Gasoline and gasoline-like fuels (naphtha) have high volatility, which results in flash boiling spray in gasoline engines when operated at throttling or low load conditions. Flash boiling can achieve better atomization, thus benefit fuel evaporation and fuel-air mixing. However, when flash boiling occurs, spray morphology, and fuel distribution are dramatically varied from the injectors' intentional design. This difference will affect the performance of combustion and emissions. Thus it is essential to investigate the spray collapse phenomenon regarding varied conditions. The currently developing gasoline compression ignition (GCI) engines, also has throttled stoichiometric spark ignition operation mode, which inevitably has flash boiling possibility. However, there is a lack of research on flash boiling spray with a GCI injector, which has a large designed cone angle. This work aims to understand the spray collapse phenomenon and fill the gap in GCI flash boiling spray. Simultaneous side-view diffused back illumination (DBI) and front-view mie-scattering are used to capture the liquid spray development. Simultaneous shadowgraph from side and front view are used for recording the liquid+vapor phase spray development. Criteria for distinguishing different spray regimes have been established from these results. It shows this GCI injector is more resistant to collapse than the other conventional gasoline direct injection (GDI) injectors reported in the literature. A combination of DBI and space-time tomographic algorithm is validated in this work, achieving 3D reconstruction of the spray volume development from non-flashing to collapsed spray regime at low cost. The 3D results help elucidate the spray collapse procedure and provide validation data for CFD simulation. Structured laser illumination planar imaging (SLIPI) is firstly implemented in flash boiling spray study in this work to suppress the multiple scattering effect. Reconstructed 3D results from slice sweeping by SLIPI methods exposes the hollow structure in the spray's collapsed central jet, which has not been reported previously by other methods. Different spray motion types are summarized for the transitional and collapsed spray regime from the SLIPI slice and confirmed by the particle image velocimetry (PIV) technique.

This research studies the use of class=SpellE>titania (titanium dioxide, TiO2) as a catalyst for deoxygenation of class=SpellE>syngas derived oxygenates. These oxygenates are formed as byproducts when biomass derived syngas (CO & H2) is converted to ethanol on Rhodium or Molybdenum based catalysts. Conversion of these oxygenates to hydrocarbon would enhance the viability of class=SpellE>syngas to gasoline technology. This study revealed that class=SpellE>titania can indeed be used to convert syngas derived oxygenates to hydrocarbon at high temperature and pressure. Acetone condensation to mesitylene was studied very closely. The study revealed that the acid-base dual nature of class=SpellE>titania is key for the success of this reaction. When titaniawas combined with the zeolite H+/ZSM-5, a broad range of gasoline type hydrocarbon could be produced. Ethanol conversion to higher alcohols was studied as part of a partial deoxygenation of ethanol research. While this conversion was possible on class=GramE>titania, zirconia proved to be a better catalyst. Ethanol could be converted to 1-butanol and other higher alcohols at high temperature and pressure. The mechanism by which this occurs was studied as well.

This thesis explores the cross-price elasticity of rail and bus usage with gasoline prices. This is done to see how the short-run cross price elasticity has changed and to see if the same long-run relationship can be seen in the long run as previous pooled models. It is done in order to investigate whether policies such as higher gasoline taxes may make consumers move from car usage towards public transportation. Historically the cross-price elasticity has been around 0.2 with a higher elasticity for rail than for buses. The relationship also seemed to be greater in the long run than short run. Investigating this long run cross price elasticity for modes of public transportation separately would give greater insight into how consumers behave when gasoline prices shift. An ARDL model was therefore used to investigate the long run coefficients of gasoline prices with rail usage and bus usage separately as well as the short run coefficients. No cointegration could be found in this model for the two different modes. The results of the short-run cross-price elasticity seemed to be greater for buses as a direct effect, while it was greater at first lag for rail usage. The cross-price elasticity was lower for the period than previous studies, indicating that the cross-price elasticity may have decreased. The reasons for this cannot be concluded, but theory may explain these differences by the availability in substitutes for the periods, or lower levels of gasoline prices in recent years. This thesis therefore suggests further studies that investigate how usage of rail affects the usage of buses in metropolitan areas, and how the attributes of a modes of public transportation may change the usage of another form of public transportation.

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No description available.

Gasoline is produced by distilling petroleum oil. This is done at a refinery, where a lot of other products are produced as well. With increasing interest in bio-fuels the fuel companies started to produce substances such as biodiesel as well as the petroleum-based fuels. These products are then transported to where they are going to be used or sold, there included both gasoline, which is a petroleum-based fuel, and biodiesel (FAME), which in Sweden is based on rapeseed oil. If the vessel for transporting gasoline, or pipeline/connections filling and emptying the tanks, has previously been used for biodiesel, there is a risk of contaminating the gasoline with biodiesel. This contamination can have a lot of different effects such as either clogging filters or injectors in both gasoline- and ethanol-based engines, or even change the properties and therefore quality of the fuel.  To ensure that the results from tests and research involving gasoline can be used and compared with each other, the quality of the fuel must have the same properties throughout all tests. This is controlled by taking samples on a regular basis and analyzing the quality and level of impurities in the fuel used in that specific test. Screening for FAME is therefore necessary which is where this thesis becomes relevant.  This thesis was carried out with the purpose to develop a new or verify an already developed method to quantify FAME in gasoline. To determine the FAME content, a standard gas chromatography method, IP 585, was used. It was changed to fit in this application, since it was originally made to determine FAME content in diesel, not gasoline. It was concluded that it was possible to determine the FAME content in gasoline when IP 585 was used as is. There were some possible alternatives to IP 585 and they will be discussed in the literature study. / Bensin framställs genom destillation av råolja. Detta görs på ett raffinaderi där ett flertal andra produkter också utvinns. På senare tid har ögonen öppnats för "biobränslen", bland annat biodiesel. Det händer därför att detta också framställs på samma plats som bensinen. Dessa produkter säljs sedan och brukar fraktas i stora tankar till företagen som köpt dem. Ifall tankarna vid transport eller rören bränslet går igenom till tankarna först använts till biodiesel och sedan används till bensin finns det stor risk att en del biodiesel hamnar i bensinen. Detta kan leda till en rad olika problem. Ett exempel är att biodieseln kan sätta igen och förstöra injektorer i bensin- och etanolmotorer. Det kan även påverka testresultat i olika testriggar, vilket är ett av fallen på Volvo. Ifall bränslet inte bibehåller samma kvalitet för varje test det används i leder det till svårigheter vid jämförelser och resultatens riktighet. Det blir därför nödvändigt att kontrollera bensinens innehåll, där inräknat screening av FAME. Detta arbete utfördes med syftet att utveckla en ny eller verifiera en redan beprövad metod för att bestämma koncentrationen FAME i bensin. För att mäta koncentrationen FAME användes en standardmetod till GC-MS, IP 585. Den modifierades något för att passa in i denna applikation då den från början var gjord för kvantifiering i diesel och inte bensin. Slutsatsen drogs att det är möjligt att mäta koncentrationen FAME i bensin med IP 585 använd som den är. Det fanns möjliga alternativ till metoden, dessa bemöts i litteraturstudien.

A gasoline direct injection engine was set-up to operate with a dynamometer in a test cell. Test cycle and emissions measurement procedures were developed for evaluating the regulated and non-regulated gaseous emissions. Equipment and techniques for particulate matter measurements were adapted for use with the gasoline direct injection engine. The particulate matter emissions produced by the engine were compared between two different fuels; gasoline and E10 (10% ethanol and 90% gasoline). The gaseous emissions generated by the engine when it was run on gasoline and E30 (30% ethanol and 70% gasoline) were also compared. Particle number decreased with E10 for hot start conditions, while the opposite was observed for cold start conditions. Particulate matter emissions were found to track with acetylene and ethylene emissions.

A gasoline direct injection engine was set-up to operate with a dynamometer in a test cell. Test cycle and emissions measurement procedures were developed for evaluating the regulated and non-regulated gaseous emissions. Equipment and techniques for particulate matter measurements were adapted for use with the gasoline direct injection engine. The particulate matter emissions produced by the engine were compared between two different fuels; gasoline and E10 (10% ethanol and 90% gasoline). The gaseous emissions generated by the engine when it was run on gasoline and E30 (30% ethanol and 70% gasoline) were also compared. Particle number decreased with E10 for hot start conditions, while the opposite was observed for cold start conditions. Particulate matter emissions were found to track with acetylene and ethylene emissions.

by Chan Yick-wing, Christopher. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1988. / Bibliography: leaf 50.

A large theoretical and empirical literature has studied the response in prices to changes in demands and costs. Three of the essays in this thesis are empirical studies of price-setting. The most important reason for studying the properties of price adjustments is the possible link between pricing and the business cycle. One family of models deals with price rigidities. If prices adjust slowly to changes in costs or demand, it will magnify fluctuations in output. A second family of models examines price changes due to changes in intensity of competition. Many of these models build on the idea that changes in demand affect the possibility of maintaining implicit collusion. Cyclical changes in the intensity of competition may cause a cyclical pricing pattern that magnifies fluctuations in output. Another line of research models the effects of liquidity constraints on the business cycle. One possible effect is that prices in markets where consumers have switching costs may increase, if the firms are hit by increased liquidity constraints. As increased liquidity constraints are common in recessions, prices will get a counter-cyclical tendency, which magnifies fluctuations in output. Another reason for studying price-setting patterns is that they can give an indication of the form of interaction between competing firms, which are of importance for competition policy. The fourth essay models sex discrimination formally. It shows that it is possible that sex discrimination in the labor market might be due to self-fulfilling sex stereotypes on the distribution of time out for child care between men and women. Both an even and an uneven distribution of time out for child care are possible equilibria in the model. The four essays can be read separatelyEssay 1 Price Responses to Seasonal Demand Changes in the Swedish Gasoline MarketA common idea in a number of papers on cyclical pricing is that implicit price collusion may be affected by changes in demand. In these models, tacit collusion is modeled as a game where agents balance gains from deviating from the collusive price, thereby gaining a short-run profit, against the gains from maintaining collusion in future periods. If demand fluctuates, the gains from deviating is high in periods of high demand; collusion may still be sustainable, however, if the collusive price is allowed to vary with demand. A lower price in high demand states reduces the gains from deviating, since it reduces the gain from each unit sold in these demand states. Hence, in order to equalize the profit from deviating and the profit from sticking to the implicit agreement, the price must move in the opposite direction to demand. Changes in demand can, naturally, be correlated with other factors affecting the price, such as cost changes. Thus, prices do not necessarily fall when demand increases in the data. According to the theory the, however, increase in demand should add a tendency to lower prices in order to make implicit collusion sustainable. The basic idea that changes in demand should affect prices if firms are engaged in implicit collusion has been employed in a number of papers, with different models for different assumptions on the pattern of demand changes. The demand for gasoline in Sweden follows a seasonal cycle, with demand being 42 percent higher in July than in January. Haltiwanger and Harrington provide a theory for implicit collusion over deterministic cycles, such as the seasonal cycle. Borenstein and Shepard (1996) tested Haltiwanger and Harrington’s model on the American gasoline retail market and found support for the theory. In this essay the model is tested for Swedish data, but no support for this theory is found. It is also investigated whether the effects on margins of the demand fluctuations induced by tax increases are compatible with theories of implicit collusion, but this is found not to be the case.Essay 2 Price Adjustments by a Gasoline Retail ChainEssay 2 is joint with Marcus Asplund and Richard Friberg. Stickiness of prices is an important building block in many business cycle models. This has spurred an empirical literature on price adjustments. Different types of price rigidities have different policy implications. Price setting can be state dependent, e.g. prices are adjusted when costs have changed by at least some minimal amount since the last price adjustment, or time-dependent e.g. adjusted once a week or once a year. Another issue is whether prices are equally rigid downwards as upwards. The second essay examines price responses in the Swedish gasoline retail market to changes in the Rotterdam spot price of gasoline, exchange rates and taxes. The main results are that cost changes are not fully passed through in the short run, but gradually moves towards the long-run equilibrium. Prices are stickier downwards than upwards. There is a minimum absolute size of price changes. Only very limited evidence of time-dependent price setting is found.Essay 3 Prices, Margins and Liquidity Constraints: Swedish Newspapers 1990-1996Essay 3 is written with Marcus Asplund and Niklas Strand. Chevalier and Scharfstein (1996) provide a model where consumer switching costs in combination with liquidity constraints give rise to a counter-cyclical tendency in prices. Customer stocks can be viewed as an investment, when consumers have switching costs when changing suppliers. Firms can exploit captured customers by setting a high price to raise short-run profits. However, a high price will induce consumers to search for alternatives, and customers once lost are costly to win back. Liquidity constraints, for instance in recessions, may force firms to sacrifice long-run profits for short-run gains. In this case, firms may have to cut back on investments in customer stocks by raising prices. Using firm level data from the Swedish daily newspaper industry, we test the effects of liquidity constraints on prices in markets with consumer switching costs. The newspaper industry is of particular interest, since firms set prices in two markets, the subscription market, where switching costs are high, and the advertising market, where switching costs are low. With accounting data from newspaper firms we can, by solvency, broadly categorize them as being more or less liquidity constrained. When Sweden enters a recession at the beginning of the nineties, we find a relative increase in subscription prices and margins for liquidity constrained firms. This is not the case for advertising prices, however. The results support the theory.Essay 4 Statistical Discrimination and Sex Stereotypes in the Labor MarketTime out for child care is unevenly distributed between the sexes. Parental leave benefits are usually exclusively given to the mother or distributed to both parents according to their choice. In Sweden, one month is reserved for each parent, however. One reason for this is to give the child better contact with both parents, but increased equality between the sexes in the labor market has also been put forward as an argument. This argument implicitly rests on the idea that sex stereotypes create sex discrimination, and that sex discrimination affects the distribution of time out for child care between the sexes. Essay 4 investigates if the uneven distribution of time out for child care can be explained by self-fulfilling sex stereotypes. It provides a model of distribution of time out for child care based on statistical discrimination and human capital investments. The model has three equilibria. In one equilibrium, time out for child care is evenly distributed between the sexes. In the second equilibrium, there is full specialization. The third equilibrium is an intermediate case, where time out for child care is unevenly distributed without full specialization There are no differences in ability or variance of ability between the sexes, the only differences between the equilibria are the self-fulfilling expectations of firms and workers. / Diss. (sammanfattning) Stockholm : Handelshögsk., 2001