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This paper presents the experimental investigation of combustion stability and nano-particle emissions from the CNG-diesel RCCI engine. A modified automotive diesel engine is used to operate in RCCI combustion mode. An open ECU is used to control the low and high reactivity fuel injection events. The engine is tested for fixed engine speed and two different engine load conditions. The tests performed for various port-injected CNG masses and diesel injection timings, including single and double diesel injection strategy. Several consecutive engine cycles are recorded using in-cylinder combustion pressure measurement system. Statistical and return map techniques are used to investigate the combustion stability in the CNG-diesel RCCI engine. Differential mobility spectrometer is used for the measurement of particle number concentration and particle-size and number distribution. It is found that advanced diesel injection timing leading to higher cyclic combustion variations.

New combustion concepts developed in internal combustion engines such as homogeneous charge compression ignition (HCCI) have attracted serious attention due to the possibilities to simultaneously achieve higher efficiency and lower emissions, which will impact the environment positively. The HCCI combustion concept has potential of ultra-low NOX and particulate matter (PM) emission in comparison to a conventional gasoline or a diesel engine. Environmental Legislation Agencies are becoming increasingly concerned with particulate emissions from engines because the health and environmental effects of particulates emitted are now known and can be measured by sophisticated instruments. Particulate emissions from HCCI engines have been usually considered negligible, and the measurement of mass emission of PM from HCCI combustion systems shows their negligible contribution to PM mass. However some recent studies suggest that PM emissions from HCCI engines cannot be neglected.

Homogeneous charge compression ignition (HCCI) engines are attracting attention as next-generation internal combustion engines mainly because of very low NOx and PM emission potential and excellent thermal efficiency. Particulate emissions from HCCI engines have been usually considered negligible however recent studies suggest that PM number emissions from HCCI engines cannot be neglected. This study is therefore conducted on a modified four cylinder diesel engine to investigate this aspect of HCCI technology. One cylinder of the engine is modified to operate in HCCI mode for the experiments and port fuel injection technique is used for preparing homogenous charge in this cylinder. Experiments are conducted at 1200 and 2400 rpm engine speeds using gasoline, ethanol, methanol and butanol fuels. A partial flow dilution tunnel was employed to measure the mass of the particulates emitted on a pre-conditioned filter paper.

The homogeneous charge compression ignition (HCCI) combustion process is capable of providing both high ‘diesel-like’ efficiencies and very low NOx and particulate emissions. However, among several technical challenges, controlling the combustion phasing, particularly during transients is a major issue, which must be resolved to exploit its commercial applications. This study is focused on the experimental investigations of behavior of combustion timing and other combustion parameters during startup and load transients. The study is conducted on a gasoline fuelled HCCI engine by varying intake air temperature and air-fuel ratio at different engine speeds. Port fuel injection technique is used for preparing homogeneous mixture of gasoline and air. For fueling startup transient test, fuel injection was turned off, and the engine was motored for several minutes until the fire-deck, intake and exhaust temperatures stabilized.

Diesel engines are lucrative in terms of high thermal efficiency and low specific fuel consumption. The major drawbacks of these engines are high NOx and particulate matter (PM) emissions due to heterogeneous combustion. In the current emissions norms (BS-VI), a limit for particle number concentration is also introduced. There are few numerical studies investigating the soot particle size and number characteristics at different engine operating conditions. In this work, a parametric numerical study is conducted to investigate the effect of engine operating parameters on PM characteristics such as number density, size, and volume fraction. Simulations were performed using the Reynolds Averaged Navier Stokes equation with renormalization group K-ε turbulence model available in ANSYS FORTE CFD software.

Increase in the air pollution has driven the research towards the cleaner combustion technology for reciprocating engines. To tackle the challenge of the trade-off between the NOx and soot emissions from a conventional diesel engine, premixed low-temperature combustion (LTC) strategies are potential technologies. Among the LTC strategies, reactivity controlled compression ignition (RCCI) strategy has a better combustion phasing control along with higher fuel conversion efficiency and lower NOx and soot emissions. The present study investigated the nano-particle emissions from RCCI engine fueled with a port injection of gasoline/methanol (low reactivity fuel) and direct injection of diesel (high reactivity fuel). The RCCI combustion experiments were performed on a modified single cylinder compression ignition engine with development ECU. The mass of injected fuel per stroke for the port as well as the direct injection is controlled through ECU.

This study presents the experimental investigation of performance, combustion, gaseous and nano-particle emission characteristics of conventional compression ignition (CI) engine fueled with neat diesel and butanol/diesel blends. The experiments were conducted for neat diesel, 10%, 20% and 30% butanol/diesel blend on the volume basis at different engine loads. Combustion characteristics were investigated on the basis of in-cylinder pressure measurement and heat release analysis. The in-cylinder combustion pressure traces were recorded for 2000 consecutive engine combustion cycles for computation of heat release and different combustion parameters. Combustion stability analysis is conducted by analyzing the coefficient of variation of in indicated mean effective pressure (IMEP) and total heat release (THR). Wavelet analysis is also used for analyzing the temporal variations in IMEP data series.

Research in the utilization of hydrogen and syngas has significantly increased due to their clean-burning properties and the prospect of production from several renewable resources. Homogeneous charge compression ignition (HCCI) engine is low-temperature combustion (LTC) concept which combines the best features of conventional spark-ignition (SI) and compression-ignition (CI) engines. HCCI combustion engine has shown the potential for higher efficiency and ultralow NOx and soot emissions. In this study, syngas fueled HCCI combustion is simulated using stochastic reactor model (SRM) with a detailed chemical kinetic mechanism (32 species and 173 reactions). Detailed syngas oxidation mechanism included NOx reactions also. In SRM models physical parameters are described by a probability density function (PDF). These parameters does not vary within the combustion chamber, and thus the spatial distribution (due to local inhomogeneity’s) of the charge is represented in terms of a PDF.

Automotive engines produce pollutant species which has the potential to damage human health as well as the environment. The toxicity potential of these species depends on the concentration, route, and exposure time. Toxicity studies are required in the current scenario due to increased pollution levels by vehicles used for transportation. This study is a review focused on the toxicity analysis of particulate, elemental (particle associated as soot), and organic carbon (organic fraction, PAHs) emission from the internal combustion engine with conventional and alternative fuels like biodiesel and alcohol. The study is focused on the formation, characterization, and quantification of particulate matter, elemental and organic carbon, and their effect on human health. The other part of the study is focused on mutagenicity (mutation in DNA) and cytotoxicity (cell toxicity) of the particulate emitted from the engines.

This study experimentally investigates the combustion stability in RCCI engines along with the gaseous (regulated and unregulated) and particle emissions. Multifractal analysis is used to characterize the cyclic combustion variations in the combustion parameters (such as IMEP, CA50, and THR). This analysis aims to investigate the multifractal characteristics of the RCCI combustion mode near the misfiring limit. The investigation is carried out on a modified single-cylinder diesel engine to operate in RCCI combustion mode.The RCCI combustion mode is tested for different diesel injection timing (SOI) at fixed engine speed (1500rpm) and load (1.5 bar BMEP). The particle number characteristics and gaseous emissions are measured using a differential mobility spectrometer (DMS500) and Fourier Transform Infrared Spectroscopy (FTIR) along with Flame Ionizing Detector (FID), respectively.