Driving cycles are acting as the basis of the evaluation of the vehicle performance from air quality point of view, such as fuel consumption or pollutant emission, especially in emission modeling and emission estimation. The original definition of the driving cycle, or drive schedule, given by U.S. Environmental Protection Agency (EPA), is basically a speed-time trajectory which is able to describe the general driving characteristics and driving patterns. Therefore, the development of drive cycles requires a large amount of real data to realize such “generalization”. Then, with such the eligible data collected, it leads to the development of modeling, from traffic modeling to emission modeling, especially for those pollutant emissions which have the public concern. In this study, focused on heavy duty diesel vehicles (HDDVs), the estimations of the common emissions are being made based on the Texas specific drive cycles, in second-by-second form, collected and generated from five local metropolitan areas, including Houston, Austin, San Antonio, Dallas-Fort Worth and El Paso. First of all, the accurate Global Positioning System (GPS) logging technique is applied for data collection in order to collect not only the moving data but also the relevant geographical information, such as location and roadway, for further analysis. Then, during the progress of data cleaning and data processing, some modifications are made subjectively to improve the deficits of the general methodologies developed by EPA. Afterwards, the specific drive cycles are presented in the format of operating mode distributions, which are also the main part of the input during the emission estimation in Motor Vehicle Emission Simulator (MOVES). Along with all the Texas specific inputs prepared, both the rates and amount of studied emissions are estimated through MOVES. A further comparison is made between the emission rates of default analysis and local analysis to verify the accuracy of MOVES at project level. It is found that the default estimation made by MOVES is accurate for mid-speed cases, at magnitude level. Significant differences happened in low-speed cases and high-speed cases, in which it shows the importance to develop the local drive cycles when estimating the emission rates regionally.

Doctor of Philosophy / Department of Biological and Agricultural Engineering / Ronaldo G. Maghirang / Emission of particulate matter (PM) and various gases from open-lot beef cattle feedlots is becoming a concern because of the adverse effects on human health and the environment; however, scientific information on feedlot emissions is limited. This research was conducted to estimate emission rates of PM[subscript]10 from large cattle feedlots. Specific objectives were to: (1) determine feedlot PM[subscript]10 emission rates by reverse dispersion modeling using AERMOD; (2) compare AERMOD and WindTrax in terms of their predicted concentrations and back-calculated PM[subscript]10 emission rates; (3) examine the sensitivity of both AERMOD and WindTrax to changes in meteorological parameters, source location, and receptor location; (4) determine feedlot PM[subscript]10 emission rates using the flux-gradient technique; and (5) compare AERMOD and computational fluid dynamics (CFD) in simulating particulate dispersion from an area source. PM[subscript]10 emission rates from two cattle feedlots in Kansas were determined by reverse dispersion modeling with AERMOD using PM[subscript]10 concentration and meteorological measurements over a 2-yr period. PM[subscript]10 emission rates for these feedlots varied seasonally, with overall medians of 1.60 and 1.10 g /m[superscript]2 -day. Warm and prolonged dry periods had significantly higher PM emissions compared to cold periods. Results also showed that the PM[subscript]10 emissions had a diurnal trend; highest PM[subscript]10 emission rates were observed during the afternoon and early evening periods. Using particulate concentration and meteorological measurements from a third cattle feedlot, PM[subscript]10 emission rates were back-calculated with AERMOD and WindTrax. Higher PM[subscript]10 emission rates were calculated by AERMOD, but their resulting PM[subscript]10 emission rates were highly linear (R[superscript]2 > 0.88). As such, development of conversion factors between these two models is feasible. AERMOD and WindTrax were also compared based on their sensitivity to changes in meteorological parameters and source locations. In general, AERMOD calculated lower concentrations than WindTrax; however, the two models responded similarly to changes in wind speed, surface roughness, atmospheric stability, and source and receptor locations. The flux-gradient technique also estimated PM[subscript]10 emission rates at the third cattle feedlot. Analyses of PM[subscript]10 emission rates and meteorological parameters indicated that PM[subscript]10 emissions at the feedlot were influenced by friction velocity, sensible heat flux, temperature, and surface roughness. Based on pen surface water content measurements, a water content of at least 20% (wet basis) significantly lowered PM[subscript]10 emissions at the feedlot. The dispersion of particulate from a simulated feedlot pen was predicted using CFD turbulence model ([kappa]-[epsilon] model) and AERMOD. Compared to CFD, AERMOD responded differently to wind speed setting, and was not able to provide detailed vertical concentration profiles such that the vertical concentration gradients at the first few meters from the ground were negligible. This demonstrates some limitations of AERMOD in simulating dispersion for area sources such as cattle feedlots and suggests the need to further evaluate its performance for area source modeling.

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This project evaluates the opportunity to convert a three-cylinder automobile piston engine (the Tiny Friendly Giant) to an aircraft engine from an environmental and practical point of view. The problem of increased emissions from aviation calls for technical and socioeconomic solutions, which is the reason why this report is written. The main goals are to choose the best fuel for the piston engine in aviation, as well as to study emissions, engine cooling and practical challenges with conversion. The structure resembles a feasibility study where the problem is solved using literature in a trade study, together with emission estimations using The Greenhouse gases, Regulated Emissions, and Energy use in Technologies Model framework and Boeing Fuel Flow Method 2. An estimation for engine cooling is done using a semiemprical method from Lycoming, showing air cooling can be sufficient for the Tiny Friendly Giant in aviation. The results furthermore show that none of the alternative automobile fuels are appropriate for use in aviation and that alternative pathways to jet fuel are more suited for high altitude. The conclusion is thus that the engine should be converted to jet fuel compatibility. To avoid large turning moment fluctuations, two-stroke can be applied. Conversion and use of the engine in aviation is not considered to be feasible because of practical limitations - instead the study concludes designing a new engine from scratch is easier and most likely quicker. The study shows that reducing carbon dioxide emissions also lead to reductions in water and sulfur- and nitrous oxides. However, the same mitigation strategy leads to increase in carbon monoxide and hydrocarbons. In general, the conclusion is that alternative fuels can significantly reduce aircraft emissions. / Detta examensarbete utvärderar möjligheten att konvertera en trecylindrig bilkolvmotor (Tiny Friendly Giant motorn) till en flygplansmotor från en miljömässig och praktisk synvinkel. Problemet med ökade utsläpp från flyget kräver tekniska och socioekonomiska lösningar, vilket är anledningen till att detta arbete är genomfört. De största målen går ut på välja det bästa bränslet för kolvmotorn inom flyget, samt att studera utsläpp, motorkylning och praktiska utmaningar med konvertering. Strukturen liknar en förstudie där problemet löses med hjälp av litteratur i en paramterstudie, tillsammans med utsläppsuppskattningar med hjälp av The Greenhouse gases, Regulated Emissions, and Energy use in Technologies Model ramverket och Boeing Fuel Flow Method 2. En uppskattning för motorkylning är beräknat med en semiemprisk metod från Lycoming, som visar att luftkylning vara tillräckligt för Tiny Friendly Giant motorn inom flyg. Resultaten visar vidare att inget av de alternativa bilbränslena är lämpliga för användning inom flyget och att alternativa vägar till flygbränsle är mer lämpat för hög höjd. Slutsatsen är att motorn bör konverteras till flygbränslekompatibilitet. För att undvika stora vridmomentfluktuationer kan tvåtakt användas. Konvertering och användning av motorn inom flyget anses inte vara genomförbart på grund av praktiska begränsningar - istället drar studien slutsatsen att design av en ny motor från grunden är enklare och med största sannolikhet snabbare. Studien visar att minskade koldioxidutsläpp också leder till minskningar av vatten och svavel- och dikväveoxider. Samma strategi leder dock till en ökning av kolmonoxid och kolväten. Generellt sett är slutsatsen att alternativa bränslen avsevärt kan minska flygplanens utsläpp.