1,720,956 research outputs found
Enhancement of Shelf-Life and Oxidative stability of Jatropha curcas Biodiesel in Zimbabwe
No full textBiodiesel is an environment friendly liquid biofuel similar to petro-diesel in terms of fuel quality and combustion characteristics. Increasing environmental concerns, fast depleting petroleum reserves and agriculture based economy of Zimbabwe are the driving forces to promote biodiesel as an alternative renewable fuel. Biodiesel, derived from Jatropha curcas seed oil has great potential to be used as a diesel engine fuel in Zimbabwe to reduce air pollution and to reduce dependence on limited fossil fuel.
Under normal storage conditions diesel fuel can be expected to stay for 12 months or more at 20oC. The research carried out showed that the Jatropha biodiesel has a storage life of 3 months. Beyond this period, the diesel reacts with oxygen from the atmosphere that forms fine sediments and gums, which block the fuel filters leading to poor performance of the engine. This is attributed to the presence of double bonds in the J. curcas oil mainly oleic, linoleic or linolenic acids. J. curcas biodiesels have different amounts of esters (which vary from different geographical location) and the trend of increasing stability is linolenic < linoleic < oleic. These esters undergo auto-oxidation with different rates depending upon the numbers and positions of the double bonds and result in the formation of a series of by-products like acids, esters, aldehydes, ketones, lactones among others. Therefore the aim of the current work is to study the oxidation stability of J. curcas biodiesel and also the effectiveness of various antioxidants which enhance its shelf life. Five antioxidants namely tertiary Butylhydroquinone (TBHQ), Butylated hydroxytoluene (BHT), Butylated hydoxanisole (BHA), Pyrogallol (PY) and Gallic Acid (GA) have been used in this work. PY was found to be the best antioxidants among all 5 antioxidants used. The optimum amount of antioxidant (PY) for pure biodiesel was 3000 ppm
Investigation of the physical and chemical stability of biodiesel produced from Jatropha Curcas Species in Zimbabwe
No full textJatropha curcas L. seeds as a raw material for biodiesel production are a rapidly growing interest over the world because of their high oil content, ecological adaptability, and excellent fuel properties. Though there is an increase in productivity of biodiesel, showing solution for future energy insecurity, there still remains some concern for commercialization due to its susceptibility to degradation during long term storage. The aim of this research work is to investigate the effect of temperature and ambient condition on Jatropha biodiesel storage. A study was conducted for a period of 12 months, where Jatropha biodiesel samples were stored at different temperatures (4°C, 25°C, and 35°C) and environmental conditions (darkness, light, and air). At regular intervals, the samples were taken out to analyze acid value, density, kinematic viscosity, and fatty acid profile to monitor the quality of biodiesel. Analysis showed that acid value, density, kinematic viscosity, and fatty acid content increases with the increase in storage time of biodiesel samples. However, Jatropha biodiesel stored at 35°C, in contact with ambient air and light showed highest degradation compared to that which was stored at 25°C and 4°C. Among all the parameters studied, high temperature and air exposure are the two most important parameters which accelerate the degradation process. Light exposure had mild but significant effect on Jatropha biodiesel degradation over a long storage period.,Zimbabwe Institution of Engineers (ZIE
Feasibility study of Biofuels energy exploitation for Southern Africa’s prosperity: Case study Zimbabwe
No full textThe Southern Africa’s Economy is slowly re-emerging from a protracted period of economic decline (in particular Zimbabwe) due to the raise in exploitation of biofuels energy resources. The energy challenge is especially acute in the transport sector, as most vehicles will continue to rely on liquid fuels for the decennia to come. Diesel and petrol (gasoline), obtained from fossil oil, will gradually be replaced by renewable liquid fuels, which are called biofuels.
Most of the Southern Africa Member States can grow most of energy crops. The ecology of the region can accommodate most crops. In some of the Member States land is still abundant e.g. in Angola, DRC, Mozambique, Tanzania, Zambia and Zimbabwe such that production of energy crops will not disturb food production. Agricultural research and the seed industry have untapped capacity to improve yields and productivity for all energy crops.
The purpose of this desk study was to assess the feasibility for the production of biofuels in the
Southern Africa Region. The study reveals that the current petroleum consumption in Southern Africa is about 0.7 million barrels a day. After refinery this produces roughly 12 million tones of diesel a year. If all of this were biodiesel region needs it could be met from 400 factories with a capacity of 30,000 tones a year each. The cost of such a plant is 40 to 50 million Euros9.
The biofuels exploitation in the Southern Africa can completely change the living standard of the people. At macro-economic level, the production of biofuel could employ millions of rural labourers, thereby boosting economic growth. Moreover, most Member States can make huge savings on foreign exchange. The region’s energy sector will be less dependent on external vagaries, and exchange rates, and will produce clean energy, which in turn will yield Kyoto-bonuses.,Southern African Sustainable Energy Initiative (SASEI
The Techno-Economic impact of Petrol- Ethanol Fuel blends on light duty vehicles: Case study- Zimbabwean Petrol Vehicle Fleet.
No full textThe Government of Zimbabwe has been promoting ethanol as a renewable, homegrown alternative vehicle fuel to gasoline. Ethanol is a form of alcohol that is combustible and can power engines easily. In Zimbabwe, it is made primarily from sugar cane.
This alternative fuel has resonated with consumers who are concerned with Zimbabwe’s dependence on foreign oil as well as pump-price volatility. The main advantages of ethanol to the Zimbabwean government are that it can be produced in large quantities, and it requires fewer technological breakthroughs and less infrastructure development than is needed to support electric vehicles and fuel cell vehicles.
However university scientists and consumers are raising questions about ethanol's viability as a fuel source and are arguing that it is (i). Unethical to produce fuel from a food crop, especially if it drives up food prices.(ii) Ethanol contains less energy than gasoline, and it takes a lot of energy to produce.(iii) A variety of conflicting studies have shown that producing ethanol may or may not increase emissions of carbon-dioxide, a gas linked to global warming.
To better judge ethanol's strengths and weaknesses, a large fleet of petrol vehicles from different government departments and individuals from the 10 provinces of Zimbabwe were used to gather data for the fuel consumption, vehicle performance/drivability and environmental effects The research was carried out at different fuel blends of increment of 10% up to 100% and under different weather and road conditions. A control set up of mounted bench engine was put at University of Zimbabwe Mechanical Engineering Workshop.
The main objectives of this research was to investigate the optimal ethanol/petrol blend and determine cold start and hot start exhaust emission.
The research revealed that most of the vehicles are non-fexi-vehicles and have a lower fuel economy at higher blends compared with conventional fuel. The exhaust emission were below the recommended levels by the Environmental Protection Agency.,International Council for Science (ICSU
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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