Search results for: volumetric heat generation

Authors: A. Ghafouri, N. Pourmahmoud, I. Mirzaee

Abstract:

In this numerical study, effects of using Al2O3-water nanofluid on the rate of heat transfer have been investigated numerically. The physical model is a square enclosure with insulated top and bottom horizontal walls while the vertical walls are kept at different constant temperatures. Two appropriate models are used to evaluate the viscosity and thermal conductivity of nanofluid. The governing stream-vorticity equations are solved using a second order central finite difference scheme, coupled to the conservation of mass and energy. The study has been carried out for the nanoparticle diameter 30, 60, and 90 nm and the solid volume fraction 0 to 0.04. Results are presented by average Nusselt number and normalized Nusselt number in the different range of φ and D for mixed convection dominated regime. It is found that different heat transfer rate is predicted when the effect of nanoparticle diameter is taken into account.

Keywords: nanofluid, nanoparticle diameter, heat transfer enhancement, square enclosure, Nusselt number

Procedia PDF Downloads 397

Authors: M. Tarik Boyraz, M. Bilge Imer

Abstract:

Conventionally cast nickel-based super alloys, such as commercial alloy IN 738 LC, are widely used in manufacturing of industrial gas turbine blades. With carefully designed microstructure and the existence of alloying elements, the blades show improved mechanical properties at high operating temperatures and corrosive environment. The aim of this work is to model and estimate these mechanical properties of IN 738 LC alloy solely based on simulations for projected heat treatment conditions or service conditions. The microstructure (size, fraction and frequency of gamma prime- γ′ and carbide phases in gamma- γ matrix, and grain size) of IN 738 LC needs to be optimized to improve the high temperature mechanical properties by heat treatment process. This process can be performed at different soaking temperature, time and cooling rates. In this work, micro-structural evolution studies were performed experimentally at various heat treatment process conditions, and these findings were used as input for further simulation studies. The operation time, soaking temperature and cooling rate provided by experimental heat treatment procedures were used as micro-structural simulation input. The results of this simulation were compared with the size, fraction and frequency of γ′ and carbide phases, and grain size provided by SEM (EDS module and mapping), EPMA (WDS module) and optical microscope for before and after heat treatment. After iterative comparison of experimental findings and simulations, an offset was determined to fit the real time and theoretical findings. Thereby, it was possible to estimate the final micro-structure without any necessity to carry out the heat treatment experiment. The output of this microstructure simulation based on heat treatment was used as input to estimate yield stress and creep properties. Yield stress was calculated mainly as a function of precipitation, solid solution and grain boundary strengthening contributors in microstructure. Creep rate was calculated as a function of stress, temperature and microstructural factors such as dislocation density, precipitate size, inter-particle spacing of precipitates. The estimated yield stress values were compared with the corresponding experimental hardness and tensile test values. The ability to determine best heat treatment conditions that achieve the desired microstructural and mechanical properties were developed for IN 738 LC based completely on simulations.

Keywords: heat treatment, IN738LC, simulations, super-alloys

Procedia PDF Downloads 249

Authors: Erich Ryan, Benjamin McDaniel, Dragoljub Kosanovic

Abstract:

Combined heat and power (CHP) plants are an efficient technology for meeting the heating and electric needs of large campus energy systems, but have come under greater scrutiny as the world pushes for emissions reductions and lower consumption of fossil fuels. The electrification of heating and cooling systems offers a great deal of potential for carbon savings, but these systems can be costly endeavors due to increased electric consumption and peak demand. Thermal energy storage (TES) has been shown to be an effective means of improving the viability of electrified systems, by shifting heating and cooling load to off-peak hours and reducing peak demand charges. In this study, we analyze the integration of an electrified heating and cooling system with thermal energy storage into a campus CHP plant, to investigate the potential of leveraging existing infrastructure and technologies with the climate goals of the 21st century. A TRNSYS model was built to simulate a ground source heat pump (GSHP) system with TES using measured campus heating and cooling loads. The GSHP with TES system is modeled to follow the parameters of industry standards and sized to provide an optimal balance of capital and operating costs. Using known CHP production information, costs and emissions were investigated for a unique large energy user rate structure that operates a CHP plant. The results highlight the cost and emissions benefits of a targeted integration of heat pump technology within the framework of existing CHP systems, along with the performance impacts and value of TES capability within the combined system.

Keywords: thermal energy storage, combined heat and power, heat pumps, electrification

Procedia PDF Downloads 89

Authors: Americo Pereira, Ricardo Carvalho, Pedro Carvalho, Luis Corte-Real

Abstract:

Generating 3D content is a task mostly done by hand. It requires specific knowledge not only on how to use the tools for the task but also on the fundamentals of a 3D environment. In this work, we show that automatic generation of content can be achieved, from a scene script, by leveraging existing tools so that non-experts can easily engage in a 3D content generation without requiring vast amounts of time in exploring and learning how to use specific tools. This proposal carries several benefits, including flexible scene synthesis with different levels of detail. Our preliminary results show that the automatically generated content is comparable to the content generated by users with low experience in 3D modeling while vastly reducing the amount of time required for the generation and adds support to implement flexible scenarios for visual scene visualization.

Keywords: 3D virtualization, multimedia, scene script, synthesis

Procedia PDF Downloads 267

Authors: Surupa Shaw, Debjyoti Banerjee

Abstract:

Enhancing heat transfer in compact volumes is a challenge when constrained by cost issues, especially those associated with requirements for minimizing pumping power consumption. This is particularly acute for electronic chip cooling applications. Technological advancements in microelectronics have led to development of chip architectures that involve increased power consumption. As a consequence packaging, technologies are saddled with needs for higher rates of power dissipation in smaller form factors. The increasing circuit density, higher heat flux values for dissipation and the significant decrease in the size of the electronic devices are posing thermal management challenges that need to be addressed with a better design of the cooling system. Maximizing surface area for heat exchanging surfaces (e.g., extended surfaces or “fins”) can enable dissipation of higher levels of heat flux. Fractal structures have been shown to maximize surface area in compact volumes. Self-replicating structures at multiple length scales are called “Fractals” (i.e., objects with fractional dimensions; unlike regular geometric objects, such as spheres or cubes whose volumes and surface area values scale as integer values of the length scale dimensions). Fractal structures are expected to provide an appropriate technology solution to meet these challenges for enhanced heat transfer in the microelectronic devices by maximizing surface area available for heat exchanging fluids within compact volumes. In this study, the effect of different fractal micro-channel architectures and flow structures on the enhancement of transport phenomena in heat exchangers is explored by parametric variation of fractal dimension. This study proposes a model that would enable cost-effective solutions for thermal-fluid transport for energy applications. The objective of this study is to ascertain the sensitivity of various parameters (such as heat flux and pressure gradient as well as pumping power) to variation in fractal dimension. The role of the fractal parameters will be instrumental in establishing the most effective design for the optimum cooling of microelectronic devices. This can help establish the requirement of minimal pumping power for enhancement of heat transfer during cooling. Results obtained in this study show that the proposed models for fractal architectures of microchannels significantly enhanced heat transfer due to augmentation of surface area in the branching networks of varying length-scales.

Keywords: fractals, microelectronics, constructal theory, heat transfer enhancement, pumping power enhancement

Procedia PDF Downloads 319

Authors: Basant Kumar Singh, S. Subhachandhar, Vineet Ranjan Tripathi, Amit Kumar Singh, Uttam Singh, Santosh Kumar Lal

Abstract:

Productivity of Blast Furnace is largely impacted by fuel efficiency and controlling heat loss is one of the enabling parameters for achieving lower fuel rate. 'I' Blast Furnace is the latest and largest Blast Furnace of Tata Steel Jamshedpur with working volume of 3230 m³ and with rated capacity of 3.055 million tons per annum. Optimizing heat losses in Belly and Bosh zone remained major challenge for blast furnace operators after its commissioning. 'I' Blast has installed Cast Iron & Copper Staves cooling members where copper staves are installed in Belly, Bosh & Lower Stack whereas cast iron staves are installed in upper stack area. Stave cooled Blast Furnaces are prone to higher heat losses in Belly and Bosh region with an increase in coal injection rate as Bosh gas volume increases. Under these conditions, managing gas flow pattern through proper burden distribution, casting techniques & by maintaining desired raw material qualities are of utmost importance for sustaining high injection rates. This study details, the burden distribution control by Ore & Coke ratio adjustment at wall and center of Blast Furnace as the coal injection rates increased from 140 kg/thm to 210 kg/thm. Control of blowing parameters, casting philosophy, specification for raw materials & devising operational practice for controlling heat losses is also elaborated with the model that is used to visualize heat loss pattern in different zones of Blast Furnace.

Keywords: blast furnace, staves, gas flow pattern, belly/bosh heat losses, ore/coke ratio, blowing parameters, casting, operation practice

Procedia PDF Downloads 375

Authors: Rajesh Kumar, Prabha Chand

Abstract:

Fins and twisted tape inserts are widely used passive elements to enhance heat transfer rate in various engineering applications. The present paper describes the theoretical analysis of solar air heater fitted with fins and twisted tape inserts. Mathematical model is develop for this novel design of solar air heater and a MATLAB code is generated for the solution of the model. The effect of twist ratio, mass flow rate and inlet temperature on the thermal efficiency and exit air temperature has been investigated. The results are compared with the results of plane solar air heater. Results show a substantial enhancement in heat transfer rate, efficiency and exit air temperature.

Keywords: solar air heater, thermal efficiency, twisted tape, twist ratio

Procedia PDF Downloads 257

Authors: Angel Fabian Mijangos, Jaime Alvarez Quintana

Abstract:

Key concepts like waste heat recycling or waste heat recovery are the basic ideas in thermoelectricity so as to the design the newest solid state sources of energy for a stable supply of electricity and environmental protection. According to several theoretical predictions; at device level, the geometry and configuration of the thermoelectric legs are crucial in the thermoelectric performance of the thermoelectric modules. Thus, in this work, it has studied the geometry effect of legs on the thermoelectric figure of merit ZT of the device. First, asymmetrical legs are proposed in order to reduce the overall thermal conductance of the device so as to increase the temperature gradient in the legs, as well as by harnessing the Thomson effect, which is generally neglected in conventional symmetrical thermoelectric legs. It has been developed a novel design of a thermoelectric module having asymmetrical legs, and by first time it has been validated experimentally its thermoelectric performance by realizing a proof-of-concept device which shows to have almost twofold the thermoelectric figure of merit as compared to conventional one. Moreover, it has been also varied the length of thermoelectric legs in order to analyze its effect on the thermoelectric performance of the device. Along with this, it has studied the impact of contact resistance in these systems. Experimental results show that device architecture can improve up to twofold the thermoelectric performance of the device.

Keywords: asymmetrical legs, heat recovery, heat recycling, thermoelectric module, Thompson effect

Procedia PDF Downloads 243

Authors: Ruyang Ren, Yaohua Zhao, Yanhua Diao

Abstract:

The intermittent and unstable characteristics of renewable energy such as solar energy can be effectively solved through battery energy storage system. Lithium-ion battery is widely used in battery energy storage system because of its advantages of high energy density, small internal resistance, low self-discharge rate, no memory effect and long service life. However, the performance and service life of lithium-ion battery is seriously affected by its operating temperature. Thus, the safety operation of the lithium-ion battery module is inseparable from an effective thermal management system (TMS). In this study, a new type of TMS based on micro heat pipe array (MHPA) for lithium-ion battery is established, and the TMS is applied to a battery energy storage box that needs to operate at a high temperature environment of 40 °C all year round. MHPA is a flat shape metal body with high thermal conductivity and excellent temperature uniformity. The battery energy storage box is composed of four battery modules, with a nominal voltage of 51.2 V, a nominal capacity of 400 Ah. Through the excellent heat transfer characteristics of the MHPA, the heat generated by the charge and discharge process can be quickly transferred out of the battery module. In addition, if only the MHPA cannot meet the heat dissipation requirements of the battery module, the TMS can automatically control the opening of the external fan outside the battery module according to the temperature of the battery, so as to further enhance the heat dissipation of the battery module. The thermal management performance of lithium-ion battery TMS based on MHPA is studied experimentally under different ambient temperatures and the condition to turn on the fan or not. Results show that when the ambient temperature is 40 °C and the fan is not turned on in the whole charge and discharge process, the maximum temperature of the battery in the energy storage box is 53.1 °C and the maximum temperature difference in the battery module is 2.4 °C. After the fan is turned on in the whole charge and discharge process, the maximum temperature is reduced to 50.1 °C, and the maximum temperature difference is reduced to 1.7 °C. Obviously, the lithium-ion battery TMS based on MHPA not only could control the maximum temperature of the battery below 55 °C, but also ensure the excellent temperature uniformity of the battery module. In conclusion, the lithium-ion battery TMS based on MHPA can ensure the safe and stable operation of the battery energy storage box in high temperature environment.

Keywords: heat dissipation, lithium-ion battery thermal management, micro heat pipe array, temperature uniformity

Procedia PDF Downloads 181

Authors: Di Han, Lingfeng Li, Peixue Zhang, Yuzhuo Zhang

Abstract:

Since natural gas extracted from the wellhead of a gas well, after passing through the throttle valve, causes a rapid decrease in temperature along with a decrease in pressure, which creates conditions for hydrate generation. In order to solve the problem of hydrate generation in the process of wellhead gathering, effective measures should be taken to prevent hydrate generation. In this paper, we firstly introduce the principle of natural gas throttling temperature drop and the theoretical basis of hydrate inhibitor injection calculation, and then use HYSYS software to simulate and calculate the three processes and determine the key process parameters. The hydrate control process applicable to the skid design of natural gas wellhead gathering skids was determined by comparing the hydrate control effect, energy consumption of key equipment and process adaptability.

Keywords: natural gas, hydrate control, skid design, HYSYS

Procedia PDF Downloads 92

Authors: M. H. Alhajeri, Hamad M. Alhajeri, A. H. Alenezi

Abstract:

Computational fluid dynamics (CFD) investigation of heat transfer in U-duct with turbulators is presented in this paper. The duct passages used to cool internally the blades in gas turbine. The study is focused in the flow behavior and the Nusselt number (Nu) distributions. The model of the u-duct contains two square legs that are connected by 180* turn. Four turbulators are located in each surface of the leg and distributed in a staggered arrangement. The turbulator height and width are equal to 0.1 of the duct width, and the turbulator height is 0.1 of the distance between the turbulators. The Reynolds number (Re) used in this study is 95000 and the inlet velocity is 10 m/s. It was noticed that, after the flow resettles from the interruptions generated by the first turbulator or the turn, the flow construct two eddies, one large and the other is small after and before the turbulator, respectively. The maximum values of the Nu are found at a distance of approximately one turbulator width w before of the flow reattachment point.

Keywords: computational fluid dynamics, CFD, rib, heat transfer, blade

Procedia PDF Downloads 151

Authors: Haolun Sun, Ping Wang, Mei Wu, Meng Zhang, Bin Hou, Ling Yang, Xiaohua Ma, Yue Hao

Abstract:

Gallium nitride (GaN) is an attractive material for next-generation power devices. It is noted that the performance of GaN-based high electron mobility transistors (HEMTs) is always limited by the self-heating effect. In response to the problem, integrating devices with polycrystalline diamond (PCD) has been demonstrated to be an efficient way to alleviate the self-heating issue of the GaN-based HEMTs. Among all the heat-spreading schemes, using PCD to cap the epitaxial layer before the HEMTs process is one of the most effective schemes. Now, the mainstream method of fabricating the PCD-capped HEMTs is to deposit the diamond heat-spreading layer on the AlGaN surface, which is covered by a thin nucleation dielectric/passivation layer. To achieve the pattern etching of the diamond heat spreader and device preparation, we selected SiN as the hard mask for diamond etching, which was deposited by plasma-enhanced chemical vapor deposition (PECVD). The conventional diamond etching method first uses F-based etching to remove the SiN from the special window region, followed by using O₂/Ar plasma to etch the diamond. However, the results of the scanning electron microscope (SEM) and focused ion beam microscopy (FIB) show that there are lots of diamond pillars on the etched diamond surface. Through our study, we found that it was caused by the high roughness of the diamond surface and the existence of the overlap between the diamond grains, which makes the etching of the SiN hard mask insufficient and leaves micro-masks on the diamond surface. Thus, a cyclic etching method was proposed to solve the problem of the residual SiN, which was left in the F-based etching. We used F-based etching during the first step to remove the SiN hard mask in the specific region; then, the O₂/Ar plasma was introduced to etch the diamond in the corresponding region. These two etching steps were set as one cycle. After the first cycle, we further used cyclic etching to clear the pillars, in which the F-based etching was used to remove the residual SiN, and then the O₂/Ar plasma was used to etch the diamond. Whether to take the next cyclic etching depends on whether there are still SiN micro-masks left. By using this method, we eventually achieved the self-terminated etching of the diamond and the smooth surface after the etching. These results demonstrate that the cyclic etching method can be successfully applied to the integrated preparation of polycrystalline diamond thin films and GaN HEMTs.

Keywords: AlGaN/GaN heterojunction, O₂/Ar plasma, cyclic etching, polycrystalline diamond

Procedia PDF Downloads 139

Authors: Onur Özdemir, M.Erhan ORHAN

Abstract:

Knowledge Development (KD) is just one of the important phases of Knowledge Management (KM). KD is the phase in which intelligence is used to see the big picture. In order to understand whether information is important or not, we have to use the intelligence cycle that includes four main steps: aiming, collecting data, processing and utilizing. KD also needs these steps. To make a precise decision, the decision maker has to be aware of his subordinates’ ideas. If the decision maker ignores the ideas of his subordinates or participants of the organization, it is not possible for him to get the target. KD is a way of using wisdom to accumulate the puzzle. If the decision maker does not bring together the puzzle pieces, he cannot get the big picture, and this shows its effects on the battlefield. In order to understand the battlefield, the decision maker has to use the intelligence cycle. To convert information to knowledge, KD is the main means for the intelligence cycle. On the other hand, the “Z Generation” born after the millennium are really the game changers. They have different attitudes from their elders. Their understanding of life is different - the definition of freedom and independence have different meanings to them than others. Decision makers have to consider these factors and rethink their decisions accordingly. This article tries to explain the relation between KD and Generation Z. KD is the main method of target managing. But if leaders neglect their people, the world will be seeing much more movements like the Arab Spring and other insurgencies.

Keywords: knowledge development, knowledge management, generation Z, intelligence cycle

Procedia PDF Downloads 519

Authors: Jin Hwa Yang, Hwang Bae, Sung Uk Ryu, Byong Guk Jeon, Sung Jae Yi, Hyun Sik Park

Abstract:

Experimental studies using a large-scale thermal-hydraulic integral test facility, System–integrated Modular Advanced Reactor Integral Test Loop (SMART-ITL), have been carried out to validate the performance of the prototype, SMART. After Fukushima accident, the passive safety systems have been dealt as important designs for retaining of nuclear safety. One of the concerned scenarios for evaluating the passive safety system is a Complete Loss of Coolant Flow (CLOF). The flowrate of coolant in the primary system is maintained by Reactor Coolant Pump (RCP). When the supply of electric power of RCP is shut off, the flowrate of coolant decreases sharply, and the temperature of the coolant increases rapidly. Therefore, the reactor trip signal is activated to prevent the over-heating of the core. In this situation, Passive Residual Heat Removal System (PRHRS) plays a significant role to assure the soundness of the SMART. The PRHRS using a two-phase natural circulation is a passive safety system in the SMART to eliminate the heat of steam generator in the secondary system with heat exchanger submarined in the Emergency Cooling Tank (ECT). As the RCPs continue to coast down, inherent natural circulation in the primary system transfers heat to the secondary system. The transferred heat is removed by PRHRS in the secondary system. In this paper, the progress of the CLOF accident is described with experimental data of transient condition performed by SMART-ITL. Finally, the capability of passive safety system and inherent natural circulation will be evaluated.

Keywords: CLOF, natural circulation, PRHRS, SMART-ITL

Procedia PDF Downloads 441

Authors: Francisco J. Arias

Abstract:

Consideration is given to a mechanism of heat and mass transport in solutions similar than that of natural convection but with one important difference. Here the mechanism is not promoted by density differences in the fluid occurring due to temperature gradients (coefficient of thermal expansion) but rather by solubility differences due to the thermal dependence of the solubility (coefficient of thermal solubility). Utilizing a simplified physical model, it is shown that by the proper choice of the concentration of a given solution, convection might be induced by the alternating precipitation of the solute -when the solution becomes supersaturated, and its posterior recombination when changes in temperature occurs. The spontaneous change in the Gibbs free energy during the mixing is the driven force for the mechanism. The maximum extractable energy from this new type of thermal convection was derived. Experimental data from a closed-loop circuit was obtained demonstrating the feasibility for continuous separation and recombination of the solution. This type of heat and mass transport -which doesn’t depend on gravity, might potentially be interesting for heat and mass transport downwards (as in solar-roof collectors to inside homes), horizontal (e.g., microelectronic applications), and in microgravity (space technology). Also, because the coefficient of thermal solubility could be positive or negative, the investigated thermo-osmosis convection can be used either for heating or cooling.

Keywords: natural convection, thermal gradient, solubility, osmotic pressure

Procedia PDF Downloads 295

Authors: Maurizio E. Picarella, Ludovica Fumelli, Francesca Siligato, Andrea Mazzucato

Abstract:

Studies on reproductive dynamics in crops subjected to heat stress are crucial to breed more tolerant cultivars. In tomato, cultivars, breeding lines, and wild species have been thoroughly evaluated for the response to heat stress in several studies. Here, we address the reaction to temperature stress in a panel of selected landraces representing genotypes cultivated before the advent of professional varieties that usually show high adaptation to local environments. We adopted an experimental design with two open field trials, where transplanting was spaced by one month. In the second field, plants were thus subjected to mild stress with natural temperature fluctuations. The genotypes showed wide variation for both vegetative (plant height) and reproductive (stigma exsertion, pollen viability, number of flowers per inflorescence, and fruit set) traits. On average, all traits were affected by heat conditions; except for the number of flowers per inflorescence, the “G*E” interaction was always significant. In agreement with studies based on different materials, estimated broad sense heritability was high for plant height, stigma exsertion, and pollen viability and low for the number of flowers per inflorescence and fruit set. Despite the interaction, traits recorded in control and in heat conditions were positively correlated. The first two principal components estimated by multivariate analysis explained more than 50% of the total variability. The study indicated that landraces present a wide variability for the response of reproductive traits to temperature stress and that such variability could be very informative to dissect the traits with higher heritability and identify new QTL useful for breeding more resilient varieties.

Keywords: fruit set, heat stress, solanum lycopersicum L., style exsertion, tomato

Procedia PDF Downloads 131

Authors: C. Patrascioiu, Cao Minh Ahn

Abstract:

The paper presents the research evolution in the propylene – propane distillation process, especially for the distillation columns equipped with heat pump. The paper is structured in three parts: separation of the propylene-propane mixture, steady state process modeling, and quality control systems. The first part is dedicated to state of art of the two distillation processes. The second part continues the author’s researches of the steady state process modeling. There has been elaborated a software simulation instrument that may be used to dynamic simulation of the process and to design the quality control systems. The last part presents the research of the control systems, especially for quality control systems.

Keywords: absorption, distillation, heat pump, Unisim design

Procedia PDF Downloads 338

Authors: Maythaya Preeyanon

Abstract:

Chanthaburi Province is a province with people of many nationalities, such as Thai, Chinese, Vietnamese, Chong, and Khmer, resulting in a cultural mix in the past. What is a famous cultural transmission of Chanthaburi province is Chanthaburi reed mat weaving. Due to the suitability of both the climate and topography near the edge of the location, reeds have the qualities to be used to produce mats very well. There have been improvements in the methods of planting, dyeing, and weaving into various patterns that have been passed down as folk wisdom from generation to generation. Currently, there are brands of products belonging to the new generation that add creativity and add value through storytelling. Revive the value of reed mat products to increase in value until they can be exported to sell abroad. This research has therefore been conducted in order to decipher the success in transferring the Chanthaboon reed mat culture capital which has successfully advanced to being a creative economy so that it can be applied to other types of local wisdom or other local products.

Keywords: cultural capital, creative economy, communication, local product

Procedia PDF Downloads 62

Authors: M. Nemer, E. I. Konukseven

Abstract:

In this paper, a motion generation algorithm for a six Degrees of Freedom (DoF) robotic hand in a static environment is presented. The purpose of developing this method is to be used in the path generation of the end-effector for edge finishing and inspection processes by utilizing the CAD model of the considered workpiece. Nonetheless, the proposed algorithm may be extended to be applicable for other similar manufacturing processes. A software package programmed in the application programming interface (API) of SolidWorks generates tool path data for the robot. The proposed method significantly simplifies the given problem, resulting in a reduction in the CPU time needed to generate the path, and offers an efficient overall solution. The ABB IRB2000 robot is chosen for executing the generated tool path.

Keywords: CAD-based tools, edge deburring, edge scanning, offline programming, path generation

Procedia PDF Downloads 284

Authors: Simran Kaur, Paul J. Van Geel

Abstract:

A coupled Thermal-Mechanical-Biological (TMB) model was developed for the analysis of impacts of temperatures on waste stabilization at a Municipal Solid Waste (MSW) landfill in Quebec, Canada using COMSOL Multiphysics, a finite element-based software. For waste placed in landfills in Northern climates during winter months, it can take months or even years before the waste approaches ideal temperatures for biodegradation to occur. Therefore, the proposed model links biodegradation induced strain in MSW to waste temperatures and corresponding heat generation rates as a result of anaerobic degradation. This provides a link between the thermal-biological and mechanical behavior of MSW. The thermal properties of MSW are further linked to density which is tracked and updated in the mechanical component of the model, providing a mechanical-thermal link. The settlement of MSW is modelled based on the concept of viscoelasticity. The specific viscoelastic model used is a single Kelvin – Voight viscoelastic body in which the finite element response is controlled by the elastic material parameters – Young’s Modulus and Poisson’s ratio. The numerical model was validated with 10 years of temperature and settlement data collected from a landfill in Ste. Sophie, Quebec. The coupled TMB modelling framework, which simulates placement of waste lifts as they are placed progressively in the landfill, allows for optimization of several thermal and mechanical parameters throughout the depth of the waste profile and helps in better understanding of temperature dependence of MSW stabilization. The model is able to illustrate how waste placed in the winter months can delay biodegradation-induced settlement and generation of landfill gas. A delay in waste stabilization will impact the utilization of the approved airspace prior to the placement of a final cover and impact post-closure maintenance. The model provides a valuable tool to assess different waste placement strategies in order to increase airspace utilization within landfills operating under different climates, in addition to understanding conditions for increased gas generation for recovery as a green and renewable energy source.

Keywords: coupled model, finite element modeling, landfill, municipal solid waste, waste stabilization

Procedia PDF Downloads 133

Authors: Stella C. Okenu, Stephen O. Adikwu, Martins E. Okoro

Abstract:

The geothermal energy resource potential of the Lower Benue Trough (LBT) in Nigeria was evaluated in this study using spectral analysis of high-resolution aeromagnetic (HRAM) data. The reduced to the equator aeromagnetic data was divided into sixteen (16) overlapping blocks, and each of the blocks was analyzed to obtain the radial averaged power spectrum which enabled the computation of the top and centroid depths to magnetic sources. The values were then used to assess the Curie Point Depth (CPD), geothermal gradients, and heat flow variations in the study area. Results showed that CPD varies from 7.03 to 18.23 km, with an average of 12.26 km; geothermal gradient values vary between 31.82 and 82.50°C/km, with an average of 51.21°C/km, while heat flow variations range from 79.54 to 206.26 mW/m², with an average of 128.02 mW/m². Shallow CPD zones that run from the eastern through the western and southwestern parts of the study area correspond to zones of high geothermal gradient values and high subsurface heat flow distributions. These areas signify zones associated with anomalous subsurface thermal conditions and are therefore recommended for detailed geothermal energy exploration studies.

Keywords: geothermal energy, curie-point depth, geothermal gradient, heat flow, aeromagnetic data, LBT

Procedia PDF Downloads 78

Authors: Athul T.

Abstract:

Kerala cities in India are grappling with an alarming rise in temperatures fueled by the Urban Heat Island (UHI) effect. This phenomenon, exacerbated by rapid urbanization and climate change, poses a significant threat to public health and environmental well-being. In response to this growing concern, this study investigates the potential of urban vegetation as a powerful mitigation strategy against UHI. The study delves into the intricate relationship between micro-climate changes, UHI intensity, and the strategic placement of greenery in alleviating these effects. Utilizing advanced simulation software, the most effective vegetation types and configurations for maximizing UHI reduction will be identified. By analyzing the current state of Kozhikode's urban vegetation and its influence on microclimates, this study aims to tailor actionable strategies for Kerala cities, potentially paving the way for a more sustainable and thermally comfortable urban future.

Keywords: urban heat island, climate change, micro climate, urban vegetation

Procedia PDF Downloads 65

Authors: Elham Zamiri

Abstract:

In this research, we have focused on numeral simulation of a fuel rod in order to examine distribution of heat temperature in components of fuel rod by Fluent software by providing steady state, single phase fluid flow, frequency heat flux in a fuel rod in nuclear reactor to numeral simulation. Results of examining different layers of a fuel rod consist of fuel layer, gap, pod, and fluid cooling flow, also examining thermal properties and fluids such as heat transition rate and pressure drop. The obtained results through analytical method and results of other sources have been compared and have appropriate correspondence. Results show that using heavy water as cooling fluid along with few layers of gas and pod have the ability of reducing the temperature from above 300 ^◦C to 70 ^◦C. This investigation is developable for any geometry and material used in the nuclear reactor.

Keywords: nuclear fuel fission, numberal simulation, fuel rod, reactor, Fluent software

Procedia PDF Downloads 166

Authors: Paulo Teodoro De Luna Carada, Toru Fujii, Kazuya Okubo

Abstract:

Natural fibers have wide variety of uses (e.g., rope, paper, and building materials). One specific application of it is in the field of composite materials (i.e., green composites). Huge amount of research are being done in this field due to rising concerns in the harmful effects of synthetic materials to the environment. There are several natural fibers used in this field, one of which can be extracted from a plant called kenaf (Hibiscus cannabinus L.). Kenaf fiber is regarded as a good alternative because the plant is easy to grow and the fiber is easy to extract. Additionally, it has good properties. Treatments, which are classified as mechanical or chemical in nature, can be done in order to improve the properties of the fiber. The aim of this study is to assess the effects of heat treatment in kenaf fiber. It specifically aims to observe the effect in the tensile strength and modulus of the fiber. Kenaf fiber bundles with an average diameter of at most 100μm was used for this purpose. Heat treatment was done using a constant temperature oven with the following heating temperatures: (1) 160̊C, (2) 180̊C, and (3) 200̊C for a duration of one hour. As a basis for comparison, tensile test was first done to kenaf fibers without any heat treatment. For every heating temperature, three groups of samples were prepared. Two groups of which were for doing tensile test (one group was tested right after heat treatment while the remaining group was kept inside a closed container with relative humidity of at least 95% for two days). The third group was used to observe how much moisture the treated fiber will absorb when it is enclosed in a high moisture environment for two days. The results showed that kenaf fiber can retain its tensile strength when heated up to a temperature of 160̊C. However, when heated at a temperature of about 180̊C or higher, the tensile strength decreases significantly. The same behavior was observed for the tensile modulus of the fiber. Additionally, the fibers which were stored for two days absorbed nearly the same amount of moisture (about 20% of the dried weight) regardless of the heating temperature. Heat treatment might have damaged the fiber in some way. Additional test was done in order to see if the damage due to heat treatment is attributed to changes in the viscoelastic property of the fiber. The findings showed that kenaf fibers can be heated for at most 160̊C to attain good tensile strength and modulus. Additionally, heating the fiber at high temperature (>180̊C) causes changes in its viscoelastic property. The results of this study is significant for processes which requires heat treatment not only in kenaf fiber but might also be helpful for natural fibers in general.

Keywords: heat treatment, kenaf fiber, natural fiber, mechanical properties

Procedia PDF Downloads 355

Authors: Eunice H. Li

Abstract:

This paper discusses and analyses a small portion of the literature that has been reviewed for research work in Distance Education (DE) pedagogies that I am currently undertaking. It begins by presenting a brief overview of Taylor's (2001) five-generation models of Distance Education. The focus of the discussion will be on the 5th generation, Intelligent Flexible Learning Model. For this generation, educational and other institutions make portal access and interactive multi-media (IMM) an integral part of their operations. The paper then takes a brief look at current trends in technologies – for example smart-watch wearable technology such as Apple Watch. The emergent trends in technologies carry many new features. These are compared to former DE generational features. Also compared is the time span that has elapsed between the generations that are referred to in Taylor's model. This paper is a work in progress. The paper therefore welcome new insights, comparisons and critique of the issues discussed.

Keywords: distance education, e-learning technologies, pedagogy, generational models

Procedia PDF Downloads 463

Authors: Kunio Yoshikawa, Ding Lu

Abstract:

Small-scale, distributed and low-cost biomass power generation technologies are highly required in the modern society. There are big needs for these technologies in the disaster areas of developed countries and un-electrified rural areas of developing countries. This work aims to present a technical feasibility of the portable ultra-small power generation system based on the gasification of carbonized wood pellets/briquettes. Our project is designed for enabling independent energy production from various kinds of biomass resources in the open-field. The whole process mainly consists of two processes: biomass and waste pretreatment; gasification and power generation. The first process includes carbonization, densification (briquetting or pelletization), and the second includes updraft fixed bed gasification of carbonized pellets/briquettes, syngas purification, and power generation employing an internal combustion gas engine. A combined pretreatment processes including carbonization without external energy and densification were adopted to deal with various biomass. Carbonized pellets showed a better gasification performance than carbonized briquettes and their mixture. The 100-hour continuous operation results indicated that pelletization/briquetting of carbonized fuel realized the stable operation of an updraft gasifier if there were no blocking issues caused by the accumulation of tar. The cold gas efficiency and the carbon conversion during carbonized wood pellets gasification was about 49.2% and 70.5% with the air equivalence ratio value of around 0.32, and the corresponding overall efficiency of the gas engine was 20.3% during the stable stage. Moreover, the maximum output power was 21 kW at the air flow rate of 40 Nm³·h⁻¹. Therefore, the comprehensive system covering biomass carbonization, densification, gasification, syngas purification, and engine system is feasible for portable, ultra-small power generation. This work has been supported by Innovative Science and Technology Initiative for Security (Ministry of Defence, Japan).

Keywords: biomass carbonization, densification, distributed power generation, gasification

Procedia PDF Downloads 158

Authors: Caighley Logan

Abstract:

The outcome of fire related fatalities, along with other research, has found fires can have a detrimental effect to the mineral and crystalline structures within bone. This study focused on the mineral and crystalline structures within porcine bone samples to analyse the changes caused, with the intent of effectively ‘reverse engineering’ the data collected from burned bone samples to discover what may have happened. Using Fourier Transform Infrared (FT-IR), and X-Ray Fluorescence (XRF), the data collected from a controlled source of intense heat (muffle furnace) and an open fire, based in a living room setting in a standard size shipping container (8.5ft x 8ft) of a similar temperature with a known ignition source, a gasoline lighter. This approach is to analyse the changes to the samples and how the changes differ depending on the heat source. Results have found significant differences in the levels of remaining minerals for each type of heat/burning (p=<0.001), particularly Phosphorus and Calcium, this also includes notable additions of absorbed elements and minerals from the surrounding materials, i.e., Cerium (Ce), Bromine (Br) and Neodymium (Ne). The analysis techniques included provide validated results in conjunction with previous studies.

Keywords: forensic anthropology, thermal alterations, porcine bone, FTIR, XRF

Procedia PDF Downloads 85

Authors: M. Zake, I. Barmina, R. Valdmanis, A. Kolmickovs

Abstract:

Experimental investigations of the DC electric field effect on thermal decomposition of biomass, formation of the axial flow of volatiles (CO, H2, CxHy), mixing of volatiles with swirling airflow at low swirl intensity (S ≈ 0.2-0.35), their ignition and on formation of combustion dynamics are carried out with the aim to understand the mechanism of electric field influence on biomass gasification, combustion of volatiles and heat energy production. The DC electric field effect on combustion dynamics was studied by varying the positive bias voltage of the central electrode from 0.6 kV to 3 kV, whereas the ion current was limited to 2 mA. The results of experimental investigations confirm the field-enhanced biomass gasification with enhanced release of volatiles and the development of endothermic processes at the primary stage of thermochemical conversion of biomass determining the field-enhanced heat energy consumption with the correlating decrease of the flame temperature and heat energy production at this stage of flame formation. Further, the field-enhanced radial expansion of the flame reaction zone correlates with a more complete combustion of volatiles increasing the combustion efficiency by 3 % and decreasing the mass fraction of CO, H2 and CxHy in the products, whereas by 10 % increases the average volume fraction of CO2 and the heat energy production downstream the combustor increases by 5-10 %

Keywords: biomass, combustion, electrodynamic control, gasification

Procedia PDF Downloads 444

Authors: Saeed Ghali

Abstract:

Designed martensitic stainless steel was produced in a 30 kg induction furnace. The molten metal was cast into a refractory sand mold at 1600 °C. The produced ingots were recharged into the reheating furnace. Martensitic stainless steel was held for 1 hour at a temperature of 1150°C. The forging process starts and finishes at 1150 °C and 900 °C, respectively. A chemical analysis was carried out. Microstructure was studied. Heat treatment for martensitic stainless steel was carried out at 300 oC, 400 oC, 500 oC, 600 oC and 700 oC for 5 min, 20 min, 45 min, 120 min and 240 min. Hardness was measured after each heat treatment. The contribution influence of each time and temperature on hardness was investigated using factorial design for tempering temperature range (500 oC – 700 oC) for time up to 240 min. It was found that the microstructure is mainly a martensitic phase, and it conforms to the Schaeffler diagram. The results showed that time, temperature and their interaction combination have a negative effect on hardness in the temperature range ( 500 oC – 700 oC) with time range (5 min – 240 min). The model was built up in the form of coded variables and in actual variables. The predicted values – from coded and actual variables - of hardness are compatible with the experimental values. Factorial design is a useful technique to predict the effect and contribution effect of both time and temperature on the hardness of 7Cr-0.93Mo-2.27W martensitic stainless steel.

Keywords: steel, factorial design, hardness, heat treatment, temperature

Procedia PDF Downloads 7

Authors: István Patkó, Hosam Bayoumi Hamuda, András Szeder

Abstract:

In order to efficiently solve the problems created by the deepening energy crisis affecting Europe and the world, governments cannot neglect the opportunities of using the energy produced by sun collectors. In many of the EU countries there are sun collectors producing heat energy, e.g. in 2011 in the area of EU27 (countries which belong to European Union) + Switzerland altogether 37519126 m2 were operated, which are capable of producing 26.3 GWh heat energy. The energy produced by these sun collectors is utilized at the place of production. In the near future governments will have to focus more on spreading and using sun collectors. Among the complex problems of operating sun collectors, this article deals with determining the optimal tilt angle, directions of sun collectors. We evaluate the contamination of glass surface of sun collector to the produced energy. Our theoretically results are confirmed by laboratory measurements. The purpose of our work is to help users and engineers in determination of optimal operation parameters of sun collectors.

Keywords: heat energy, tilt angle, direction of sun collector, contamination of surface

Procedia PDF Downloads 433