Call number: LD2668 .T4 1978 B34 / Master of Science

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No description available.

A study was made of the feasibility of putting hazardous area classification (HAC) on a more quantitative basis. A review of current HAC practice showed that the widespread policy of setting fixed zone distances around sources of hazard was subjective and sometimes led to inconsistencies between different codes of practice when applied to the same situation. Fatality and injury statistics were used to show that there is a significant risk to workers from the ignition of flammable atmospheres. which should be reduced. Data were researched and compiled to fit into a proposed framework for the quantification of HAC. These included information concerning leak source inventory: source leak frequency: and source leak size distribution. Mathematical models were collected which could be used to describe the emission and dispersion of flammable releases. Example calculations were performed for typical leak scenarios to illustrate the variation in hazard distances. Estimates were made of the ignition and explosion probabilities of flammable leaks. which depended princi pally on emission size. To compensate for uncertainties in the researched data. a fire and explosion model was devised to estimate the ignition frequency on a typical process plant. The model was applied to a "standard" plant which was formulated from researched data. By iteratively checking the estimated ignition frequencies against historical data it was concluded that reasonable agreement was achieved with some adjustment of the input data. The special problems of HAC of indoor plants were also addressed. It was concluded that the results of this study provided a basic framework for the quantification of HAC. although the quality of currently available data necessary for quantification is generally poor. The acquisition of better quality leak and ignition data should provide a platform from which the current work may progress. Further work should include the further refinement of the basic fire and explosion model to account for ignitions which HAC cannot protect against such as autoignitions. It was also noted that the behaviour of indoor releases requires clarification. together with the concept of a minimum flammable inventory below which there is negligible risk of ignition.

Elimination or reduction of auxiliary oxygen use in Pulse Detonation Engines (PDEs) is necessary if the technology is to compete with existing Ramjet systems. This thesis investigated a Transient Plasma Ignition (TPI) system and found that the technology can at least reduce and may be able to completely remove the auxiliary oxygen requirement of current PDE systems. TPI was tested and compared with a traditional capacitive discharge spark plug system in a dynamic flow, ethylene/air mixture combustor. Ignition delay time, Deflagration-to-Detonation transition (DDT) distance and time, detonation wave speed and fire success rate performance were analyzed for various mass flow rates and stoichiometric ratios. A transient plasma dualelectrode concept was also employed and analyzed. Results show that TPI is more effective and reliable than the spark plug ignition with considerable improvements to DDT performance. The TPI dual-electrode concept was proven to be the most effective configuration with average reductions in DDT distance and time of 17% and 41% respectively when compared to the capacitive discharge spark plug system configuration.

Despite the increasing popularity of hybrid-electric vehicles (HEVs), few studies have quantified their real-world particle emissions from internal combustion engine (ICE) re-ignition events (RIEVs). RIEVs have been known to occur under unstable combustion conditions which frequently result in particle number emission rates (PNERs) that exceed stabilized engine operation. Tailpipe total PN (5 to 560 nm diameter) emission rates (#/s) from a conventional vehicle (CV) and hybrid electric vehicle (HEV) 2010 Toyota Camry were quantified on a 50 km (32 mi) route over a variety of roadways in Chittenden County, Vermont using the Total On-board Tailpipe Emissions Measurement System (TOTEMS). While HEVs are known to have significant fuel conserving benefits compared to conventional vehicles, less is known about the relative emissions performance of HEVs. This study is the first to characterize RIEVs under a range of real-world driving conditions and to directly compare HEV and CV PNER during driving on different road sections. A total of 28 CV and 33 HEV sampling runs were conducted over an 18-month period under ambient temperatures ranging between -4 and 35 °C. A road classification based upon speed and intersection density divided the route into four different road sections: Freeway, Rural, Urban I and Urban II. Due to the distinct on-off cycling of the HEV ICE, a new operational mode framework (ICE OpMode) was developed to characterize shutdown, off, re-ignition and stabilized HEV ICE operation. Road section was found to affect overall ICE OpMode distribution, with HEV engine-off operation averaging 57%, 36% and 5% of total operation for combined Urban, Rural and Freeway road sections, respectively. Re-ignition frequency was found to range between 11 and 133 events per hour, with spatial density ranging between 0.1 and 5.6 events per kilometer of roadway. A total of 3212 re-ignition events were observed and recorded, and mean HEV PNER during RIEVs, on average, ranged between 2.4 and 4.4 times greater than that of HEV Stabilized operation. Approximately 65% of all re-ignition events resulted in a peak PNER exceeding the 95% percentile for all ICE-on activity in both vehicles (9.3 x 1011 #/s), known as a High Emission Event Record (HEER). RIEV operation made up only 7.4% of total ICE-on operation for both vehicles but accounted for 35.4% of all HEERs. Overall, total particles emitted during HEV operation associated with re-ignition events ranged from 5% for Freeway driving to 60% for Urban I driving. Comparisons between vehicles found an average of 37% and 7% fuel conserving benefits of the HEV during Urban I and Freeway driving, respectively. However, a different effect was found for PN emissions. During Urban I driving, where RIEVs were most frequent, on average HEV PNER was 2.3 times greater than overall mean CV PNER. For Freeway driving, where the HEV operated similar to a conventional vehicle, mean CV PNER was 2.4 times greater than mean HEV PNER. PNER from partial re-ignition events following an incomplete ICE shutdown (no period of prior engine off operation) were on average 1.65 times greater than those occurring when the ICE shutdown for at least one second. The typical fuel consumption benefits of HEVs in urban driving are associated with a tradeoff in PN emissions. The HEV ICE operating behavior has implications for the spatial distribution of PN hot-spots as well as the associated micro-scale modeling of alternative vehicle technology emissions. It is likely that building a model of HEV behavior based upon CV activity will be appropriate, with consideration of a hybridization factor and, as a result of these analyses, a re-ignition factor.

Carbon Capture and Storage (CCS) is a legitimate technology option that should be part of a balanced portfolio of mitigation technologies available Post-Kyoto Protocol framework after Paris 2015 and beyond the 2020s or the cost achieving 2 degrees Celsius stabilisation scenario will significantly increase. Oxy-fuel combustion as a CCS technology option increases fuel flexibility. Additionally, oxy-biomass as a bio-energy with CCS (BECCS) technology can achieve negative carbon dioxide (CO2) emissions in sustainable biomass systems. Also, oxygen (O2) production in an air separation unit (ASU) gives potential for extra operational flexibility and energy storage. In this work, new designs of 20 litre spherical (R-20) and 30 litre non-spherical (R-30) ignition chambers have been built at the University of Edinburgh to carry-out dust ignition experiments with different ignition energies for evaluating pulverised fuel ignitability as a function of primary recycle (PR) O2 content for oxy-fuel PF milling safety. A set of coals and biomasses being used (at the time of submitting this work) in the utility pulverised fuel boilers in the UK have been employed. Coal and biomass dusts were ignited in air and oxy-fuel mixtures up to 30 % v/v O2 balance mixture CO2 where peak pressures (Pmax) from ignition were recorded. Pressure ratios (Pmax/Pinitial) were determined the key parameter for positive ignition identification with a value above 2.5 to be considered positive. Particle size effects in coal and biomass ignition were evaluated. Results on biomass were more variable than with coals, requiring a stronger ignition source (5,000 J) mainly due to larger particle sizes. Finer biomass particles behaved similarly to air ignition in 25 % v/v O2 in CO2. Larger particles of biomass did not ignite at all for most cases even reaching 30 % v/v O2 in CO2. A reference coal used, El Cerrejon, behaved as expected with 30 % v/v O2 balance CO2 matching air case; particles between 75-53 microns had lower ignitability than finer below 53 microns but were critical in devolatilisation. Most fuels did not ignite in 21 % v/v in CO2 below 200 g/m3 concentrations. The use of adequate ignition energy strength is needed for the PF mill safety case, with 5,000 J energy required for the biomasses tested. An indication of potential ignition chamber volume and geometry effect has also been observed when comparing results from R-20 and R-30 ignition chambers. Important implications include that oxy-biomass PR with 21 % v/v O2 content would give improved pulverised fuel (PF) milling safety when compared to air firing but reduced ignitability and a 25 % v/v O2 balance CO2 atmosphere would approach to oxy-biomass ignition behaviour in air in mills.

After reaching its light-off temperature, the catalytic aftertreatment system plays a major part in maintaining emissions at low levels for vehicles equipped with combustion engines. In this thesis, modelling of the exhaust gas temperature is investigated along with optimal control strategy for variable ignition and exhaust valve opening angles for optimal catalytic converter heating. Models for exhaust gas temperature and mass flow are presented and validated against measurement data. According to the model validation, the proposed models capture variations in ignition and exhaust valve opening angles well. Optimal control strategy for the ignition and exhaust valve opening angles to heat the catalytic converter to a predetermined temperature in the most fuel and time optimal ways are investigated by implementation of the validated models. Optimal control analysis indicates that with open wastegate, the heating time for the catalytic converter can be reduced by up to 16.4 % and the accumulated fuel to reach the desired temperature can be reduced by up to 4.6 %, compared to the case with ignition and exhaust valve opening angles fixed at nominal values. With closed wastegate the corresponding figures are 16.4 % and 4.7 %. By also including control of the variable λ-value, the heating time can be further reduced by up to 19.8 %, and the accumulated fuel consumption by up to 9.5 % with open wastegate. With closed wastegate the corresponding figures are 20.1 % decrease in heating time, and 9.8 % decrease in accumulated fuel consumption.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Stephen Gregory Poulos. / M.S.