Effect of curing conditions and harvesting stage of maturity on Ethiopian onion bulb drying properties

The study was conducted to investigate the impact of curing conditions and harvesting stageson the drying quality of onion bulbs. The onion bulbs (Bombay Red cultivar) were harvested at three harvesting stages (early, optimum, and late maturity) and cured at three different temperatures (30, 40 and 50 oC) and relative humidity (30, 50 and 70%). The results revealed that curing temperature, RH, and maturity stage had significant effects on all measuredattributesexcept total soluble solids

Polymer pyrolysis and oxidation studies in a continuous feed and flow reactor : cellulose, polystyrene, and polyethylene

A dual zone, continuous feed tubular reactor is developed to assessthe potential for formation of products from incomplete combustion in thermal oxidation of common polymers. Solid polymer powder (cellulose,polystyrene, or polyethylene) is fed continuously into a volatilization oven where it fragments and vaporizes under continuous steady state conditions. The gas phase polymer fragments flow directly into a second, main flow reactor oven and undergo further pyrolysis and oxidation reaction. Temperatures in the main flow reactor are varied independently of the volatilization zone to observe conditions needed to convert the initial polymer fragmentsto CO2 and H2O. Combustion products are monitored at main reactor temperatures from 400°C to 750°C and at 2 seconds residence time with four, on-line GC/FID\u27s; polymer reaction products and intermediates are further identified by GC/MS. Forty one species are positively identified in the volatilization of cellulose. Increases in temperature at constant fragment reaction time shift the molecular weight distribution of gas products toward lower mass and increase extent of conversion. Complete conversion (mineralization) of identified cellulose fragments is observed at 2 seconds reaction time and 750°C under fuel lean conditions. Major volatilization products at 400°C are carbonyl compounds, hydrocarbons, furans, pyrans, and anhydrosugars. Cellulose in the presence of NaCl (5% of Cl) shows higher decomposition of levoglucosan and more rapid conversion of major initial products to CO and CO2. Formation of major initial products, C6 oxygenated species, hydrocarbons (C5-C7), furan derivatives (C4 and C5), and light species (C1 - C4) are somewhat inhibited by NaCl at fuel equivalence ratios Φ = ~0.25 and Φ = ~ 0.8, but increase higher at Φ= ~0.8 except for light species at low temperatures. Fifty two initial fragments from combustion of polystyrene are positively. Major initial products are monomer, dimer, and trimer styrene. Increases in temperature of the main reactor increase production of polynuclear aromatic hydrocarbons (PAHs) and the extent of conversion. Complete conversion of identified initial fragments is observed at 2 seconds residence time and 750°C under both Φ = ~0.1 and Φ =~0.8. There are no observed NaCl effects on combustion of polystyrene: The product distribution versus temperature is changed for high yield species and complete decomposition of initial products is increased by about 50°C at Φ =~0.8 relative to Φ = ~0.1. The pyrolysis and oxidation of medium density polyethylene (MDPE) with branch chains is conducted in the main reactor temperature range of 400°C to 650°C. Fuel equivalence ratios are between Φ = 0.24 and 0.32 at 2 seconds residence time. Ninety species are positively identified. Major products are alkanes, alkenes, aldehydes, ketones, and alcohols in the range of C1 to C22. Most prominent products over 1% (by mass) are CO, CO2, methane, ethene, formaldehyde, propene, propane, butene, 2-pentanone, and pentanal. Complete combustion is achieved at relatively low temperature of the main reactor, 650°C

Reduction of scrap percentage of cast parts by optimizing the process parameters

Casting is a widely used manufacturing process in the automotive industry. Die casting is the most popular type of casting processes. But the fact observed in many industries is the scraps or wastages occurring after the process. Thus, this thesis is primarily based on understanding the die-casting process and the factors governing them. In this study, the part to be studied is a throttle body. The raw material used for the production is AlSi9Cu3. The main concern in this part is the occurrence of defects such as bad filling, heat bubbles, and porosity. Thus, it is important to perform process optimization. Techniques or methods such as Design of Experiments, ANOVA analysis, and numerical simulations are used. This thesis also focuses on the use of brainstorming as an industrial discussion tool and the use of quality tools for process optimization. Thus, these techniques are utilized in order to eliminate the defects. The scrap after using these techniques and methods is reduced to 9% from 14% initially found. This investigation has been performed as a continuous improvement project in Sonafi and as a master thesis for “Instituto Superior de Engenharia do Porto”.A fundição é um processo de fabrico amplamente utilizado na indústria automóvel. A fundição injetada é o tipo mais popular de processos de fundição. Mas, o facto observado em muitas indústrias é o aumento de sucatas ou desperdícios que ocorrem após o processo. Assim, esta tese é baseada principalmente na compreensão do processo de fundição e nos factores que a governa. Neste estudo, a parte a ser estudada é um corpo do acelerador. A matéria-prima usada para a produção é AlSi9Cu3. A principal preocupação nesta parte é a ocorrência de defeitos como mau preenchimento, bolhas de calor e porosidade. Assim, é importante realizar a otimização do processo. São utilizadas métodologias como o Desenho de Experiências, análise ANOVA e simulações numéricas. Esta tese também se concentra no uso do brainstorming como uma ferramenta de discussão industrial e uso de ferramentas de qualidade para otimização de processos. Assim, essas técnicas são utilizadas para eliminar problemas ocorridos na produção. Esta investigação foi realizada como um projeto de melhoria contínua na Sonafi e como uma tese de mestrado para o Instituto Superior de Engenharia do Porto

Synthesis and Characterization of Nanomaterials

Nanomaterial is defined a natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50 % or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm to 100 nm. Nanomaterials not only differ from the corresponding bulk materials in morphological properties but they can also demonstrate different physico-chemical characteristics. Manufactured nanomaterials are regarded as key components of innovations in various fields with high potential impact, such as energy generation and storage, electronics, photonics, diagnostics, integrated sensors, semiconductors, foods, textiles, structural materials, sunscreens, cosmetics, and coatings or drug delivery systems, and medical imaging equipment. Widespread use of nanomaterials raises concerns about their safety for humans and the environment, possibly limiting the impact of the nanotechnology-based innovation. The development of safe nanomaterials has to result in a safe, as well as functional material or product. Its safe use, and disposal at the end of its life cycle must be taken into account too. Responsibility for the safe handling of synthetic nanomaterials therefore rests with the manufacturer and importer. This book gathers and reviews the collection of five contributions (four articles and one review), with authors from Europe and America accepted for publication in the aforementioned Special Issue of Fibers