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An Optimization Study of Lipid Extraction from Chlorella minutissima for Biodiesel Production
Get PDFNowadays, researches on microalgal biodiesel production are focused on to improve the process efficiency and reduce the operational costs. One of the most expensive steps in microalgal biodiesel production is lipid extraction of microalgae. In this study, C. minutissima microalgae was produced in photobioreactor, and then solvent extraction of microalgal lipids were investigated. Box-Behnken design (BBD) was used to study the effect of extraction temperature, solvent/biomass ratio and residence time of solvent on the oil yield and to optimize lipid extraction. The maximum extraction yield was found to be 75% under the conditions of at the temperature of 70°C, 30:1 solvent/biomass ratio and 8 h. This study showed that the most effective parameter on extraction yield was temperature among three parameters. The results showed that optimized process conditions improved the extraction yield and it is a cost-effective way to produce biodiesel efficiently
Understanding the Energy Requirements for Microwave Weed and Soil Treatment
Get PDF Crop yield gaps, due to abiotic and biotic stresses undermine efforts to secure food for the world. Weeds are a significant biotic stress in cropping systems and can reduce productivity by 35 % to 55 % in some cases. Herbicide resistance is a compounding effect to control weeds. Non-chemical methods are being considered, especially thermal treatments, which are compatible with zero-till systems. Microwave weed and soil treatment has been shown to control weeds, weed seeds and pathogens in cropping systems. This paper explores the thermal efficiency of several thermal weed control systems, with an emphasis on microwave systems
Investigation Results and Analysis of Solar Cells Performance Enhancement by Cooling using Thermoelectric Cooling (TEC)
Get PDF Solar energy received special attention and extensive studies were conducted to increase the efficiency of solar collectors and solar cells. One of the major problems of the operation of solar cells is the temperature rising which causes a reduction in the energy yield. The main objective of this work is to experimentally investigate the cooling effect of thermoelectric cooling devices (TEC) on solar cell performance. To overcome the rising temperature effect, the cooling by using the Peltier device is proposed and investigated. In this approach, the TEC cooling module is attached to the backside of the photovoltaic cell. It is assumed that the required power to run the TEC module is provided by the photovoltaic cell itself when the additional power obtained by the cooling is more than the needed power to operates the TEC device. The results show that the cooling of the tested PV cells/modules samples by using the Peltier TEC device was slightly enhanced the PV cells' performance. In our case of study for a 2Wp solar cell sample, the maximum temperature difference obtained due to Peltier cooling is about 5.3C° which produced an enhancement for the produced power and the open-circuit voltage by 7.02% and 2.64% respectively. However, the needed power to feed the Peltier element is significantly higher than the recovered power due to the Peltier cooling. The same trend was investigated for the tested samples of PV modules. So, the proposed combination of PV and Peltier cooling system was investigated to be economically not feasible regardless of the cost evaluation. Finally, the spatial effect and the proposed system can be improved significantly by altering and improving the performance of the Peltier element and the thermal characteristics of the solar cells/modules encapsulation material
Minimal Path Technique for Congestion Management in Electrical Market
Get PDF Restructuring of electric power system was mainly introduced in order to create a competition through an electricity market, in such a way to dispatch generators with the lowest bidding prices. However, limitations on the power carrying capability of transmission lines created the problem of congestion. This paper presents a developed technique based on the minimal path concept for managing the congestion problem. The main achievement of this technique, in comparison with other developed methods, is that it does not have to evaluate the contribution of each generator (i.e. distribution factors) in the power flow through each line in the given system, which results in the formulation of a large number of equations to be solved. Instead, it identifies the generators connected to the receiving and sending ends of the congested line, classify these generators into three types (increasing, decreasing and critical) and according to this classification their outputs are decreased and/or increased by specified increments until congestion is solved. Hence, one does not need to formulate equations and then solve it
Phenomenology and Space in Architecture: Experience, Sensation and Meaning
Get PDFUntil recently, architecture has been mostly evaluated over its stylistic and visual characteristics. Whereas, the architectural space is primarily vital and therefore, it should not be evaluated independently of its environment and users. Pallasmaa emphasizes on the significance of experience and connection with the environment in architecture. Phenomenology, which aims to create sensory perception, is about creating an abstract experience beyond tangibility. Sensing beyond physical entities in spatial experience deepens meaning. Buildings and cities, essentially provide the necessary view to understand and confront the human existence. It is, therefore, important for architecture to be seen as the subject of phenomenology. This paper explores the relationship between phenomenology and architectural space through experience, sensation, and meaning. It argues that the relationship between human and built environment will be strengthened to the extent that the mentioned features could participate in the space
The Important Role of Diagnostics for the Structural Recovery of Historic Buildings
Get PDF Diagnostic tests represent a fundamental phase of knowledge for historical masonry buildings. The correct design of structural recovery and seismic improvement work must be based on the results of the preliminary tests, for a better knowledge of the vulnerabilities and the mechanical characteristics of ancient masonry structures. The Italian technical codes have given great importance to the level of knowledge reached on the existing buildings, promoting the investment of diagnostics as a fundamental phase of the design work. Two case studies of multidisciplinary diagnostic tests, carried out on monumental buildings, are described for the preliminary evaluation of the quantitative and qualitative characteristics of the masonry structures. In both cases the tests allowed to better understand the vulnerabilities of the masonry section and to design the most appropriate strengthening work. The interpretation of the results coming from tests of different typologies allowed to investigate in depth the hidden peculiarities of the historical masonry structures
Preparation and Properties of Foaming Agent for Air Foam Flooding
Get PDF In order to meet the requirements of air foam flooding in Dagang Gangdong Oilfield, two kinds of foaming agents, GFPA-1 and GFPA-2, were prepared by sulfonation, neutralization and high-temperature hydrolysis of α-olefins with different carbon chain lengths in the laboratory. The test results of foaming agents for its properties showed that when the concentration of foaming agent was over 0.5%, the initial foaming volumes of the two foaming agent systems were more than 500mL, and the foam half-life of GFPA-2 was about 3.5 hours, obviously longer than that of GFPA-1. Therefore, GFPA-2 was selected as the foaming agent for air foam flooding. The experimental results of static adsorption, plugging and core displacement performance of GFPA-2 foaming agent showed that the initial foaming volume of GFPA-2 foaming agent could still maintain 500mL after 48 hours of adsorption at a concentration of 0.5%, and when the ratio of gas to liquid was 1: 1, the resistance factor was more than 50. When a 0.4% foaming agent was injected with 0.35 PV slug, the displacement efficiency of air foaming flooding was 17.4% higher than that of water flooding
Experimental Investigation Thermal Performance of Loop Heat Pipe Operating with Different Working Fluids
Get PDF Nowadays, due to the tremendous development of data centers (DCs), studying the effective cooling methods that can face to the challenges such as the high power or heat flux dissipation and the efficient electricity consumption in DCs has never been unnecessary. Loop heat pipe (LHP), a two-phase heat transfer device, is being considered as one of the potential solutions for the above problems. This paper introduces the experimental study on the thermal performances of LHP functioning under gravity assisted condition with different working fluids that are water and ethanol (C2H5OH). This LHP has the flat-rectangular evaporator with the stainless-steel (SS) sintering wick installed inside. The results demonstrate that under the same condenser cooling condition, water LHP performed better than ethanol LHP. In the case of water LHP, when heating power was increased from 33 to 535 W, the temperature at the top surface of the heating block raised from 38oC to 110oC. With the ethanol LHP, this temperature reached 133oC at the heating power of 395 W. If temperature limitation of microprocessors functioning inside the DCs is recognized at 85oC, the cooling capabilities of LHP are 220 W and 350 W corresponding to the working fluid are ethanol and water respectively. In addition, the discussions about the difference in boiling heating transfer characteristics as well as condenser performances between water LHP and ethanol LHP are also presented in this study
Enhancement of Thermophilic Digestion of Food Waste (FW) via Trace Element Supplementation
Get PDFIn this study, the role of trace element (TE) supplementation and performance characteristics of a thermophilic anaerobic digester fed by food wastes (FW) is investigated in the long run, and a representative operational data set for field application is reported over the whole experimental period. Continuous feeding of food wastes with a dry matter of 5% for 150 days was carried out using a 100 L pilot-scale CSTR type anaerobic digester under thermophilic operation conditions. Hydraulic retention time (HRT) and organic loading rate (OLR) were kept around 28 days and less than 3.0 kg oDM m3 day-1, respectively. Volumetric biogas production values were reported to be 0.32 m3 m-3 day-1 during the period where there is no TE supplementation; on the other hand, biogas production was doubled (0.69 m3m-3day-1) following TE supplementation. This corresponds to an average unit biogas production of 317 and 443 L kg-1 oDM, during TE supplementation and no TE supplementation periods, respectively. Statistical analysis indicated that Co, As, Se, and Al were the most significant trace elements affecting the digester performance
Compare to Planting on Bed and Flad Surface Systems in Wheat and Barley
Get PDFThe main principle of a bed planting system is basically of sowing crops on beds or ridges instead of sowing on the flat surface. The aim of the study was to compare the new (bed) and traditional planting system for wheat and barley in Southeastern Anatolia Region and to identify and quantify potential grain yield and quality, because this planting system is becoming common in farming areas. On the other hand; it was compared with the cost of sowing, seed, irrigation, chemical struggle, harvest and observed the germination of seeds in both the flat surface and bed systems. Traditional, all agricultural applications were sown in flat surface, but special applications were used in bed planting systems. The study was conducted in Diyarbakir ecological conditions in the 2010-2011 production season. Acording to the combined analysis, significant differences were determined at the level of 1% and 5%, in the planting system, genotype and genotype x planting system interactions in terms of grain yield and quality parameters in wheat and barley. The results showed that grain yield and quality were higher in the conventional method than planting on bed (new) system, but, irrigation, struggle with weeds, disease and pest management, the operation of harvesting can be made more comfortable in the bed planting system than conventional system. According to the result of this study, bed planting system can be applied successfully as economic savings for growers through reduced crop inputs and improved production efficiency in wheat and barley, depending on hard conditions (alternation planting cotton, irrigated areas and when the price of seed is high)