Muhammad Penta Helios*, Wanchai Asvapoositkul and Kyung Chun Kim
Abstract: This paper presented an experimental study of water-air two-phase flow in the throat-diffuser region of a horizontal ejector. The aims are to visualize flow patterns and to assess the performance of ejector at different backpressure. The performance was described into dimensionless terms, i.e., the pressure ratio and volumetric ratio. The ejector operated at a constant water flow rate and six different back pressure as the operating condition. Both non-intrusive and intrusive methods were applied to visualize the flow and to record related data of performance, i.e., flow rate, pressure, and temperature simultaneously. An image processing algorithm and performance analysis were employed simultaneously to analyze the images, while sensor data recording was used to evaluate the ejector's performance. The results revealed that the two flow patterns appeared with increasing of backpressure, namely the stratified-wavy and bubbly flows. The binary image exposed that the highest performance of the ejector obtained when the bubble generation and mixing process happened at the middle and end section of the throat, respectively. As the mixing process results, the highest area gas fraction and performance increased with increasing backpressure ratio. It indicated intimate air dispersed in water occurs pointed by declining of the volumetric ratio.
Keywords: High-speed camera, stratified-wavy flow, bubbly flow, mixing process, ejector performance.
Ahsan Farooq, Athikom Bangviwat and Shabbir H. Gheewala
Abstract: The transportation sector is growing rapidly in a developing country like Pakistan and it mostly depends on imported petroleum products. To substitute these limited and environment-offending fuels with renewable and more sustainable fuels, ethanol has been recognized as one of the possible solutions. However, the economic competitiveness of ethanol against gasoline must be investigated to ensure its economic sustainability. The present study has adopted a life cycle costing approach for the economic analysis of sugarcane molasses-based ethanol production. The economic feasibility of gasoline substitution by molasses-based ethanol in the form of gasoline-ethanol blends E10 and E20 (10% and 20% blends of ethanol with gasoline, respectively) has been explored. The results of cost breakdown analysis showed that the net feedstock cost had the highest contribution followed by operation and maintenance cost, and capital investment cost respectively, in the estimated ethanol production cost. Both blends showed comparative economic advantages over gasoline in terms of energy production. It is concluded that E20 is the better option because of its lower production cost, better environmental performance and the potential to bring better social reforms as compared to E10.
Keywords: Life cycle costing, Molasses, Ethanol, Gasoline, Pakistan.
Kanjarat Fangmongkol and Shabbir H. Gheewala*
Abstract: Biodegradable products are generally considered an eco-friendly alternative to petroleum-based product due to the advantages of using renewable feedstock in their production as well as biodegradability at end-of-life. This study aims to assess the potential impacts and find the pros and cons of lunch boxes in Thailand made from sugarcane bagasse and polystyrene (PS) foam considering different waste management options. A comparative life cycle assessment was performed to this end. The cradle-to-gate results showed that, contrary to popular belief, PS foam lunch boxes performed better than their bagasse-based alternatives in all the impact categories. The major phase contributing to the impacts of bagasse lunch boxes is bleached bagasse pulp production stage followed by the lunch box production stage. However, the analysis of the full life cycle of both lunch boxes showed that bagasse lunch boxes with the recycling option had lower impacts than PS foam lunch boxes in all impacts categories. Recycling is also the most appropriate waste management option for PS foam lunch boxes. Overall, it can be concluded that the bagasse lunch box has a good environmental performance provided that the waste management at the end of life is handled appropriately.
Keywords: Life cycle assessment (LCA), Sugarcane bagasse, Polystyrene (PS) foam, Single use lunch box.
Imad Abdella Idris, Suneerat Fukuda* and Patrick Rousset
Abstract: Using large biomass particles for torrefaction can decrease the grinding costs and therefore the total operating costs. However, the heat and mass transfer phenomena in larger particles are more pronounced during torrefaction compared to smaller ones. In this study, the effect of temperature gradient and exothermicity generated inside the biomass on the yield and physicochemical properties of biomass torrefied at 260°C and 300°C were studied. Cylindrical eucalyptus wood particles prepared into different dimensions based on aspect ratios (length to diameter ratio or L/D ratio) as L/D = 2, L/D = 3 and L/D = 5 were used. Increasing length (from 60 to 100 mm) with fixed diameter (20 mm) showed negligible effect on the temperature profile and core peak temperature, while a higher thermal shoot was clearly observed when increasing particle diameter (from 20 to 30 mm) with fixed length (10 mm). Higher torrefaction temperature enhanced the energy density of the torrefied products. Increasing particle length (from L/D 3 to L/D 5)lowered the degree of degradation resulting in higher mass and energy yield at 300°C. However, increasing diameter (20 to 30 mm)or reduction in L/D ratio resulted in lower mass and energy yield due to the exacerbated thermal decomposition in thicker particles.
Keywords: Biomass, Torrefaction, Aspect ratio, Core temperature, Mass yield, Energy yield.