Combustion Noise Analysis for Combustion and Fuels Diagnosis of a CI Diesel Engine Operating with Biodiesels

In this paper, the combustion noise of a compression ignition (CI) diesel engine operating with biodiesels has been investigated experimentally. It aims to explore an effective method for combustion process monitoring and fuel quality evaluation through analysing the characteristics of the engine combustion noise. The experiments were conducted on a four-cylinder, four-stroke, direct injection and turbocharged diesel engine fuelled with biodiesels (B50 and B100) and normal pure diesel, and operating under different loads and speeds. The signals of cylinder head vibration, engine noise and in-cylinder pressure were measured during the tests. A coherent power spectrum analysis method was used to investigate the vibration and noise signals that related to the combustion process. The results shown that the noise components at the frequency band of 2 -3 kHz are closely related to the combustion process. Subsequently, the Wigner-Ville distribution is employed to present the energy distribution of engine noise in the time-frequency domain. Then a band-pass filter based on fractional Fourier transform (FRFT) is developed to extract the main component of the combustion noise for feature extraction. The results show that the sound pressure levels (SPLs) of the extracted combustion noise of the test diesel engine fuelled with biodiesels are higher than that fuelled with diesel. This is also identical to the variation of in-cylinder pressure. The results demonstrate that the features of the extracted combustion noise can indicate the combustion characteristics and provide useful information for monitoring the combustion process and evaluating the fuel quality of diesel engines

Identification of acoustic emission sources in machinery; application to injection/combustion processes in diesel engines

The high temporal resolution of Acoustic Emission offers great promise in the on-line monitoring of complex machines such as diesel engines. The fuel injection process is one of the most important processes in the diesel engine and its timing and fuel delivery control are critical in combustion efficiency. In this work, the phenomena leading to the generation of acoustic emission during injection are investigated by simulation of the injection process in a specially designed rig and through test in running engines on a test-bed. Signal processing approaches are devised to produce diagnostic indicators for the quality of the injection process. The novelty of the research lies in; 1) obtaining a coherent set of data which allows the separation of the part of the signal associated with injection in a given cylinder from other sources adjacent in time and space, and 2) in developing a signal processing approach which allows this separation to be achieved on line using an array of sensors. As such, the research is generic to multi-source multi-sensor analysis in machines. A series of experiments were performed on an experimental injector rig, and two-stroke and four-stroke diesel engines under different operating conditions. The injector rig experiments provided useful information on the characteristic signatures of the injection events, finding which could be implemented to the more complex signal from the running engines. A number of sensor arrays (sets of two and three sensors) were used on two types of four-stroke engine at different running speeds to investigate the source identification of the injection events, the essential strategy being to add complexity to the information in the AE record by using engines of varying degrees of mechanical sophistication. It has been concluded that the AE signals are generated by the mechanical movements of the components in the pump and injector as well as aspects of the fuel flow through the injector and the piping. Also, it is found that the temporal structure of the AE is highly sensitive to sensor position, and that transmission path differences to a sensor array are generally large enough to allow source separation. Applying a purpose-designed thresholding technique, followed by canonical correlation allows the separate identification of parts of the AE signal in the short crank angle widow where sources involved in injection, inlet valve opening and combustion are operating

THE INTERACTION BETWEEN UNBURNT HYDROCARBONS AND SOOT IN DIESEL EXHAUSTS

The potential health risk of diesel particulate (DP) has stimulated research into its physical and chemical composition. Its interaction with unburnt hydrocarbons (UHC) at exhaust temperatures was studied (i.e. composition and microstructure), at varying engine conditions. A hot whole exhaust filtration system was developed to collect DP on Pallflex TX-40 PTFE coated filters (for minimal artefact formation) down the exhaust of a Ricardo E6/T IDI diesel engine. Electron microscopy (SEM and TEM) and a gravimetric BET method determined particle size, specific surface area (SSA) and pore character. An in vacuo gravimetric thermal degassing (TD) apparatus was constructed to extract adsorbed volatiles (filter extractable sample - FES). The volatile FES was trapped and analysed by gas chromatography and identified as fuel and oil derived UHC's. Ultrasonic and soxhlet extraction techniques were employed for comparison studies. DP are graphitic carbonaceous aggregates of 30-40nm mean particle diameter. Structural analysis indicated that slit-shaped pores (Type II isotherm) were formed between crystallite layers. Highly adsorbed pore-bound FES fractions were identified (fuel i n ultramicropores, 0.355-lnm; fuel/oil in supermicropores, 1-2nm), trapped by overlapping crystallite van der Waal's fields. Engine load influenced micropore adsorption and DP SSA. High loads with high combustion temperatures, efficiently pyrolysed fuel, producing DP with little adsorbed FES and SSA's of 100m² /g. Low loads with lower in-cylinder temperatures, formed less DP and more fuel survived, producing soots of low SSA(<20m² /g). Between aggregated particles, 'ink-bottle' mesopores (2-50nm) were evident (Type IV isotherm) where fuel FES was weakly adsorbed by temperature dependent chemical scavenging as exhaust temperature declined , reducing SSA and increasing particle size. Thermal degassing was more efficient than soxhlet or ultrasonic extraction methods, because the solvent methods failed to penetrate the smallest pores. TD increased soot SSA, greatest for low load samples (by 200m²/g) compared to high load samples (by 50m² /g). TD was highly advantageous for DP extraction and allowed progressive removal of volatiles. A modern DI engine showed structurally similar soots, but the lower DP emissions produced high relative %FES for all engine conditions giving low SSA's. The research findings are related to cylinder and environmental processes for engineers and environmental scientists to improve control strategies.PERKINS TECHNOLOGY BUSINESS PETERBOROUGH CAMBRIDGESHIR

Noise and vibration analysis in the diesel engine based on biodiesel usage

Utilization of biodiesel has become one of the major interests in substituting fossil fuel parallel to the implementation of green technology which emphasizes the products to be more environmental-friendly. Nevertheless, despite having various kinds of biodiesel, this does not ensure suitability since the usage could improve or aggravate the engine due to higher combustion effects that further influence the higher level of engine noise and vibration, albeit major modification on the engine is not required. Therefore, this study had been conducted by experimental analysis to investigate the relation of noise and vibration level with biodiesel as a substitution fuel in the single cylinder, direct-injection diesel engine produced from various biodiesel blends, engine speed and engine load. The Root Mean Square (RMS) velocity, Sound Intensity Mapping (SIM) together with Sound Power Level (SPL) analyses were used to indicate the effectiveness of biodiesel in the attenuation of the noise and vibration level generated by the diesel engine. D100, B5, B10 and B20 of Palm Oil Methyl Ester (POME) had been utilized to operate the engine by 1200 to 2160 RPM with the application of engine load varied from 0 to 28 Nm. The measurement of the vibration data was done using the uniaxial accelerometer, while for the noise emission data, a pair of ½ inch of microphones were used. In the vibration aspect, the usage of the B20 blend was found to be the lowest level in almost all conditions tested due to the higher cetane number and oxygen content while the B5 and B10 usage tend to increase the vibration level compared to D100. It also can be noticed that the increment of engine load significantly increases the vibration level while increasing the engine speed does not influence the vibration to be higher since an incomplete combustion occurred which led to a reduction in the rate of pressure rise, thus reducing the vibration level in higher engine speed. In the noise emission analysis, the competitiveness between B20 and D100 could be seen in the low engine speed, where the lowest noise level was obtained by B20 while in the high engine speed, the lowest was obtained by D100. On top of that, the highest location of noise source was recorded at the cylinder head, crank-link components, radiator, flywheel and dynamometer. As can be concluded, the usage of POME as a biodiesel could be owed to the lower vibration and partially reducing the noise generated by the engine. Also, the most significant parameter that could contribute to the decrement of the level was the blend ratio followed by the engine load and engine speed

Diesel Engine

Diesel engines, also known as CI engines, possess a wide field of applications as energy converters because of their higher efficiency. However, diesel engines are a major source of NOX and particulate matter (PM) emissions. Because of its importance, five chapters in this book have been devoted to the formulation and control of these pollutants. The world is currently experiencing an oil crisis. Gaseous fuels like natural gas, pure hydrogen gas, biomass-based and coke-based syngas can be considered as alternative fuels for diesel engines. Their combustion and exhaust emissions characteristics are described in this book. Reliable early detection of malfunction and failure of any parts in diesel engines can save the engine from failing completely and save high repair cost. Tools are discussed in this book to detect common failure modes of diesel engine that can detect early signs of failure

Theoretical and experimental investigation of a CDI injection system operating on neat rapeseed oil - feasibility and operational studies

This thesis presents the work done within the PhD research project focusing on the utilisation of plant oils in Common Rail (CR) diesel engines. The work scope included fundamental experimental studies of rapeseed oil (RSO) in comparison to diesel fuel, the feasibility analysis of diesel substitution with various plant oils, the definition and implementation of modifications of a common rail injection system and future work recommendations of possible changes to the injection system. It was recognised that neat plant oils can be considered as an alternative substitute for diesel fuel offering a natural way to balance the CO2 emissions. However, due to the differences between diesel and plant oils, such as density, viscosity and surface tension, the direct application of plant oils in common rail diesel engines could cause degradation of the injection process and in turn adversely affect the diesel engine’s performance. RSO was chosen to perform the spray characterisation studies at various injection pressures and oil temperatures under conditions similar to the operation of the common rail engine. High speed camera, Phase Doppler Anemometry and Malvern laser techniques were used to study spray penetration length and cone angle of RSO in comparison to diesel. To study the internal flow inside the CR injector the acoustic emission technique was applied. It was found that for oil temperatures below 40°C the RSO viscosity, density and surface tension are higher in comparison to diesel, therefore at injection pressures around 37.50 MPa the RSO spray is not fully developed. The spray penetration and cone angle at these spray conditions exhibit significant spray deterioration. In addition to the lab experiments, KIVA code simulated RSO sprays under CR conditions. The KH-RT and RD breakup models were successfully applied to simulate the non-evaporating sprays corresponding to the experimental spray tests and finally to predict i real in-cylinder injection conditions. Numerical results showed acceptable agreement with the experimental data of RSO penetration. Based on experimental and numerical results it was concluded that elevated temperature and injection pressure could be the efficient measures to overcome operational obstacles when using RSO in the CR diesel engine. A series of modifications of low- and highpressure loops was performed and experimentally assessed throughout the engine tests. The results revealed that the modifications allowed to run the engine at the power and emission outputs very close to diesel operation. However, more fundamental changes were suggested as future work to ensure efficient and trouble-free long-term operation. It is believed that these changed should be applied to meet Euro IV and V requirements

Investigations of a Surrogate Fuel Based on Fischer-Tropsch GTL and CTL in CVCC, IDI and DI Compression Ignition Engines

With the increase in availability, feedstocks, and properties of alternative fuels, compatibility issues emerge between current engine platforms often requiring a limit on the blend percentage of alternative fuel in conventional fuel or alteration to the engine platform. Two key metrics were identified, autoignition quality and lubrication characteristics, as vital for the proper function of a compression ignition engine, and if the blend of alternative fuels matches these two criteria for the diesel standard, then the resulting blend percentage can be considered as a viable alternative for complete replacement of conventional petroleum ULSD. Autoignition quality was matched using blends S-8, DCN 62, and IPK, DCN 26, with three blends labeled as B1, B2, and B3. A modified DCN equation was then derived for the F-T fuels based on measured ID, CD, and DCN. The results of which determined that a 60% S-8 and 40% IPK blend percentage match the DCN set point of 50 and denoted in the text as S1. The lubricity investigation found that a 3% of a biodiesel compound, methyl oleate, improved average friction force and wear scar depth to within 1% of ULSD. This final surrogate blend is denoted as S2 for the duration of this study. All researched neat fuels and blends were investigated in the CVCC for LTHR, NTC, HTHR, peak pressure ringing, and energy released and duration of each combustion region. The analysis of peak pressure ringing indicated an increase in combustion stability for S2 when compared to ULSD. The LTHR analysis revealed that S2 has a much longer NTC region when compared to ULSD despite its increase in DCN. Three representative fuels were chosen for further investigation in both dual combustion chamber indirect injection and common rail direct injection engine platforms: ULSD (baseline), S2, and IPK. In both engines, the combustion of S2 resulted in a reduction in ringing intensity, BSFC, NOx emissions, CO2 emissions. No significant differences were found in peak pressure, peak pressure rise rate, or combustion phasing between the combustion of S2 and the combustion of ULSD indicating its high viability as a functional drop-in fuel replacement

The Investigation of CNG Dual-Biodiesel fuel Approach to Address the Performance - Emission Assisted Multipurpose Diesel Engine

AbstractDiesel engines can operate on a variety of the different fuels such as diesel fuel derived from crude oil, natural gas and biodiesel. Nowadays, the price of compress natural gas (CNG) and biodiesel is cheaper than diesel fuel since it is a potential advantage to use a combined CNG and biodiesel for multipurpose diesel engine. The aims of this work were to investigate the efficiency and emission from the multipurpose diesel engine. In the experiments, the fuel used in a combustion chamber was diesel, biodiesel derived from waste cooking oil (B100) and combined B100 and CNG. Effect of the various ratios of CNG (10, 20 and 30%), engine load (25, 50 and 75%) and exhaust gas recirculation (EGR: 0, 10 and 20%) were also investigated. Based on these experiments, the brake thermal efficiency decreased with an increase in CNG ratio. However, the brake thermal efficiency increased with an increase in the engine load. When the CNG ratio in a combustion chamber increased, the hydrocarbon concentration and Smoke number (SN) increased whereas the nitrogen oxide decreased. In term of exhaust gas recirculation (EGR), the use of EGR was not significant effect to brake thermal efficiency for various fuels. However, the increasing of EGR and CNG ratio led to an increase in hydrocarbon, carbon monoxide and Bosch smoke number. It should be noted that the nitrogen oxide decreased with an increase in EGR and CNG ratio

Online Big-Data Monitoring and Assessment Framework for Internal Combustion Engine with Various Biofuels

As the primary power source for automobiles, the internal combustion (IC) engines have been widely used and served millions of people worldwide. With increasingly stringent environmental regulations, biofuels have been obtained more attentions and are being used as alternative fuel to power IC engines. However, there are currently no standard solutions or well-established monitoring and assessment methods that can effectively evaluate the IC engine’s performance with biofuels. The expectation for biofuels is to keep the engine’s lifetime as long as the conventional fuels, or even longer. Otherwise, their usage would be unnecessary because they would reduce the lifecycle of the engine and also cause more waste and pollution. To address this challenge, we initially designed two biofuels: waste cooking oil biofuel (WCOB) and lamb fat biofuel (LFB). Then we proposed an online big-data monitoring and assessment framework for IC engines operating with various types of fuel. We conducted comprehensive experiments and comparisons based on the proposed framework. The results indicate that LFB performs best under all the performance indicators

Strategic Research Partnership on Automotive Powertrain & Fuels in Universiti Malaysia Pahang, Universiti Teknikal Malaysia Melaka & Universiti Tun Hussein Onn Malaysia

Malaysia has been known as one of the competitive automotive manufacturers and consumers in the ASEAN region. This is as a result of the government initiative of promoting the automotive industry as one of the key industries in Malaysia. However, depleting fuel sources, unstable oil price (Yr 2008, USD50/barrel – Yr 2011, USD100/barrel) and the increasing climate problems have prompt major research and development works on optimum automotive powertrain technologies with reduced emissions. Among the universities in the Malaysia Technical University Network (MTUN), three universities - Universiti Malaysia Pahang (UMP), Universiti Teknikal Malaysia (UTeM) & Universiti Tun Hussein Onn Malaysia (UTHM) - have take up the challenge in championing R & D works in producing efficient powertrain and emissions control systems. In this paper, existing research efforts and a proposed strategic partnership are outlined. This initiative will focus on strengthening the research and consultancy capabilities that include utilization of research facilities and expertise among the universities. It is also expected that the outcomes from the partnership will foster better engagement between automotive related industries and universities, at the same time resolving the related R & D issues