Mohit Raj Saxena

Experimental Investigation of Cyclic Variation in a Diesel Engine Using Wavelets

In this study, cyclic variations of combustion parameters (IMEP and THR) are analyzed using morlet wavelet transform in a diesel engine. Experiments were conducted at 1500 rpm for different engine load conditions and compression ratios. Combustion parameters were calculated from measured cylinder pressure trace. In-cylinder pressure data of 2500 consecutive engine cycles were acquired and processed for the analysis of cyclic variations. Results revealed that cyclic variability in THR decreases with increase in engine load and compression ratio. Cyclic variability is highest in idle load conditions at lowest compression ratio. Low frequency cyclic variations are observed at low loads conditions and with increase in engine load variations shift to high frequency range. Results can be utilized for the development of effective engine control strategies.

Optimization of engine operating conditions and investigation of nano-particle emissions from a non-road engine fuelled with butanol/diesel blends

ABSTRACT This study presents the experimental investigation of performance and emission characteristics (including nano-particle emissions) of a non-road diesel engine fuelled with neat diesel and butanol/diesel blends. Experiments were performed at optimal engine operating conditions for a constant engine speed of 1500 rpm. To find the optimal engine operating conditions, first experiments were conducted using diesel fuel. Engine operating parameters were optimized for higher brake thermal efficiency and lower exhaust emissions (i.e. gaseous as well as nano-particle emissions). Taguchis design of experiment was used to optimize the compression ratio, injection pressure and engine operating load. To investigate the effect of butanol blends on the performance and emissions characteristics, experiments were conducted at three different butanol/diesel blend ratios (i.e. 10, 20 and 30% of butanol by volume) at optimum engine operating conditions. Results indicate that butanol/diesel blends have the potential to reduce CO, NO and particle emissions. The results also revealed that the concentration of ultrafine particle number reduces with diesel/butanol blends for all tested load conditions. The highest reductions in total particle number concentration for all butanol blends were found at 25% and 50% engine load conditions, as compared to neat diesel.

Investigation of Effect of Butanol Addition on Cyclic Variability in a Diesel Engine Using Wavelets

This study focuses on the experimental investigation of the cyclic variations of maximum cylinder pressure (Pmax) in a stationary diesel engine using continuous wavelet transform. Experiments were performed on a stationary diesel engine at a constant speed (1500 rpm) for low, medium and high engine load conditions with neat diesel and butanol/diesel blends (10%, 20%, and 30% butanol by volume). In-cylinder pressure history data was recorded for 2000 consecutive engine operating cycles for the investigation of cyclic variability. Cyclic variations were analyzed for maximum cylinder pressure. The results indicated that variations in the Pmax is highest at lower load condition and decreases with an increase in the engine load. Global wavelet spectrum (GWS) power decreases with an increase in the engine operating load indicating decrease in cyclic variability with the engine load. The results also revealed that lower cyclic variations obtained with butanol/diesel blends in comparison to neat diesel.

Characterization of Ringing Operation in Ethanol-Fueled HCCI Engine Using Chemical Kinetics and Artificial Neural Network

The homogeneous charge compression ignition (HCCI) strategy is an advanced engine combustion concept having higher thermal efficiency while maintaining the NO x and soot emission to an ultra-low level. Intense ringing operation in HCCI engine is one of the major challenges at high engine load conditions, which limit the HCCI engine operation range and can also damage engine parts. Ethanol is a promising alternative to conventional fuel, especially for utilization in advanced engine combustion modes such as HCCI. This chapter presents the overview of HCCI combustion along with its numerical simulation using stochastic reactor model. This chapter also presents detailed characterization of ringing operation, and HCCI operating range of ethanol-fueled HCCI engine. Ringing operation is typically characterized by either ringing intensity or peak pressure rise rate (PPRR). Characterization of PPRR and its prediction using artificial neural network (ANN) in ethanol-fueled HCCI engine is also presented. The ANN model is of utility to identify engine operating limits to avoid the ringing operation.

Characterization of Cycle-to-Cycle Variations in Conventional Diesel Engine Using Wavelets

Higher cycle-to-cycle variations in combustion engines lead to efficiency losses, engine roughness, lower power output, and higher exhaust emissions. Cycle-to-cycle variations in combustion engines are typically characterized by several techniques such as statistical method, symbol sequence statistics, chaotic methods, and wavelet analysis. Each strategy for cyclic variation characterization has its benefits and limitations depending on the application. Wavelet transform has a potential to analyze non-stationary signal in time domain as well as frequency domain simultaneously. This strategy has better temporal and spectral resolution; thus, wavelet analysis can be used to analyze the periodicities as well as magnitude of variations in the engine combustion cycles. This chapter presents the characterization of cycle-to-cycle variations in conventional diesel engine using statistical technique as well as wavelet technique. Cyclic variations in various combustion parameters (such as indicated mean effective pressure, total heat release rate, and peak pressure) are discussed in diesel engine operated at different operating conditions with diesel as well as butanol/diesel blends. Typically, cyclic variations in indicated mean effective pressure, peak pressure, and total heat release rate are found higher at lower engine loads and decrease with increase in engine load.

Performance, Combustion, and Emissions Characteristics of Conventional Diesel Engine Using Butanol Blends

Energy security concern and stringent emission legislations norms demand a clean and high fuel conversion efficiency engines. Diesel compression ignition (CI) engines are more preferred over the spark-ignition (SI) engines in commercial applications due to their higher fuel conversion efficiency. Present chapter focuses on the effect of butanol addition in the diesel fuel on the combustion and emissions characteristics of a diesel engine. Butanol has inimitable properties, which makes it more suitable candidate fuel for diesel engine in comparison to other alcohol fuels such as ethanol and methanol. Combustion characteristics of the engine are analyzed from heat release analysis of measured in-cylinder pressure data at different engine operating conditions. Combustion stability is also discussed with respect to diesel engine operation with butanol blends. Carbon monoxide (CO), unburned hydrocarbons (HC), and nitrogen oxides (NOx) emission characteristics of diesel engine using butanol blends are discussed in this chapter. Special emphasis is placed on the discussion of particulate emission (soot particle numbers) in diesel engine with butanol blends.

Chemical Kinetic Simulation of Syngas-Fueled HCCI Engine

Energy safety concern and depletion of fossil fuel resources lead towards the investigation of an efficient and clean alternative combustion strategy as well as renewable biofuels. Homogeneous charge compression ignition (HCCI) engine has demonstrated the potential for higher thermal efficiency along with simultaneous reduction of NO x and PM emissions to ultra-low level. Syngas is a potential alternative fuel. Syngas-fueled HCCI engine combines the advantages of advanced combustion strategy and biofuels. This chapter provides the overview of HCCI combustion and its chemical kinetic simulation using stochastic reactor model (SRM). This chapter also presents the comparative analysis of performance of various syngas reaction mechanisms in the HCCI engine at different inlet temperature and equivalence ratio using stochastic reactor model. For validating the reaction mechanisms, experimental in-cylinder pressure data is compared with the numerically simulated data. Syngas reaction mechanism CRECK-2014 (consisting of 32 species and 173 reactions) is found suitable for syngas-fueled HCCI combustion simulation.

Effect of compression ratio, nozzle opening pressure, engine load, and butanol addition on nanoparticle emissions from a non-road diesel engine

Currently, diesel engines are more preferred over gasoline engines due to their higher torque output and fuel economy. However, diesel engines confront major challenge of meeting the future stringent emission norms (especially soot particle emissions) while maintaining the same fuel economy. In this study, nanosize range soot particle emission characteristics of a stationary (non-road) diesel engine have been experimentally investigated. Experiments are conducted at a constant speed of 1500xa0rpm for three compression ratios and nozzle opening pressures at different engine loads. In-cylinder pressure history for 2000 consecutive engine cycles is recorded and averaged data is used for analysis of combustion characteristics. An electrical mobility-based fast particle sizer is used for analyzing particle size and mass distributions of engine exhaust particles at different test conditions. Soot particle distribution from 5 to 1000xa0nm was recorded. Results show that total particle concentration decreases with an increase in engine operating loads. Moreover, the addition of butanol in the diesel fuel leads to the reduction in soot particle concentration. Regression analysis was also conducted to derive a correlation between combustion parameters and particle number emissions for different compression ratios. Regression analysis shows a strong correlation between cylinder pressure-based combustion parameters and particle number emission.

Impact of Fuel Premixing Ratio and Injection Timing on Reactivity Controlled Compression Ignition Engine

Stringent emission mandates and harmful effect of engine emissions on human health as well as environment has driven the research into alternative combustion strategy for internal combustion engines. Low temperature combustion (LTC) concept is a promising approach to achieve higher fuel conversion efficiency along with lower NOx and particulate emissions. Among all the LTC strategies, reactivity controlled compression ignition (RCCI) strategy has potential to mitigate the limitations of conventional diesel combustion (CDC) engines. This study provides an overview of different LTC concepts and demonstrates the benefits of the RCCI combustion strategy over other LTC strategies. In present study, the impact of the fuel premixing ratio and fuel injection timing of high reactivity fuel on the combustion and emission characteristics of RCCI engine is investigated. Proportion of fuel premixing and injection events affect the combustion and emission characteristics of RCCI engine. Study shows that the RCCI engine has a lower operating range as compared to CDC strategy, which can be extended by using optimized premixing ratio and fuel injection events. Results show that RCCI combustion strategy has lower NOx and soot emissions as compared to CDC strategy while maintaining higher thermal efficiency. However, RCCI combustion has a higher HC and CO emissions.