engine characteristics such as BTE, HRR and cylinder pressure increased by 20.83%, 24.35% and 9.55%, and BSFC, ID, CD, smoke, CO, HC and CO2 reduced by 20.07%, 20.64%, 14.5%, 27.90%, 47.63%, 26.81%, and 34.9%, while slight increase in NOx for all nanofuel blends was observed.

Novel strategies to overcome the limitations of a low compression ratio light duty diesel engine

Low compression ratio (LCR) approach in diesel engines can reduce the oxides of nitrogen (NOx) and soot emissions simultaneously owing to lower temperatures and longer fuel-air premixing time. The present work investigates the effects of lowering the geometric compression ratio (CR) from 18:1 to 14:1 in a naturally aspirated (NA) single cylinder common rail direct injection (CRDI) diesel engine. Based on the investigations done across the entire speed and load range, significant benefits were observed in the NOx and soot emissions. However, lowering the compression ratio had adverse effects on brake specific fuel consumption (BSFC), unburned hydrocarbon (HC) and carbon monoxide (CO) emissions, especially at low-load and high-speed operating points. To overcome these limitations, novel strategies including split-cooling system (SCS) and secondary exhaust valve opening (SEVO) are proposed in the present work. While the fuel injection parameters optimization specific to LCR could help to improve the BSFC, HC and CO emissions penalty to a reasonable extent, the SCS concept can provide further benefits by reducing the heat loss to coolant and improving the engine component temperatures. Increasing the residual gas fraction using the optimized SEVO concept could further improve the charge temperature leading to a further reduction in the BSFC, HC and CO emissions. The net benefits of the optimized LCR approach are quantified for the modified Indian drive cycle (MIDC) using a one-dimensional simulation tool. The results obtained show a signification reduction of 22% and 74% in NOx and soot emissions respectively as compared to the base 18 CR engine results. Moreover, the penalty in HC and CO emissions could be contained to a large extent resulting in only a slight penalty of 23% and 20% respectively. Furthermore, the higher BSFC with the LCR approach could be successfully addressed and the final values were found to be better than the stock compression ratio by 1.5%. Overall, the strategies proposed in the present work are found to be beneficial to develop modern diesel engines in compliance with the future emission regulations which demand extreme control on NOx and soot emissions.

Effect of injection time on combustion, performance and emission characteristics of direct injection CI engine fuelled with equi-volume of 1-hexanol/diesel blends

In this experimental research work, the effect of 1-Hexanol on engine parameters is studied and to improve the combustion, performance and emission characteristics of CI engine, fuel injection time is advanced and retarded to know the best possible injection time. The experiment is conducted in a twin-cylinder, common rail direct injection diesel engine, speed (2000 rpm) of the engine is constant throughout the experiment and the engine load is varied as 20%, 40%, 60% and 80%. In this experiment equi-volume of 1-Hexanol/diesel blends is used as a fuel, the experiment is conducted for standard (12°BTDC), advanced (15°BTDC) and retard (9°BTDC) injection time. The obtained results are compared with baseline readings taken at standard injection time. The advanced injection time shows the best results compared to standard and retard injection time. The advanced injection time shows improved combustion parameters, the combustion peak moves near to TDC. An increment of 14.28% in BTE is noted for 1-Hexanol blend. The CO and HC emission decreases with advanced injection time, whereas higher NOx emission is noted. It is concluded that 50% of 1-Hexanol can be used in CI engine with slight modification in injection time; the advanced injection time gives improved efficiency.

Field-Testing of Biodiesel (B100) and Diesel-Fueled Vehicles: Part 2—Lubricating Oil Condition Monitoring

AbstractThis study investigated the use of biodiesel (B100) and baseline diesel in two identical unmodified vehicles to realistically assess different aspects of biodiesel’s compatibility with modern common rail direct injection (CRDI) diesel engines and its effects on lubricating oil degradation and wear. Two identical vehicles were operated for 30,000 km each under identical operating conditions on highway during a field-trial while using biodiesel (B100) and baseline mineral diesel. Exhaustive experimental results from this series of tests were divided into four segments, and this paper covers the second segment showing the effect of long-term usage of biodiesel on the lubricating oil properties and traces of wear metal addition compared to baseline mineral diesel. Lubricating oil samples were drawn periodically from these vehicles for condition monitoring such as lubricating oil viscosity, density, soot content, total base number (TBN), ash content, trace metal concentrations, and thermal stability. The viscosity of lubricating oil samples drawn from biodiesel fueled vehicles were found to be ∼10–15% lower compared to that from diesel-fueled vehicles, whereas density and ash content were relatively lower by ∼5–10%. Carbon residues of lubricating oil samples drawn from B100 fueled vehicles were lower by ∼15–20% compared to that of diesel-fueled vehicles. There was a very strong reduction (∼70%) in the soot content of lubricating oil from biodiesel fueled vehicles. Trace metal analysis to compare wear debris addition was also done for all lubricating oil samples. Thermo-gravimetric analyses of lubricating oil samples from biodiesel fueled vehicles showed lower mass loss with increasing temperature hence relatively higher thermal stability and lower deterioration. Results also suggested that operational and durability issues associated with vegetable oils as alternate fuel were completely eliminated by using them after converting them into biodiesel meeting prevailing biodiesel specifications.

Field-Testing of Biodiesel (B100) and Diesel-Fueled Vehicles: Part 1—No Load and Highway Driving Emissions, and Acceleration Characteristics

AbstractBiodiesel has emerged as a sustainable renewable transport fuel worldwide. This study investigated the use of biodiesel (B100) and mineral diesel in two identical unmodified vehicles to realistically assess different aspects of biodiesel’s compatibility with modern common rail direct injection (CRDI) diesel engines. Exhaustive experimental results from this series of tests are divided into four segments and no-load engine speed emissions, highway driving emissions, and acceleration characteristics of biodiesel and diesel-fueled vehicles are included in this first paper of the series of four papers. First, the emissions were measured at different engine speeds at no load, when the vehicles were stationary. Thereafter, the real highway driving emissions were measured at different vehicle speeds using on-board emission analyzers. CO and HC emissions from biodiesel fueled stationary vehicle were negligible but relatively higher than mineral diesel-fueled stationary vehicle. NOx emissions increased with increasing engine speed at no-load condition for both stationary vehicles and smoke opacity was also very low for most engine speeds at no load. Among real highway driving emissions, CO and HC from biodiesel-fueled vehicles were ∼13% and ∼30% lower than mineral diesel-fueled vehicles, respectively, at varying vehicle speeds. Emissions of CO2 were not too different in these two vehicles but NOx emissions from biodiesel-fueled vehicle were ∼32% higher than mineral diesel-fueled vehicle. Smoke opacity from biodiesel-fueled vehicle was lower by ∼80% than mineral diesel-fueled vehicle and it didn’t increase with increasing vehicle speed. Acceleration characteristics of biodiesel-fueled vehicle were as good as diesel-fueled vehicle up to a speed of 90 kmph using stock electronic control unit (ECU), however, beyond 90 kmph vehicle speed, the acceleration of biodiesel-fueled vehicle was noticeably lower than baseline mineral diesel-fueled vehicle. This underlines the need for ECU recalibration before the large-scale implementation of biodiesel in existing diesel vehicles.

A computational study and experiments to investigate the combustion and emission characteristics of a small naturally aspirated diesel engine through changes in combustion chamber geometry, injection parameters and EGR

Investigation of the combustion process in engines for improved fuel economy and emissions is best done by combining experiments and simulations. In the present work both experiments and simulations are conducted considering a naturally aspirated common-rail direct-injection (CRDI) diesel engine. The CFD model is developed based on experiments conducted at two operating points, representing to a 0.9 l, two-cylinder, diesel engine. The developed CFD model is then used to study the effects of different in-cylinder strategies attempted at reducing emissions, without compromising on performance. Previous researches conducted on diesel engine CFD simulations are generally based on large-bore large-capacity single-cylinder engines, and mostly investigated a single operating point. The present study investigates the effects of combustion chamber geometry, injection timing, multiple injections as well as EGR, individually as well as in combination, on NOx and soot emissions, at two different operating points in a small naturally aspirated CRDI diesel engine.

Influence of injection parameters on combustion, gaseous emissions and particle size distribution of a CRDI diesel engine operating with PODE/diesel blends

This study deals with the experimental research on combustion process, gaseous emissions characteristics and particle size distributions of a high pressure common-rail direct injection (CRDI) diesel engine operating with PODE/diesel blends at different injection pressures (80 MPa, 90 MPa and 100 MPa) and injection timings (0.5°CA ATDC, 2.5°CA ATDC and 4.5°CA ATDC). The testing fuels were neat diesel, PODE/diesel blends with PODE volume fractions of 10% and 20%, which were marked as P0, P10 and P20 respectively. The results show that the maximum combustion pressure and peak value of heat release rate increase with the increment of injection pressure while the combustion pressure decreases slightly with the delay of injection timing. The CO, HC and soot emissions of the blended fuels decrease obviously with the increase of injection pressure, while the NOx increases, in which the increasing extent of NOx by fueling P10 is smaller than those of P0 and P20 fuels. Even though CO, HC and soot of the three fuels increase with the delay of injection timing, the NOx emissions decrease and the gaseous emissions of P10 fuel are still less affected by injection timing. The peak values of particle number concentration curves of the blends decrease with higher injection pressure, among which the proportion of accumulation particles decreases and the proportion of nucleation particles increases. The particle number concentration increases with the delay of injection timing for each testing fuel, but the geometric mean diameter (GMD) of P10 particles is little affected by the injection timing. Also, the particle diameter corresponding to the peak concentration for each testing fuel decreases with the increase of injection pressure and the advance of injection timing.

Study on Volatile Organic Compounds from Diesel Engine Fueled with Palm Oil Biodiesel Blends at Low Idle Speed

This paper presents the combustion and emissions characteristics including volatile organic compound (VOC) of a common rail direct injection diesel engine fueled with palm oil biodiesel blends contained 0%, 10%, 30%, and 100% (by volume) biodiesel at low idle speed, i.e., 750 rpm. The nitrogen oxide (NOx) emissions of biodiesel blends were lower than that of pure diesel and NOx tended to decrease as the blending ratio increased. Soot opacity and hydrocarbon (HC) were reduced with an increasing blend ratio. Carbon monoxide (CO) varied with the engine load conditions. Under low load, CO emissions tended to decrease with increasing blending ratio and increased under high load. Alkane and aromatic VOCs were mostly emitted. Benzene and tetrahydrofuran accounted for the largest percentage of total detected VOCs in all test conditions. Benzene, toluene, ethylbenzene, xylene (BTEX, toxic aromatic VOCs) were detected for all tests. Among BTEX, benzene has the highest emission ratio, followed by xylene, toluene, and ethylbenzene. Benzene increased for all tests. At low engine load, toluene, ethylbenzene, and xylene decreased with increasing blend ratio. However, these increased at high engine load. When pure palm oil biodiesel was applied at high engine load, benzene decreased.

Emission profiling of a common rail direct injection diesel engine fueled with hydrocarbon fuel extracted from waste high density polyethylene as a partial replacement for diesel with some modifications

A hydrocarbon fuel extracted from waste high-density polyethylene (WHDPE) by catalytic pyrolysis in a batch scale reactor is blended with diesel by 30% vol. (called as D70H30) is tested in a variable compression ratio engine equipped with a common rail system. Experiments were conducted at three compression ratios (16:1, 17.5:1, and 19:1) and exhaust gas re-circulation (EGR) rates (0%, 10%, and 20%) at the engine’s rated power to evaluate its combustion, performance and emission characteristics. The results revealed that, increasing the compression ratio resulted in higher peak cylinder pressure (PCP) and heat release rates (HRR). Introduction of EGR diminished both PCP and HRR peaks. The brake thermal efficiency of D70H30 blend was 4% lower than diesel at same operating conditions which got better at higher compression ratio without EGR. NOx emission was highest when injected at compression ratio 19:1 and at 0% EGR rate which was 6% and 3% higher than diesel and D70H30 blend operated at engine stock settings. In comparison with baseline diesel smoke opacity remained lower at all operating conditions, where lowest smoke emission was recorded at CR19 and at 0% EGR rate. UHC and CO emission followed the similar trend of smoke opacity. Whereas CO2 emission increased with compression ratio and reduced with induction of EGR. It can be concluded from the study that at higher compression ratio and low EGR rates D70H30 blend can be effectively utilized in a CRDi engine.

Effect of pilot and post fueling on the combustion and emission characteristics of a light-duty diesel engine powered with diesel and waste cooking biodiesel blend

ABSTRACT Biodiesel produced from waste resources provides both environmental and economic benefits. The use of biodiesel blends in tandem with advanced fuel injection strategies enables effective control over engine-out emissions. The current study investigates the effect of the pilot and post fuel injection on combustion and emission characteristics of a light-duty diesel engine fueled with standard diesel and waste cooking biodiesel blend. The engine adopted for this study is an automotive common rail direct injection (CRDI) diesel engine, wherein the electronically controlled fuel injection system provides flexibility to control single and multiple injection schedules along with the provision for change in fuel injection pressure. A blend of 80% diesel and 20% waste cooking biodiesel (B20) was tested at four-part loads and three fuel injection pressures. The test results indicated a considerable reduction in smoke (84.4%), hydrocarbon (71.8%), and carbon monoxide (46.8%), compared to the base diesel (D100) operating at a single injection and lower fuel injection pressure. Also, Brake thermal efficiency was improved by 4.46%. However, nitric oxide emission was found to be 15% higher due to the higher fuel injection pressure. The experimental results affirm that the usage of pilot and post-injection along with higher fuel injection pressure for waste cooking biodiesel blend yielded a significant reduction in emissions at part-load condition.

Effects of injection timing and rail pressure on combustion characteristics and cyclic variations of a common rail DI engine fuelled with F-T diesel synthesized from coal

The use of Fischer-Tropsch (F-T) diesel synthesized from coal in automobiles can alleviate the shortage of petroleum and promote clean utilization of coal. In this study, the effects of injection timing (IT) and rail pressure (RP) on the brake thermal efficiency (BTE), combustion characteristics, and cyclic variations of F-T diesel were investigated on a turbocharged, 6-cylinder, common rail direct injection (CRDI) diesel engine. The results indicate that increasing RP results in higher BTE, whereas advancing IT results in an initial BTE increase and a subsequent BTE decrease. In comparison with petroleum diesel, the BTE of F-T diesel increased by 0.54% on average and by a maximum of 1% under different conditions. When the IT was advanced from 2 °CA to 18 °CA BTDC, the ignition delay periods (IDP) first decreased and then increased, whereas the combustion durations (CD) first lengthened and then shortened; peak cylinder pressure (PCP), peak pressure rise rate (PPRR), and peak combustion temperature (PCT) gradually increased; peak heat release rate (PHRR) first decreased and then increased at the low loads, whereas it always increased at medium and high loads. In comparison with petroleum diesel, the IDP of F-T diesel decreased by 22–31% at various conditions, and the CD was slightly longer than that of petroleum diesel at most conditions. Additionally, increasing RP resulted in a decrease in the IDP and CD, and a significant increase in PCP, PPRR, PHRR, and PCT. At low loads, the PPRR and PHRR of F-T diesel were 32.72% and 32.13% lower than that of diesel owing to the shorter ignition delay. This implies that using F-T diesel can help in attaining smoother engine running and has lower combustion noise. Advancing the injection timing or increasing the engine loads can decrease the cyclic variations, whereas increasing rail pressure results in the increment of COVpmax at low loads and the significant decrement of COVpmax at medium and high loads. In comparison with petroleum diesel, F-T diesel exhibits higher combustion stability owing to the better volatility and higher fuel reactivity.

Effects of Ethanol–Diesel on the Combustion and Emissions from a Diesel Engine at a Low Idle Speed

In this study, detailed experiments were conducted on the combustion and exhaust characteristics of ethanol–diesel blended fuels. The four-stroke four-cylinder common-rail direct injection diesel engine was used. The experiment was carried out at 750 rpm at a low speed idle, and a 40 Nm engine load was applied to simulate the operation of the accessories during the low idle operation of the actual vehicles. The test fuels were four types of ethanol-blended fuel. The ethanol blending ratios were 0% (DE_0) for pure diesel, and 3% (DE_3), 5% (DE_5) and 10% (DE_10) for 3%, 5% and 10% ethanol mixtures (by vol.%). Blending ethanol with diesel fuel increased the maximum combustion pressure by up to 4.1% compared with that of pure diesel fuel, and the maximum heat release rate increased by 13.5%. The brake specific fuel consumption (BSFC) increased, up to 5.9%, as the ethanol blending ratio increased, while the brake thermal efficiency (BTE) for diesel-ethanol blended fuels remained low, and was maintained at 23.8%. The coefficient of variation (COV) of the indicated mean effective pressure (IMEP) was consistently lower than 1% when ethanol was blended. The blending of ethanol increased the ignition delay from a 12.0 degree crank angle (°CA) at DE_0 to 13.7 °CA at DE_10, and the combustion duration was reduced from 21.5 °CA at DE_0 to 20.8 °CA at DE_10. When ethanol blending was applied, nitrogen oxides (NOx) reduced to 93.5% of the level of pure diesel fuel, the soot opacity decreased from 5.3% to 3% at DE_0, and carbon monoxide increased (CO) by 27.4% at DE_10 compared with DE_0. The presence of hydrocarbon (HC) decreased to 50% of the level of pure diesel fuel, but increased with a further increase in the ethanol blending ratio. The mean size of the soot particulates was reduced by 26.7%, from 33.9 nm for pure diesel fuel, DE_0, to 24.8 nm for DE_10.

Comparative analysis on the effect of 1-decanol and di-n-butyl ether as additive with diesel/LDPE blends in compression ignition engine

ABSTRACT The present study utilizes (a) recycled low density polyethylene oil extracted through catalytic pyrolysis and (b) 1-decanol and di-n-butyl ether, as a blend component with diesel to power a single-cylinder, light-duty, water-cooled, four-stroke, common rail direct injection diesel engine. Experiments were conducted with two ternary blends and they were designated as (1) D70L20D10 (2) D70L20DNBE10. Later these results were compared with baseline diesel and D70L30 blend. Results indicated that replacing 10% by vol. of LDPE oil in D70L30 blend with 1-decanol and di-n-butyl ether was beneficial in increasing the combustion characteristics of the research engine, ignition delay period of oxygenated blends got shorter when compared to D70L30 blend. Slightly higher peak pressures were observed with the ternary blends than baseline fuels. Brake thermal efficiency of diesel was high at part load, whereas at peak load, D70L20DNBE10 shown 0.7% and 3.1% superior performance than diesel and D70L30 blend respectively. NOx emission for D70L20D10 and D70L20DNBE10 blend was found lower by 17.9% and 5.7% respectively than the D70L30 blend. Smoke opacity of the ternary blend was found to be lower against D70L30 and higher with diesel operations. The study revealed that 1-decanol and di-n-butyl ether could be a potential fuel additives for diesel engines operating with LDPE oil extracted from LDPE plastic waste.