Turbocharged Compression Ignition Engine Research Articles

Experimental analysis of the effect of hydrogen as the main fuel on the performance and emissions of a modified compression ignition engine with water injection and compression ratio reduction

This study aimed to investigate the combined effects of compression ratio (CR), start of injection angle (SOI) and water injection (WI) on the performance, including NOx emissions, of a modified turbocharged compression ignition engine using H2 as the primary fuel and diesel solely as a pilot ignition source. WI and H2 were both injected into the intake manifold just after the charge heat exchanger. Test conditions varied the engine speed from 1500 rpm to 2750 rpm, covering a wide range of the original engine's operating conditions, water mass flow varied from 0 to 0.795 g/cycle and SOI for pilot ignition was studied in the range 10°, 5°, 0° before top dead center. Subsequently, the study examined the combined effect of reducing the engine's CR from 17.5:1 (base) to 13.5:1, in one-point increments, reducing SOI and water addition to further enhance the hydrogen energy share (HES).HES varied from 0 % to 85 % under different engine conditions, and WI and SOI were employed to prevent knocking and ensure that the maximum combustion pressure did not exceed 160 bar. The test results indicate that NOx emissions increase with HES, but reducing the CR results in a reduction in NOx emissions of approximately 50 %. Additionally, WI further reduces NOx emissions by up to 50 %. The experimental evidence demonstrates that combining WI with CR and SOI reduction can effectively lower NOx emissions, achieving an efficiency greater than 35 % and therefore approaching the base diesel mode's efficiency. This also reduces the maximum in-cylinder pressure, allowing for an increase in turbocharger pressure and consequently enhancing the engine's specific power. The maximum engine power achieved was 31.6 kW at 2500 rpm (mean effective pressure of 10.1 bar), with a CR of 15.5, SOI at 10°, 1.5 kg/kWh of water, a HES of 81 %, and a minimum NOx level of approximately 480 ppm, with a maximum combustion pressure below 120 bar.

Transient Response of Turbocharged Compression Ignition Engine under Different Load Conditions

<div>In urban roads the engine speed and the load vary suddenly and frequently, resulting in increased exhaust emissions. In such operations, the effect of air injection technique to access the transient response of the engine is of great interest. The effectiveness of air injection technique in improving the transient response under speed transient is investigated in detail [<span>1</span>]; however, it is not evaluated for the load transients. Load step demand of the engine is another important event that limits the transient response of the turbocharger. In the present study, response of a heavy-duty turbocharged diesel engine is investigated for different load conditions. Three cases of load transients are considered: constant load, load magnitude variation, and load scheduling. Air injection technique is simulated and after optimization of injection pressure based on orifice diameter, its effect on the transient response is presented. The results reveal that air injection into the intake manifold is an effective technique to improve the turbo lag of a heavy-duty turbocharged diesel engine under the transient conditions of load.</div>

Investigation of combustion characteristics, physical and chemical ignition delay of methanol fuel in a heavy-duty turbo-charged compression ignition engine

In previous research, there have been more investigations on methanol blended with other fuels such as diesel, biodiesel, gasoline, etc., but fewer investigations on methanol with ignition additives as a mono-fuel. To better understand the methanol mono-fuel combustion characteristics and to further apply them, a combined experimental and simulation study of methanol in a Scania heavy-duty compression ignition (CI) engine was carried out in this work. The experiments consisted of four groups with variable injection timings, variable fraction of ignition additives, variable charge air temperatures, and variable overall excess air ratios/power sweeps. Heat release rate (HRR), cylinder pressure, ignition delay and indicated efficiency were analyzed for each case. The analysis showed that the combustion type was partially premixed combustion (PPC) in some cases and diesel-like combustion in the rest. By observing all cases, the shortest ignition delay was 14.1°, and the longest was 22.8°. The indicated efficiencies were in the range of 0.35 to 0.43. Simulations and validation analyses were performed for all cases by a multi-packets model. The physical and chemical ignition delays were predicted. The physical ignition delays were in the range of 4.25 to 8.10°, and the chemical ignition delays were in the range of 6.66 to 17.1°. The chemical ignition delay was always longer than the physical one. This indicates that chemical ignition delay has to be prioritized to improve the ignition performance of methanol fuel.

In-Cylinder Pressure Estimation from Rotational Speed Measurements via Extended Kalman Filter.

Real-time estimation of the in-cylinder pressure of combustion engines is crucial to detect failures and improve the performance of the engine control system. A new estimation scheme is proposed based on the Extended Kalman Filter, which exploits measurements of the engine rotational speed provided by a standard phonic wheel sensor. The main novelty lies in a parameterization of the combustion pressure, which is generated by averaging experimental data collected in different operating points. The proposed approach is validated on real data from a turbocharged compression ignition engine, including both nominal and off-nominal working conditions. The experimental results show that the proposed technique accurately reconstructs the pressure profile, featuring a fit performance index exceeding 90% most of the time. Moreover, it can track changes in the engine operating conditions as well as detect the presence of cylinder-to-cylinder variations.

An Experimental and Computational Study on Triple Injection Strategies to Reduce Cold Start Diesel Engine Emissions

Abstract The effect of triple injection strategies in a diesel engine to reduce cold start emissions were experimentally and computationally investigated in this work. The experiments were performed using a 1.9 L four-cylinder, turbocharged compression ignition engine with diesel fuel. As a representative of the cold start condition in the diesel engine, a low load condition of 1500 rpm and 2 bar brake mean effective pressure (BMEP) was chosen as the fixed condition for this study. The injection strategy made use of a late post injection to reduce catalyst light-off time. The pilot and main injections are fixed and the post injection timing is swept later into the expansion stroke to increase exhaust enthalpy available to heat the aftertreatment system. To further understand the source of hydrocarbon (HC) emissions from late injections, equivalent experiments were conducted with a mixture of n-heptane and iso-octane that matched the reactivity of the diesel fuel. The mixture of primary reference fuels (i.e., PRF 34) obtained by matching the cetane number (CN) of diesel fuel, showed similar combustion characteristics of diesel, but is much more volatile due to lighter components in the PRF mixture. The increased volatility of PRF 34 suppressed liquid fuel impingement on the cylinder liner, which isolated liner impingement as a possible source of HC emissions. Simulations were also performed for the present engine configuration and operating conditions in a sector mesh using CONVERGE™. The physical properties of diesel fuel were modeled using a five-component surrogate. The chemical kinetics of the diesel fuel were modeled with a reduced n-heptane model. The simulations were able to capture the experimental trends of combustion characteristics and emissions. The HC emissions were observed to increase for both fuels with retarded post injection timings in engine experiments. PRF 34 had comparable HC emissions to diesel experiments, which indicated that the liner impingement is not the main source of the increase in HC emissions. Overmixing of the fuel and air was identified as the major cause of increase in HC emissions. Additionally, exhaust gas recirculation (EGR) also intensified the overmixing phenomenon and thereby increase in HC emissions.

Investigation of Combustion Characteristics, Physical and Chemical Ignition Delay of Methanol Fuel in a Heavy-Duty Turbo-Charged Compression Ignition Engine

Investigation of Combustion Characteristics, Physical and Chemical Ignition Delay of Methanol Fuel in a Heavy-Duty Turbo-Charged Compression Ignition Engine

Potential Improvement in PM-NOX Trade-Off in a Compression Ignition Engine by n-Octanol Addition and Injection Pressure

n-Octanol, as an oxygenated fuel, is considered as one of the most promising alternative fuels, owing to advantages such as its low hygroscopic nature, high cetane number, and high energy content. However, the introduction of n-octanol leads to a higher viscosity and latent heat of evaporation (LHOE), affecting the combustion and emission performances of compression ignition (CI) engines. This study sheds light on the effect of injection pressures (IPs, ranging from 60 to 160 MPa) on the combustion and emission performances of a turbocharged CI engine, in conjunction with n-octanol/diesel blends. According to the proportion of oxygen content, the test fuels contain pure diesel (N0), N2.5 (2.5% oxygen content in the blending fuels), and N5 (5% oxygen content in the blending fuels). The results indicate that the blending fuels have little influence on the in-cylinder pressure, ignition delay (ID), and CA50, but they improve the brake thermal efficiency (BTE). In terms of emissions, with the use of blending fuels, the levels of carbon monoxide (CO), soot, and nitrogen oxides (NOX) decrease, whereas emissions of hydrocarbons (HC) slightly increase. With increasing IP, the ID, brake specific fuel consumption (BSFC), HC, CO, and soot decrease significantly, and the BTE and NOX increase. In addition, the combination of n-octanol and IP improves the trade-off between NOX and soot and reduces the CO emissions.

Combustion characteristics of compression ignition engine fuelled with rapeseed oil–diesel fuel–n-butanol blends

Liquid biofuels for compression ignition engines are often based on vegetable oils. In order to be used in compression ignition engine the vegetable oils have to be processed because of their high viscosity or it is also possible to use vegetable oils in fuel blends. In order to decrease the viscosity of the fuel blends containing crude vegetable oil the alcohol-based fuel admixtures can be used. The paper describes the effect of rapeseed oil–diesel fuel–n-butanol blends on combustion characteristics and solid particles production of turbocharged compression ignition engine. The 10% and 20% concentrations of n-butanol in the fuel blend were measured and analysed. The engine Zetor 1204, located in tractor Zetor Forterra 8641 with the power of 60kW and direct injection was used for the measurement. The engine was loaded through power take off shaft of the tractor using mobile dynamometer MAHA ZW500. The measurement was carried out in stabilized conditions at 20%, 60% and 100% engine load. The engine speed was kept at 1950 rpm. Tested fuel blends showed lower production of solid particles than diesel fuel and lower peak cylinder pressure and with increasing concentration of n-butanol in the fuel blend the ignition delay was prolonged and premixed phase of combustion was increased.

Effect of hydrogen addition on performance and emission characteristics of a common-rail CI engine fueled with diesel/waste cooking oil biodiesel blends

In this study, the effect of hydrogen addition to a compression ignition (CI) engine fueled with the diesel fuel-waste cooking oil biodiesel (WCOB) blend (B25) on the engine performance, and exhaust emissions was examined experimentally. In the tests, a four-cylinder, four-stroke, water-cooled, 1.461-L, turbocharged CI engine was used. The engine tests were performed at the fixed engine speed of 1750 rpm and at the diverse engine loads of 40, 60 and 80 Nm. The hydrogen was added to the intake air at the flow rates of 10, 20, 30 and 40 lpm. According to the results obtained, hydrogen had a positive effect on break specific fuel consumption (BSFC) for all test conditions. The increase occurred at the exhaust gas temperatures (EGTs) and cylinder pressures (CPs) with hydrogen addition. The NOx and total hydrocarbon (THC) emissions decreased with the hydrogen addition until 30 lpm at 40 and 60 Nm engine loads. On the other hand, they increased at 80 Nm engine load for all hydrogen additions. While CO2 and O2 emissions decreased with the hydrogen addition, the smoke emissions increased. It was found that the value of 30 lpm was the optimum condition of the hydrogen addition rates.

A numerical study of a compression ignition engine operating with constant volume combustion phase: Effects of constant volume phase on combustion performance and emissions

A detailed numerical study is carried out to investigate the performance of a turbocharged compression ignition engine operating under a novel combustion strategy in which fuel injection and most of the combustion occur at a constant volume. Simulations have been performed using URANS based modelling approach along with several other sub-models. A detailed validation of the CFD model has been carried out using data from a conventional crank engine.A parametric study has been performed to investigate the effects of the duration and timing of the constant volume combustion phase (CVCP) on the engine’s thermal efficiency and emissions, with comparisons against the conventional engine. Much higher in-cylinder pressures and temperatures are observed in the CVCP strategy.The results demonstrate that the CVCP strategy is capable of yielding reduced gross indicated specific fuel consumptions of up to 20% and far lower CO2 and soot emissions but incurs unacceptable increase to nitrogen oxide emissions. However, it was found that a combination of exhaust gas recirculation and improved fuel injection methods can counter the increased nitrogen oxide emissions under the CVCP strategy, while still maintaining the improved engine performance and low carbon-based emissions.

Environment-friendly novel fuel additives: Investigation of the effects of graphite nanoparticles on performance and regulated gaseous emissions of CI engine

Increased menacing engine emissions and threat to human health from metallic combustion catalysts demand a shift towards the application of non-metallic fuel additives. Therefore, the current study is an effort, conducted to introduce a new, less toxic and non-metallic graphite (G) nano diesel-fuel additive, by investigating its effects on the performance and regulated gaseous emissions of a four-cylinder, water-cooled, compression ignition (CI) engine. The experiments were also repeated with Iron oxide (Fe2O3) nanoparticles and statistical analyses were implemented to have a comparison with graphite nanoparticles. The G and Fe2O3 nanoparticles, in concentrations of 50, 100 and 150 mg per litre (mg/l), were mixed with neat diesel by magnetic stirring to prepare homogeneous fuel blends. The physicochemical properties of the fuel blends were determined. A maximum decrease of 4.9% in viscosity and an increase of 3.26% in Cetane index was observed for graphite blends. The investigated parameters include torque (T), brake power (BP), brake specific fuel consumption (bsfc), brake thermal efficiency (BTE), carbon monoxide (CO) and nitrogen oxides (NOx) emissions at engine speed varying from 1500 to 3000 rpm with an interval of 300 rpm at full load. The results revealed that at a confidence level of 95% (significance level α = 0.05), G-blends indicated a higher increase in torque, power, BTE and a greater decrease in bsfc than Fe2O3 blends. Graphite blends produced significantly lower NOx emissions than Fe2O3 treated blends. The increase in T, BP and BTE was 2.4%, 8.9% and 3.9% respectively, with 150 mg/l Fe2O3 blends and 2.9%, 9.6% and 4.1% respectively, with 150 mg/l G-blends. Graphite blends resulted in a 2.6% reduction in bsfc. The increase in NOx emissions was 34.7% with Fe2O3 and 29.2% with G at concentrations of 150 mg/l. The CO increased by 14.2% with G blends. A negative statistical correlation was observed for CO emissions between G and Fe2O3 blends. We conclude that G nanoparticles are more environmentally friendly fuel additives than Fe2O3; however, their application is more recommended for large turbocharged CI engines with improved oxygen density in inlet compressed air.

Comparison between Organic Working Fluids in order to Improve Waste Heat Recovery from Internal Combustion Engines by means of Rankine Cycle Systems

The present works deals with waste heat recovery from internal combustion engines using Rankine cycle systems where working fluid are organic liquids (ORC). The first part of the paper presents the ORC technology as one of the most suitable procedure for waste heat recovery from exhaust gas of internal combustion engine (ICE). The particular engine considered in the present work is a turbocharged compression ignition engine mounted on an experimental setup. The working fluids for ORC system are: isobutene, propane, RE245fa2, RE245cb2, R245fa, R236fa, R365mfc, R1233zd(E), R1234yf and R1234ze(Z). Experimental data derived from the experimental setup has been used for 40%, 55% and 70% engine load. This papers focusses on superheating increment, on thermal efficiency and on net power output, obtained with each working fluids in Rankine cycle. Results point out the superheating increment that gives the highest thermal efficiency for each working fluid. The highest thermal efficiency is achieved in case of using R1233zd(E) as working fluid. In case of using R1233zd(E) as working fluid at 40 % load of the engine, the output power of the Rankine cycle is 3.6 kW representing 6.2 %, from the rated power at this load; at 55% load it is 5.7 kW representing 6.7 % the rated power and at 70% it is 6.7 kW representing 6.5 % from the rated power. Future perspectives are given.

Comparative study of oxihydrogen injection in turbocharged compression ignition engines

This document proposes for analysis, comparative study of the turbocharged, compression-ignition engine, equipped with EGR valve, operation in case the injection in intake manifold thereof a maximum flow rate of 1l/min oxyhydrogen resulted of water electrolysis, at two different injection pressures, namely 100 Pa and 3000 Pa, from the point of view of flue gas opacity. We found a substantial reduction of flue gas opacity in both cases compared to conventional diesel operation, but in different proportions.

Low pressure injection of oxyhydrogen in turbocharged compression ignition engines

Low pressure injection of oxyhydrogen in turbocharged compression ignition engines

The influence of oxygenated fuels on transient and steady-state engine emissions

This research studies the influence of oxygenated fuels on transient and steady-state engine performance and emissions using a fully instrumented, 6-cylinder, common rail turbocharged compression ignition engine. Beside diesel, the other tested fuels were based on waste cooking biodiesel (primary fuel) with triacetin (highly oxygenated additive). A custom test was designed for this study to investigate the engine performance and emissions during steady-state, load acceptance and acceleration operation modes. Furthermore, to study the engine performance and emissions during a whole transient cycle, a legislative cycle (NRTC), which contains numerous discrete transient modes, was utilised. In this paper, the turbocharger lag, engine power, NOx, PM, PN and PN size distribution were investigated. During NRTC the brake power, PM and PN decreased with fuel oxygen content. During steady-state operation, compared to diesel, the oxygenated fuels showed lower indicated power, while they showed higher values during acceleration and turbocharger lag. During acceleration and load increase modes, NOx, PM and PN peaked over the steady-state counterpart, also, the accumulation mode count median diameter moved toward the larger particle sizes. Increasing the fuel oxygen content increased the indicated specific NOx and PN maximum overshoot, while engine power, PM, PN and PM maximum overshoot decreased. Also, the accumulation mode count median diameter moved toward the smaller particle sizes.

The Influence of Magnetic Field on Low Pressure Injection of Oxyhydrogen in Turbocharged Compression Ignition Engines

The paper analyzed experimentally the influence of magnetic field on low pressure injection of oxyhydrogen gas, in supercharged compression ignition engine. The experiment consists in the series of power and tests on the chassis dynamometer, and opacity measurements of flue gas by free acceleration the engine. Initially the engine is tested with standard diesel fuel, followed by the oxyhydrogen blended diesel fuel with different volume percentages, and finally oxyhydrogen blended diesel fuel is passed through the magnetic device. The experimental data revealed a positive influence, of the magnetic device on opacity of the flue gas and indicated specific fuel consumption.

Thermodynamic Analysis of a Turbocharged Diesel Engine Operating under Steady State Condition

The purpose of this work is to provide a flexible thermodynamic model based on the filling and emptying approach for the performance prediction of turbocharged compression ignition engine. To validate the model, comparisons are made between results of a developed a computer program in FORTRAN language and the commercial GT-Power software operating under different conditions. The comparisons show that there is a good concurrence between the developed program and the commercial GT-Power software. The variation of the speed of the diesel engine chosen extends from 800 RPM to 2100 RPM. In this work, we studied the influence of several engine parameters on the power and efficiency. Moreover, it puts in evidence the existence of two optimal points in the engine, one relative to maximum power and another to maximum efficiency. It is found that if the injection time is advanced, so the maximum levels of pressure and temperature in the cylinder will be high.

Novel approaches to improve the gas exchange process of downsized turbocharged spark-ignition engines: A review

Engine downsizing, which is the use of a smaller engine that provides the power of a larger engine, is now considered a mega-trend for the internal combustion engine market. It is usually achieved using one or more boosting devices including a supercharger or a turbocharger. Although supercharging is beneficial for engine’s transient response, turbocharging technology is more widely adopted considering its advantages in fuel efficiency. Compared to turbocharged compression ignition engines, turbocharged spark-ignition engines tend to be more challenging with respect to the gas exchange process mainly due to their higher pumping loss, the need for throttling and the fact that spark-ignition engines demand more controllability due to the mitigation of knock, particularly with regard to minimizing trapped residuals. These challenges encourage the entire gas exchange process of turbocharged spark-ignition engines to be regarded as a complete air management system instead of just looking at the boosting system in isolation. In addition, more research emphasis should be focused on novel approaches to improve the gas exchange process of downsized turbocharged spark-ignition engines because the refinement of the conventional technologies cannot provide continuous gains indefinitely and only innovative concept may improve the engine performance to meet the fuel efficiency target and the more stringent emission regulation in the future. This article will first briefly review knowledge of the current state of the art technologies that are in production as opposed to approaches that are currently only being investigated at a research level. Next, more novel methods of the gas exchange process are introduced to identify the improved synergies between the engine and the boosting machine. The major findings to improve the gas exchange process that emerge from this review comprise four aspects (depending on the location where the novel technologies are implemented) which are as follows: charge air pressurization/de-pressurization improvement, combustion efficiency enhancement within the chamber, valve event–associated development and exhaust system optimization. Although the interaction between these technologies on different aspects of the gas exchange process was found to be highly complex, the optimization or the combination of these technologies is anticipated to further improve a downsized turbocharged spark-ignition engine’s performance.

The influence of different parameters on the performance of the compression ignition engine

The purpose of this work was to provide a flexible thermodynamic model based on the filling-and-emptying approach for the performance prediction of a four-stroke turbocharged compression ignition engine. To validate the model, comparisons were made between results from a computer program developed using FORTRAN language and the commercial GT-Power software operating under different conditions. The comparisons showed that there was a good concurrence between the developed program and the commercial GT-Power software. The range of variation of the rotational speed of the diesel engine chosen extends from 800 to 2100 RPM. By analysing these parameters with regard to two optimal points in the engine, one relative to maximum power and another to maximum efficiency, it was found that if the injection timing is advanced, the maximum levels of pressure and temperature in the cylinder are high.

Computational Thermodynamic of a Turbocharged Direct Injection Diesel Engine

The purpose of this work is to provide a flexible thermodynamic model based on the filling and emptying approach for the performance prediction of turbocharged compression ignition engine. To validate the model, comparisons between the developed a computer program in FORTRAN language and the commercial GT-Power software results operating under different conditions. The comparisons show that there is a good concurrence between the developed program and the commercial GT-Power software. The variation of the speed of the diesel engine chosen extends from 800 RPM to 2100 RPM. In this work, we studied the influence of several engine parameters on the power and efficiency. Moreover, it puts in evidence the existence of two optimal points in the engine, one relative to maximum power and another to maximum efficiency; it was found that if the injection time is advanced, so the maximum levels of pressure and temperature in the cylinder are high, it was found that if the injection time is advanced, so the maximum levels of pressure and temperature in the cylinder are high.DOI: http://dx.doi.org/10.5755/j01.mech.21.1.8690