Search results for: volumetric heat generation

Authors: F. R. M. Nascimento, E. E. S. Lora, J. C. E. Palácio

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A mathematical model to investigate the performance of a two stage fixed bed downdraft gasifier operating with air, steam and oxygen mixtures as the gasifying fluid has been developed. The various conditions of mixtures for a double stage fluid entry, have been performed. The model has been validated through a series of experimental tests performed by NEST – The Excellence Group in Thermal and Distributed Generation of the Federal University of Itajubá. Influence of mixtures are analyzed through the Steam to Biomass (SB), Equivalence Ratio (ER) and the Oxygen Concentration (OP) parameters in order to predict the best operating conditions to obtain adequate output gas quality, once is a key parameter for subsequent gas processing in the synthesis of biofuels, heat and electricity generation. Results show that there is an optimal combination in the steam and oxygen content of the gasifying fluid which allows the user find the best conditions to design and operate the equipment according to the desired application.

Keywords: air, equilibrium, downdraft, fixed bed gasification, mathematical modeling, mixtures, oxygen steam

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Authors: Mahmoud S. Ahmed, Hany A. Mohamed, Mohamed A. Omara, Mohamed F. Abdeen

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Experimental study of natural convection heat transfer inside smooth and rough surfaces of vertical and inclined equilateral triangular channels of different inclination angles with a uniformly heated surface are performed. The inclination angle is changed from 15º to 90º. Smooth and rough surface of average roughness (0.02 mm) are used and their effect on the heat transfer characteristics are studied. The local and average heat transfer coefficients and Nusselt number are obtained for smooth and rough channels at different heat flux values, different inclination angles and different Rayleigh numbers (Ra) 6.48 × 105 ≤ Ra ≤ 4.78 × 106. The results show that the local Nusselt number decreases with increase of axial distance from the lower end of the triangular channel to a point near the upper end of channel, and then, it slightly increases. Higher values of local Nusselt number for rough channel along the axial distance compared with the smooth channel. The average Nusselt number of rough channel is higher than that of smooth channel by about 8.1% for inclined case at θ = 45o and 10% for vertical case. The results obtained are correlated using dimensionless groups for both rough and smooth surfaces of the inclined and vertical triangular channels.

Keywords: natural heat transfer convection, constant heat flux, open channels, heat transfer

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Authors: Hitesh Tahbildar

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The cost of test data generation for a program is computationally very high. In general case, no algorithm to generate test data for all types of algorithms has been found. The cost of generating test data for different types of algorithm is different. Till date, people are emphasizing the need to generate test data for different types of programming constructs rather than different types of algorithms. The test data generation methods have been implemented to find heuristics for different types of algorithms. Some algorithms that includes divide and conquer, backtracking, greedy approach, dynamic programming to find the minimum cost of test data generation have been tested. Our experimental results say that some of these types of algorithm can be used as a necessary condition for selecting heuristics and programming constructs are sufficient condition for selecting our heuristics. Finally we recommend the different heuristics for test data generation to be selected for different types of algorithms.

Keywords: ongest path, saturation point, lmax, kL, kS

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Authors: Buket Boz, Alvaro Diez

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Waste heat recovery by means of Organic Rankine Cycle is a promising technology for the recovery of engine exhaust heat. However, it is complex to find out the optimum cycle conditions with appropriate working fluids to match exhaust gas waste heat due to its high temperature. Hence, this paper focuses on comparing sub-critical and supercritical ORC conditions with eight working fluids on a combined diesel engine-ORC system. The model employs two ORC designs, Regenerative-ORC and Pre-Heating-Regenerative-ORC respectively. The thermodynamic calculations rely on the first and second law of thermodynamics, thermal efficiency and exergy destruction factors are the fundamental parameters evaluated. Additionally, in this study, environmental and safety, GWP (Global Warming Potential) and ODP (Ozone Depletion Potential), characteristic of the refrigerants are taken into consideration as evaluation criteria to define the optimal ORC configuration and conditions. Consequently, the studys outcomes reveal that supercritical ORCs with alkane and siloxane are more suitable for high temperature exhaust waste heat recovery in contrast to sub-critical conditions.

Keywords: internal combustion engine, organic Rankine cycle, waste heat recovery, working fluids

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Authors: S. Sambath, P. Palanivel

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Research conducted in the last few decades has proven that an inclusion of Distributed Genaration (DG) into distribution systems considerably lowers the level of power losses and the power quality improved. Moreover, the choice of DG is even more attractive since it provides not only benefits in power loss minimisation, but also a wide range of other advantages including environment, economic, power qualities and technical issues. This paper is an intent to quantify and analyse the impact of distributed generation (DG) in Tamil Nadu, India to examine what the benefits of decentralized generation would be for meeting rural loads. We used load flow analysis to simulate and quantify the loss reduction and power quality enhancement by having decentralized generation available line conditions for actual rural feeders in Tamil Nadu, India. Reactive and voltage profile was considered. This helps utilities to better plan their system in rural areas to meet dispersed loads, while optimizing the renewable and decentralised generation sources.

Keywords: distributed generation, distribution system, load flow analysis, optimal location, power quality

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Authors: Ilham S. M. Elsayed

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The purpose of this study is to investigate Alahsa Governorate status and its vulnerability to generate urban heat islands. Alahsa Governorate is a famous oasis in the Arabic Peninsula including several oil centers. Extensive literature review was done to collect previous relative data on the urban heat island of Alahsa Governorate. Data used for the purpose of this research were collected from authorized bodies who control weather station networks over Alahsa Governorate, Eastern Province, Saudi Arabia. Although, the number of weather station networks within the region is very limited and the analysis using GIS software and its techniques is difficult and limited, the data analyzed confirm an increase in temperature for more than 2 °C from 2004 to 2014. Such increase is considerable whenever human health and comfort are the concern. The increase of temperature within one decade confirms the availability of urban heat islands. The study concludes that, Alahsa Governorate is vulnerable to create urban heat islands and more attention should be drawn to strategic planning of the governorate that is developing with a high pace and considerable increasing levels of urbanization.

Keywords: Alahsa Governorate, population density, Urban Heat Island, weather station

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Authors: Mohammed Nabeel Khan, C. Perisamy

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Convective vortices are normal highlights of air that ingest lower-entropy-energy at higher temperatures than they dismiss higher-entropy-energy to space. By means of the thermodynamic proficiency, it has been anticipated that the force of convective vortices relies upon the profundity of the convective layer. The atmospheric vortex engine is proposed as a gadget for delivering mechanical energy by methods for artificially produced vortex. The task of the engine is in view of the certainties that the environment is warmed from the base and cooled from the top. By generation of the artificial vortex, it is planned to take out the physical solar updraft tower and decrease the capital of the solar chimney power plants. The study shows the essentials of the atmospheric vortex engine, furthermore, audits the cutting edge in subject. Moreover, the study talks about a thought on using the solar energy as heat source to work the framework. All in all, the framework is attainable and promising for electrical power production.

Keywords: AVE, atmospheric vortex engine, atmosphere, updraft, vortex

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Authors: Suwimon Saneewong Na Ayuttaya, Chainarong Chaktranond, Phadungsak Rattanadecho

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This study numerically investigates the effects of Electrohydrodynamic on flow patterns and heat transfer enhancement within a cavity which is on the lower wall of channel. In this simulation, effects of using ground wire and ground plate on the flow patterns are compared. Moreover, the positions of electrode wire respecting with ground are tested in the range of angles θ = 0 - 180°. High electrical voltage exposes to air is 20 kV. Bulk mean velocity and temperature of inlet air are controlled at 0.1 m/s and 60°C, respectively. The result shows when electric field is applied, swirling flow is appeared in the channel. In addition, swirling flow patterns in the main flow of using ground plate are widely spreader than that of using ground wire. Moreover, direction of swirling flow also affects the flow pattern and heat transfer in a cavity. These cause the using ground wire to give the maximum temperature and heat transfer higher than using ground plate. Furthermore, when the angle is at θ = 60°, high shear flow effect is obtained. This results show high strength of swirling flow and effective heat transfer enhancement.

Keywords: swirling flow, heat transfer, electrohydrodynamic, numerical analysis

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Authors: Deisy Becerra, Nicolas Rios, Miguel Asuaje

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The Electrical Submersible Pump (ESP) is one of the most artificial lifting methods used in the last years, which consists of a serial arrangement of centrifugal pumps. One of the main concerns when handling crude oil is the formation of O/W or W/O (oil/water or water/oil) emulsions inside the pump, due to the shear rate imparted and the presence of high molecular weight substances that act as natural surfactants. Therefore, it is important to perform an analysis of the flow patterns inside the pump to increase the percentage of oil recovered using the centrifugal force and the difference in density between the oil and the water to generate the separation of liquid phases. For this study, a Computational Fluid Dynamic (CFD) model was developed on STAR-CCM+ software based on 3D geometry of a Franklin Electric 4400 4' four-stage ESP. In this case, the modification of the last stage was carried out to improve the centrifugal effect inside the pump, and a perforated double tube was designed with three different holes configurations disposed at the outlet section, through which the cut water flows. The arrangement of holes used has different geometrical configurations such as circles, rectangles, and irregular shapes determined as grating around the tube. The two-phase flow was modeled using an Eulerian approach with the Volume of Fluid (VOF) method, which predicts the distribution and movement of larger interfaces in immiscible phases. Different water-oil compositions were evaluated, such as 70-30% v/v, 80-20% v/v and 90-10% v/v, respectively. Finally, greater recovery of oil was obtained. For the several compositions evaluated, the volumetric oil fraction was greater than 0.55 at the pump outlet. Similarly, it is possible to show an inversely proportional relationship between the Water/Oil rate (WOR) and the volumetric flow. The volumetric fractions evaluated, the oil flow increased approximately between 41%-10% for circular perforations and 49%-19% for rectangular shaped perforations, regarding the inlet flow. Besides, the elimination of the pump diffuser in the last stage of the pump reduced the head by approximately 20%.

Keywords: computational fluid dynamic, CFD, electrical submersible pump, ESP, two phase flow, volume of fluid, VOF, water/oil rate, WOR

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Authors: Tu-Chieh Hung, Wei-Mon Yan, Xiao-Dong Wang, Yu-Xian Huang

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This work employs a combined optimization procedure including a simplified conjugate-gradient method and a three-dimensional fluid flow and heat transfer model to study the optimal geometric parameter design of double-layered microchannel heat sinks. The overall thermal resistance RT is the objective function to be minimized with number of channels, N, the channel width ratio, β, the bottom channel aspect ratio, αb, and upper channel aspect ratio, αu, as the search variables. It is shown that, for the given bottom area (10 mm×10 mm) and heat flux (100 W cm-2), the optimal (minimum) thermal resistance of double-layered microchannel heat sinks is about RT=0.12 ℃/m2W with the corresponding optimal geometric parameters N=73, β=0.50, αb=3.52, and, αu= 7.21 under a constant pumping power of 0.05 W. The optimization process produces a maximum reduction by 52.8% in the overall thermal resistance compared with an initial guess (N=112, β=0.37, αb=10.32 and, αu=10.93). The results also show that the optimal thermal resistance decreases rapidly with the pumping power and tends to be a saturated value afterward. The corresponding optimal values of parameters N, αb, and αu increase while that of β decrease as the pumping power increases. However, further increasing pumping power is not always cost-effective for the application of heat sink designs.

Keywords: optimization, double-layered microchannel heat sink, simplified conjugate-gradient method, thermal resistance

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Authors: S. Naveen, V. Sivasubramanian

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A modeling theory is proposed to consider the vaporization of LNG during its contact with water following its release from an underwater source. The spillage of LNG underwater can lead to a decrease in the surface temperature of water and subsequent freezing. This can in turn affect the heat flux distribution from the released LNG onto the water surrounding it. The available models predict the rate of vaporization considering the surface of contact as a solid wall, and considering the entire phenomena as a solid-liquid operation. This assumption greatly under-predicted the overall heat transfer on LNG water interface. The vaporization flux would first decrease during the film boiling, followed by an increase during the transition boiling and a steady decrease during the nucleate boiling. A superheat theory is introduced to enhance the accuracy in the prediction of the heat transfer between LNG and water. The work suggests that considering the superheat theory can greatly enhance the prediction of LNG vaporization on underwater releases and also help improve the study of overall thermodynamics.

Keywords: evaporation rate, heat transfer, LNG vaporization, underwater LNG release

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Authors: Pitchayanin Sukholthaman

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Gradually accumulated, the enormous amount of waste has caused tremendous adverse impacts to the world. Bangkok, Thailand, is chosen as an urban city of a developing country having coped with serious MSW problems due to the vast amount of waste generated, ineffective and improper waste management problems. Waste generation is the most important factor for successful planning of MSW management system. Thus, the prediction of MSW is a very important role to understand MSW distribution and characteristic; to be used for strategic planning issues. This study aims to find influencing variables that affect the amount of Bangkok MSW generation quantity.

Keywords: MSW generation, MSW quantity prediction, MSW management, multiple regression, Bangkok

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Authors: Chen Xiong, Tong Xin, Li Hao, Xu Jin-Sheng

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Experiment and simulation researches on the structural integrity of propellant grain in solid rocket motor (SRM) with high volumetric fraction were conducted. First, by using SRM parametric modeling functions with secondary development tool Python of ABAQUS, the three dimensional parameterized modeling programs of star shaped grain, wheel shaped grain and wing cylindrical grain were accomplished. Then, the mechanical properties under different loads for star shaped grain were obtained with the application of automatically established finite element model in ABAQUS. Next, several optimization algorithms are introduced to optimize the star shaped grain, wheel shaped grain and wing cylindrical grain. After meeting the demands of burning surface changes and volumetric fraction, the optimum three dimensional shapes of grain were obtained. Finally, by means of parametric modeling functions, pressure data of SRM’s cold pressurization test was directly applied to simulation of grain in terms of mechanical performance. The results verify the reliability and practical of parameterized modeling program of SRM.

Keywords: cold pressurization test, ğarametric modeling, structural integrity, propellant grain, SRM

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Authors: Louvill M. Ozarraga

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this study was designed to ascertain the concept of the revenue generation system of Bacolod, Lanao del Norte, through the completely enumerated elected officials and permanent employees sample respondents. The pertinent data were obtained through the use of a structured questionnaire and with the help of key informants. The study utilized a cross-sectional survey design to analyze and interpret the data using frequency count, percentage distribution, and weighted mean. For the major findings, the local revenue generation of the Municipality has increased by Php 4,465,394.21, roughly 73.52%, from the years 2018 to 2020. Administrative activities help the Municipality cope with development, namely, the issuance of ordinances, personnel augmentation, and collection strategies. Moreover, respondents were undecided about whether revenue generation contributed to infrastructures and purchases of assets. The majority of the respondents agreed that the municipality’s local revenue generation contributes to the social welfare of its constituents. Also, the respondents disagreed that locally generated revenue augments the 20% development fund. The study revealed that there is a big difference between the 2018 and 2020 Real Property Tax (RPT) collection. No committee was created to monitor and supervise the municipal revenue generation system. The Municipality, through a partnership with TESDA, provides skilled-job opportunity to its constituents and participants

Keywords: Local Revenue Generation: Its Contribution To The Development Of The Municipality Of Bacolod, Lanao Del Sur

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Authors: A. M. Gheitaghy, H. Saffari, G. Q. Zhang

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Numerical approach based on the electrical simulation method is proposed to solve a nonlinear transient heat conduction problem with nonlinear boundary for a spherical body. This problem represents a strong nonlinearity in both the governing equation for temperature dependent thermal property and the boundary condition for combined convective and radiative cooling. By analysing the equivalent electrical model using the electrical circuit simulation program HSPICE, transient temperature and heat flux distributions at sphere can be obtained easily and fast. The solutions clearly illustrate the effect of the radiation-conduction parameter Nrc, the Biot number and the linear coefficient of temperature dependent conductivity and heat capacity. On comparing the results with corresponding numerical solutions, the accuracy and efficiency of this computational method are found to be good.

Keywords: convective and radiative boundary, electrical simulation method, nonlinear heat conduction, spherical coordinate

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Authors: V. Nikkhah Rashidabad, M. Manteghian, M. Masoumi, S. Mousavian

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In this research, the changes in bubbles diameter and number that may occur due to the change in heat flux of pure water during pool boiling process. For this purpose, test equipment was designed and developed to collect test data. The bubbles were graded using Caliper Screen software. To calculate the growth and nucleation rates of bubbles under different fluxes, population balance model was employed. The results show that the increase in heat flux from q=20 kw/m2 to q=102 kw/m2 raised the growth and nucleation rates of bubbles.

Keywords: heat flux, bubble growth, bubble nucleation, population balance model

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Authors: Gyo Woo Lee, Man Young Kim

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A mathematical heat transfer model for the prediction of transient heating of the slab in a direct-fired walking beam type reheating furnace has been developed by considering the nongray thermal radiation with given furnace environments. The furnace is modeled as radiating nongray medium with carbon dioxide and water with five-zoned gas temperature and the furnace wall is considered as a constant temperature lower than furnace gas one. The slabs are moving with constant velocity depending on the residence time through the non-firing, charging, preheating, heating, and final soaking zones. Radiative heat flux obtained by considering the radiative heat exchange inside the furnace as well as convective one from the surrounding hot gases are introduced as boundary condition of the transient heat conduction within the slab. After validating thermal radiation model adopted in this work, thermal fields in both model and real reheating furnace are investigated in terms of radiative heat flux in the furnace and temperature inside the slab. The results show that the slab in the furnace can be more heated with higher slab emissivity and residence time.

Keywords: reheating furnace, steel slab, radiative heat transfer, WSGGM, emissivity, residence time

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Authors: A. M. Tiara, Sudipto Chakraborty, S. K. Pal

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Impinging jets and their different configurations are important from the viewpoint of the fluid flow characteristics and their influence on heat transfer from metal surfaces due to their complex flow characteristics. Such flow characteristics results in highly variable heat transfer from the surface, resulting in varying cooling rates which affects the mechanical properties including hardness and strength. The overall objective of the current research is to conduct a fundamental investigation of the heat transfer mechanisms for an impinging coolant jet. Numerical simulation of the cooling process gives a detailed analysis of the different parameters involved even though employing Computational Fluid Dynamics (CFD) to simulate the real time process, being a relatively new research area, poses many challenges. The heat transfer mechanism in the current research is actuated by jet cooling. The computational tool used in the ongoing research for simulation of the cooling process is ANSYS Workbench software. The temperature and heat flux distribution along the steel strip with the effect of various flow parameters on the heat transfer rate can be observed in addition to determination of the jet impingement patterns, which is the major aim of the present analysis. Modelling both jet and air atomized cooling techniques using CFD methodology and validating with those obtained experimentally- including trial and error with different models and comparison of cooling rates from both the techniques have been included in this work. Finally some concluding remarks are made that identify some gaps in the available literature that have influenced the path of the current investigation.

Keywords: CFD, heat transfer, impinging jets, numerical simulation

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Authors: Pradeepa Teegala, Ramreddy Chitteti

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This article analyzes the mixed convection flow of chemically reacting micropolar fluid over a truncated cone embedded in non-Darcy porous medium with convective boundary condition. In addition, heat generation/absorption and Joule heating effects are taken into consideration. The similarity solution does not exist for this complex fluid flow problem, and hence non-similarity transformations are used to convert the governing fluid flow equations along with related boundary conditions into a set of nondimensional partial differential equations. Many authors have been applied the spectral quasi-linearization method to solve the ordinary differential equations, but here the resulting nonlinear partial differential equations are solved for non-similarity solution by using a recently developed method called the spectral quasi-linearization method (SQLM). Comparison with previously published work on special cases of the problem is performed and found to be in excellent agreement. The effect of pertinent parameters namely, Biot number, mixed convection parameter, heat generation/absorption, Joule heating, Forchheimer number, chemical reaction, micropolar and magnetic field on physical quantities of the flow are displayed through graphs and the salient features are explored in detail. Further, the results are analyzed by comparing with two special cases, namely, vertical plate and full cone wherever possible.

Keywords: chemical reaction, convective boundary condition, joule heating, micropolar fluid, mixed convection, spectral quasi-linearization method

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Authors: Hideyuki Onodera, Ryoji Imai, Masahiro Sakai

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Explosions have occurred in incineration plants in conveyors, ash pits, and other locations. The cause of such explosions is thought to be the reaction of metallic aluminum contained in the ash with water used to cool the ash and prevent scattering, resulting in the generation of hydrogen. Given this background, conveyors and other equipment have been damaged by explosions, which has hindered the stable operation of incineration plants. In addition, workers may be injured by equipment explosions, creating an unsafe situation. To remedy these problems, it is necessary to devise a way to prevent hydrogen explosions from occurring. To overcome this problem, we conducted a hydrogen generation reaction experiment using simulated incinerator ash powder containing aluminum, calcium oxide, and water and confirmed that conditions exist to stop the hydrogen generation reaction. The results of this research may contribute to the suppression of hydrogen explosions at incineration plants.

Keywords: waste incinerated ash, aluminum, water, hydrogen, suppression of hydrogen generation, incineration plant

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Authors: Nadjiba Mahfoudi, Abdelhafid Moummi , Mohammed El Ganaoui

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Thermal applications are drawing increasing attention in the solar energy research field, due to their high performance in energy storage density and energy conversion efficiency. In these applications, solar collectors and thermal energy storage systems are the two core components. This paper presents a thermal analysis of the transient behavior and storage capability of a sensible heat storage device in which sand is used as a storage media. The TES unit with embedded charging tubes is connected to a solar air collector. To investigate it storage characteristics a 3D-model using no linear coupled partial differential equations for both temperature of storage medium and heat transfer fluid (HTF), has been developed. Performances of thermal storage bed of capacity of 17 MJ (including bed temperature, charging time, energy storage rate, charging energy efficiency) have been evaluated. The effect of the number of charging tubes (3 configurations) is presented.

Keywords: design, thermal modeling, heat transfer enhancement, sand, sensible heat storage

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Authors: Ahmed Ramadhan Al-Obaidi, Jassim Alhamid

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In this investigation, the flow pattern, characteristics of thermal-hydraulic, and improvement of heat transfer performance are evaluated using a numerical technique in three dimensions corrugated pipe heat exchanger. The modification was made under different corrugated pipe geometrical parameters, including corrugated ring angle (CRA), distance between corrugated ring (DBCR), and corrugated diameter (CD), the range of Re number from 2000 to 12000. The numerical results are validated with available experimental data. The numerical outcomes reveal that there is an important change in flow field behaviour and a significant increase in friction factor and improvement in heat transfer performance owing to the use of the corrugated shape in the heat exchanger pipe as compared to the conventional smooth pipe. Using corrugated pipe with different configurations makes the flow more turbulence, flow separation, boundary layer distribution, flow mixing, and that leads to augmenting the performance of heat transfer. Moreover, the value of pressure drop, and the Nusselt number increases as the corrugated pipe geometrical parameters increase. Furthermore, the corrugation configuration shapes have an important influence on the thermal evaluation performance factor, and the maximum value was more than 1.3. Numerical simulation can be performed to predict the various geometrical configurations effects on fluid flow, thermal performance, and heat transfer enhancement.

Keywords: corrugated ring angle, corrugated diameter, Nusselt number, heat transfer

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Authors: Amira Abdelhafez, Rufus Brunt

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Geothermal energy in Egypt represents a significant untapped renewable resource that can reduce reliance on conventional power generation. Exploiting these geothermal resources depends on depth, temperature range, and geological characteristics. The intracontinental rift setting of the Gulf of Suez (GoS)-Red Sea rift is a favourable tectonic setting for convection-dominated geothermal plays. The geothermal gradient across the GoS ranges from 24.9 to 86.66 °C/km, with a heat flow of 31-127.2 mW/m². Surface expressions of convective heat loss emerge along the gulf flanks as hot springs (e.g., Hammam Faraun) accompanying deeper geothermal resources. These thermal anomalies are driven mainly by the local tectonic configuration. Characterizing the structural framework of major faults and their control on reservoir properties and subsurface hydrothermal fluid circulation is vital for geothermal applications in the gulf. The geothermal play systems of the GoS depend on structural and lithological properties that contribute to heat storage and vertical transport. Potential geothermal reservoirs include the Nubia sandstones, which, due to their thickness, continuity, and contact with hot basement rocks at a mean depth of 3 km, create an extensive reservoir for geothermal fluids. To develop these geothermal resources for energy production, defining the permeability anisotropy of the reservoir due to faults and facies variation is a crucial step in our study, particularly the evaluation of influence on thermal breakthrough and production rates.

Keywords: geothermal, October field, site specific study, reservoir modelling

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Authors: Lolade Siyonbola

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Nigerians are often celebrated as being the most educated cultural group in America. The cultural values and history that have led to this reality are particular to a generation that came of age post colonialism. Many of these cultural values have been passed down from post-colonial parent to millennial child, but most have not. This study, based on interviews and surveys of Nigerian millennials and their parents in the United States, explores the degree to which identity has been eroded in the millennial generation due to a lack of imparted cultural values and knowledge from the previous generation. Most of the subjects do not speak their native language or identify with their cultural heritage sufficiently to build ties with their native land. Most are experiencing some degree of identity crisis, and therefore limited self-actualization, with little to no support; as there are few successful tools available to this population. If governmental programs to reverse these trends are not implemented within this generation, the implications to the individual, family and home nation (Nigeria), will be felt for generations to come.

Keywords: identity, culture, self-actualization, social identity theory, migration, transnationalism, value systems

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Authors: Lei Lei, Hongbo Zhang, Donald J. Bergstrom, Bing Zhang, K. Y. Song, W. J. Zhang

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This paper presents a model for a modified T-junction device for microspheres generation. The numerical model is developed using a commercial software package: COMSOL Multiphysics. In order to test the accuracy of the numerical model, multiple variables, such as the flow rate of cross-flow, fluid properties, structure, and geometry of the microdevice are applied. The results from the model are compared with the experimental results in the diameter of the microsphere generated. The comparison shows a good agreement. Therefore the model is useful in further optimization of the device and feedback control of microsphere generation if any.

Keywords: CFD modeling, validation, microsphere generation, modified T-junction

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Authors: Alibakhsh Kasaeian, Mohammad Sameti, Zahra Noori, Mona Rastgoo Bahambari

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Nowadays, the parabolic trough solar collector technology has become the most promising large-scale technology among various solar thermal generations. In this paper, a detailed numerical heat transfer model for a parabolic trough collector with nanofluid is presented based on the finite difference approach for which a MATLAB code was developed. The model was used to simulate the performance of a parabolic trough solar collector’s linear receiver, called a heat collector element (HCE). In this model, the heat collector element of the receiver was discretized into several segments in axial directions and energy balances were used for each control volume. All the heat transfer correlations, the thermodynamic equations and the optical properties were considered in details and the set of algebraic equations were solved simultaneously using iterative numerical solutions. The modeling assumptions and limitations are also discussed, along with recommendations for model improvement.

Keywords: heat transfer, nanofluid, numerical analysis, trough

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Authors: Kukuh Suprayogi, Muhamad Natsir, Olif Kurniawan, Hot Parulian, Bayu Fitriana, Fery Mustofa

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The new approach by utilizing the heat propagation analysis carried out by studying and evaluating the effect of the presence of hydrocarbons to the flow of heat that goes from the bottom surface to surface. Heat propagation is determined by the thermal conductivity of rocks. The thermal conductivity of rock itself is a quantity that describes the ability of a rock to deliver heat. This quantity depends on the constituent rock lithology, large porosity, and pore fluid filler. The higher the thermal conductivity of a rock, the more easily the flow of heat passing through these rocks. With the same sense, the heat flow will more easily pass through the rock when the rock is filled with water than hydrocarbons, given the nature of the hydrocarbons having more insulator against heat. The main objective of this research is to try to make the model the heat propagation calculations in degrees Celsius from the subsurface to the surface which is then compared with the surface temperature is measured directly at the point of location. In calculating the propagation of heat, we need to first determine the thermal conductivity of rocks, where the rocks at the point calculation are not composed of homogeneous but consist of strata. Therefore, we need to determine the mineral constituent and porosity values of each stratum. As for the parameters of pore fluid filler, we assume that all the pores filled with water. Once we get a thermal conductivity value of each unit of the rock, then we begin to model the propagation of heat profile from the bottom to the surface. The initial value of the temperature that we use comes from the data bottom hole temperature (BHT) is obtained from drilling results. Results of calculations per depths the temperature is displayed in plotting temperature versus depth profiles that describe the propagation of heat from the bottom of the well to the surface, note that pore fluid is water. In the technical implementation, we can identify the magnitude of the effect of hydrocarbons in reducing the amount of heat that crept to the surface based on the calculation of propagation of heat at a certain point and compared with measurements of surface temperature at that point, assuming that the surface temperature measured is the temperature that comes from the asthenosphere. This publication proves that the accumulation of hydrocarbon can be identified by analysis of heat propagation profile which could be a method for identifying the presence of hydrocarbons.

Keywords: thermal conductivity, rock, pore fluid, heat propagation

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Authors: Hüseyin Altubaş, Hasret Aktaş, A. Mücahid Zengin

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Children determine the direction of the power of consumption. They affect the decisions of their parents but they also reached to a significant purchasing power themselves. Children, who are turning interactive behavior to normal behavior are becoming the decision makers in a company’s survival. Companies that analyze this effective target audience can communicate successfully with children. Children, who are interactive individuals, are closer to advertising. They are almost talking better with advertising. They are not afraid to express their likings, as well as their dislikes. Children have an interactive lifestyle and they were exposed to the vast changes in technology after year 2000. They do not know a life without internet, they spend mobile life in internet. This Z generation is the new determinants of brands. Z generation finds it appropriate to be brand ambassadors and they completely changed traditional media and traditional consumer behavior. These children live social reality with virtual reality and they feed brands differently. Brands that interact with Z generation are affected by this feeding positively, while brands that keep interaction in traditional levels are affected negatively. In this research we examine the communication, advertising and brand behaviors of Z generation. We especially analyze this generation’s interaction with social media brands and their interactive attitudes.

Keywords: social media, Z generation, children, advertising, brand choice

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Authors: Hamid El Qarnia

Abstract:

This study investigates the impact of the eccentricity of the central tube on the thermal and fluid characteristics of a triplex tube used in latent heat energy storage technologies. Two triplex tube orientations are considered in the proposed study: vertical and horizontal. The energy storage material, which is a phase change material (PCM), is placed in the space between the inside and outside tubes. During the thermal energy storage period, a heat transfer fluid (HTF) flows inside the two tubes, transmitting the heat to the PCM through two heat exchange surfaces instead of one heat exchange surface as it is the case for double tube heat storage systems. A CFD model is developed and validated against experimental data available in the literature. The mesh independency study is carried out to select the appropriate mesh. In addition, different time steps are examined to determine a time step ensuring accuracy of the numerical results and reduction in the computational time. The numerical model is then used to conduct numerical investigations of the thermal behavior and thermal performance of the storage unit. The effects of eccentricity of the central tube and HTF mass flow rate on thermal characteristics and performance indicators are examined for two flow arrangements: co-current and counter current flows. The results are given in terms of isotherm plots, streamlines, melting time and thermal energy storage efficiency.

Keywords: energy storage, heat transfer, melting, solidification

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Authors: Amthal Al-Gailani, Olujide Sanni, Thibaut Charpentier, Anne Neville

Abstract:

Formation of inorganic scale on heat transfer surfaces is a serious problem encountered in industrial, commercial, and domestic heat exchangers and systems. Several industries use potable/groundwater sources such as rivers, lakes, and oceans to use water as a working fluid in heat exchangers and steamers. As potable/surface water contains diverse salt ionic species, the scaling kinetics and deposit morphology are expected to be different from those found in artificially hardened solutions. In this work, scale formation on the heat transfer surfaces from potable water has been studied using a once-through open flow cell under atmospheric pressure. The surface scaling mechanism and deposit morphology are investigated at high surface temperature. Thus the water evaporation process has to be considered. The effect of surface temperature, flow rate, and inhibitor deployment on the thermal resistance and morphology of the scale have been investigated. The study findings show how an increase in surface temperature enhances the crystallization reaction kinetics on the surface. There is an increase in the amount of scale and the resistance to heat transfer. The fluid flow rate also increases the fouling resistance and the thickness of the scale layer.

Keywords: fouling, heat exchanger, thermal resistance, crystallization, potable water

Procedia PDF Downloads 149