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The characterization of flammability parameters such as time to ignition, mass loss rate (MLR), and extinction criteria is critical for understanding ignition and burning behavior of timber products. These parameters, often determined with bench scale experiments, have previously been presented in literature. However, standard test methods generally use relatively low trial quantities (e.g., n=3) which can potentially cause large variation in reported values. This study investigates the influence of trial quantity on observed statistical variation in key flammability metrics for timber products (e.g., ignition time, peak MLR, MLR at extinction). Using a conical heater, 100 repeat trials were conducted at incident heat exposures of 20 kW/m2, 40 kW/m2, and 50 kW/m2 on 12.7 mm thick ACX cross laminated plywood samples. Ignition time data was found to exhibit significant positive skew and 20-30 trials were required for the reduction in uncertainty with each additional trial to fall below 0.1s at each heat flux. The normalized uncertainty in ignition time was greatest at 50 kW/m2 and was 20-70% than at 20 kW/m2 and 40 kW/m2. Significant variability was observed in the extinction characteristics of samples exposed to 40 kW/m2 where 39 samples experienced self-extinction while the remainder sustained combustion until burnout. Uncertainty in MLR at extinction for these trials was nearly double that of trials exposed to 20 kW/m2. These results exhibit the significance of large trial quantities when determining flammability characteristics.

Diesel Engine has been the most powerful and relevant source of power in the automobile industryfor decades due to their excellent performance, efficiency and power. On the contrary, there arenumerous environmental issues of the diesel engines hampering the environment. It has been agreat challenge for the researchers and scientists to minimize these issues. In the recent years, severalstrategies have been introduced to eradicate the emissions of the diesel engines. Among them,Partially Premixed Combustion (PPC) is one of the most emerging and reliable strategies. PPC is acompression ignited combustion process in which ignition delay is controlled. PPC is intended toendow with better combustion with low soot and NOx emission.The engine used in the present study is a single-cylinder research engine, installed in Aalto UniversityInternal Combustion Engine Laboratory with the bore diameter of 200 mm. The thesis presentsthe validation of the measurement data with the simulated cases followed by the study of the sprayimpingement and fuel vapor mixing in PPC mode for different injection timing. A detailed study ofthe correlation of early injection with the fuel vapor distribution and wall impingement has beenmade.The simulations are carried out with the commercial CFD software STAR CD. Different injectionparameters have been considered and taken into an account to lower the wall impingement and toproduce better air-fuel mixing with the purpose of good combustion and reduction of the emissions.The result of the penetration length of the spray and the fuel vapor distribution for different earlyinjection cases have been illustrated in the study. Comparisons of different thermodynamic propertiesand spray analysis for different injection timing have been very clearly illustrated to get insightof effect of early injection. The parameters like injection timing, injection period, injection pressure,inclusion angle of the spray have an influence the combustion process in PPC mode. Extensivestudy has been made for each of these parameters to better understand their effects in the combustionprocess. Different split injection profiles have been implemented for the study of better fuelvapor distribution in the combustion chamber.The final part of the thesis includes the study of the combustion and implementation of EGR tocontrol the temperature so as to get more prolonged ignition delay to accompany the PPC strategyfor standard piston top and deep bowl piston top. With the injection optimization and implementationof EGR, NOx has been reduced by around 44%, CO by 60% and Soot by 66% in the standardpiston top. The piston optimization resulted in more promising result with 58% reduction in NOx,55% reduction in CO and 67% reduction in Soot. In both cases the percentage of fuel burnt wasincreased by around 8%.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2012. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student submitted PDF version of thesis. / Includes bibliographical references (p. 139-148). / A novel neutron spectrometer, called the Magnetic Recoil Spectrometer (MRS), was designed, built, and implemented on the OMEGA laser facility and the National Ignition Facility (NIF) to measure the neutron spectra from inertial confinement fusion (ICF) implosions. Using the MRS, the down-scattered neutron (DSn) spectrum has been used to infer the areal density ([rho]R) of ICF implosions for the first time. The DSn technique is essential for diagnosing high [rho]R (>180mg/cm²) cryogenic deuterium-tritium (DT) implosions, where most other methods fail. The MRS has helped to guide the cryogenic campaign toward the highest [rho]Rs ever achieved at OMEGA. In addition, the MRS is currently being used to diagnose the DSn spectrum from cryogenic implosions at the NIF during the beginning phases of the National Ignition Campaign (NIC). MRS data have already been essential for tuning these implosions to the highest [rho]Rs ever achieved in an ICF implosion (>1 g/cm²), and thus for guiding the NIC toward the realization of thermonuclear ignition. The first measurements of the T(t,2n)⁴He (TT) neutron spectrum in DT implosions at OMEGA have also been conducted using the MRS. The TT-neutron (TTn) spectrum was measured at low reactant central-mass energies of ~23 keV. The results from these measurements indicate that the TT reaction proceeds primarily through the direct three-body reaction channel, which is in contrast to the results obtained in higher energy accelerator experiments. Measurements of the TTn and DD proton yields were also conducted and compared to the DT neutron yield in DT implosions. From these measurements, it is concluded that the DD yield is anomalously low and the TTn yield is anomalously high, relative to the DT yield. These results have been explained by a stratification of the fuel in the core of an ICF implosion. / by Daniel Thomas Casey. / Ph.D.

Recent approval of emission standards for small utility engines by the California Air Resources Board suggested that substantial reductions in emissions from small utility engines will soon be required. Although the 1994 standards can be met by simple engine modifications, the 1999 standards may require the use of emission control technologies such as catalytic converters because they are more stringent. In this research catalytic control of individual hydrocarbons such as methane, ethylene, benzene, and toluene were evaluated. A platinum coated catalyst treated emissions from a 107cc, four-cycle gasoline engine loaded with a 1.4KW portable generator. Determination of emissions was performed at three different load levels: 0%, 50% and 92% of the engine rated load. Among the four hydrocarbons, toluene was oxidized as much as 60%, and benzene 40%, whereas ethylene remained unaffected by the catalyst. Also, a 5% to 10% methane oxidation occurred in one trial. / Master of Science

The motivation for this work stems from the enacting of stricter emissions requirements for the mid 1990's by the California Air Resources Board. It is foreseen that these requirements will favor the use of alcohol fuels in quantities comparable to the present usage of gasoline and diesel in order to reduce emissions of carbon monoxides (CO) and nitrogen oxides (NOx). The use of alcohol fuels at this level will substantially increase the amount of aldehyde emissions. This poses a problem in that aldehydes are odorants, components of photochemical smog, and volatile aldehydes are eye and respiratory tract irritants; therefore, it is only a matter of time before they too are strictly regulated. This thesis focuses on a systematic analysis of aldehyde emissions from alcohol fuels with respect to compression ratio. Compression ratio has been selected as the primary variable for this study, because alcohol-fueled vehicles are usually modified to have higher compression ratios than their gasoline-fueled counterparts in order to take advantage of alcohols' higher octane rating. The investigation is being conducted using a single-cylinder variable-compression ratio Waukesha-CFR engine. The aldehyde emissions are measured for various fuel alcohol percentages at different compression ratios and MBT timing. The effects on conventional vehicle emissions (Le. NOx, CO, unburned hydrocarbons) are also being measured so that tradeoffs between conventional emissions and aldehyde emissions can be determined. The goal of this research was to locate any trends between alcohol fuels and compression ratios which will allow for an optimization of these parameters to minimize aldehyde emissions. It was desired that this be achieved without sacrificing engine performance or increasing other regulated emissions. The variance of compression ratio was found to affect the pollutant formation process via its effects on temperature. The increasing expansion ratio, which accompanies increasing compression ratio, resulted in lower post .. expansion burned-gas temperatures. Temperature's influence on the rate of reactions was found to be the driving force in the formation of most of the pollutants. The experiment showed a definitive reduction in CO emissions with the use of alcohol fuels. The results also indicated an inherent tradeoff between NOx and formaldehyde emissions. / Master of Science

It is quite common practice in automotive and aircraft engine maintenance, operation, and research to employ any one of several types of instruments now on the market for determining the air-fuel ratio by exhaust gas analysis. It was the purpose of this investigation to determine the most important operating characteristics, especially range and accuracy, of each of these types of instruments. The theory underlying the operation of this kind of apparatus was studied critically, and certain tests were performed on representative makes in order to observe the operation of each type under service conditions. These tests consisted essentially of connecting the analyzers to the exhaust pipe of a single-cylinder engine and comparing the analyazer readings with the true air-fuel ratio determined by accurately measuring the air and fuel supplied to the engine while the instruments were being observed. This procedure was repeated for a number of different carburetor settings, all other factors being kept as nearly constant as possible during a given series of runs. The effect of variations in engine spark advance and the pressure of the gas supplied to the instruments was also investigated. The test revealed several interesting facts. Study of the operating principles of the several instruments indicated that they were limited te air fue1 ratios below about 14 to 1, and this has been conclusively proved by these experiments. This limitation applies to thermal conductivity, hot-wire catalytic, and relative density types. W While the most expensive makes of instruments were not tested, it was found that, in general, the limit of accuracy is not greater than one-half of one air-fue1 ratio, regardless of the operating principle employed. Large variations in the pressure and rate of flow of the exhaust supplied to the analyzers were found to cause considerable deviations in those instruments which did not employ some kind of device to insure a steady and uniform supply. Certain features of design and construction which effect the reliability of the various types of exhaust gas analyzers are also reviewed in this thesis, and some of the more important chemical methods of analysis are treated briefly. / Master of Science

Aqueous film-forming foam (AFFF) used for fuel firefighting contains polyfluoroalkyl substances (PFAS) that have been identified as environmentally persistent and bioaccumulative resulting in phase out of AFFF. Currently, there are no environmentally friendly foams available that can perform at the same level as AFFF. Fuel transport has been recognized as a potential mechanism behind poor fire extinguishment, but the key features are yet unidentified. To fill these knowledge gaps, identifying the properties and features of surfactants used in firefighting foam that will prevent the transport of liquid fuel through the surfactant solution was imperative. To achieve that, this research was performed exclusively on single surfactants that have applications in firefighting foam. Impact of single surfactants on fuel transport was evaluated. Thermodynamics of the interaction between single surfactants and fuel; and kinetics of fuel transport through single surfactant solutions was observed. It was hypothesized that the liquid fuel transport would influence microstructure in the bulk of the surfactant solution. Experiments were conducted for different single surfactant structures. Various methods were applied to identify the microstructure and interfacial properties of surfactants with and without exposure to liquid fuel. The factor affecting microstructure, identified through this study was further used to evaluate the firefighting performance of single surfactants through ignition test. The thermodynamics of the interaction between fuel and single surfactants helped us to understand the fuel transport mechanism and role of micelle on fuel transport. Surfactant and fuel interaction has been studied below, at, and above the critical micelle concentration of surfactants. The effect of surfactant concentration, convection, and surfactant types were observed on the fuel transport. Moreover, an ignition test was conducted to evaluate the firefighting performance of single surfactants for various fuel types. Overall, the findings from this study will help design a new type of superefficient, environmentally acceptable surfactant for firefighting foam application. / Doctor of Philosophy / Aqueous film-forming foam (AFFF) used for fuel firefighting contains fluorinated compounds which are environmentally persistent and bioaccumulative. Therefore, AFFF has been phased out. There are no environmentally friendly foams available as efficient as current AFFF. Researchers have found that fuel transport through surfactant foam solution is the reason for foam collapse and poor fire extinguishment performance. However, the key parameters affecting fuel transport through foam solution have not been identified. Therefore, new formulations have become challenging, and it is important to identify the parameters affecting fuel transport through the firefighting foams. Surfactants are the key components of firefighting foam. The liquid fuel transport affects the microstructure of the surfactants in the bulk solution. Through this research microstructural and interfacial properties of single surfactants have been studied with and without exposure to liquid fuel. The factors affecting microstructure and firefighting performance of surfactants have been identified. Moreover, the interaction between fuel and single surfactants has been evaluated. The effect of surfactant concentration and fuel type on fuel transport has been observed. Moreover, the effect of convection (at the foam-fuel interface) on fuel transport has been observed. Overall, an understanding of factors affecting fuel transport of firefighting foam is achieved through this research, which can guide new types of efficient, environmentally friendly surfactant design.

No / This paper presents the development and implementation of an Analytical Target Cascading (ATC) Multi-disciplinary Design Optimisation (MDO) framework for the steady state engine calibration optimisation problem. The case is made that the ATC offers a convenient framework for the engine calibration optimisation problem based on steady state engine test data collected at specified engine speed / load points, which is naturally structured on 2 hierarchical levels: the ‘Global’ level, associated with performance over a drive cycle, and ‘Local’ level, relating to engine operation at each speed / load point. The case study of a diesel engine was considered to study the application of the ATC framework to a calibration optimisation problem. The paper describes the analysis and mathematical formulation of the diesel engine calibration optimisation as an ATC framework, and its Matlab implementation with gradient based and evolutionary optimisation algorithms. The results and performance of the ATC are discussed comparatively with the benchmark steady state solution for the engineering calibration of the diesel engine. The main conclusion from this research is that ATC optimisation framework offers an effective approach for engine calibration, with a potential to deliver significant fuel economy benefits. Further advantages of the ATC framework is that it is flexible and scalable to the complexity of the calibration problem, and enables calibrator preference to be incorporated a priori in the optimisation problem formulation, delivering important time saving for the overall calibration development process.

This work concerns a systematic study of IC engine operation with 100% biogas as fuel (as opposed to the dual-fuel mode) with particular emphasis on operational issues and the quest for high efficiency strategies. As a first step, a commercially available 1.2 kW genset engine is modified for biogas operation. The conventional premixing of air and biogas is compared with a new manifold injection strategy. The effect of biogas composition on engine performance is also studied. Results from the genset engine study indicate a very low overall efficiency of the system. This is mainly due to the very low compression ratio (4.5) of the engine. To gain further insight into factors that contribute to this low efficiency, thermodynamic engine simulations are conducted. Reasonable agreement with experiments is obtained after incorporating estimated combustion durations. Subsequently, the model is used as a tool to predict effect of different parameters such as compression ratio, spark timing and combustion durations on engine performance and efficiency. Simulations show that significant improvement in performance can be obtained at high compression ratios. As a step towards developing a more efficient system and based on insight obtained from simulations, a high compression ratio (9.2) engine is selected. This engine is coupled to a 3 kW alternator and operated on 100% biogas. Both strategies, i.e., premixing and manifold injection are implemented. The results show very high overall (chemical to electrical) efficiencies with a maximum value of 22% at 1.4 kW with the manifold injection strategy. The new manifold injection strategy proposed here is found to be clearly superior to the conventional premixing method. The main reasons are the higher volumetric efficiency (25% higher than that for the premixing mode of supply) and overall lean operation of the engine across the entire load range. Predictions show excellent agreement with measurements, enabling the model to be used as a tool for further study. Simulations suggest that a higher compression ratio (up to 13) and appropriate spark advance can lead to higher engine power output and efficiency.