Effect of split fuel injection and EGR on NOx and PM emission reduction in a low temperature combustion (LTC) mode diesel engine (original) (raw)
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International Journal of Engine Research, 2019
From the different power plants, the compression ignition diesel engines are considered the best alternative to be used in the transport sector due to its high efficiency. However, the current emission standards impose drastic reductions for the main pollutants, that is, NO x and soot, emitted by this type of engines. To accomplish with these restrictions, alternative combustion concepts as the premixed charge compression ignition are being investigated nowadays. The objective of this work is to evaluate the impact of different fuel injection strategies on the combustion performance and engine-out emissions of the premixed charge compression ignition combustion regime. For that, experimental measurements were carried out in a single-cylinder medium-duty compression ignition diesel engine at low-load operation. Different engine parameters as the injection pattern timing, main injection timing and main injection fuel quantity were sweep. The best injection strategy was determined by m...
SAE Technical Paper Series, 2007
Homogeneous Charge Compression Ignition (HCCI) combustion is a combustion concept which offers simultaneous reductions in both NO x and soot emissions from internal combustion engines. In light of increasingly stringent diesel emissions limits, research efforts have been invested into HCCI combustion as an alternative to conventional diesel combustion. This paper reviews the implementation of HCCI combustion in direct injection diesel engines using early, multiple and late injection strategies. Governing factors in HCCI operations such as injector characteristics, injection pressure, piston bowl geometry, compression ratio, intake charge temperature, exhaust gas recirculation (EGR) and supercharging or turbocharging are discussed in this review. The effects of design and operating parameters on HCCI diesel emissions, particularly NO x and soot, are also investigated. For each of these parameters, the theories are discussed in conjunction with comparative evaluation of studies reported in the specialised literature.
Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
In conventional diesel engines (DEs), the auto-ignition and decomposition reactions are considerably dependent on the disintegration of fuel spray and the fuel-air mixing quality. While mixed, localized fuel-rich areas in the combustion chamber also strongly affected the results of the combustion period as well as the emission formation of particulate matters (PM) and nitrogen oxides (NOx). Due to this above-mentioned reason, the combustion of diesel fuel acts as a toxic emission resource released into the environment. It is thus necessary to question that how to use this type of engine with minimizing emissions of PM and NOx without affecting significantly the thermal efficiency of engine. Involving with the use of premixed charge compression ignition (PCCI) mode is considered as an advanced combustion mode for the strategy of NOx and PM emission reduction. In this article, the combination of fuel injection under high pressure applied to PCCI combustion mode was assessed on the basis of the emission characteristics of NOx and PM. The changing trends of NOx and PM emissions were thoroughly analyzed to have a comprehensive overview on the effects of fuel injection pressure (IP) on controlling emissions of NOx and PM when DEs were operated under PCCI combustion conditions. In closing, it is worth mentioning that the increase in fuel IP was demonstrated to improve the engine performance, while the emission control based on PCCI combustion strategy was found to bring several benefits for the control and management of combustion process under lower temperatures compared to conventional DE.
2010
Homogeneous Charge Compression Ignition (HCCI) combustion is a combustion concept which offers simultaneous reductions in both NOx and soot emissions from internal combustion engines. In light of increasingly stringent diesel emissions limits, research efforts have been invested into HCCI combustion as an alternative to conventional diesel combustion. This paper reviews the implementation of HCCI combustion in direct injection diesel engines using early, multiple and late injection strategies. Governing factors in HCCI operations such as injector characteristics, injection pressure, piston bowl geometry, compression ratio, intake charge temperature, exhaust gas recirculation (EGR) and supercharging or turbocharging are discussed in this review. The effects of design and operating parameters on HCCI diesel emissions, particularly NOx and soot, are also investigated. For each of these parameters, the theories are discussed in conjunction with comparative evaluation of studies reported in the specialised literature.
2017
Partially premixed dual fuel strategy has been suggested as a new strategy for Compression Ignition (CI) engines because it could be effective for simultaneous reduction in NOx and soot exhaust emission accompanied. This strategy uses premixed low reactivity fuel as main fuel and advanced injection of high reactivity fuel as pilot fuel to reach a Reactivity Controlled Compression Ignition (RCCI) in CI engines. The current paper presents results from a study about NG-Diesel RCCI combustion with variable intake charge temperature in a CI engine. The results from the developed CFD model with a reduced chemical kinetic mechanism verify that the model can simulate the in-cylinder process, accurately. Based on the results, intake temperature impact the engine operation at RCCI combustion, significantly. The high intake temperature could result in advanced combustion phasing and higher ringing intensity (RI) as well as enhanced combustion efficiency. It is due combustion improvement with h...
SAE Technical Paper Series, 2005
The effects of exhaust gas recirculation (EGR) cooling, in combination with a partially-premixed charge obtained by a very advanced fuel injection (early injection), on the combustion of a Common-Rail Diesel engine, have been experimentally investigated. The combustion behavior, for different injection strategies, has been analyzed as well as the emission levels. Experimental tests have been carried out on a direct injection Fiat 1929 cm 3 Common Rail Diesel engine. Two different injection strategies have been investigated: the first one was obtained performing pilot and main injections only, the second one adding an early injection. The effects on engine combustion of hot and water cooled EGR have been compared with the combustion behavior without EGR, also showing the effect produced by different pilot injection timings and quantities. Results show that cooled EGR can improve both pilot and early injection combustion causing an increase in the peak values of the heat release (GHRR), and a decrease of the NO x emissions. The use of a small early injection in addition to a pilot one contributes to reduce NO x emissions, causing a reduction of the peak heat release of pilot + early injection and an increase of the peak of heat release of main injection. NO x emissions can be reduced by the increase of EGR percentage, more with cooled than with hot EGR.
Thermal Science, 2015
The use of diesel engines for vehicle has been increasing recently due to its higher thermal efficiency and lower CO2 emission level. However, in the case of diesel engine, NOx increases in a high temperature combustion region and particulate matter is generated in a fuel rich region. Therefore, the technique of PCCI (premixed charge compression ignition) is often studied to get the peak combustion temperature down and to make a better air-fuel mixing. However it also has got a limited operating range and lower engine power produced by the wall wetting and the difficulty of the ignition timing control. In this research, the effect of injection strategies on the injected fuel behavior, combustion and emission characteristics in a PCCI engine were investigated to find out the optimal conditions for fuel injection, and then ethanol blended diesel fuel was used to control the ignition timing. As a result, the combustion pressures and ROHR (rate of heat release) of the blended fuel becam...
Energy & Fuels, 2009
This paper presents a dual-injection strategy to achieve diesel partial homogeneous charge compression ignition (p-HCCI), which is the combination of HCCI-like combustion and traditional diesel combustion. The dual-injection strategy involves a negative valve overlap (NVO) fuel injection and a traditional fuel injection. The NVO injection occurs during the negative valve overlap period to prepare the homogeneous mixture for HCCI combustion. The traditional injection occurs at the end of the compression stroke to achieve diffused combustion. The results indicate that the NVO injection affects the combustion and emission characteristics in a different way compared to the traditional injection. The increase of NVO injection turns the combustion into HCCI-like combustion and advances the combustion phase. The increase of traditional injection makes the maximum heat release rate (HRR) higher. The emissions results indicate that p-HCCI can greatly reduce the NO x emissions compared to the baseline engine and maintain the same thermal efficiency. However, the NO x emissions increase with the increase of total injection. More traditional injection deteriorates the smoke emissions easily because of little time for fuel to mix with the intake air. The NVO injection ratio has been optimized at medium load according to the emissions and the thermal efficiency, and the optimum result is in the range of 30-40%, which can reduce the NO x emissions by about 40% and the smoke emissions by about 30%. However, the NVO injection should not be used at low load to stabilize the combustion.
Thermal Science
New combustion concepts have been recently developed with the purpose to tackle the problem of high emissions level of traditional direct injection Diesel engines. A good example is the premixed charge compression ignition combustion. A strategy in which early injection is used causing a burning process in which the fuel burns in the premixed condition. In compression ignition engines, soot (particulate matter) and NOx emissions are an extremely unsolved issue. Premixed charge compression ignition is one of the most promising solutions that combine the advantages of both spark ignition and compression ignition combustion modes. It gives thermal efficiency close to the compression ignition engines and resolves the associated issues of high NOx and particulate matter, simultaneously. Premixing of air and fuel preparation is the challenging part to achieve premixed charge compression ignition combustion. In the present experimental study a diesel vaporizer is used to achieve premixed c...
Energy Conversion and Management, 2015
The influence of exhaust gas recirculation (EGR) has been analyzed considering experimental results obtained from a Euro 5 diesel engine calibrated with an optimized pilot-main double injection strategy. The engine features a late premixed charge compression ignition (PCCI) type combustion mode and different steady-state key-points that are representative of the engine application in a passenger car over the New European Driving Cycle (NEDC) have been studied. The engine was fully instrumented to obtain a complete overview of the most important variables. The pressure time history in the combustion chamber has been measured to perform calculations with single and three-zone combustion diagnostic models. These models allow the in-cylinder emissions and the temperature of the burned and unburned zones to be evaluated as functions of the crankshaft angle. The EGR mass fraction was experimentally varied within the 050% range. The results of the investigation have shown the influence that high EGR rates can have on intake and exhaust temperatures, in-cylinder pressure and heat release rate time histories, engine-out emissions (CO, HC, NO x , soot), brake specific fuel consumption and combustion noise for a PCCI type combustion strategy. The outputs of the diagnostic models have been used to conduct a detailed analysis of the cause-and-effect relationships between the EGR rate variations and the engine performance. Finally, the effect of the EGR on the cycle-to-cycle variability of the engine torque has been experimentally investigated.