Search Results

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.

To mitigate the NOx emissions from diesel engines, the adoption of exhaust gas recirculation (EGR) has gained widespread acceptance as a technology. Employing EGR has the drawback of elevating soot emissions. Using hydrogen-enriched air with EGR in a diesel engine (dual-fuel operation), offers the potential to decrease in-cylinder soot formation while simultaneously reducing NOx emissions. The present study numerically investigates the effect of hydrogen energy share and engine load on the formation and emission of soot and NOx from hydrogen-diesel dual-fuel engines. The numerical investigation uses an n-heptane/H2 reduced reaction mechanism with a two-step soot model in ANSYS FORTE. A reduced n-heptane reaction mechanism is integrated with a hydrogen reaction mechanism using CHEMKIN to enhance the accuracy of predicting dual-fuel combustion in a hydrogen dual-fuel engine.

The influence of engine load and fuel premixing ratio (PMR) on unregulated emission from a methanol-diesel dual-fuel RCCI (MD-RCCI) engine is examined in this study. The study focuses on assessing the adverse effects of unregulated emissions (saturated HC, unsaturated HC, carbonyl compounds, aromatic hydrocarbon, NH3, and SO2) on the health of human beings and the environment. To quantify the effect on the environment, the greenhouse gas potential (GWPs), Eutrophication potential (EP), Acidification potential (AP), and Ozone forming potential (OFP) are calculated and presented. The cancer risk potential (CRP) of the carbonyl compounds (HCHO and CH3CHO) is calculated and presented to see the effect on human health. The results demonstrate that at lower engine load, with an increase in PMR, the OFP and CRP for MD-RCCI operation increase significantly, whereas AP, EP, and GWPs decrease. Additionally, with a rise in the load at a constant PMR, the AP, EP and OFP decrease significantly.

This study numerically investigates the toxicity potential of polycyclic aromatic hydrocarbon (PAHs) emitted from conventional diesel and hydrogen–diesel dual-fuel combustion engine. The simulations are performed on ANSYS Forte using a detailed chemical reaction mechanism of diesel surrogate (66.8% n − decane/33.2% alpha − methylnaphthalene). The used reaction mechanism consists of 189 species and 1392 reactions. The study numerically predicts the concentration of eight toxic PAHs (naphthalene, phenanthrene, acenaphthene, pyrene, chrysene, benzo[a]pyrene, benzo perylene, and benzo [g, h, i] perylene) emission for which carcinogenicity and mutagenicity potential is determined. Results demonstrate that hydrogen-diesel dual-fuel engine has lower carcinogenicity and mutagenicity potential than the conventional diesel engine.

Di-ethyl ether (DEE) belongs to the family of oxygenated fuels, which have been investigated as an alternative to conventional diesel. However, increasing the proportion of DEE in DEE-diesel blends changes its physicochemical properties. This work shows the non-evaporating and non-reacting spray characteristics of diesel, DEE20 (20% v/v DEE and 80% v/v diesel), and DEE40 (40% v/v DEE and 60% v/v diesel) were investigated. The effect of fuel injection pressure (FIP: 500 and 800 bar) on the spray morphology and droplet size distribution at different axial locations along the spray axis was done. FIP of 800 bar showed a reduction in Sauter mean diameter (SMD) of spray droplets with increasing axial distance due to improved spray atomisation because of the drag forces of the surrounding air on the fuel droplets. DEE20 showed a higher number of droplets having a smaller diameter than DEE40. DEE20 and DEE40 showed superior spray atomisation characteristics than diesel.

Considering the demand for sustainable transport, alternative fuels are a keen research topic for IC engine researchers. Among various alternative fuels being explored, Di-ethyl ether (DEE) is gaining popularity off-late for compression-ignition (CI) engines owing to its high cetane rating, oxygen presence in its molecular structure, and lower carbon content. This study explores the suitability of DEE blends in tractor engines. DEE blends [15% and 30% (v/v)] with diesel were compared with baseline diesel for combustion, and emission characterisation, keeping all parameters identical, including the fuel injection timings. Results were analysed for different engine loads at 1500 rpm. Delayed combustion was observed with DEE blends with diesel, possibly due to a higher cooling effect from DEE vaporisation and retarded dynamic fuel injection due to its higher compressibility. However, the DEE blend fuelled engine performance was comparable to baseline diesel.

The development of automotive engines continues to be determined by gradually more stringent emission norms including CO2 emissions and fuel consumption. To fulfill the simultaneous emission requirements for near-zero pollutants and low CO2 levels, several research studies are currently being carried out around the world on new engine combustion process, such as Homogeneous Charge Compression Ignition (HCCI). In HCCI engines, combustion rate, and ignition timing are dominated by physical and chemical properties of fuel/air/residual gas mixtures, boundary conditions including ambient temperature, pressure, and humidity, and engine operating conditions such as load, speed, etc. Higher cycle-to-cycle variations are observed in HCCI combustion engines due to the large variability of these factors. The cyclic variations in the HCCI engine are investigated on a modified four-stroke, four-cylinder engine. The HCCI combustion mode is tested with methanol fuel.

Homogeneous charged compression ignition (HCCI) engine is a low-temperature combustion (LTC) strategy with higher thermal efficiency and ultra-low NOx and particulate matter emission. Syngas is a renewable and clean alternative fuel that has gained researchers' interest, and it is one of the alternatives to fossil fuels. Syngas can be a suitable fuel for HCCI Engines due to their characteristics of high flame speed, lower flammability limits, and low auto-ignition temperatures. This paper presents the crank angle-based exergy analysis of syngas fuelled HCCI engines. Energy and exergy analysis is essential for the better performance and utilization of the HCCI engine. The syngas HCCI engine is numerically simulated in this study using a stochastic reactor model (SRM). In SRM models, physical parameters are described by a probability density function (PDF), and these parameters do not vary within the combustion chamber.

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.

The potential for simultaneous reduction of soot and NOx emissions and higher fuel conversion efficiency has already been demonstrated for reactivity-controlled compression ignition (RCCI) engines. The RCCI engine has a relatively higher peak pressure rise rate (PPRR) and cyclic variations compared to the conventional diesel engine. The upper and lower operating load boundaries of the RCCI engine are restricted by higher PPRR and cyclic variations, respectively. The cyclic variations in the air-fuel ratio are one of the main factors which govern the variations in combustion parameters. The cyclic variations in combustion need to be controlled for stable engine operation. The present study estimates the cyclic air-fuel ratio from the measured in-cylinder pressure data for the RCCI engine. The RCCI experiments are performed on a modified single-cylinder compression ignition (CI) engine equipped with a development ECU.

Engine design and selection of fuels for automotive applications are required to minimize noise and exhaust emissions without compromising fuel economy. The knocking combustion investigation is essential as it directly affects the performance and durability as well as the thermal efficiency of the engine. Several fuel additives were suggested in the previous studies to mitigate the knocking combustion in spark ignition (SI) engines. The present study reviews the effect of antiknock fuel additives such as ethanol, methanol, prenol, n-butanol, furan mixtures, etc., on knocking behavior in SI engines. Additionally, this paper aims to present a systematic review of the studies conducted to investigate the effect of EGR on the knocking in SI engines. The EGR is often considered an effective means to suppress knocking in SI engines. The thermal effect of EGR in controlling the knocking is well known as EGR affects the temperature and pressure history of the combustion chamber.

This study examines the cycle-to-cycle variations (combustion instability) in the dual-fuel stationary compression ignition engine. The variations in the consecutive engine cycles are characterized under different load, gasoline/methanol-diesel premixing ratio (rp) and diesel injection timing (SOI). To investigate the combustion instability in dual-fuel CI-engine, gasoline and methanol are used as a low reactivity fuel (LRF) and is fed in the modified intake manifold during the suction stroke. The tests are performed for different fuel rp using developed port-fuel injector controller in the laboratory. The combustion instability is analyzed using the statistical method and Wavelet Transform (WT). Results indicate that combustion instability is more prone to lower and medium engine load, and variations are significantly higher for the high substitution fraction of LRF. The upper limit of fuel rp is restricted by higher variations in the combustion parameters.

Homogenous charge compression ignition (HCCI) combustion emerged as a potential technique for reducing automotive pollution. Controlling the combustion timing at different engine operating conditions is one of the major challenges for the commercial application of HCCI combustion engines. To control HCCI ignition timing, it is often necessary to know the characteristics of HCCI cyclic variations. In this study, cyclic combustion variations in an HCCI engine are analyzed. Combustion stability and cycle-to-cycle variations of HCCI combustion parameters were investigated on a modified four-stroke diesel engine. The experiments were conducted by varying intake air temperatures and relative air-fuel ratios at constant engine speed. In the steady-state engine operating condition, in-cylinder pressure signals of 2000 consecutive engine combustion cycles are acquired for each test condition.

Mixture formation in GDI engine is considered crucial in determining combustion and emissions characteristics, which mainly depend on fuel spray quality. However, spray characteristics change with variations in control parameters such as fuel injection parameters, fuel injection strategy, engine operating conditions, and fuel properties. Growing research interest in the use of methanol as an additive with gasoline has motivated the need for deeper investigations of spray characteristics of these fuels. Although, it can be noted that sufficient literature is available in the area of spray characterization under several independent influencing factors, however, comparative analysis of gasohol spray behavior under different ambient conditions is hardly studied.

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.

Emission regulations mandate the measurement of solid particles of size greater than 23 nm according to UNECE informal working group particle measurement protocol (PMP). The volatile particles from the engine exhaust are removed by heating and dilution in a device according to the UNECE PMP program. The analysis of solid particles from diesel engines requires aerosol conditioning systems, which can effectively remove volatile particles/species with minimum solid particle losses. Currently, the regulations only allow using an evaporation tube for the measurement of solid particles. Different laboratories have also demonstrated other alternatives such as thermodenuder and catalytic stripper for measuring the solid ultrafine particles emitted from the diesel engine. This paper reviews the recent literature related to the thermodenuder and catalytic striper’s design and operating characteristics.

The rising concerns of emissions have put enormous strain on the automotive industry. Industry is, therefore looking for next-generation engines and advanced combustion technologies with ultra-low emissions and high efficiency. To achieve this, more insights into the combustion and pollutant formation processes in IC engines is required. Since conventional measures have not been insightful, in-situ measurement of combustion and pollution formation through optical diagnostics is being explored. Gaining full optical access into the diesel engine combustion chamber is a challenging task. The late-compression flow dynamics is not well understood due to limited access into the engine combustion chamber. These flow structures contribute immensely to fuel-air mixing and combustion. The objective of this study is to understand the role of combustion chamber design on vertical plane air-flow structures.

Cyclic variations are inherent in the combustion of internal combustion engines. However, extreme cyclic combustion variations limit the operation of spark-ignition (SI) engines, particularly at highly lean and diluted charge operation. Lean charge operation is desired due to its expected benefits in fuel efficiency and engine-out NOx and HC emissions. Studies suggested the existence of the low-dimensional deterministic nature of cyclic variations, which is essential from the perspective of designing a high-frequency controller. The lean limit of a SI engine operation may be extended by controlling the deterministic component of cyclic variations to meet the future strict emissions and fuel economy regulations. This paper presents a review of the evolution of the experimental and analytical understanding of cyclic combustion variations of spark-ignition engines.

Petroleum products are used to power internal combustion engines (ICEs). Emissions and depletion of petroleum reserves are important questions that need to be answered to ensure existence of ICEs. Indian Railways (IR) operates diesel locomotives, which emit large volume of pollutants into the environment. IR is looking for an alternative to diesel for powering the Locomotives. Methanol has emerged as a replacement for petroleum fuels because it can be produced from renewable resources as well as from non-renewable resources in large quantities on a commercially viable scale. It has similar/superior physico-chemical properties, which reduce tailpipe emissions significantly. It is therefore necessary to understand the in-cylinder phenomenon in methanol fueled engines before its implementation on a large-scale.

Alternative fuels, coupled with advanced engine technologies, are potential solutions to overcome energy crisis and environmental degradation challenges, that transport sector faces. Methanol has emerged as a potential candidate as an alternate fuel due to adequate availability of indigenous feedstocks, such as coal, biomass, and municipal solid waste (MSW). Policy makers of several countries are focusing on developing roadmap for methanol fueled vehicles, especially in developing countries like China and India. These countries have the largest two-wheeler market globally; therefore, methanol adaptability on 2-wheeler engine becomes important national priority. This study is aimed at feasibility assessment of methanol (M100) fueled two-wheeler engine using simulations. Present study was divided into four different phases.