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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Characteristics of diesel sprays at high temperatures and pressures

Lacoste, Julien January 2006 (has links)
A high-speed video camera was used to obtain photographs of a transient spray. The spray images were analysed to provide spray characteristics which include the spray tip penetration length, initial spray hesitation, nozzle opening time delay, hole-to-hole spray variation and spray structure. Both single and multi-hole nozzles were used to study these parameters. Fuel droplet characteristics within dense Diesel sprays were studied using Phase Doppler Anemometry (PDA) in an optical rapid compression machine. A comprehensive study of the PDA operating parameters was conducted. Additionally, the effects of injection pressure and in-cylinder pressure and temperature upon spray properties were studied. PDA has proved to be a valuable technique in providing an understanding of the structure and characteristics of sprays. However, the application of PDA to dense sprays is difficult. The results obtained are not always reliable and the accuracy of the results is often questionable. Phase Doppler Anemometers are not immune to errors and by carefully identifying these errors, the accuracy of the technique can be significantly improved. The effects of the PDA system parameters on the measurement accuracy have been studied. It was found that a thorough study of the operating parameters was required to tailor the system to the measurements of dense sprays. The photomultipliers voltages, the laser beam power and the size of the measurement volume all show significant effects on measured droplet diameters. Spray produced from a common-rail injection system proved to be a challenging environment for the PDA. Following the calibration of the PDA, investigations were conducted to study the effects of various parameters on spray characteristics including injection pressure, in-cylinder pressure and temperature. Results are presented for incylinder pressures ranging from 1.6 to 6 MPa and injection pressures from 60 to 160 MPa. The highest injection pressure produced faster droplets and improved the spray atomisation.
82

Modelling of multi-component fuel droplet heating and evaporation

Elwardani, Ahmed Elsaid Youssef Mohamed January 2012 (has links)
The results of numerical study of heating and evaporation of monodisperse fuel droplets in an ambient air of fixed temperature and atmospheric pressure are reported and compared to experimental data from the literature. The numerical model is based on the Effective Thermal Conductivity (ETC) model and the analytical solution to the heat conduction equation inside droplets. It is pointed out that the interactions between droplets lead to noticeable reduction of their heating in the case of ethanol, 3-pentanone, n-heptane, n-decane and n-dodecane droplets, and reduction of their cooling in the case of acetone. A simplified model for bi- component droplet heating and evaporation is developed. The predicted time evolution of the average temperatures is shown to be reasonably close to the measured one (ethanol/acetone mixture). The above-mentioned simplified model is generalised to take into account the coupling between droplets and the ambient gas. The model is applied to the analysis of the experimentally observed heating and evaporation of a monodispersed n-decane/3-pentanone mixture of droplets at atmospheric pressure. It is pointed out that the number of terms in the series in the expressions for droplet temperature and species mass fractions can be reduced to as few as three, with possible errors less than about 0.5%. In this case, the model can be recommended for implementation into CFD codes. The simplified model for bi- component droplet heating and evaporation, based on the analytical solutions to the heat transfer and species diffusion equations, is generalised to take into account the effect of the moving boundary and its predictions are compared with those of the model based on the numerical solutions to the heat transfer and species diffusion equations for both moving and stationary boundary conditions. A new model for heating and evaporation of complex multi-component hydrocarbons fuel droplets is developed and applied to Diesel and gasoline fuels. In contrast to all previous models for multi-component fuel droplets with large number of components, the new model takes into account the effects of thermal diffusion and diffusion of components within the droplets.
83

Waste heat recovery using fluid bottoming cycles for heavy duty diesel engines

Panesar, Angad Singh January 2015 (has links)
A typical long-haul heavy duty Diesel engine currently rejects up to 50% of the total fuel energy in the form of heat. Due to increasing CO2 emissions and fuel costs, there is a growing interest in techniques that can even partially utilise this wasted resource to improve the overall system efficiency. Fluid Bottoming Cycles (FBC) including Rankine and organic Rankine cycles offer one means towards converting waste heat into usable power. This thesis investigates the potential of FBCs to improve the net power of two computationally modelled (Ricardo WAVE V8.1) 10 litre engine platforms operating at Euro 6 emission levels.
84

Contribution to Development of Copper Free Automotive Brake Pad

Lee, Lin 01 August 2013 (has links)
When passenger vehicle drivers hit the brakes of their cars, the friction releases airborne wear particles from the contact between rotor and brake pad onto the road which are eventually washed down storm drains and into rivers. The wear particles includes copper, which functions as solid lubricant for increasing thermal heat fade as well as increasing friction coefficient for the brake pad. Nevertheless, copper not only endangers aquatic life, but it also directly affects the economy by lowering the supply of salmon. Copper is toxic to most aquatic life and is especially harmful to the sensory systems of salmon. Copper impairs salmon's sense of smell, thus reducing their ability to escape from predators. Up to half of the copper found in waterways from urban areas are from copper brake pads and is a key factor in the reduction of salmon population. In 2010, Washington and California each passed laws to ban production of brake pads containing more than 0.5% copper which will be effective in 2025. Since then, several other states including New York, Rhode Island, and Oregon have all introduced similar bills to ban copper brake pads. The raw materials that were added to the newly developed copper free sample brake pads are geopolymers; they are synthetic mineral products that combine properties of polymers, ceramics and cements. Geopolymers have the characteristic of behaving as adhesive rubber in order to replace phenolic resin matrix in the brake materials also it can be harden at room temperature which can increase friction coefficient of the brake pad. Sample brake pads manufactured on site with known constituents were tested with friction assessment and screening test machine, which measured and recorded the friction coefficient and wear of the brake pad. According to the experience in the past, the sample brake pads will be analyzed with density test and Shore Durometer test. The results presented in this report shows that geopolymers brake pad shows promising results for copper replacement for low-metallic friction material. Developed copper free friction sample shows promising result of coefficient of friction of 0.44 with thickness loss of 0.62 mm from friction assessment and screening test machine compare to commercial brake pad.
85

Aging Automotive Technicians Extend Their Work Life Through Service Teams Seeking Total Service Excellence

Weldon, Rodney H. 01 May 2012 (has links)
AN ABSTRACT OF THE THESIS OF RODNEY H. WELDON, for the Masters of Science degree in WORKFORCE EDUCATION, presented on APRIL 28, 2012, at Southern Illinois University Carbondale. TITLE: AGING AUTOMOTIVE TECHNICIANS EXTEND THEIR WORK LIFE THROUGH SERVICE TEAMS SEEKING TOTAL SERVICE EXCELLENCE MAJOR PROFESSOR: Dr. Elizabeth Freeburg The purpose of this paper was to contribute to the body of knowledge about the automotive technician's work life. More specifically, the study addressed the identification of change in technician production, how this change affects and was affected by the issues through out their work life. The author analyzed automotive technician productivity and efficiency calculations of automotive dealership technician production and the issues that impacted change. 40 years of hands on service department management recalled from the researchers personal records applied what worked and redefined what did not.
86

Model Based Automotive System Integration: Fuel Cell Vehicle Hardware-In-The-Loop

January 2014 (has links)
abstract: Over the past decade, proton exchange membrane fuel cells have gained much momentum due to their environmental advantages and commutability over internal combustion engines. To carefully study the dynamic behavior of the fuel cells, a dynamic test stand to validate their performance is necessary. Much attention has been given to HiL (Hardware-in-loop) testing of the fuel cells, where the simulated FC model is replaced by a real hardware. This thesis presents an economical approach for closed loop HiL testing of PEM fuel cell. After evaluating the performance of the standalone fuel cell system, a fuel cell hybrid electric vehicle model was developed by incorporating a battery system. The FCHEV was tested with two different control strategies, viz. load following and thermostatic. The study was done to determine the dynamic behavior of the FC when exposed to real-world drive cycles. Different parameters associated with the efficiency of the fuel cell were monitored. An electronic DC load was used to draw current from the FC. The DC load was controlled in real time with a NI PXIe-1071 controller chassis incorporated with NI PXI-6722 and NI PXIe-6341 controllers. The closed loop feedback was obtained with the temperatures from two surface mount thermocouples on the FC. The temperature of these thermocouples follows the curve of the FC core temperature, which is measured with a thermocouple located inside the fuel cell system. This indicates successful implementation of the closed loop feedback. The results show that the FC was able to satisfy the required power when continuous shifting load was present, but there was a discrepancy between the power requirements at times of peak acceleration and also at constant loads when ran for a longer time. It has also been found that further research is required to fully understand the transient behavior of the fuel cell temperature distribution in relation to their use in automotive industry. In the experimental runs involving the FCHEV model with different control strategies, it was noticed that the fuel cell response to transient loads improved and the hydrogen consumption of the fuel cell drastically decreased. / Dissertation/Thesis / Masters Thesis Engineering 2014
87

Development of metastable aluminum alloy coatings and parts for automotive applications

Berube, Gregoire January 2009 (has links)
In this study, a metastable Al-Fe-V-Si alloy powder was produced by rapid solidification using the gas atomization process. The alloy composition was chosen for its mechanical properties at elevated temperature for potential applications in internal combustion gasoline engines. The microstructural properties of the Al-Fe-V-Si powder were determined through transmission electron microscopy imaging and selected area electron diffraction indexing, energy dispersive spectroscopy, X-ray diffraction and differential scanning calorimetry. Three distinct microstructures were observed as well as two different phases, namely a Al13(Fe,V)3Si silicide phase and a metastable (Al,Si)x(Fe,V) micro-quasicrystalline icosahedral (MI) phase. The metastable MI phase was determined to be thermally stable up to 380°C, after which a phase transformation to silicide occurs. The Cold Gas Dynamic Spraying (CGDS) process was used to produce coatings of the alloy. This spray process was selected due to its relatively low operating temperature, thus preventing significant heating of the particles during spraying and as such allowing the original microstructure of the feedstock powder to be preserved within the coatings. Coatings were produced by CGDS using Helium and Nitrogen as propellant gases. The coatings microstructure was investigated using scanning electron microscopy and transmission electron microscopy analyses. The mechanical properties of the coatings were then evaluated through bond strength testing and microhardness testing.
88

Sol-gel derived palladium catalysts for the removal of automotive chemical pollutants

Salvesen, Thomas Alexander January 1999 (has links)
Sol-gel production of catalyst supports has been investigated in order to produce homogeneous, high surface area alumina/zirconia materials. A novel microwave method of preparing colloidal Pd has been developed and a range of alumina/zirconia supported Pd catalysts has been produced. These have been tested for activity in terms of temperature programmed three way catalysis (simultaneous removal of NO, CO and C3H8 from a simulated car exhaust stream) and from the array of catalysts produced a suitable catalyst was chosen for further investigation. This catalyst had a 3% zirconia / 97% alumina support and contained ~1% Pd by weight and was examined for activity in the NO + CO + O2 system at temperatures below 500°C. Temperature programmed catalytic experiments revealed the reactions to be chemically controlled below ~400°C but diffusion controlled above this. CO temperature programmed reduction was used to examine the oxidation state of the Pd and revealed a complex Pd/PdO system to be present involving bulk PdO and surface oxide. Further kinetic studies showed that the reactions between NO, CO and O2 to have positive orders in all components. The reaction rates were stable over a wide range of conditions and the NO + CO reaction proved to have a low selectivity towards N2O. In-situ DBIFTS experiments alongside transient pulse work were used to illustrate low CO adsorption which indicated that these reactions proceeded via a redox mechanism in which Pd is oxidised by NO or O2 before being reduced by CO. The support material was examined by XRD following extended heating regimes and then compared to an identically treated sol-gel alumina. The zirconia doped alumina was found to possess a far greater thermal resistance to sintering than the pure alumina material and this was attributed to Zr4+ ions preventing the diffusion of Al3+ to form a-alumina.
89

Development of a strategy for the management and control of multiple energy sources within series hybrid electric vehicles

Kok, Theodorus Antonius Hendrik January 2015 (has links)
The battery in an EV is designed according to a power to energy ratio and is a trade-off in the design of the pack. It also suffers from effects such as rate capacity effect, ripple effects and inefficiency under charging. These effects result in losses through which the capacity and life span of the batteries are compromised affecting range and drivability. In this thesis a novel development path resulting in a novel Power and Energy Management Strategy (PEMS) is presented. The effects of (dis)charging a battery are researched and converted to an energy optimisation formula and result in reduced power demand for the converter which reduces weight. The resulting Power Management Strategy (PMS) aims to recover energy more efficiently into UC while responding fast to a change in demand. The effects of converters on the battery current ripple are researched and discussed, resulting in an optimal topology layout, improved battery life and reduced losses. Through the use of Markov Chain analysis and a newly derived Bias function a predictive Energy Management Strategy (EMS) is developed which is practical to use in EVs. This resulted in a PEMS which because of the fast PMS results in a fast response time. The use of Markov Chain results in predictive EMS and improves the efficiency of the energy sources and allows the design to be reduced in size. Through the design methodology used the parallel topology (the battery converter parallel to the UC Module) was rated preferred choice over battery only and battery with UC Module. The rating was based on capacity, ripple control, weight, 10 year cost, potential for motor controller efficiency improvement, range and efficiency. v The combination of method and PEMS resulted in an improved life expectancy of the pack to over 10 year (up from 7) while increasing range and without sacrificing drivability.
90

Correlation of subjective and objective handling of vehicle behaviour

Ash, Howard Alan Simon January 2002 (has links)
This thesis presents the results of a research project which sought to find links between driver subjective ratings and objective measures of vehicle handling. The experimental data used in this project has been made available from a previous research project. The experimental data was collected using a prototype vehicle which was used in 16 different configurations. Objective data was collected based around the ISO defined steady state, step input, and frequency response tests. Subjective assessments were collected from eight trained test drivers using a numerical rating scale to a questionnaire covering various aspects of vehicle handling. Analysis of the subjective assessments has been done to identify any shortcomings that may affect any subsequent analysis. From the literature review, an approach that claims to relate four simple objective metrics to subjective measures of vehicle handling has been developed in two new ways. Firstly, the proposal was tested [1] with the large amount of subjective data available to see if good levels of correlation could be found between the proposed metrics and driver subjective ratings to specific handling questions. Secondly, the method was extended to include further simple metrics to try and improve links between the subjective and objective data [2]. Non-linear relationships in the correlation of subjective vs. objective data have been investigated for the first time [3] using non-linear genetic algorithms, which, in addition have not previously been used to correlate driver subjective ratings with objective measures that describe vehicle handling. From the results, it has been possible to specify ranges of preferred values of objective metrics in order to produce a subjectively satisfying vehicle. Finally, the work discusses how the results obtained can be used by engineers to aid the vehicle design and development process.

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