Search results for: thermal fluid characteristics

Authors: Abderrahim Sidi Mohammed Nekrouf, Sarra Youcefi

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Fluid mixing plays a crucial role in numerous industries as it has a significant impact on the final product quality and performance. In certain cases, the circulation of viscous fluids presents challenges, leading to the formation of stagnant zones. To overcome this issue, stirring devices are employed for fluid mixing. This study focuses on a numerical analysis aimed at understanding the behavior of Newtonian fluids when agitated by a two-blade agitator in a cylindrical vessel. We investigate the influence of the agitator shape on fluid motion. Bi-blade agitators of this type are commonly used in the food, cosmetic, and chemical industries to agitate both viscous and non-viscous liquids. Numerical simulations were conducted using Computational Fluid Dynamics (CFD) software to obtain velocity profiles, streamlines, velocity contours, and the associated power number. The obtained results were compared with experimental data available in the literature, validating the accuracy of our numerical approach. The results clearly demonstrate that modifying the agitator shape has a significant impact on fluid motion. This modification generates an axial flow that enhances the efficiency of the fluid flow. The various velocity results convincingly reveal that the fluid is more uniformly agitated with this modification, resulting in improved circulation and a substantial reduction in stagnant zones.

Keywords: Newtonian fluids, numerical modeling, two blade., CFD

Procedia PDF Downloads 53

Authors: Kimi Ueda, Kosuke Sugita, Soma Kawamoto, Hiroshi Shimoda, Hirotake Ishii, Fumiaki Obayashi, Kazuhiro Taniguchi, Ayaka Suzuki

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The authors have focused on the thermal difference between office rooms and break rooms, and proposed an integrated thermal control method to improve workers’ intellectual concentration. First, a trial experiment was conducted to verify the effect of temperature difference on workers’ intellectual concentration with using two experimental rooms; a thermally neutral break room and a cooler office room. As the result of the experiment, it was found that the thermal difference had a significant effect on improving their intellectual concentration. Workers, however, often take a short break at their desks without moving to a break room, so that the thermal difference cannot be given to them. So utilization of airflow was proposed as an integrated thermal control method instead of the temperature difference to realize the similar effect. Concretely, they are exposed to airflow when working in order to reduce their effective temperature while it is weakened when taking a break. Another experiment was conducted to confirm the effect of the airflow control on their intellectual concentration. As the result of concentration index and questionnaire survey, their intellectual concentration was significantly improved in the integrated thermal controlled environment. It was also found that most of them felt more comfortable and had higher motivation and higher degree of concentration in the environment.

Keywords: airflow, evaluation experiment, intellectual concentration, thermal difference

Procedia PDF Downloads 268

Authors: Megha Jain, K. K. Pathak

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In sub-tropical humid climates, it is estimated most of the urban peak load of energy consumption is used to satisfy air-conditioning or air-coolers cooling demand in summer time. As the urbanization rate in developing nation – like the case in India is rising rapidly, the pressure placed on energy resources to satisfy inhabitants’ indoor comfort requirements is consequently increasing too. This paper introduces passive cooling through roof as a means of reducing energy cooling loads for satisfying human comfort requirements in a sub-tropical climate. Experiments were performed by applying different insulators which are locally available solar reflective materials to insulate the roofs of five rooms of 4 case buildings; three rooms having RCC (Reinforced Cement Concrete) roof and two having Asbestos sheet roof of existing buildings. The results are verified by computer simulation using Computational Fluid Dynamics tools with FLUENT software. The result of using solar reflective paint with high albedo coating shows a fall of 4.8⁰C in peak hours and saves 303 kWh considering energy load with air conditioner during the summer season in comparison to non insulated flat roof energy load of residential buildings in Bhopal. An optimum solution of insulator for both types of roofs is presented. It is recommended that the selected cool roof solution be combined with insulation on other elements of envelope, to increase the indoor thermal comfort. The application is intended for low cost residential buildings in composite and warm climate like Bhopal.

Keywords: cool roof, computational fluid dynamics, energy loads, insulators, passive cooling, subtropical climate, thermal performance

Procedia PDF Downloads 152

Authors: Jun Byung Joon, Seo Seok Hyun, Lee Seo Young

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As carbon dioxide emissions increase due to rapid industrialization and reckless development, abnormal climates such as floods and droughts are occurring. In order to respond to such climate change, the use of existing fossil fuels is reduced, and the proportion of eco-friendly renewable energy is gradually increasing. Korea is an energy resource-poor country that depends on imports for 93% of its total energy. As the global energy supply chain instability experienced due to the Russia-Ukraine crisis increases, countries around the world are resetting energy policies to minimize energy dependence and strengthen security. Seawater thermal energy is a renewable energy that replaces the existing air heat energy. It uses the characteristic of having a higher specific heat than air to cool and heat main spaces of buildings to increase heat transfer efficiency and minimize power consumption to generate electricity using fossil fuels, and Carbon dioxide emissions can be minimized. In addition, the effect on the marine environment is very small by using only the temperature characteristics of seawater in a limited way. K-water carried out a demonstration project of supplying cooling and heating energy to spaces such as the central control room and presentation room in the management building by acquiring the heat source of seawater circulated through the power plant's waterway by using the characteristics of the tidal power plant. Compared to the East Sea and the South Sea, the main system was designed in consideration of the large tidal difference, small temperature difference, and low-temperature characteristics, and its performance was verified through operation during the demonstration period. In addition, facility improvements were made for major deficiencies to strengthen monitoring functions, provide user convenience, and improve facility soundness. To spread these achievements, the basic concept was to expand the seawater heating and cooling system with a scale of 200 USRT at the Tidal Culture Center. With the operational experience of the demonstration system, it will be possible to establish an optimal seawater heat cooling and heating system suitable for the characteristics of the west coast ocean. Through this, it is possible to reduce operating costs by KRW 33,31 million per year compared to air heat, and through industry-university-research joint research, it is possible to localize major equipment and materials and develop key element technologies to revitalize the seawater heat business and to advance into overseas markets. The government's efforts are needed to expand the seawater heating and cooling system. Seawater thermal energy utilizes only the thermal energy of infinite seawater. Seawater thermal energy has less impact on the environment than river water thermal energy, except for environmental pollution factors such as bottom dredging, excavation, and sand or stone extraction. Therefore, it is necessary to increase the sense of speed in project promotion by innovatively simplifying unnecessary licensing/permission procedures. In addition, support should be provided to secure business feasibility by dramatically exempting the usage fee of public waters to actively encourage development in the private sector.

Keywords: seawater thermal energy, marine energy, tidal power plant, energy consumption

Procedia PDF Downloads 84

Authors: Im-Nam Jang, Yong-Sik Ahn

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In this study sintered wick was formed in a heat pipe through the process of sintering a mixture of copper powder with particle sizes of 100μm and 200μm, mixed with a pore-forming agent. The heat pipe's thermal resistance, which affects its heat transfer efficiency, is determined during manufacturing according to powder type, thickness of the sintered wick, and filling rate of the working fluid. Heat transfer efficiency was then tested at various inclination angles (0°, 45°, 90°) to evaluate the performance of heat pipes. Regardless of the filling amount and test angle, the 200μm copper powder type exhibited superior heat transfer efficiency compared to the 100μm type. After analyzing heat transfer performance at various filling rates between 20% and 50%, it was determined that the heat pipe's optimal heat transfer capability occurred at a working fluid filling rate of 30%. The width of the wick was directly related to the heat transfer performance.

Keywords: heat pipe, heat transfer performance, effective pore size, capillary force, sintered wick

Procedia PDF Downloads 36

Authors: M. Alipanah, A. Ranjbar, E. Farnad, F. Alipanah

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Entropy generation of an Al2O3-water nanofluid due to heat transfer and fluid friction irreversibility has been investigated in a square cavity subject to different side wall temperatures using a nanofluid for natural convection flow. This study has been carried out for the pertinent parameters in the following ranges: Rayleigh number between 104 to 107 and volume fraction between 0 to 0.05. Based on the obtained dimensionless velocity and temperature values, the distributions of local entropy generation, average entropy generation and average Bejan number are determined. The results are compared for a pure fluid and a nanofluid. It is totally found that the heat transfer and entropy generation of the nanofluid is more than the pure fluid and minimum entropy generation and Nusselt number occur in the pure fluid at any Rayleigh number. Results depict that the addition of nanoparticles to the pure fluid has more effect on the entropy generation as the Rayleigh number goes up.

Keywords: entropy generation, natural convection, bejan number, nuselt number, nanofluid

Procedia PDF Downloads 480

Authors: M. Capocelli, A. Caputo, M. De Falco, D. Mazzei, V. Piemonte

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This paper presents the experimental results and the related modeling of a thermal energy storage (TES) facility, ideated and realized by ENEA and realizing the thermocline with an innovative geometry. Firstly, the thermal energy exchange model of an equivalent shell & tube heat exchanger is described and tested to reproduce the performance of the spiral exchanger installed in the TES. Through the regression of the experimental data, a first-order thermocline model was also validated to provide an analytical function of the thermocline, useful for the performance evaluation and the comparison with other systems and implementation in simulations of integrated systems (e.g. power plants). The experimental data obtained from the plant start-up and the short-cut modeling of the system can be useful for the process analysis, for the scale-up of the thermal storage system and to investigate the feasibility of its implementation in actual case-studies.

Keywords: CSP plants, thermal energy storage, thermocline, mathematical modelling, experimental data

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Authors: Miladi Yasmine, Bouhlel Salah, Garnit Hechmi, David Banks

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The Jebel Mecella F (Ba-Pb-Zn) ore deposits of the Zaghouan district are located in northeastern Tunisia, 60 km south of Tunis. The host rocks belong to the Ressas Formation of Kimmeridgian-Tithonian age and lower Cretaceous layers. Mineralisations occur as stratiform lenses and fracture fillings. The ore mineral assemblage is composed of fluorite, barite, sphalerite galena, and quartz. Primary fluid inclusions in sphalerite have homogenization temperatures ranging from 129 to 145°C final melting temperature range from -14.9 to -10.0, corresponding to salinities of 14.0 to 17.7 wt% NaCl equivalent. Fluid inclusions in fluorite homogenize to the liquid phase between 116 and 160°C. The final ice melting temperature ranges from -23 to -15 °C, corresponding to salinities between 17 and 24 wt% NaCl equivalent. The LAICP-MS analyses of the fluid inclusions in fluorite show that these fluids are dominated by Na>K>Mg. Furthermore, the high K/Na values from fluid inclusions suggest the brine interacted with K-rich rocks in the basement or in siliciclastic sediments in the basins. The ore fluids in Jebel Mecella are highly saline and Na-K dominated with lower Mg concentrations, and come from the leaching of the dolomitic host rocks. These results are compatible with Mississippi-Valley-type mineralizing fluids.

Keywords: Jebel Mecella, fluid inclusions, micro thermometry, LA-ICP-MS

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Authors: T. Walczak, J. K. Grabski, P. Fritzkowski, M. Stopa

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Objectives of the study are i) to perform numerical simulations that permit an analysis of the dynamics of subretinal fluid when an implant has induced scleral intussusception and ii) assess the impact of the physical parameters of the model on the flow rate. Computer simulations were created using finite element method (FEM) based on a model that takes into account the interaction of a viscous fluid (subretinal fluid) with a hyperelastic body (retina). The purpose of the calculation was to investigate the dependence of the flow rate of subretinal fluid through a hole in the retina on different factors such as viscosity of subretinal fluid, material parameters of the retina, and the offset of the implant from the retina’s hole. These simulations were performed for different speeds of eye movement that reflect the behavior of the eye when reading, REM, and saccadic movements. Similar to other works in the field of subretinal fluid flow, it was assumed stationary, single sided, forced fluid flow in the considered area simulating the subretinal space. Additionally, a hyperelastic material model of the retina and parameterized geometry of the considered model was adopted. The calculations also examined the influence the direction of the force of gravity due to the position of the patient’s head on the trend of outflow of fluid. The simulations revealed that fluid outflow from the retina becomes significant with eyeball movement speed of 100°/sec. This speed is greater than in the case of reading but is four times less than saccadic movement. The increase of viscosity of the fluid increased beneficial effect. Further, the simulation results suggest that moderate eye movement speed is optimal and that the conventional prescription of the avoidance of routine eye movement following retinal detachment surgery should be relaxed. Additionally, to verify numerical results, some calculations were repeated with use of meshless method (method of fundamental solutions), which is relatively fast and easy to implement. The paper has been supported by 02/21/DSPB/3477 grant.

Keywords: CFD simulations, FEM analysis, meshless method, retinal detachment

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Authors: Ahmed R. Ballil

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Heat exchangers are devices used to transfer heat between two fluids. These devices are utilized in many engineering and industrial applications such as heating, cooling, condensation and boiling processes. The fluids might be in direct contact (mixed), or they separated by a solid wall to avoid mixing. In the present paper, interactive computer-aided design of shell and tube heat exchangers is developed using Visual Basic computer code as a framework. This design is based on the Bell-Delaware method, which is one of the very well known methods reported in the literature for the design of shell and tube heat exchangers. Physical properties for either the tube or the shell side fluids are internally evaluated by calling on an enormous data bank composed of more than a hundred fluid compounds. This contributes to increase the accuracy of the present design. The international system of units is considered in the developed computer program. The present design has an added feature of being capable of performing modification based upon a preset design criterion, such that an optimum design is obtained at satisfying constraints set either by the user or by the method itself. Also, the present code is capable of giving an estimate of the approximate cost of the heat exchanger based on the predicted surface area of the exchanger evaluated by the program. Finally, the present thermal and hydraulic design code is tested for accuracy and consistency against some of existed and approved designs of shell and tube heat exchangers.

Keywords: bell-delaware method, heat exchangers, shell and tube, thermal and hydraulic design

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Authors: Santhosh A. K.

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This work presents an efficient monolithic finite element strategy for solving thermo-fluid-structure interaction problems involving compressible fluids and linear-elastic structure. This formulation uses displacement variables for structure and velocity variables for the fluid, with no additional variables required to ensure traction, velocity, temperature, and heat flux continuity at the fluid-structure interface. Rate of convergence in each time step is quadratic, which is achieved in this formulation by deriving an exact tangent stiffness matrix. The robustness and good performance of the method is ascertained by applying the proposed strategy on a wide spectrum of problems taken from the literature pertaining to steady, transient, two dimensional, axisymmetric, and three dimensional fluid flow and conjugate heat transfer. It is shown that the current formulation gives excellent results on all the case studies conducted, which includes problems involving compressibility effects as well as problems where fluid can be treated as incompressible.

Keywords: linear thermoelasticity, compressible flow, conjugate heat transfer, monolithic FEM

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Authors: Maged Assem Soliman Mossallam

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Microsatellites' low available power limits the usage of active thermal control techniques in these categories of satellites. Passive thermal control techniques are preferred due to their high reliability and power saving which increase the satellite's survivability in orbit. Steady-state and transient simulations are applied to the microsatellite design in order to define severe conditions in orbit. Satellite thermal orbital three-dimensional simulation is performed using thermal orbit propagator coupled with Comsol Multiphysics finite element solver. Sensitivity study shows the dependence of the satellite temperatures on the internal heat dissipation and the thermooptical properties of anodization coatings. The critical case is defined as low power orbiting mode at the eclipse zone. Using black anodized aluminum drops the internal temperatures to severe values which exceed the permissible cold limits. Replacement with anodized titanium returns the internal subsystems' temperatures back to adequate temperature fluctuations limits.

Keywords: passive thermal control, thermooptical, anodized titanium, emissivity, absorbtiviy

Procedia PDF Downloads 116

Authors: A. de Folly d’Auris, R. Bagatin, P. Filtri

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This paper discusses the importance of having a good initial characterization of soil samples when thermal desorption has to be applied to polluted soils for the removal of contaminants. Particular attention has to be devoted on the desorption kinetics of the samples to identify the gases evolved during the heating, and contaminant degradation pathways. In this study, two samples coming from different points of the same contaminated site were considered. The samples are much different from each other. Moreover, the presence of high initial quantity of heavy hydrocarbons strongly affected the performance of thermal desorption, resulting in formation of dangerous intermediates. Analytical techniques such TGA (Thermogravimetric Analysis), DSC (Differential Scanning Calorimetry) and GC-MS (Gas Chromatography-Mass) provided a good support to give correct indication for field application.

Keywords: desorption kinetics, hydrocarbons, thermal desorption, thermogravimetric measurements

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Authors: Yasith Mindula Saipath Wickramasinghe

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Augmented reality applications require a high processing power to load, render and live stream high-definition AR models and virtual scenes; it also requires device sensors to work excessively to coordinate with internal hardware, OS and give the expected outcome in advance features like object detection, real time tracking, as well as voice and text recognition. Excessive thermal generation due to these advanced functionalities has become a major research problem as it is unbearable for smaller mobile devices to manage such heat increment and battery drainage as it causes physical harm to the devices in the long term. Therefore, effective thermal management is one of the major requirements in Augmented Reality application development. As this paper discusses major causes for this issue, it also provides possible solutions in the means of operating system adaptations as well as further research on best coding practises to optimize the application performance that reduces thermal excessive thermal generation.

Keywords: augmented reality, device thermal management, GPU, operating systems, device I/O, overheating

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Authors: Baha-Aldeen S. Algmati, Ahmed R. Ballil

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Multiphase flows occur widely in many engineering and industrial processes as well as in the environment we live in. In particular, bubbly flows are considered to be crucial phenomena in fluid flow applications and can be studied and analyzed experimentally, analytically, and computationally. In the present paper, the dynamic motion of an air bubble rising within a column of liquid is numerically simulated using an open-source CFD modeling tool 'OpenFOAM'. An interface tracking numerical algorithm called MULES algorithm, which is built-in OpenFOAM, is chosen to solve an appropriate mathematical model based on the volume of fluid (VOF) numerical method. The bubbles initially have a spherical shape and starting from rest in the stagnant column of liquid. The algorithm is initially verified against numerical results and is also validated against available experimental data. The comparison revealed that this algorithm provides results that are in a very good agreement with the 2D numerical data of other CFD codes. Also, the results of the bubble shape and terminal velocity obtained from the 3D numerical simulation showed a very good qualitative and quantitative agreement with the experimental data. The simulated rising bubbles yield a very small percentage of error in the bubble terminal velocity compared with the experimental data. The obtained results prove the capability of OpenFOAM as a powerful tool to predict the behavior of rising characteristics of the spherical bubbles in the stagnant column of liquid. This will pave the way for a deeper understanding of the phenomenon of the rise of bubbles in liquids.

Keywords: CFD simulations, multiphase flows, OpenFOAM, rise of bubble, volume of fluid method, VOF

Procedia PDF Downloads 107

Authors: Isa Moazen, Ali Nahvi

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Driver drowsiness is a major cause of vehicle accidents, and facial images are highly valuable to detect drowsiness. In this paper, we perform our research via a thermal camera to record drivers' facial images on a driving simulator. A robust real-time algorithm extracts the features using horizontal and vertical integration projection, contours, contour orientations, and cropping tools. The features are included four target areas on the cheeks and forehead. Qt compiler and OpenCV are used with two cameras with different resolutions. A high-resolution thermal camera is used for fifteen subjects, and a low-resolution one is used for a person. The results are investigated by four temperature plots and evaluated by observer rating of drowsiness.

Keywords: advanced driver assistance systems, thermal imaging, driver drowsiness detection, feature extraction

Procedia PDF Downloads 117

Authors: R. Yuan, S. Sivasankaran, N. Dutta, K. Ebrahimi

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This paper investigates the software capability and computer-aided engineering (CAE) method of modelling transient heat transfer process occurred in the vehicle underhood region during vehicle thermal soak phase. The heat retention from the soak period will be beneficial to the cold start with reduced friction loss for the second 14°C worldwide harmonized light-duty vehicle test procedure (WLTP) cycle, therefore provides benefits on both CO₂ emission reduction and fuel economy. When vehicle undergoes soak stage, the airflow and the associated convective heat transfer around and inside the engine bay is driven by the buoyancy effect. This effect along with thermal radiation and conduction are the key factors to the thermal simulation of the engine bay to obtain the accurate fluids and metal temperature cool-down trajectories and to predict the temperatures at the end of the soak period. Method development has been investigated in this study on a light-duty passenger vehicle using coupled aerodynamic-heat transfer thermal transient modelling method for the full vehicle under 9 hours of thermal soak. The 3D underhood flow dynamics were solved inherently transient by the Lattice-Boltzmann Method (LBM) method using the PowerFlow software. This was further coupled with heat transfer modelling using the PowerTHERM software provided by Exa Corporation. The particle-based LBM method was capable of accurately handling extremely complicated transient flow behavior on complex surface geometries. The detailed thermal modelling, including heat conduction, radiation, and buoyancy-driven heat convection, were integrated solved by PowerTHERM. The 9 hours cool-down period was simulated and compared with the vehicle testing data of the key fluid (coolant, oil) and metal temperatures. The developed CAE method was able to predict the cool-down behaviour of the key fluids and components in agreement with the experimental data and also visualised the air leakage paths and thermal retention around the engine bay. The cool-down trajectories of the key components obtained for the 9 hours thermal soak period provide vital information and a basis for the further development of reduced-order modelling studies in future work. This allows a fast-running model to be developed and be further imbedded with the holistic study of vehicle energy modelling and thermal management. It is also found that the buoyancy effect plays an important part at the first stage of the 9 hours soak and the flow development during this stage is vital to accurately predict the heat transfer coefficients for the heat retention modelling. The developed method has demonstrated the software integration for simulating buoyancy-driven heat transfer in a vehicle underhood region during thermal soak with satisfying accuracy and efficient computing time. The CAE method developed will allow integration of the design of engine encapsulations for improving fuel consumption and reducing CO₂ emissions in a timely and robust manner, aiding the development of low-carbon transport technologies.

Keywords: ATCT/WLTC driving cycle, buoyancy-driven heat transfer, CAE method, heat retention, underhood modeling, vehicle thermal soak

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Authors: Andrey A. Chernousov, Ben Y. B. Chan

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The use of the low-cost paraffinic phase change material can be rather effective in smart building envelopes in the South China region. Particular attention has to be paid to the PCM optimization as an exploitation conditions and the envelope insulation changes its thermal characteristics. The studied smart building envelope consists of a reinforced aluminum exterior, polymeric insulation foam, phase change material and reinforced interior gypsum board. A prototype sample was tested to validate the numerical scheme using EnergryPlus software. Three scenarios of insulation thermal resistance loss (ΔR/R = 0%, 25%, 50%) were compared with the different PCM thicknesses (tP=0, 1, 2.5, 5 mm). The comparisons were carried out for a west facing enveloped office building (50 storey). PCM optimization was applied to find the maximum efficiency for the different ΔR/R cases. It was found, during the optimization, that the PCM is an important smart component, lowering the peak energy demand up to 2.7 times. The results are not influenced by the insulation aging in terms of ΔR/R during long-term exploitation. In hot and humid climates like Hong Kong, the insulation core of the smart systems is recommended to be laminated completely. This can be very helpful in achieving an acceptable payback period.

Keywords: smart building envelope, thermal performance, phase change material, energy efficiency, large-scale sandwich panel

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Authors: Wenfeng Xie

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Bulk/hull cavitation evolution induced by an underwater explosion (UNDEX) near a free surface (bulk) or a deformable structure (hull) is numerically investigated using a multiphase compressible fluid solver coupled with a one-fluid cavitation model. A series of two-dimensional computations is conducted with varying material elasticity and surface curvature. Results suggest that material elasticity and surface curvature influence the peak pressures generated from UNDEX shock and cavitation collapse, as well as the bulk/hull cavitation regions near the surface. Results also show that such effects can be different for bulk cavitation generated from UNDEX-free surface interaction and for hull cavitation generated from UNDEX-structure interaction. More importantly, results demonstrate that shock wave focusing caused by a concave solid surface can lead to a larger cavitation region and thus intensify the cavitation reload. The findings can be linked to the strength and the direction of reflected waves from the structural surface and reflected waves from the expanding bubble surface, which are functions of material elasticity and surface curvature. Shockwave focusing effects are also observed for axisymmetric simulations, but the strength of the pressure contours for the axisymmetric simulations is less than those for the 2D simulations due to the difference between the initial shock energy. The current method is limited to two-dimensional or axisymmetric applications. Moreover, the thermal effects are neglected and the liquid is not allowed to sustain tension in the cavitation model.

Keywords: cavitation, UNDEX, fluid-structure interaction, multiphase

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Authors: Bambang Ariantara, Nandy Putra, Rangga Aji Pamungkas

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The development of electric vehicle batteries has resulted in very high energy density lithium-ion batteries. However, this progress is accompanied by the risk of thermal runaway, which can result in serious accidents. Heat pipes are heat exchangers that are suitable to be applied in electric vehicle battery thermal management for their lightweight, compact size and do not require external power supply. This paper aims to examine experimentally a flat plate loop heat pipe (FPLHP) performance as a heat exchanger in the thermal management system of the lithium-ion battery for electric vehicle application. The heat generation of the battery was simulated using a cartridge heater. Stainless steel screen mesh was used as the capillary wick. Distilled water, alcohol and acetone were used as working fluids with a filling ratio of 60%. It was found that acetone gives the best performance that produces the thermal resistance of 0.22 W/°C with 50 °C evaporator temperature at heat flux load of 1.61 W/cm2.

Keywords: electric vehicle, flat-plate loop heat pipe, lithium-ion battery, thermal management system

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Authors: H. Babou, S. Ridjla, B. Amerate, R. Ferhoum, M. Aberkane

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This work is devoted to the experimental study of thermal ageing effect on the mechanical and micro structural behavior of polycarbonate (PC). A simple compression tests, micro hardness and an IRTF analysis were completed in order to characterize the response of material on specimens after ageing at a temperature of order 100 C° and for serval maintain duration 72, 144 and 216 hours. These investigations showed a decrease of the intrinsic properties of polycarbonate (Young modulus, yield stress, etc.); the superposition of spectra IRTF shows that the intensity of chemical connections C=C, C-O, CH3 and C-H are influenced by the duration of thermal ageing; in addition, an increase of 30 % of micro hardness was detected after 216 hour of ageing.

Keywords: amorphous polymer, polycarbonate, mechanical behavior, compression test, thermal ageing

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Authors: Arya Pirooz

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The effects of different fuels (DME, RME B100, and SME B100) on barrel engines were studied as a general, single dimensional investigation for characterization of these types of engines. A base computational model was created as reference point to be used as a point of comparison with different cases. The models were computed using the commercial computational fluid dynamics program, Diesel-RK. The base model was created using basic dimensions of the PAMAR-3 engine with inline unit injectors. Four fuel cases were considered. Optimized models were also considered for diesel and DME cases with respect to injection duration, fuel, injection timing, exhaust and intake port opening, CR, angular offset. These factors were optimized for highest BMEP, combined PM and NOx emissions, and highest SFC. Results included mechanical efficiency (eta_m), efficiency and power, emission characteristics, combustion characteristics. DME proved to have the highest performing characteristics in relation to diesel and RME fuels for this type of barrel engine.

Keywords: DME, RME, Diesel-RK, characterization, inline unit injector

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Authors: Steven Latré, Frederik Desplentere, Ilya Straumit, Stepan V. Lomov

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A method is proposed in order to create a three-dimensional finite element model representing fibre reinforced insulation materials for the simulation software Siemens NX. VoxTex software, a tool for quantification of µCT images of fibrous materials, is used for the transformation of microtomography images of random fibre reinforced composites into finite element models. An automatic tool was developed to execute the import of the models to the thermal solver module of Siemens NX. The paper describes the numerical tools used for the image quantification and the transformation and illustrates them on several thermal simulations of fibre reinforced insulation blankets filled with low thermal conductive fillers. The calculation of thermal conductivity is validated by comparison with the experimental data.

Keywords: analysis, modelling, thermal, voxel

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Authors: Vitaly Haslavsky, Helena Vitoshkin

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The total energy saving effect of different types of greenhouse thermal/shade screens was determined by measuring and calculating the overall heat transfer coefficients (U-values) for single and several layers of screens. The measurements were carried out using the hot box method, and the calculations were performed according to the ISO Standard 15099. The goal was to examine different types of materials with a wide range of thermal radiation properties used for thermal screens in combination with a dehumidification system in order to improve greenhouse insulation. The experimental results were in good agreement with the calculated heat transfer coefficients. It was shown that a high amount of infra-red (IR) radiation can be blocked by the greenhouse covering material in combination with moveable thermal screens. The aluminum foil screen could be replaced by transparent screens, depending on shading requirements. The results indicated that using a single layer, the U-value was reduced by approximately 70% compared to covering material alone, while the contributions of additional screen layers containing aluminum foil strips could reduce the U-value by approximately 90%. It was shown that three screen layers are sufficient for effective insulation.

Keywords: greenhouse insulation, heat loss, thermal screens, U-value

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Authors: Lakrim Abderrazak, Tahri Driss

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This paper presents a new behavioural electrothermal model of power Silicon Carbide (SiC) MOSFET under SPICE. This model is based on the MOS model level 1 of SPICE, in which phenomena such as Drain Leakage Current IDSS, On-State Resistance RDSon, gate Threshold voltage VGSth, the transconductance (gfs), I-V Characteristics Body diode, temperature-dependent and self-heating are included and represented using behavioural blocks ABM (Analog Behavioural Models) of Spice library. This ultimately makes this model flexible and easily can be integrated into the various Spice -based simulation softwares. The internal junction temperature of the component is calculated on the basis of the thermal model through the electric power dissipated inside and its thermal impedance in the form of the localized Foster canonical network. The model parameters are extracted from manufacturers' data (curves data sheets) using polynomial interpolation with the method of simulated annealing (S A) and weighted least squares (WLS). This model takes into account the various important phenomena within transistor. The effectiveness of the presented model has been verified by Spice simulation results and as well as by data measurement for SiC MOS transistor C2M0025120D CREE (1200V, 90A).

Keywords: SiC power MOSFET, DC electro-thermal model, ABM Spice library, SPICE modelling, behavioural model, C2M0025120D CREE.

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Authors: P. Hashim, M. S. Mohd Ridzwan, J. Bakar

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Collagen was isolated from chicken feet by using papain and pepsin enzymes in acetic acid solution at 4°C for 24h with a yield of 18.16% and 22.94% by dry weight, respectively. Chemical composition and characteristics of chicken feet collagen such as amino acid composition, SDS-PAGE patterns, FTIR spectra and thermal properties were evaluated. The chicken feet collagen is rich in the amino acids glycine, glutamic acid, proline and hydroxyproline. Electrophoresis pattern demonstrated two distinct α-chains (α1 and α2) and β chain, indicating that type I collagen is a major component of chicken feet collagen. The thermal stability of collagen isolated by papain and pepsin revealed stable denaturation temperatures of 48.40 and 53.35°C, respectively. The FTIR spectra of both collagens were similar with amide regions in A, B, I, II, and III. The study demonstrated that chicken feet collagen using papain isolation method is possible as commercial alternative ingredient.

Keywords: chicken feet, collagen, papain, pepsin

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Authors: Kanit Manatura

Abstract:

The combustion and pyrolysis behavior of Palm Kernel Shell (PKS) were investigated in a thermogravimetric analyzer. A 10 mg sample of each biomass was heated from 30 °C to 800 °C at four heating rates (within 5, 10, 15 and 30 °C/min) in nitrogen and dry air flow of 20 ml/min instead of pyrolysis and combustion process respectively. During pyrolysis, thermal decomposition occurred on three different stages include dehydration, hemicellulose-cellulose and lignin decomposition on each temperature range. The TG/DTG curves showed the degradation behavior and the pyrolysis/combustion characteristics of the PKS samples which led to apply in thermogravimetric analysis. The kinetic factors including activation energy and pre-exponential factor were determined by the Coats-Redfern method. The obtained kinetic factors are used to simulate the thermal decomposition and compare with experimental data. Rising heating rate leads to shift the mass loss towards higher temperature.

Keywords: combustion, palm kernel shell, pyrolysis, thermogravimetric analyzer

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Authors: Emre Basturk, Memet Vezir Kahraman

Abstract:

In many developing countries, with the rapid economic improvements, energy shortage and environmental issues have become a serious problem. Therefore, it has become a very critical issue to improve energy usage efficiency and also protect the environment. Thermal energy storage system is an essential approach to match the thermal energy claim and supply. Thermal energy can be stored by heating, cooling or melting a material with the energy and then enhancing accessible when the procedure is reversed. The overall thermal energy storage techniques are sorted as; latent heat or sensible heat thermal energy storage technology segments. Among these methods, latent heat storage is the most effective method of collecting thermal energy. Latent heat thermal energy storage depend on the storage material, emitting or discharging heat as it undergoes a solid to liquid, solid to solid or liquid to gas phase change or vice versa. Phase change materials (PCMs) are promising materials for latent heat storage applications due to their capacities to accumulate high latent heat storage per unit volume by phase change at an almost constant temperature. Phase change materials (PCMs) are being utilized to absorb, collect and discharge thermal energy during the cycle of melting and freezing, converting from one phase to another. Phase Change Materials (PCMs) can generally be arranged into three classes: organic materials, salt hydrates and eutectics. Many kinds of organic and inorganic PCMs and their blends have been examined as latent heat storage materials. Organic PCMs are rather expensive and they have average latent heat storage per unit volume and also have low density. Most organic PCMs are combustible in nature and also have a wide range of melting point. Organic PCMs can be categorized into two major categories: non-paraffinic and paraffin materials. Paraffin materials have been extensively used, due to their high latent heat and right thermal characteristics, such as minimal super cooling, varying phase change temperature, low vapor pressure while melting, good chemical and thermal stability, and self-nucleating behavior. Ultraviolet (UV)-curing technology has been generally used because it has many advantages, such as low energy consumption , high speed, high chemical stability, room-temperature operation, low processing costs and environmental friendly. For many years, PCMs have been used for heating and cooling industrial applications including textiles, refrigerators, construction, transportation packaging for temperature-sensitive products, a few solar energy based systems, biomedical and electronic materials. In this study, UV-curable, fatty alcohol containing soybean oil based phase change materials (PCMs) were obtained and characterized. The phase transition behaviors and thermal stability of the prepared UV-cured biobased PCMs were analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The heating process phase change enthalpy is measured between 30 and 68 J/g, and the freezing process phase change enthalpy is found between 18 and 70 J/g. The decomposition of UVcured PCMs started at 260 ºC and reached a maximum of 430 ºC.

Keywords: fatty alcohol, phase change material, thermal energy storage, UV curing

Procedia PDF Downloads 353

Authors: M. S. Baazzim, M. S. Al-Saud, M. A. El-Kady

Abstract:

In this paper, steady-state ampacity (current carrying capacity) evaluation of underground power cable system by using analytical and numerical methods for different conditions (depth of cable, spacing between phases, soil thermal resistivity, ambient temperature, wind speed), for two system voltage level were used 132 and 380 kV. The analytical method or traditional method that was used is based on the thermal analysis method developed by Neher-McGrath and further enhanced by International Electrotechnical Commission (IEC) and published in standard IEC 60287. The numerical method that was used is finite element method and it was recourse commercial software based on finite element method.

Keywords: cable ampacity, finite element method, underground cable, thermal rating

Procedia PDF Downloads 353

Authors: Mokhtar Bouazza

Abstract:

In this paper, the simplified theory will be used to predict the thermoelastic buckling behavior of rectangular functionally graded plates. The material properties of the functionally graded plates are assumed to vary continuously through the thickness, according to a simple power law distribution of the volume fraction of the constituents. The simplified theory is used to obtain the buckling of the plate under different types of thermal loads. The thermal loads are assumed to be uniform, linear, and non-linear distribution through the thickness. Additional numerical results are presented for FGM plates that show the effects of various parameters on thermal buckling response.

Keywords: buckling, functionally graded, plate, simplified higher-order deformation theory, thermal loading

Procedia PDF Downloads 359