Refine
Document Type
- Doctoral thesis (2)
Has Fulltext
- yes (2)
Is part of the Bibliography
- no (2)
Language
- English (2)
Keywords
- Biodiesel (2) (remove)
Institute
In recent years, biodiesel is an alternative fuel to petroleum diesel that is renewable and creates less harmful emissions than conventional diesel. Biodiesel blends – usually B20 or below, have been the most commonly used biodiesel blends. In current study, the kinetic mechanism of n-decane/α-methylnaphthalene (AMN)/methyl-decanoate (MD) blend is developed and validated as the surrogate for biodiesel/diesel blends. The IDEA reference fuel (70% n-decane/30% AMN by liquid volume) was formulated in the past as a two-component diesel surrogate fuel. A comprehensive and compact oxidation model for the IDEA reference fuel is developed. One important fuel-fuel interaction pathway via reaction pathway of A2CH2 + HO2 is observed and detailed discussed. The IDEA blends are validated by comprehensive target experiments for n-decane, AMN, and the AMN/n-decane blends. Ignition delay times, flame speeds, and species composition in jet stirred reactor and counter flow flames are successfully simulated for a broad range of temperatures (500-2000 K) and pressures (1-50 bar). The simulations of the IDEA blend with current mod-el show acceptable agreement when compared with different experiments of ignition delay times for diesel fuels as well as flame speed experiments. With a chain of ten carbon atoms and a methyl-ester group attached, MD is considered as a one-component surrogate fuel for biodiesel. A comprehensive and compact kinetic model for MD is developed. The mechanism is critically tested by comparison of model predictions with experimental data over a wide temperature (500 to 1500 K) and pressure (1 to 20 bar) range and for different fuel/oxidizer ratios. The good maintenance of chemical information during the reduction has been confirmed by simulation results, as well as the sensitivity and flow analyses performed using the detailed and the skeletal model. The MD model is compared with available experimental ignition delay times of biodiesel fuels. The good agreement between the simulations and the experiments proves that this model is a reliable kinetic model for simulations, either used by itself or in combination with IDEA blend. To improve the mechanism analysis, this thesis introduces a new three-stage reactive flow analysis. The final skeletal n-decane/AMN/MD blend with skeletal base mechanism includes 295 species and 3500 reactions by using the CGR approach. Based on the above validations and comparisons, current blend is considered as one surrogate for biodiesel/diesel blends that is suitable for improving kinetic understanding and for application in engine simulations.
The ever-increasing price of fossil diesel oil, its availability and affordability has prompted the search for cheaper sources of diesel fuel especially in rural Ghana where it could be used by small to medium scale processors. The aims of this project were to provide a readily available and renewable fuel that will serve as a diesel substitute: to power diesel engines running equipment in a shea butter extraction unit at Gbimsi, to provide a readily available fuel to serve as a kerosene substitute for lighting local lanterns, to evaluate the economic viability of the use of the bio-fuel as both diesel and kerosene substitutes. in Ghana. A pilot Jatropha plantation was established for the Gbimsi women’s group. A pilot processing unit was also established. The women were taken through series of training which included the extraction and utilization of Jatropha biofuel and soap making using the Jatropha oil. The Jatropha biofuel extracted by the women mixed with various amounts of mineral diesel oil was tested on lister-type diesel engines and in lanterns to ascertain its performance. A combination of 30% mineral diesel oil: 70% Jatropha bio-fuel was found to be appropriate for running the diesel engines. Local lanterns were found to give smokeless light and were found to last four times longer than kerosene when the Jatropha oil was used. In conclusion, the Jatropha biofuel helps in achieving energy security in communities that are otherwise inaccessible and constantly in search of regular supply of mineral fuels like diesel and kerosene. The press cake obtained after the oil extraction could be used as an organic fertilizer for improving soil fertility. Questionnaires were administered to ninety (90) shea butter producers and ten (10) exporters selected at random from the Northern, Upper East, Upper West and Greater Accra regions of Ghana in order to gather information from the producers/users as well as exporters on the Knowledge, Attitude, Beliefs and Practices (KABP) of shea butter production, consumption and export. The outcome of the study suggested that shea butter export has increased tremendously over the past decade as a result of very high demand for the product from both the local and international markets. The existing and potential export maket for shea butter were identified to be Japan, United Kingdom, Netherlands and United States of America. In addition, the shea butter produced were evaluated for the quality characteristics as well as their storability in different storage (packaging) materials. These were conducted using standard analytical methods. The minimum quality requirement of shea butter for export are : Moisture (0.01-1.0%), Free fatty acid (3.5-4.0), acid value (1.0-10.0) and the product should not be dark in colour. The best packaging material used for the export of the product are metal drums and card boxes and the only constraint faced by the exporters is the cost of the packaging materials which is considered to be expensive. The producers in the studied communities treated shea butter as their main farming activity. In an attempt to investigate the changes in chemical and physical properties of shea butter during storage, various chemical and physical quality indices were monitored. A 3 x 4 x 4 factorial experimental design with storage condition [open air (28-34°C), tropical ambient (26-31°C) and refrigeration (4-7°C) conditions], packaging material (metal cans, polyethylene bags, plastic containers and calabash), storage time (0,1,2 and 3 months) as variables was performed. Changes in the chemical and physical properties of the butter were observed during storage of the product under the different storage conditions and packaging materials. Storage caused slight increases in moisture content (0.01-0.07%), free fatty acid (3.29-4.38%), acid value 6.55-8.20%), iodine value (59.86-60.06) and peroxide value (8.24-10.64 mEq/kg) within the three months storage period. Products stored under open air (28-34°C) conditions generally significantly (p<0.05) affected the chemical properties of the butter during storage whilst those stored under ambient (26-31°C) and refrigeration (4-7°C) conditions did not have significant (p<0.05) effect on the chemical properties. No wide variations in physical properties were noted for the products during storage under the different storage conditions and packaging materials. Shea butter can be stored using all the four different packaging materials studied. However, it is highly recommended that the products are kept under tropical ambient (26-31°C) and refrigeration conditions (4-7°C) during storage. The best condition for the storage of shea butter is refrigeration which maintains the quality of the product during prolonged stored periods. Storage of the shea butter under open air (28-34°C) conditions allows for oxidative and hydrolytic rancidity rendering the products unsuitable for consumption after long storage periods.