Search results for: volumetric heat generation

Authors: Xinke Huang, Huan Wang, Lidong Guo, Changbin Ju, Runbiao Liu, Shanshan Meng, Yibo Wang, Honghua Xu

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Large-scale photovoltaic (PV) generation system connected to HVDC grid has many advantages compared to its counterpart of AC grid. DC connection can solve many problems that AC connection faces, such as the grid-connection and power transmission, and DC connection is the tendency. DC/DC converter as the most important device in the system has become one of the hot spots recently. The paper proposes a centralized DC/DC converter which uses Boost Full Bridge Isolated DC/DC Converter(BFBIC) topology and combination through input parallel output series(IPOS) method to improve power capacity and output voltage to match with the HVDC grid voltage. Meanwhile, it adopts input current sharing control strategy to realize input current and output voltage balance. A ±30kV/1MW system is modeled in MATLAB/SIMULINK, and a downscaled ±10kV/200kW DC/DC converter platform is built to verify the proposed topology and control strategy.

Keywords: photovoltaic generation, cascaded dc/dc converter, galvanic isolation, high-voltage, direct current (HVDC)

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Authors: Staņislavs Gendelis, Andris Jakovičs, Jānis Ratnieks, Aigars Laizāns, Dāvids Vardanjans

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Dehumidification of biogas at the biomass plants is very important to provide the energy efficient burning of biomethane at the outlet. A few methods are widely used to reduce the water content in biogas, e.g. chiller/heat exchanger based cooling, usage of different adsorbents like PSA, or the combination of such approaches. A quite different method of biogas dehumidification is offered and analyzed in this paper. The main idea is to direct the flow of biogas from the plant around it downwards; thus, creating additional insulation layer. As the temperature in gas shell layer around the plant will decrease from ~ 38°C to 20°C in the summer or even to 0°C in the winter, condensation of water vapor occurs. The water from the bottom of the gas shell can be collected and drain away. In addition, another upward shell layer is created after the condensate drainage place on the outer side to further reducing heat losses. Thus, counterflow biogas heat exchanger is created around the biogas plant. This research work deals with the numerical modelling of biogas flow, taking into account heat exchange and condensation on cold surfaces. Different kinds of boundary conditions (air and ground temperatures in summer/winter) and various physical properties of constructions (insulation between layers, wall thickness) are included in the model to make it more general and useful for different biogas flow conditions. The complexity of this problem is fact, that the temperatures in both channels are conjugated in case of low thermal resistance between layers. MATLAB programming language is used for multiphysical model development, numerical calculations and result visualization. Experimental installation of a biogas plant’s vertical wall with an additional 2 layers of polycarbonate sheets with the controlled gas flow was set up to verify the modelling results. Gas flow at inlet/outlet, temperatures between the layers and humidity were controlled and measured during a number of experiments. Good correlation with modelling results for vertical wall section allows using of developed numerical model for an estimation of parameters for the whole biogas dehumidification system. Numerical modelling of biogas counterflow heat exchanger system placed on the plant’s wall for various cases allows optimizing of thickness for gas layers and insulation layer to ensure necessary dehumidification of the gas under different climatic conditions. Modelling of system’s defined configuration with known conditions helps to predict the temperature and humidity content of the biogas at the outlet.

Keywords: biogas dehumidification, numerical modelling, condensation, biogas plant experimental model

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Authors: Nikolaos Katsoulas, Sofia Faliagka, Athanasios Sapounas

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Greenhouse ventilation is an effective way to remove the extra heat from the greenhouse through air exchange between inside and outside when outside air temperature is lower. However, in the Mediterranean areas during summer, most of the day, the outside air temperature reaches values above 25 C; and natural ventilation can not remove the excess heat outside the greenhouse. Shade screens and whitewash are major existing measures used to reduce the greenhouse air temperature during summer by reducing the solar radiation entering the greenhouse. However, the greenhouse air temperature is reduced with a cost in radiation reduction. In addition, due to high air temperature values outside the greenhouse, generally, these systems are not sufficient for extracting the excess energy during sunny summer days and therefore, other cooling methods, such as forced ventilation combined with evaporative cooling, are needed. Evaporative cooling by means of pad and fan or fog systems is a common technique to reduce sensible heat load by increasing the latent heat fraction of dissipated energy. In most of the cases, the greenhouse growers, when all the above systems are available, apply both shading and evaporative cooling. If a movable screen is available, then the screen is usually activated when a certain radiation level is reached. It is not clear whether the shading screens should be used over the growth cycle or only during the most sensitive stages when the crops had a low leaf area and the canopy transpiration rate cannot significantly contribute to the greenhouse cooling. Furthermore, it is not clear which is the optimum radiation level that screen must be activated. This work aims to present the microclimate and cucumber crop physiological response and yield observed in two greenhouse compartments equipped with a pad and fan evaporative cooling system and a thermal/shading screen that is activated at different radiation levels: when the outside solar radiation reaches 700 or 900 W/m2. The greenhouse is located in Velestino, in Central Greece and the measurements are performed during the spring -summer period with the outside air temperature during summer reaching values up to 42C.

Keywords: microclimate, shading, screen, pad and fan, cooling

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Authors: Ibrahim S. Seddiek, Nader R. Ammar

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One of the most important equipment that affects the performance of passenger ships is the air conditioning system, which in turn consumes considerable electric loads. In this paper, the waste heat energies of exhaust gases and jacket cooling water of marine diesel engines for these ships are analyzed to be used as heat sources for absorption refrigeration unit (ARU). Economic and environmental analysis of the absorption refrigeration cycle operated with the two heat sources that use lithium bromide as absorbent is carried out. In addition, environmental and economic analysis for the absorption cycle is performed. As a case study, high-speed passenger vessel operating in the Red Sea area has been investigated. The results show that a considerable specific economic benefit could be achieved in case of applying absorption air condition that operates by water cooling system over that operates by main engine exhaust gases. Environmentally, applying ARU machine during cruise will reduce total ship’s fuel consumption by about 104 ton per year. This will result in reducing NOₓ, SOₓ, and CO₂ emissions with cost-effectiveness of 6.99 $/kg, 18.44 $/kg, and 0.117 $/kg, respectively.

Keywords: ship emissions, IMO, lithium bromide-water ARU, analysis, thermodynamic, economic and environmental analysis

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Authors: Oluwole A. Solanke

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This article explores internal generation of revenues in higher education institutions. The research focuses on how polytechnic institutions in Nigeria generate other sources of revenues to augment government subventions and tuition fees. The study provides a qualitative case study and triangulation data on three polytechnics representing tertiary institution structure of federal, state and private ownership in Nigeria. The article argues that dependence on government subventions by the public polytechnics and tuition fees by private polytechnic would not provide funding adequacy for the activities of the institutions under study. Findings revealed that there are basically seven themes; guest houses; poly consult; part-time courses; tuition fees; capitation fees; ownership contribution; and printing and business centre by which the polytechnics generate additional sources of revenues in the management of the institutions. The research concludes that for the polytechnics to gain financial adequacy, entrepreneurial activities must be embarked upon vigorously by stakeholders of the polytechnics as this is the only way by which financial self-reliance can be achieved.

Keywords: entrepreneurial, government subventions, internal generation, polytechnics, revenues

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Authors: Emmanuel Ophel Gilbert, Williams Speret

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The control for fluid flow behaviours of viscous fluids and heat transfer occurrences within heated mini-channel is considered. Heat transfer and flow characteristics of different viscous liquids, such as engine oil, automatic transmission fluid, one-half ethylene glycol, and deionized water were numerically analyzed. Some mathematical applications such as Fourier series and Laplace Z-Transforms were employed to ascertain the behaviour-wave like structure of these each viscous fluids. The steady, laminar flow and heat transfer equations are reckoned by the aid of numerical simulation technique. Further, this numerical simulation technique is endorsed by using the accessible practical values in comparison with the anticipated local thermal resistances. However, the roughness of this mini-channel that is one of the physical limitations was also predicted in this study. This affects the frictional factor. When an additive such as tetracycline was introduced in the fluid, the heat input was lowered, and this caused pro rata effect on the minor and major frictional losses, mostly at a very minute Reynolds number circa 60-80. At this ascertained lower value of Reynolds numbers, there exists decrease in the viscosity and minute frictional losses as a result of the temperature of these viscous liquids been increased. It is inferred that the three equations and models are identified which supported the numerical simulation via interpolation and integration of the variables extended to the walls of the mini-channel, yields the utmost reliance for engineering and technology calculations for turbulence impacting jets in the near imminent age. Out of reasoning with a true equation that could support this control for the fluid flow, Navier-stokes equations were found to tangential to this finding. Though, other physical factors with respect to these Navier-stokes equations are required to be checkmated to avoid uncertain turbulence of the fluid flow. This paradox is resolved within the framework of continuum mechanics using the classical slip condition and an iteration scheme via numerical simulation method that takes into account certain terms in the full Navier-Stokes equations. However, this resulted in dropping out in the approximation of certain assumptions. Concrete questions raised in the main body of the work are sightseen further in the appendices.

Keywords: frictional losses, heat transfer, laminar flow, mini-channel, number simulation, Reynolds number, turbulence, viscous fluids

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Authors: Rose-Juliet Anyanwu

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The principal objective of this paper is to investigate whether some sort of phonological processes, such as elision, aspiration, glottalisation, and hardening can be used to account for the behaviour of the glottal fricative (or approximant, as the case may be) ‘h’ in both French and Yoruba. French and Yoruba speakers generally tend to say, for instance ‘ockey’ and ‘amburger’, instead of ‘hockey’ and ‘hamburger’, respectively. Whereas the Yoruba conversely say, for instance ‘hadd’ for ‘add’, ‘heat’ for ‘eat’ on the one hand and ‘ard’ for ‘hard’, ‘eat’ for ‘heat’ on the other hand, on a similar note, it is not quite clear whether the French, however, if not at least in rare instances, would tend to force themselves to pronounce (in any form whatsoever) the h-sound. Recorded sentences containing h-initial as well as vowel-initial words will be used for the investigation. The present paper is meant to contribute to work on aspiration, compensation, elision, and glottalisation, as well as hardening.

Keywords: aspiration, compensation, glottalisation, hardening

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Authors: Balkar Singh, Gurpreet Singh, Vivek Aggarwal, Sehijpal Singh

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The present research focused to improve the machinability of Hastelloy C-276 at different machining speeds such as 31, 55, and 79 m/min. The use of CO2 gas and Minimum quantity lubrication (MQL) was applied as coolant and lubrication purposes to enhance the machinability of the superalloy. The output in the form of surface roughness (S.R) and heat generation was monitored under dry, MQL, and MQL-CO2-cooled conditions. The Design of the Experiment was prepared using MINITAB software utilizing Taguchi L-27 orthogonal arrays followed by ANOVA analysis for finding the impact of input variables on output responses. At different speeds and lubrication conditions, different behavioral patterns for Surface Roughness and the temperature was observed. ANOVA analysis depicted that the cooling environment impacted the S.R. majorly (50%) followed by cutting speed (29.84%), feed rate (5.09%), and least through depth of cut (4.95%). On the other side, the temperature was greatly influenced by cutting speed (69.12%), Cryo-MQL (8.09%), feed rate (7.59%), and depth of cut (6.20%). Experimental results revealed that Cryo-MQL cooling enhanced the Surface roughness by 12% compared to MQL condition.

Keywords: Hastelloy C-276, minimum quantity lubrication, olive oil, cryogenic Cooling (CO2)

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Authors: Rade M. Ciric, Nikola L. J. Rajakovic

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This paper presents a curriculum of the subject small power plants and renewable energy sources, dealing with the concept of distributed generation, renewable energy sources, hydropower, wind farms, geothermal power plants, cogeneration plants, biogas plants of agriculture and animal origin, solar power and fuel cells. The course is taught the manner of connecting small power plants to the grid, the impact of small generators on the distribution system, as well as economic, environmental and legal aspects of operation of distributed generators.

Keywords: distributed generation, renewable energy sources, energy policy, curriculum

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Authors: Susana Gonçalves, Joana Lencart, Anabela Gregório Dias

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Introduction: In combination with chemotherapy, Total Body Irradiation (TBI) is most used as part of the conditioning regimen prior to allogeneic hematopoietic stem cell transplantation. Conventional TBI techniques have a long application time but non-conformality of beam-application with the inability to individually spare organs at risk. Our institution’s intention is to start using Volumetric Modulated Arc Therapy (VMAT) techniques to increase homogeneity of delivered radiation. As a first approach, a dosimetric plan was performed on a computed tomography (CT) scan of a Rando Alderson antropomorfic phantom (head and torso), using a set of six arcs distributed along the phantom. However, a full body anthropomorphic phantom is essential to carry out technique validation and implementation. Our aim is to define the physical and chemical characteristics and the ideal manufacturing procedure of upper and lower limbs to our anthropomorphic phantom, for later validate TBI using VMAT. Materials and Methods: To study the better fit between our phantom and limbs, a CT scan of Rando Alderson anthropomorphic phantom was acquired. CT was performed on GE Healthcare equipment (model Optima CT580 W), with slice thickness of 2.5 mm. This CT was also used to access the electronic density of soft tissue and bone through Hounsfield units (HU) analysis. Results: CT images were analyzed and measures were made for the ideal upper and lower limbs. Upper limbs should be build under the following measures: 43cm length and 7cm diameter (next to the shoulder section). Lower limbs should be build under the following measures: 79cm length and 16.5cm diameter (next to the thigh section). As expected, soft tissue and bone have very different electronic density. This is important to choose and analyze different materials to better represent soft tissue and bone characteristics. The approximate HU values of the soft tissue and for bone shall be 35HU and 250HU, respectively. Conclusion: At the moment, several compounds are being developed based on different types of resins and additives in order to be able to control and mimic the various constituent densities of the tissues. Concurrently, several manufacturing techniques are being explored to make it possible to produce the upper and lower limbs in a simple and non-expensive way, in order to finally carry out a systematic and appropriate study of the total body irradiation. This preliminary study was a good starting point to demonstrate the feasibility of TBI with VMAT.

Keywords: TBI, VMAT, anthropomorphic phantom, tissue equivalent materials

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Authors: Mulue Girmay Gebreslasie

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Entomopathogenic fungi are naturally safe and eco-friendly biological agents. Their potential of host specificity and ease handling made them appealing options to substitute synthetic pesticides in pest control programs. However, they are highly delicate and unstable under field conditions. Therefore, the current experiment was held to search out persistent fungal strains by defining the relationship between invitro heat tolerance and field persistence. Current results on leaf and soil persistence assay revealed that strains of Metarhizium species, M. pingshaense (F2685), M. pingshaense (MS2) and M. brunneum (F709) exhibit maximum cumulative CFUs count, relative survival rate and least percent of CFUs reductions showed significant difference at 7 days and 28 days post inoculations (dpi) in hot seasons from sampled soils and leaves and in cold season from soil samples. Whereas relative survival of B. brongniartii (TNO6) found significantly higher in cold weather leaf treatment application as compared to hot season and found as persistent as other fungal strains, while higher deterioration of fungal conidia seen with M. pingshaense (MS2). In the current study, strains of Beauveria brongniartii (TNO6) and Cordyceps javanica (Czy-LP) were relatively vulnerable in field condition with utmost colony forming units (CFUs) reduction and least survival rates. Further, the relationship of the two parameters (heat tolerance and field persistence) was seen with strong linear positive correlations elucidated that heat test could be used in selection of field persistent fungal strains for hot season applications.

Keywords: integrated pest management, biopesticides, Insect pathology and microbial control, entomology

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Authors: Ekaterina Artiukhina, Panagiotis Grammelis

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Torrefaction of biomass pellets is considered as a useful pretreatment technology in order to convert them into a high quality solid biofuel that is more suitable for pyrolysis, gasification, combustion and co-firing applications. In the course of torrefaction the temperature varies across the pellet, and therefore chemical reactions proceed unevenly within the pellet. However, the uniformity of the thermal distribution along the pellet is generally assumed. The torrefaction process of a single cylindrical pellet is modeled here, accounting for heat transfer coupled with chemical kinetics. The drying sub-model was also introduced. The non-stationary process of wood pellet decomposition is described by the system of non-linear partial differential equations over the temperature and mass. The model captures well the main features of the experimental data.

Keywords: torrefaction, biomass pellets, model, heat, mass transfer

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Authors: Liu Si, Wang Chunmei, Liu Huangmei

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A prominent component of the semantic versus pragmatic debate, scalar implicature (SI) has been gaining great attention ever since it was proposed by Horn. The constant debate is between the structural and pragmatic approach. The former claims that generation of SI is costless, automatic, and dependent mostly on the structural properties of sentences, whereas the latter advocates both that such generation is largely dependent upon context, and that the process is costly. Many experiments, among which Katsos’s text comprehension experiments are influential, have been designed and conducted in order to verify their views, but the results are not conclusive. Besides, most of the experiments were conducted in English language materials. Katsos conducted one off-line and three on-line text comprehension experiments, in which the previous shortcomings were addressed on a certain extent and the conclusion was in favor of the pragmatic approach. We intend to test the results of Katsos’s experiment in Chinese scalar implicature. Four experiments in both off-line and on-line conditions to examine the generation and response time of SI in Chinese "yixie" (some) and "quanbu (dou)" (all) will be conducted in order to find out whether the structural or the pragmatic approach could be sustained. The study mainly aims to answer the following questions: (1) Can SI be generated in the upper- and lower-bound contexts as Katsos confirmed when Chinese language materials are used in the experiment? (2) Can SI be first generated, then cancelled as default view claimed or can it not be generated in a neutral context when Chinese language materials are used in the experiment? (3) Is SI generation costless or costly in terms of processing resources? (4) In line with the SI generation process, what conclusion can be made about the cognitive processing model of language meaning? Is it a parallel model or a linear model? Or is it a dynamic and hierarchical model? According to previous theoretical debates and experimental conflicts, presumptions could be made that SI, in Chinese language, might be generated in the upper-bound contexts. Besides, the response time might be faster in upper-bound than that found in lower-bound context. SI generation in neutral context might be the slowest. At last, a conclusion would be made that the processing model of SI could not be verified by either absolute structural or pragmatic approaches. It is, rather, a dynamic and complex processing mechanism, in which the interaction of language forms, ad hoc context, mental context, background knowledge, speakers’ interaction, etc. are involved.

Keywords: cognitive linguistics, pragmatics, scalar implicture, experimental study, Chinese language

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Authors: Adine Gericke, Jiri Militky, Mohanapriya Venkataraman

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Mohair, obtained from the Angora goat, is a luxury fiber and recognized as one of the best quality natural fibers. Expansion of the use of mohair into technical and functional textile products necessitates the need for a better understanding of how the use of mohair in fabrics will impact on its thermo-physiological comfort related properties. Despite its popularity, very little information is available on the quantification of the thermal and moisture management properties of mohair fabrics. This study investigated the effect of fibrous matter composition and fabric structural parameters on conductive and convective heat transfers to attain more information on the thermal comfort properties of mohair fabrics. Dry heat transfer through textiles may involve conduction through the fibrous phase, radiation through fabric interstices and convection of air within the structure. Factors that play a major role in heat transfer by conduction are fabric areal density (g/m2) and derived quantities such as cover factor and porosity. Convective heat transfer through fabrics is found in environmental conditions where there is wind-flow or the object is moving (e.g. running or walking). The thermal comfort properties of mohair fibers were objectively evaluated firstly in comparison with other textile fibers and secondly in a variety of fabric structures. Two sample sets were developed for this purpose, with fibre content, yarn structure and fabric design as main variables. SEM and microscopic images were obtained to closely examine the physical structures of the fibers and fabrics. Thermal comfort properties such as thermal resistance and thermal conductivity, as well as fabric thickness, were measured on the well-known Alambeta test instrument. Clothing insulation (clo) was calculated from the above. The thermal properties of fabrics under heat convection was evaluated using a laboratory model device developed at the Technical University of Liberec (referred to as the TP2-instrument). The effects of the different variables on fabric thermal comfort properties were analyzed statistically using TIBCO Statistica Software. The results showed that fabric structural properties, specifically sample thickness, played a significant role in determining the thermal comfort properties of the fabrics tested. It was found that regarding thermal resistance related to conductive heat flow, the effect of fiber type was not always statistically significant, probably as a result of the amount of trapped air within the fabric structure. The very low thermal conductivity of air, compared to that of the fibers, had a significant influence on the total conductivity and thermal resistance of the samples. This was confirmed by the high correlation of these factors with sample thickness. Regarding convective heat flow, the most important factor influencing the ability of the fabric to allow dry heat to move through the structure, was again fabric thickness. However, it would be wrong to totally disregard the effect of fiber composition on the thermal resistance of textile fabrics. In this study, the samples containing mohair or mohair/wool were consistently thicker than the others even though weaving parameters were kept constant. This can be ascribed to the physical properties of the mohair fibers that renders it exceptionally well towards trapping air among fibers (in a yarn) as well as among yarns (inside a fabric structure). The thicker structures trap more air to provide higher thermal insulation, but also prevent the free flow of air that allow thermal convection.

Keywords: mohair fabrics, convective heat transfer, thermal comfort properties, thermal resistance

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Authors: Frederick N. F. Chou, Nguyen Thi Thuy Linh

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The impact of water shortages has been increasingly severe as a consequence of population growth, urbanization, economic development, and climate change. The need for improvements in reliable water supply systems is urgent with the increasing living standards of regions. In this study, a suitable shortage index capable of multi-aspect description - frequency, magnitude, and duration - is adopted to more accurately describe the characteristics of a shortage situation. The values of the index were determined to cope with the increasing need for reliability. There are four reservoirs in series located on the Be River of the Dong Nai River Basin in Southern Vietnam. The primary purpose of the three upstream reservoirs is hydropower generation while the primary purpose of the fourth is water supply. A compromise between hydropower generation and water supply can be negotiated for these four reservoirs to reduce the severity of water shortages. A generalized water allocation model was applied to simulate the water supply, and hydropower generation of various management alternatives and the system’s reliability was evaluated using the adopted multiple shortage indices. Modifying management policies of water resources using data-based indexes can improve the reliability of water supply.

Keywords: cascade reservoirs, hydropower, shortage index, water supply

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Authors: K.Ishii, T. Furuichi, A. Fujiyama, S. Hariya

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Rice straw pellets are a promising fuel as a renewable energy source. Financial analysis is needed to make a utilization system using rise straw pellets financially feasible, considering all regional conditions including stakeholders related to the collection and storage, production, transportation and heat utilization. We conducted the financial analysis of feasibility for a heat utilization system using rice straw pellets which has been developed for the first time in Nanporo, Hokkaido, Japan. Especially, we attempted to clarify the effect of factors required for the system to be financial feasibility, such as the heating energy demand and collection and storage method of rice straw. The financial feasibility was found to improve when increasing the heating energy demand and collecting wheat straw in August separately from collection of rice straw in November because the costs of storing rice straw and producing pellets were reduced. However, the system remained financially unfeasible. This study proposed a contractor program funded by a subsidy from Nanporo local government where a contracted company, instead of farmers, collects and transports rice straw in order to ensure the financial feasibility of the system, contributing to job creation in the region.

Keywords: rice straw, pellets, heating energy demand, collection, storage

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Authors: Ying-Ming Su, Mei-Shu Huang

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To mitigate the urban heat island effect has become a global issue facing the challenge of climate change. Through literature reviews, plant photosynthesis can reduce the carbon dioxide and mitigate the urban heat island effect relatively. Because there are not enough open space and park, green roof has become an important policy in Taiwan. We selected elementary school buildings in northern New Taipei City as research subjects since elementary school is asked priority to build green roof and important educational place to promote green roof concept. Testo 175-H1 recording device was used to record the temperature and humidity difference between roof surface and interior space below roof with and without green roof for the long-term. We also use questionnaire to investigate the awareness of comfort level of green roof and sensation of teachers and students of the elementary school. The results indicated the temperature of roof without greening was higher than that with greening about 2°C. But sometimes during noontime, the temperature of green roof was higher than that of non-green roof related to the character of the accumulation and dissipation of heat of greening probably. The temperature of interior space below green roof was normally lower than that without green roof about 1°C showed that green roof could lower the temperature. The humidity of the green roof was higher than the one without greening also indicated that green roof retained water better. Teachers liked to combine green roof concept in the curriculum, students wished all classes can take turns to maintain the green roof. Teachers and students that school had integrated green roof concept in the curriculum were more willing to participate in the maintenance work of green roof. Teachers and students who may access and touch the green roof can be more aware of the green roof benefit. We suggest architect to increase the accessibility and visibility of green roof, such as a part of the activity space. This idea can be a reference of the green roof curriculum design.

Keywords: comfort level, elementary school, green roof, heat island effect

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Authors: Nabil A. Ahmed, Nasser A. N. Mhaisen

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The paper presents a solution to enhance the power quality and to reduce the peak load demand in Kuwait electric grid as a solution to the shortage of electricity production. Technical, environmental and economic feasibility study of utilizing integrated grid-connected photovoltaic (PV) system in residential buildings for supplying 7.1% of electrical power consumption in Kuwait is carried out using RETScreen software. A 10 KWp on-grid PV power generation system spread on the rooftop of the residential buildings is adopted and investigated and the complete system performance is simulated using PSIM software. Taking into account the international prices of electricity and natural gas, the proposed solution is investigated and tested for four different types of installation systems in terms of power generation and costs which includes horizontal installation, 25º tilted angle, single axis tracking and dual axis tracking. Results shows that the 25º tilted angle fixed mounted system is the most efficient type. The payback period as a tool of benefit analysis of the proposed system is calculated and it found to be 2.55 years.

Keywords: photovoltaics, residential buildings, electrical grid, production capacity, on-grid, power generation

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Authors: Min-Shiuan Liou, Yi Shan Yang, Yang-Zhan Huang, Chia-Wen Hsieh

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A high speed growing and butanol-tolerant Clostridium acetobutylicum HOL1 mutant was screened throughout continuous adaption culture with C. acetobutylicum ATCC 824. The HOL1 strain can grow well in 10 g/L butanol contained CGM medium and can produce about 12.8 g /L butanol during 24 hrs. The C. acetobutylicum HOL1 strain was able to produce 166 mM butanol with 21 mM acetone at pH 4.8, resulting in a butanol selectivity (a molar ratio of butanol to total solvents) of 0.79, which is much higher than that (0.6) of the wild-type strain C. acetobutylicum ATCC 824. The acetate and butyrate accumulation were not observed during fermentation of the HOL1 strain. A hyper-butanol producing C. acetobutylicum HOL1 (pBPHS-3), which was created to overexpress the Bacillus psychrosaccharolyticus originated specific heat-shock protein gene, hspX, from a clostridial phosphotransbutyrylase promoter, was studied for its potential to produce a high titer of butanol. Overexpression of hspX resulted in increased final butanol yield 47% and 30% higher than those of the the ATCC824 and the HOL1 strains, respectively. The remarkable high-speed growth and butanol tolerance of strain HOL1 (pBPHS-3) demonstrates that overexpression of heterogeneous stress protein-encoding gene, hspX, could help C. acetobutylicum to effectively produce a high concentration of butanol.

Keywords: Clostridium acetobutylicum, butanol, heat-shock protein, resistance

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Authors: Elmo Thiago Lins Cöuras Ford, Valentina Alessandra Carvalho do Vale, Rubens Maribondo do Nascimento, José Ubiragi de Lima Mendes

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Given the unquestionable need of environmental preservation of discarded industrial residues, The scrape of tires have been seen as a salutary alternative for addictive in concrete, asphalt production and of other composites materials. In this work, grew a composite the base of scrape of tire as reinforcement and latex as matrix, to be used as insulating thermal in "cold" systems (0º). Analyzed the acting of the material was what plays the thermal conservation when submitted the flow of heat. Verified the temperature profiles in the internal surfaces and it expresses of the composite as well as the temperature gradient in the same. As a consequence, in function of the answers of the system, conclusions were reached.

Keywords: cold system, latex, flow of heat, asphalt production

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Authors: Soo-Yeon Seo, Jong-Wook Lim, Se-Ki Song

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Currently, FRP (Fiber Reinforced Polymer) materials have been widely used for reinforcement of building structural members. However, since the FRP and the epoxy material for attaching it have very low resistance to heat, there is a problem in application where high temperature is an issue. In this paper, the resistance performance of FRP member made of carbon fiber at high temperature was investigated through experiment under temperature change. As a result, epoxy encapsulating FRP is damaged at not high temperatures, and the fibers are degraded. Therefore, when reinforcing a structure using FRP, a separate refractory heat treatment is necessary. The use of a 30 mm thick calcium silicate board as a fireproofing method can protect FRP up to 600ᵒC outside temperature.

Keywords: FRP (Fiber Reinforced Polymer), high temperature, experiment under temperature change, calcium silicate board

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Authors: A. Ja, J. Belabid, A. Cheddadi

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This paper reports the numerical simulation of double diffusive natural convection flows within a horizontal annular filled with a saturated porous medium. The analysis concerns the influence of the different parameters governing the problem, namely, the Rayleigh number Ra, the Lewis number Le and the buoyancy ratio N, on the heat and mass transfer and on the flow structure, in the case of a fixed radius ratio R = 2. The numerical model used for the discretization of the dimensionless equations governing the problem is based on the finite difference method, using the ADI scheme. The study is focused on steady-state solutions in the cooperation situation.

Keywords: natural convection, double-diffusion, porous medium, annular geometry, finite differences

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Authors: Azzedine Abdedou, Khedidja Bouhadef

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The present study is an analysis of the forced convection heat transfer in porous channel with an oriented jet at the inlet with uniform velocity and temperature distributions. The upper wall is insulated when the bottom one is kept at constant temperature higher than that of the fluid at the entrance. The dynamic field is analysed by the Brinkman-Forchheimer extended Darcy model and the thermal field is traduced by the energy one equation model. The numerical solution of the governing equations is obtained by using the finite volume method. The results mainly concern the effect of Reynolds number, jet angle and thermal conductivity ratio on the flow structure and local and average Nusselt numbers evolutions.

Keywords: forced convection, porous media, oriented confined jet, fluid mechanics

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Authors: Gilbert Makanda

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The problem of free convection from a perforated spinning cone with viscous dissipation, temperature-dependent viscosity, and partial slip was studied. The boundary layer velocity and temperature profiles were numerically computed for different values of the spin, viscosity variation, inertia drag force, Eckert, suction/blowing parameters. The partial differential equations were transformed into a system of ordinary differential equations which were solved using the fourth-order Runge-Kutta method. This paper considered the effect of partial slip and spin parameters on the swirling velocity profiles which are rarely reported in the literature. The results obtained by this method was compared to those in the literature and found to be in agreement. Increasing the viscosity variation parameter, spin, partial slip, Eckert number, Darcian drag force parameters reduce swirling velocity profiles.

Keywords: free convection, suction/injection, partial slip, viscous dissipation

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Authors: Kostas Kouvaris, Anastasia Eleftheriou, Georgios A. Sarantitis, Apostolos Chondronasios

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To achieve the objective of almost zero carbon energy solutions by 2050, the EU needs to accelerate the development of integrated, highly efficient and environmentally friendly solutions. In this direction, district heating and cooling (DHC) emerges as a viable and more efficient alternative to conventional, decentralized heating and cooling systems, enabling a combination of more efficient renewable and competitive energy supplies. In this paper, we develop a forecasting tool for near real-time local weather and thermal energy demand predictions for an entire DHC network. In this fashion, we are able to extend the functionality and to improve the energy efficiency of the DHC network by predicting and adjusting the heat load that is distributed from the heat generation plant to the connected buildings by the heat pipe network. Two case-studies are considered; one for Vransko, Slovenia and one for Montpellier, France. The data consists of i) local weather data, such as humidity, temperature, and precipitation, ii) weather forecast data, such as the outdoor temperature and iii) DHC operational parameters, such as the mass flow rate, supply and return temperature. The external temperature is found to be the most important energy-related variable for space conditioning, and thus it is used as an external parameter for the energy demand models. For the development of the forecasting tool, we use state-of-the-art deep neural networks and more specifically, recurrent networks with long-short-term memory cells, which are able to capture complex non-linear relations among temporal variables. Firstly, we develop models to forecast outdoor temperatures for the next 24 hours using local weather data for each case-study. Subsequently, we develop models to forecast thermal demand for the same period, taking under consideration past energy demand values as well as the predicted temperature values from the weather forecasting models. The contributions to the scientific and industrial community are three-fold, and the empirical results are highly encouraging. First, we are able to predict future thermal demand levels for the two locations under consideration with minimal errors. Second, we examine the impact of the outdoor temperature on the predictive ability of the models and how the accuracy of the energy demand forecasts decreases with the forecast horizon. Third, we extend the relevant literature with a new dataset of thermal demand and examine the performance and applicability of machine learning techniques to solve real-world problems. Overall, the solution proposed in this paper is in accordance with EU targets, providing an automated smart energy management system, decreasing human errors and reducing excessive energy production.

Keywords: machine learning, LSTMs, district heating and cooling system, thermal demand

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Authors: A. S. Walkey, N. P. Patidar

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It is not always economical to provide reactive power using synchronous alternators. The cost of reactive power can be minimized by optimal placing of FACTS devices in power systems. In this paper a Particle Swarm Optimization- Sequential Quadratic Programming (PSO-SQP) algorithm is applied to minimize the cost of reactive power generation along with real power generation to alleviate the bus voltage violations. The effectiveness of proposed approach tested on IEEE-14 bus systems. In this paper in addition to synchronous generators, an opportunity of FACTS devices are also proposed to procure the reactive power demands in the power system.

Keywords: reactive power, reactive power cost, voltage security margins, capability curve, FACTS devices

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Authors: B. Shahzamanian, S. Varga, D. C. Alarcón-Padilla

Abstract:

Desalination is considered the primary alternative to increase water supply for domestic, agricultural and industrial use. Sustainable desalination is only possible in places where renewable energy resources are available. Solar energy is the most relevant type of renewable energy to driving desalination systems since most of the areas suffering from water scarcity are characterized by a high amount of available solar radiation during the year. Multi-Effect Desalination (MED) technology integrated with solar thermal concentrators is a suitable combination for heat-driven desalination. It can also be coupled with thermal vapour compressors or absorption heat pumps to boost overall system performance. The most interesting advantage of MED is the suitability to be used with a transient source of energy like solar. An experimental study was carried out to assess the performance of the most important life-size multi-effect desalination plant driven by solar energy located in the Plataforma Solar de Almería (PSA). The MED plant is used as a reference in many studies regarding multi-effect distillation. The system consists of a 14-effect MED plant coupled with a double-effect absorption heat pump. The required thermal energy to run the desalination system is supplied by means of hot water generated from 60 static flat-plate solar collectors with a total aperture area of 606 m2. In order to compensate for the solar energy variation, a thermal storage system with two interconnected tanks and an overall volume of 40 m3 is coupled to the MED unit. The multi-effect distillation unit is built in a forward feed configuration, and the last effect is connected to a double-effect LiBr-H2O absorption heat pump. The heat pump requires steam at 180 ºC (10 bar a) that is supplied by a small-aperture parabolic trough solar field with a total aperture area of 230 m2. When needed, a gas boiler is used as an auxiliary heat source for operating the heat pump and the MED plant when solar energy is not available. A set of experiments was carried out for evaluating the impact of the heating water temperature (Th), top brine temperature (TBT) and temperature difference between effects (ΔT) on the performance ratio of the MED plant. The considered range for variation of Th, TBT and ΔT was 60-70°C, 54-63°C and 1.1-1.6°C, respectively. The performance ratio (PR), defined as kg of distillate produced for every 2326 kJ of thermal energy supplied to the MED system, was almost independent of the applied variables with a variation of less than 5% for all the cases. The maximum recorded PR was 12.4. The results indicated that the system demonstrated robustness for the whole range of operating conditions considered. Author gratitude is expressed to the PSA for providing access to its installations, the support of its scientific and technical staff, and the financial support of the SFERA-III project (Grant Agreement No 823802). Special thanks to the access provider staff members who ensured the access support.

Keywords: multi-effect distillation, performance ratio, robustness, solar energy

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Authors: Esther, Queeny

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The main goal of this paper is to reflect on the overwhelming, rich folklore of Telugu people through their proverbs, which are assumed to be in a state of endangerment. In order to prove the statement made that the proverbs in Telugu are endangered, we have to delve deeper. We hardly found two or three papers related to Telugu proverbs. So, though the process was weary of sorting out the different proverbs in Telugu, to translate them etc. we found it necessary to do a survey in the form of a questionnaire and draw conclusions so that we could address this issue to the readers. We began with a basic assumption that the older generation may have a wider knowledge of their folklore when compared to the younger generation. The results obtained are quite remarkable, which strengthened our assumptions. Statistical analysis was adopted for quantitative analysis. Through this paper, we hope to kindle cultural awareness among the youngsters regarding the use of one’s own mother tongue.

Keywords: sociolinguistics, Telugu proverbs, folklore, endangerment

Procedia PDF Downloads 212

Authors: Amal A. Hassan, Faten H. Fahmy, Abd El-Shafy A. Nafeh, Hosam K. M. Youssef

Abstract:

Due to the growing penetration of wind energy into the power grid, it is very important to study its interactions with the power system and to provide good control technique in order to deliver high quality power. In this paper, an intelligent control methodology is proposed for optimizing the controllers’ parameters of doubly fed induction generator (DFIG) based wind turbine generation system (WTGS). The genetic algorithm (GA) and particle swarm optimization (PSO) are employed and compared for the parameters adaptive tuning of the proposed proportional integral (PI) multiple controllers of the back to back converters of the DFIG based WTGS. For this purpose, the dynamic model of WTGS with DFIG and its associated controllers is presented. Furthermore, the simulation of the system is performed using MATLAB/SIMULINK and SIMPOWERSYSTEM toolbox to illustrate the performance of the optimized controllers. Finally, this work is validated to 33-bus test radial system to show the interaction between wind distributed generation (DG) systems and the distribution network.

Keywords: DFIG wind turine, intelligent control, distributed generation, particle swarm optimization, genetic algorithm

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Authors: Sreejani Barua, P. P. Srivastav

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Formulation of new functional food products for diabetes patients and obsessed people is a challenge for food industries till date. Starch is a certainly happening, ecological, reasonable and profusely obtainable polysaccharide in plant material. In the present scenario, there is a great interest in modifying starch functional properties without destroying its granular structure using different modification techniques. Resistant starch (RS) contains almost zero calories and can control blood glucose level to prevent diabetes. The current study focused on modification of mung bean starch which is a good source of legumes carbohydrate for the production of functional food. Heat moisture treatment (HMT) of mung starch was conducted at moisture content of 10-30%, temperature of 80-120 °C and time of 8-24 h.The content of resistant starch after modification was significantly increased from native starches containing RS 7.6%. The design combinations of HMT had been completed through Central Composite Rotatable Design (CCRD). The effects of HMT process variables on the yield of resistant starch was studied through Rapid Surface Methodology (RSM). The highest increase of resistant starch was found up to 34.39% when treated the native starch with 30% m.c at 120 °C temperature for 24 h.The functional properties of both native and modified mung bean starches showed that there was a reduction in the swelling power and swelling volume of HMT starches. However, the solubility of the HMT starches was higher than that of untreated native starch and also observed change in structural (scanning electron microscopy), X-Ray diffraction (XRD) pattern, blue value and thermal (differential scanning calorimetry) properties. Therefore, replacing native mung bean starch with heat-moisture treated mung bean starch leads to the development of new products with higher resistant starch levels and functional properties.

Keywords: Mung bean starch, heat moisture treatment, functional properties, resistant starch

Procedia PDF Downloads 203