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Ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and sec-butanol are six potential carbon-neutral fuels of the future. One application of these carbon-neutral fuels is in high-dilution spark ignition. To understand the potential of these fuels in high-dilution spark ignition, this work experimentally determines the spark ignition lean flammability limit of each fuel with no external, cooled exhaust gas recirculation (EGR), and with 20% external, EGR. The spark ignition lean flammability limit in this work is defined as the excess-air ratio that results in a coefficient of variance of gross indicated mean effective pressure greater than 5%. This is done on an engine with a compression ratio of 12.5, using an intake pressure of 1 bar and an intake temperature of 320 K. It was found that ethanol had the leanest lean limit, due to its high flame speed, followed by n-propanol, isopropanol, and sec-butanol, which all had similar lean limits. n-Butanol and isobutanol had the richest lean limits due their high knock propensity and low flame speed, respectively. The lean limit of each fuel decreased with external, cooled EGR addition, with ethanol as the least sensitive and isopropanol as the most sensitive to EGR addition. Overall, using a high dilution strategy increased the cycle efficiency for each fuel. Ethanol, n-propanol, isopropanol, and sec-butanol all showed promising performance and are great candidates to be combined with an advanced high-dilution SI strategy to enable high-dilution SI with a carbon-neutral fuel.

Wet ethanol is a biofuel with unique fuel properties: a high latent heat of vaporization and low equivalence ratio sensitivity. These two fuel properties enable control over the heat release process in low temperature combustion through the enhancement of in-cylinder thermal stratification. In this work, it is shown that the direct injection of wet ethanol 80 (80% ethanol, 20% water, by mass) during the intake stroke on a mid-compression ratio engine with a side-mounted gasoline direct injector does not fully premix with incoming air, leaving stratification in the cylinder which elongates the combustion process, enabling high-load low temperature combustion without engine-damaging knock. As a result, the load under naturally aspirated conditions was only limited by oxygen content as the global equivalence ratio approached stoichiometry. The results show that swirl can not only modulate the induced stratification effectively by increasing the amount of bulk motion in the cylinder but also cause a thermal efficiency penalty, since swirl increases heat transfer losses. Modulation over the induced stratification can be achieved without an efficiency penalty by employing either a dual injector system where a fraction of the total fuel is injected into the port or a split injection strategy where a fraction of the total fuel is injected during the compression stroke. This strategy enables high-load low temperature combustion, while reducing the number of regions that form NOx and avoiding excessively rich regions that contribute to combustion inefficiency.

Gasoline particulate filters (GPFs) are the most promising and practically applicable devices to reduce Particulate Matter (PM) and Particulate Number (PN) emissions from gasoline direct ignition engines. A model that can predict internal GPF temperature dynamics during regeneration events can then be implemented online to maintain GPF health and aide in exotherm control algorithms without the associated instrumentation costs. This work demonstrates a control-oriented model, which captures the thermal dynamics in a catalyzed, ceria-coated GPF in the axial direction. The model utilizes soot oxidation reaction kinetics to predict internal GPF temperature dynamics during regeneration events using three finite volume cells. A model methodology initially proposed by Arunachalam et al [18] is utilized with the GPF of this work, validating the broad applicability of that methodology. Then, the model’s temperature prediction fidelity is improved through axial discretization. The zonal model parameters are identified via a Particle Swarm Optimization using experimental results from the instrumented GPF. Identified parameters from the various data sets are used to develop a linear parameter varying model for prediction of the axial temperature distribution within the GPF. The resulting model is then validated against an experimental data set utilizing the exhaust temperature entering the GPF. The spatial discretization methodology employed both enables the prediction of spatial temperature variation within the GPF and improves the accuracy of the peak temperature prediction by a factor ranging from 2–10x.

The abundance, recruitment and mortality of the mud crab S. olivacea were studied in mangrove forests associated with the Kra Buri River in Ranong, southern Thailand. Data were obtained for mud crabs from two catch series. From March 1998 to March 2000, mud crabs were collected at monthly intervals from four to six fishermen who trapped the crabs at three different locations in the Kra Buri River estuary (commercial catch series). In addition, mud crabs were trapped experimentally in a 2000 ha mangrove area from March 1999 to May 2000 (experimental catch series). The external carapace width (ECW) and sex of each crab caught in this area were recorded and the population estimated from the average number of fishermen operating there. The size distribution in the mud crab catch was mono-modal with a size range of 5.0–13.5 cm ECW. Fewer female crabs were caught than male crabs and berried females were observed only in offshore catches (ECW: 8.2–11.6 cm). The size distributions from the two catch series were analysed using catch-at-length analysis with natural mortality rates set to 0.05, 0.1, 0.2. Mortality rates were lower for females (0.49 and 0.53 per month) than for males (0.90 and 1.00 per month). Estimated abundance increased with the size of the selected natural mortality rate, but irrespective of the rate set, the estimate of mud crab abundance remained within a narrow range with no significant upward or downward trend. In the experimental fishing area, average abundance was estimated to be 21–28 crabs/ha (min: 14 ha−1, max: 38 ha−1) including both males and females. Recruitment into the fishery was continuous throughout the year without any strong seasonal fluctuation, but the trends for male and female mud crabs were slightly different. Females also recruited into the fishery at a smaller average size compared to males.

The present study followed the temporal recruitment pattern of brachyuran larvae in a mangrove tidal creek on the Andaman Sea coast of Ranong Province, Thailand, based on the assumption that the processes governing recruitment are important for the overall population dynamics of mangrove brachyuran crabs. Plankton net samples were taken on five occasions: on two new moon spring tides, one waxing moon neap tide, one full moon spring tide and one waning moon neap tide during October and November 1997. In addition collectors for larval crab megalopae were employed every 3 days through one dry season and one wet season (March–October 1998). Both the plankton net samples and collector samples revealed four major brachyuran groups in three families: Ocypodidae, Grapsidae and Portunidae. The grapsid group was further separated into two morphotypes which were identified as Metaplax and sesarmid species. Identified group mean numbers per cubic metre were ocypodids 3.0, sesarmids 0.8 and Metaplax 0.5, while portunid megalopae were very scarce (≪0.1 m−3). Further analysis of plankton net samples showed that when considering the parameters date, depth, current direction and the diel cycle, Metaplax and ocypodids distribute differently in the tidal and lunar cycle. Metaplax recruitment dominates on flood tides and on bottom layers, followed by middle and surface layers. Conversely, ocypodid abundance varied significantly with date only. Notably recruitment was not dependent on the diel cycle for either group. The collector samples of megalopae showed that recruitment of ocypodids, Metaplax and sesarmids occurred on full and new moon spring tides, while portunid megalopae preferred to settle on full moon spring tides. Since tidal currents were related to the lunar cycle megalopa groups are also cross-correlated with tidal amplitude, except for the portunid group. It is concluded that megalopae recruit in a similar manner to what has been found in other regions of the world, except that the abundance of ocypodids and Metaplax is not influenced by the diel cycle.