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Reactivity controlled compression ignition (RCCI) engines are considered as a potent solution to realize near zero nitrogen oxides (NOx) and soot emission with higher thermal efficiency. However, operational control in RCCI engines is challenging, as events such as ignition and combustion phasing etc. are mostly decoupled from hardware induced start of injection. In modern control architecture, these real time data are internally computed using signals from cylinder pressure sensor (CPS). Lately, physics based control models or grey box models in RCCI engines were considered as a cost competitive and smart alternative to hardware signal source. In this work, an attempt was made to develop and compare physics based grey box model with data based neural networks, trained through supervised learning (or the black box models) to accurately predict dynamic combustion control parameters across five engine loads and incremental premix energy share not exceeding 60%.

The present study depicts cubic polynomial function based parametric mapping of reactivity controlled compression ignition (RCCI) engine, across load sweep and gasoline energy share (GES). Based on the pilot experimental findings, the diesel (main) injection timing is determined followed by a set of experiments across the engine load sweep and GES, not exceeding 50%. Based on cycle to cycle variation of peak pressure, 50% burn crank angle (CA50) and indicated mean effective pressure (IMEP), engine stability values are computed. A set of RCCI engine parameters such as peak pressure, ringing intensity (RI), IMEP, CA50 etc. are normalized. The coefficients of polynomial are generated through surface fit to map all these parameters with normalized load and GES. Good conformity was observed between the predicted and modelled data. Subsequently, an operation window is proposed based on stability, combustion efficiency and thermal efficiency considerations.

The present paper proposed a cycle to cycle prediction of in-cylinder pressure profile using double Wiebe function in a reactivity controlled compression ignition (RCCI) engine. RCCI engines lack direct control over combustion by means of any explicit hardware such as fuel injection or spark timing. Therefore, cylinder pressure sensor based control or model driven control is necessary for RCCI engines. In this work, an iterative algorithm to generate double Wiebe function parameters, were designed to model cycle average measured cylinder pressure. The model and measured data were in good agreement. However, when, this model was compared with measured cycles, the error and regression exhibited a near normal distribution. The quality of error and regression was found to deteriorate with premix energy share (ES) in RCCI mode due to higher cycle to cycle variations.

In the present work, a tuned gas dynamics based blow by model was used for prediction of thermodynamic state variables till start of combustion in a high speed diesel engine. The burn rate fraction was determined from experimental pressure trace using Rassweiller-Withrow method. Furthermore, suitable single and double Wiebe parameters, consistent with the experimental combustion behavior were determined statistically. The comparison with experimental heat release and burn rate fraction confirmed the unsuitability of single Wiebe function for diesel combustion. A stochastic zero-dimensional thermodynamic model was used to predict pressure traces for various load/fueling conditions. The results exhibited a sub-15% error margin between predicted and experimental pressure traces across all crank angles and fuelling rates. Finally, the model constants are proposed as a function of non-dimensional fuelling rate.

In the present experimental investigation, performance, emission and combustion characteristics of a single cylinder diesel engine using diesel-biodiesel blends and antioxidant containing biodiesel test fuels was carried out. The potential suitability of aromatic amine based antioxidants to enhance the oxidation stability of biodiesel on one hand and reduction of tail pipe oxides of nitrogen (NOx) on the other were evaluated. Tertiary Butyl Hydroquinone (TBHQ) was considered as the antioxidant and Calophyllum Inophyllum vegetable oil was taken as the feedstock for biodiesel production. The test fuel samples were neat diesel (D100), 10% and 20% blend of Calophyllum biodiesel with diesel (CB10 and CB20) and 1500 ppm of TBHQ in CB10 and CB20 (CBT10 and CBT20). The results indicated that neat biodiesel blended test fuels (CB10 and CB20) exhibited lower brake thermal efficiency compared to the diesel baseline by a margin of 3% to 10% at full load.

Use of diluting agents in neat vegetable oil to reduce its density and viscosity, is arguably the best alternative route for vegetable oil usage in diesel engines. It is suitable where the complex transesterification process for biodiesel production is not feasible. In this study, Calophyllum vegetable oil was diluted with 10%, 20% and 30% by volume of Isopropyl alcohol and named as CI10, CI20 and CI30 respectively. Neat diesel was termed as D100. An exhaustive field trial on a single cylinder agricultural diesel engine indicated that full load brake thermal efficiency of D100 was 26.4% followed by CI10, CI20 and CI30 test fuels. Emissions of carbon monoxide, hydrocarbons and smoke were impressively reduced by a margin of 17-63% for the isopropyl alcohol containing test fuels as compared to the diesel baseline. However, oxides of nitrogen emissions were marginally higher for the isopropyl alcohol blends.

In the present study, ethanol was added in lower proportions to non-edible vegetable oil “Schleichera oleosa” or “Kusum”, to evaluate various performance and emission characteristics of a single cylinder; diesel engine. For engine's trial, four samples were prepared with 5%, 10%, 15% and 20% ethanol in kusum oil (v/v) and the blends were named as E5K95, E10K90, E15K85 and E20K80 respectively. Neat Kusum oil was named as K100. The results indicated that brake thermal efficiency (BTE) was found to increase with increase in volume fraction of ethanol in the kusum oil. E5K95, E10K90, E15K85 and E20K80 test fuels exhibited maximum BTE of 25.4%, 26.4%, 27.4% and 27.7% respectively as compared to 23.6% exhibited by the neat Kusum oil. Similarly, full load brake specific energy consumption (BSEC) decreased from 16.3MJ/kWh in case of neat Kusum oil to 15.1MJ/kWh for E20K80 with an almost linear reduction pattern with increased ethanol composition in the test fuel.

Biodiesel from non-edible vegetable oils is of paramount significance in India due to insufficient edible oil production. The present work deals with relatively underutilized non-edible oil “Schleichera oleosa” or “Kusum”. The Kusum biodiesel (KB) was produced using a two stage esterification cum transesterification process as the free fatty acid content of the oil was high. Important physico-chemical properties were evaluated and they were found to conform with corresponding ASTM/EN standards. Various test fuels were prepared for the engine trial by blending 10%, 20%, 30% and 40% of KB in diesel by volume and were named as KB10, KB20, KB30 and KB40 respectively. The results showed that full load brake thermal efficiency was dropped by 3.8% to 17% with increase in KB composition in the test fuel. Diesel (D100) showed the maximum full load brake specific energy consumption followed by KB10, KB20, KB30 and KB40.

Dwindling petroleum reserves and alarming level of air pollution has been an issue of great concern in recent times and researchers across the world are experimenting on variety of renewable fuels for meeting the future energy demands. Within the gamut of alternative fuels, biofuels are the most promising and have the potential to mitigate climate change and lease a new life to existing IC engines. The vegetable oils are having immense potential in this context and have been used either in neat or modified form by large number of researchers. Jatropha curcus is a perennial plant and bears non edible oil. The plant is drought tolerant and has been cultivated all over the arid and semi-arid areas for reforestation. In the present study, blends of jatropha oil and ethanol have been prepared in 5, 10, 15 and 20% (v/v) and evaluation of important properties of blends has been carried. The results show that properties are quite similar to diesel fuel.

Phenomenal industrial activities worldwide in the last couple of centuries have resulted in indiscriminate use of conventional energy resources and environmental degradation. The consumption of petroleum-derived fuels has increased exponentially due to enhanced mobility and also caused serious threat to earth's eco-system. The need to explore variety of alternative fuels in transportation sector has been the subject of research all over the world. In this context, alcohols like butanol and isopropyl alcohol seem to present a viable option for potential application in diesel engines. In the present investigation, 5%, 10%, 15%, 20% (v/v) blends of isopropyl alcohol and diesel was prepared. The various blends were found to be homogenous and stable. The exhaustive engine trials were carried out on a single-cylinder unmodified diesel engine. The results suggest significant reduction in emission of oxides of nitrogen (NOx for various blends as compared to baseline data of diesel.

Ever increasing consumption of petroleum derived fuels has been a matter of grave concern due to rapidly depleting global reserves and alarming levels of emissions leading to global warming and climate change. Exhaustive research has been carried out globally to evaluate the suitability of variety of renewable fuels for internal combustion engine applications. Amongst them, vegetable oil methyl esters or biodiesel seem to be a promising alternative for diesel in vital sectors such as transportation, industrial and rural agriculture. For quite some time, the focus for production of biodiesel has shifted towards non-edible oil feedstock from the edible ones, mostly due to food security issues. One such non-edible oil, locally known as Mahua in Indian subcontinent, is a very promising feed stock for biodiesel production. In the present investigation, 5%, 10%, 15% and 20% (v/v %) blends of mahua oil methyl ester (MOME) and diesel were prepared.