Search results for: durability of chemical heat storage material

Authors: A. Jamal, M. A. I. El-Shaarawi, E. M. A. Mokheimer

Abstract:

Combined conduction-free convection heat transfer in vertical eccentric annuli is numerically investigated using a finitedifference technique. Numerical results, representing the heat transfer parameters such as annulus walls temperature, heat flux, and heat absorbed in the developing region of the annulus, are presented for a Newtonian fluid of Prandtl number 0.7, fluid-annulus radius ratio 0.5, solid-fluid thermal conductivity ratio 10, inner and outer wall dimensionless thicknesses 0.1 and 0.2, respectively, and dimensionless eccentricities 0.1, 0.3, 0.5, and 0.7. The annulus walls are subjected to thermal boundary conditions, which are obtained by heating one wall isothermally whereas keeping the other wall at inlet fluid temperature. In the present paper, the annulus heights required to achieve thermal full development for prescribed eccentricities are obtained. Furthermore, the variation in the height of thermal full development as function of the geometrical parameter, i.e., eccentricity is also investigated.

Keywords: Conjugate natural convection, eccentricity, heat transfer, vertical eccentric annuli.

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Authors: Hanan Rizk

Abstract:

Heat exchanger is a device used to mix liquids having different temperatures. In this case, the temperature control becomes a critical objective. This research work presents the temperature control of the double-pipe heat exchanger (multi-input multi-output (MIMO) system), which is modeled as first-order coupled hyperbolic partial differential equations (PDEs), using conventional and advanced control techniques, and develops appropriate robust control strategy to meet stability requirements and performance objectives. We designed the proportional–integral–derivative (PID) controller and H-infinity controller for a heat exchanger (HE) system. Frequency characteristics of sensitivity functions and open-loop and closed-loop time responses are simulated using MATLAB software and the stability of the system is analyzed using Kalman's test. The simulation results have demonstrated that the H-infinity controller is more efficient than PID in terms of robustness and performance.

Keywords: heat exchanger, multi-input multi-output system, MATLAB simulation, partial differential equations, PID controller, robust control

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Authors: Shigenori Togashi, Mitsuhiro Matsuzawa

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A pilot plant for continuous flow microwave-assisted chemical reaction combined with microreactors was developed and water heating tests were conducted for evaluation of the developed plant. We developed a microwave apparatus having a single microwave generator that can heat reaction solutions in four reaction fields simultaneously in order to increase throughput. We also designed a four-branch waveguide using electromagnetic simulation, and found that the transmission efficiency at 99%. Finally, we developed the pilot plant using the developed microwave apparatus and conducted water heating tests. The temperatures in the respective reaction fields were controlled within ±1.1 K at 353.2 K. Moreover, the energy absorption rates by the water were about 90% in the respective reaction fields, whereas the energy absorption rate was about 40% when 100 cm3 of water was heated by a commercially available multimode microwave chemical reactor.

Keywords: Microwave, Microreactor, Heating, Electromagnetic Simulation

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Authors: Zhang Lei, Liu Gaotong

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The atomization effect is an important factor of the heat transfer of liquid nitrogen spray. In this paper, two kinds of internal-mixing twin-fluid atomizers were design. According to the fracture theory and fluid mechanics, the model is established to simulate atomization effect. The results showed that: Internal-mixing atomizers, with the liquid nitrogen atomization size from 20um to 40um, have superior performance. Y-jet atomizer spray speed is greater than Multi-jet atomizer, and it can improve the efficiency of heat transfer between the liquid nitrogen and its spray object. Multi-jet atomizer atomization cone angle is about 30°, Y-jet atomizer atomization cone angle is about 20°. During atomizer selection, the size of the heat transfer area should be considered.

Keywords: Atomization, two-phase flow, atomizer, heat transfer.

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Authors: Joan Goh, Ahmad Abd. Majid, Ahmad Izani Md. Ismail

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In this paper, collocation based cubic B-spline and extended cubic uniform B-spline method are considered for solving one-dimensional heat equation with a nonlocal initial condition. Finite difference and θ-weighted scheme is used for time and space discretization respectively. The stability of the method is analyzed by the Von Neumann method. Accuracy of the methods is illustrated with an example. The numerical results are obtained and compared with the analytical solutions.

Keywords: Heat equation, Collocation based, Cubic Bspline, Extended cubic uniform B-spline.

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Authors: K. Kalaiselvan, A. Elango, N. M. Nagarajan

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Laser beam welding for the dissimilar Titanium and Aluminium thin sheets is an emerging area which is having wider applications in aerospace, aircraft, automotive, electronics and in other industries due to its high speed, non-contact, precision with low heat effects, least welding distortion, low labor costs and convenient operation. Laser beam welding of dissimilar metal combinations are increasingly demanded due to high energy densities with small fusion and heat affected zones. Furthermore, no filler or electrode material is required and contamination of weld is also very small. The present study is to reviews the influence of different parameters like laser power, welding speed, power density, beam diameter, focusing distance and type of shielding gas on the mechanical properties of dissimilar metal combinations like SS/Al, Cu/Al and Ti/Al focusing on aluminum to other materials. Research findings reveal that Ti/Al combination gives better metallurgical and mechanical properties than other combinations such as SS/Al and Cu/Al.

Keywords: Laser Beam Welding, dissimilar metals, SS/Al, Cu/Al and Ti/Al sheets.

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Authors: Alena Sicakova

Abstract:

Air-cooled Blast Furnace Slag Aggregate (BFSA) is usually referred to as a material providing for unique properties of concrete. On the other hand, negative influences are also presented in many aspects. The freeze-thaw resistance of concrete is dependent on many factors, including regional specifics and when a concrete mix is specified it is still difficult to tell its exact freeze-thaw resistance due to the different components affecting it. An important consideration in working with BFSA is the granularity and whether slag is sorted or not. The experimental part of the article represents a comparative testing of concrete using both the sorted and unsorted BFSA through the freeze-thaw resistance as an indicator of durability. Unsorted BFSA is able to be successfully used for concretes as they are specified for exposure class XF4 with providing that the type of cement is precisely selected.

Keywords: Blast furnace slag aggregate, concrete, freeze-thaw resistance.

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Authors: Usman Mahmood, Khawaja M. U. Suleman

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A peer-to-peer storage system has challenges like; peer availability, data protection, churn rate. To address these challenges different redundancy, replacement and repair schemes are used. This paper presents a hybrid scheme of redundancy using replication and erasure coding. We calculate and compare the storage, access, and maintenance costs of our proposed scheme with existing redundancy schemes. For realistic behaviour of peers a trace of live peer-to-peer system is used. The effect of different replication, and repair schemes are also shown. The proposed hybrid scheme performs better than existing double coding hybrid scheme in all metrics and have an improved maintenance cost than hierarchical codes.

Keywords: Erasure Coding, P2P, Redundancy, Replication.

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Authors: Shaival H. Nagarsheth, Utpal Pandya, Hemant J. Nagarsheth

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Cross flow water tube heat exchanger can be designed and made operational using methods of model building and simulation of the system. This paper projects the design and development of a model of cross flow water tube heat-exchanger system, simulation and validation of control analysis of different tuning methods. Feedback and override control system is developed using inputs acquired with the help of sensory system. A mathematical model is formulated for analysis of system behaviour. The temperature is regulated at the desired set point automatically.

Keywords: Heat Exchanger, Feedback, Override, Temperature, PID.

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Authors: Phool Singh, Ashok Jangid, N.S. Tomer, Deepa Sinha

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The aim of this paper is to study the oblique stagnation point flow on vertical plate with uniform surface heat flux in presence of magnetic field. Using Stream function, partial differential equations corresponding to the momentum and energy equations are converted into non-linear ordinary differential equations. Numerical solutions of these equations are obtained using Runge-Kutta Fehlberg method with the help of shooting technique. In the present work the effects of striking angle, magnetic field parameter, Grashoff number, the Prandtl number on velocity and heat transfer characteristics have been discussed. Effect of above mentioned parameter on the position of stagnation point are also studied.

Keywords: Heat flux, Oblique stagnation point, Mixedconvection, Magneto hydrodynamics

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Authors: Aminat. O Adelekan, Olawale T. Gbadebo

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Biscuit is one of the most consumed cereal foods in Nigeria and research has shown that locally available tropical crops like cassava, sweet potato can be made into flour and used in the production of biscuits and other pastries. This study investigates some quality parameters in biscuits made from blends of wheat, cassava and carrot flour. The values of result of samples increased with increasing percentage substitution of cassava and carrot flour in some quality parameter like fiber, ash, gluten content, and carbohydrate. The protein content reduced significantly (P < 0.05) with increasing percentage substitution of cassava and carrot flour which ranged from 14.80% to 11.80% compared with the control sample which had 15.60%. There was a recorded significant increase (P < 0.05) in some mineral composition such as calcium, magnesium, sodium, iron, phosphorus, and vitamin A and C composition as the percentage substitution of cassava and carrot flour increased. During storage stability test, samples stored in the fridge and freezer were found to be the best storage location to preserve the sensory attributes and inhibit microbial growth when compared with storage under the sun and on the shelf. Biscuit made with blends of wheat, cassava and carrot flour can therefore serve as an alternative to biscuits made from 100% wheat flour, as they are richer in vitamin A, vitamin C, carbohydrate, dietary fiber and some essential minerals.

Keywords: Biscuit, carrot, flour blends, storage.

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Authors: Muzna Tariq, Ihtzaz Qamar

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In most engineering cases, the working temperatures inside a combustion chamber are high enough that they lie beyond the operational range of thermocouples. Furthermore, design and manufacturing limitations restrict the use of internal thermocouples in many applications. Heat transfer inside a combustion chamber is caused due to interaction of the post-combustion hot fluid with the chamber wall. Heat transfer that involves an interaction between the fluid and solid is categorized as Conjugate Heat Transfer (CHT). Therefore, to satisfy the needs of CHT, CHT Analysis is performed by using ANSYS CFD tool to estimate theoretically precise thermocouple positions at the combustion chamber wall where excessive temperatures (beyond thermocouple range) can be avoided. In accordance with these Computational Fluid Dynamics (CFD) results, a combustion chamber is designed, and a prototype is manufactured with multiple thermocouple ports positioned at the specified distances so that the temperature of hot gases can be measured on the chamber wall where the temperatures do not exceed the thermocouple working range.

Keywords: Computational Fluid Dynamics, CFD, conduction, conjugate heat transfer, CHT, convection, fluid flow, thermocouples.

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Authors: Mohammad Asif

Abstract:

Heterogeneous catalysis is vital for a number of chemical, refinery and pollution control processes. The use of catalyst pellets of hollow cylindrical shape provide several distinct advantages over other common shapes, and can therefore help to enhance conversion levels in reactors. A better utilization of the catalytic material is probably most notable of these features due to the absence of the pellet core, which helps to significantly lower the effect of the internal transport resistance. This is reflected in the enhancement of the effectiveness factor. For the case of the first order irreversible kinetics, a substantial increase in the effectiveness factor can be obtained by varying shape parameters. Important shape parameters of a finite hollow cylinder are the ratio of the inside to the outside radii (κ) and the height to the diameter ratio (γ). A high value of κ the generally helps to enhance the effectiveness factor. On the other hand, lower values of the effectiveness factors are obtained when the dimension of the height and the diameter are comparable. Thus, the departure of parameter γ from the unity favors higher effectiveness factor. Since a higher effectiveness factor is a measure of a greater utilization of the catalytic material, higher conversion levels can be achieved using the hollow cylindrical pellets possessing optimized shape parameters.

Keywords: Finite hollow cylinder, Catalyst pellet, Effectiveness factor, Thiele Modulus, Conversion

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Authors: M. A. Elbagermia, A. I. Alajtala, M. Alkerzab

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This study compares the quality of different brands of Portland Cement (PC) available in Libyan market. The amounts of chemical constituents like SiO2, Al2O3, Fe2O3, CaO, MgO, SO3 and Lime Saturation Factor (LSF) were determined in accordance with Libyan (L.S.S) and Amrican (A.S.S) Standard Specifications. All the cement studies were found to be good for concrete work especially where no special property is required. The chemical and mineralogical analyses for studied clinker samples show that the dominant phases composition are C3S and C2S while the C3A and C4AF are less abundant.

Keywords: Portland cement, Chemical Composition, Libyan market, X-ray fluorescence.

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Authors: A. A. M. Azoddein, Y. Nuratri, A. B. Bustary, F. A. M. Azli, S. C. Sayuti

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Pseudomonas putida is a potential strain in biological treatment to remove mercury contained in the effluent of petrochemical industry due to its mercury reductase enzyme that able to reduce ionic mercury to elementary mercury. Freeze-dried P. putida allows easy, inexpensive shipping, handling and high stability of the product. This study was aimed to freeze dry P. putida cells with addition of lyoprotectant. Lyoprotectant was added into the cells suspension prior to freezing. Dried P. putida obtained was then mixed with synthetic mercury. Viability of recovery P. putida after freeze dry was significantly influenced by the type of lyoprotectant. Among the lyoprotectants, tween 80/ sucrose was found to be the best lyoprotectant. Sucrose able to recover more than 78% (6.2E+09 CFU/ml) of the original cells (7.90E+09CFU/ml) after freeze dry and able to retain 5.40E+05 viable cells after 4 weeks storage in 4oC without vacuum. Polyethylene glycol (PEG) pre-treated freeze dry cells and broth pre-treated freeze dry cells after freeze-dry recovered more than 64% (5.0 E+09CFU/ml) and >0.1% (5.60E+07CFU/ml). Freeze-dried P. putida cells in PEG and broth cannot survive after 4 weeks storage. Freeze dry also does not really change the pattern of growth P. putida but extension of lag time was found 1 hour after 3 weeks of storage. Additional time was required for freeze-dried P. putida cells to recover before introduce freeze-dried cells to more complicated condition such as mercury solution. The maximum mercury reduction of PEG pre-treated freeze-dried cells after freeze dry and after storage 3 weeks was 56.78% and 17.91%. The maximum of mercury reduction of tween 80/sucrose pre-treated freeze-dried cells after freeze dry and after storage 3 weeks were 26.35% and 25.03%. Freeze dried P. putida was found to have lower mercury reduction compare to the fresh P. putida that has been growth in agar. Result from this study may be beneficial and useful as initial reference before commercialize freeze-dried P. putida.

Keywords: Pseudomonas putida, freeze-dry, PEG, Tween80/Sucrose, mercury, cell viability.

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Authors: Iuliia Zarubiieva, Joyun Tseng, Vishwesh Kulkarni

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Recent researches has focused on nucleic acids as a substrate for designing biomolecular circuits for in situ monitoring and control. A common approach is to express them by a set of idealised abstract chemical reaction networks (ACRNs). Here, we present new results on how abstract chemical reactions, viz., catalysis, annihilation and degradation, can be used to implement circuit that accurately computes logarithm function using the method of Arithmetic-Geometric Mean (AGM), which has not been previously used in conjunction with ACRNs.

Keywords: Abstract chemical reaction network, DNA strand displacement, natural logarithm.

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Authors: Igor Nedelkovski, Ilios Vilos, Tale Geramitcioski

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Computational simulation of steam flow and heat transfer in power plant condensers on the basis of the threedimensional mathematical model for the flow through porous media is presented. In order to solve the mathematical model of steam flow and heat transfer in power plant condensers, the Streamline Upwind Petrov-Galerkin finite element method is applied. By comparison of the results of simulation with experimental results about an experimental condenser, it is confirmed that SUPG finite element method can be successfully applied for solving the three-dimensional mathematical model of steam flow and heat transfer in power plant condensers.

Keywords: Navier-Stokes, FEM, condensers, steam.

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Authors: E. Çetin, A. Kurşun, Ş. Aksoy, M. Tunay Çetin

Abstract:

The closed form study deals with elastic stress analysis of annular bi-material discs with variable thickness subjected to the mechanical and thermomechanical loads. Those discs have many applications in the aerospace industry, such as gas turbines and gears. Those discs normally work under thermal and mechanical loads. Their life cycle can increase when stress components are minimized. Each material property is assumed to be isotropic. The results show that material combinations and thickness of profiles play an important role in determining the responses of bi-material discs and an optimal design of those structures. Stress distribution is investigated and results are shown as graphs.

Keywords: Bi-material discs, elastic stress analysis, mechanical loads, rotating discs.

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Authors: S. Padma, Dr. R. Lakshmipathi, K. Ramash Kumar, P. Nandagopal

Abstract:

The power system network is becoming more complex nowadays and it is very difficult to maintain the stability of the system. Today-s enhancement of technology makes it possible to include new energy storage devices in the electric power system. In addition, with the aid of power electronic devices, it is possible to independently exchange active and reactive power flow with the utility grid. The main purpose of this paper proposes a Proportional – Integral (PI) control based 48 – pulse Inverter based Static Synchronous Series Compensator (SSSC) with and without Superconducting Magnetic Energy Storage (SMES) used for enhancing the transient stability and regulating power flow in automatic mode. Using a test power system through the dynamic simulation in Matlab/Simulink platform validates the performance of the proposed SSSC with and without SMES system.

Keywords: Flexible AC transmission system (FACTS), PIControl, Superconducting Magnetic Energy Storage (SMES), Static Synchronous Series Compensator (SSSC).

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Authors: D. K. Tiwari, Mukesh Kumar Awasthi, G. S. Agrawal

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The effect of an axial electric field on the capillary instability of a cylindrical interface in the presence of heat and mass transfer has been investigated using viscous potential flow theory. In viscous potential flow, the viscous term in Navier-Stokes equation vanishes as vorticity is zero but viscosity is not zero. Viscosity enters through normal stress balance in the viscous potential flow theory and tangential stresses are not considered. A dispersion relation that accounts for the growth of axisymmetric waves is derived and stability is discussed theoretically as well as numerically. Stability criterion is given by critical value of applied electric field as well as critical wave number. Various graphs have been drawn to show the effect of various physical parameters such as electric field, heat transfer capillary number, conductivity ratio, permittivity ratio on the stability of the system. It has been observed that the axial electric field and heat and mass transfer both have stabilizing effect on the stability of the system.

Keywords: Capillary instability, Viscous potential flow, Heat and mass transfer, Axial electric field.

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Authors: Amin Eisazadeh, Khairul Anuar Kassim, Hadi Nur

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The expansive nature of soils containing high amounts of clay minerals can be altered through chemical stabilization, resulting in a material suitable for construction purposes. The primary objective of this investigation was to study the changes induced in the molecular structure of phosphoric acid stabilized bentonite and lateritic soil using Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) spectroscopy. Based on the obtained data, it was found that a surface alteration mechanism was the main reason responsible for the improvement of treated soils. Furthermore, the results indicated that the Al present in the octahedral layer of clay minerals were more amenable to chemical attacks and also partly responsible for the formation of new products.

Keywords: Bentonite, Laterite clay, Molecularcharacterization, Phosphoric acid, Stabilization

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Authors: Seungyeong Choi, Namkyu Lee, Dong Il Shim, Young Mun Lee, Yong-Ki Park, Hyung Hee Cho

Abstract:

Effect of the cross-sectional geometry on heat transfer and particle motion of circulating fluidized bed riser for CO₂ capture was investigated. Numerical simulation using Eulerian-eulerian method with kinetic theory of granular flow was adopted to analyze gas-solid flow consisting in circulating fluidized bed riser. Circular, square, and rectangular cross-sectional geometry cases of the same area were carried out. Rectangular cross-sectional geometries were analyzed having aspect ratios of 1: 2, 1: 4, 1: 8, and 1:16. The cross-sectional geometry significantly influenced the particle motion and heat transfer. The downward flow pattern of solid particles near the wall was changed. The gas-solid mixing degree of the riser with the rectangular cross section of the high aspect ratio was the lowest. There were differences in bed-to-wall heat transfer coefficient according to rectangular geometry with different aspect ratios.

Keywords: Bed geometry, computational fluid dynamics, circulating fluidized bed riser, heat transfer.

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Authors: A. Giraldo, A. Lapatka, A. Namyslak, S. Pilny, J. B. Miima

Abstract:

This paper explains how the New Jersey Institute of Technology surveying student team members designed and created an interactive GIS map, the purpose of which is to be useful to the land surveyor and engineer for project management. This was achieved by building a research and storage database that can be easily integrated into any land surveyor’s current operations through the use of ArcGIS 10, Arc Catalog, and AutoCAD. This GIS database allows for visual representation and information querying for multiple job sites, and simple access to uploaded data, which is geospatially referenced to each individual job site or project. It can also be utilized by engineers to determine design criteria, or to store important files. This cost-effective approach to a surveying map not only saves time, but saves physical storage space and paper resources.

Keywords: Data Storage, GIS, Land Surveying, Mapping.

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Authors: A. Buruzs, A. Torma

Abstract:

The relationship of the automotive industry with raw material supply is a major challenge and presents obstacles. Automobiles are ones of the most complex products using a large variety of materials. Safety, eco-friendliness and comfort requirements, physical, chemical and economic limitations set the framework in which this industry continuously optimizes the efficient and responsible use of resources. The concept of circular economy covers the issues of waste generation, resource scarcity and economic advantages. However, circularity is already known for the automobile industry – several efforts are done to foster material reuse, product remanufacturing and recycling. The aim of this study is to give an overview on how the producers comply with the growing demands on one hand, and gain efficiency and increase profitability on the other hand from circular economy.

Keywords: Automotive industry, circular economy, international requirements, natural resources.

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Authors: Abdulbasit G. A. Abdulsayid

Abstract:

The main focus of the work was concerned with hydrodynamic and thermal analysis of the plate heat exchanger channel with corrugation patterns suggested to be triangular, sinusoidal, and square corrugation. This study was to numerically model and validate the triangular corrugated channel with dimensions/parameters taken from open literature, and then model/analyze both sinusoidal, and square corrugated channel referred to the triangular model. Initially, 2D modeling with local extensive analysis for triangular corrugated channel was carried out. By that, all local pressure drop, wall shear stress, friction factor, static temperature, heat flux, Nusselt number, and surface heat coefficient, were analyzed to interpret the hydrodynamic and thermal phenomena occurred in the flow. Furthermore, in order to facilitate confidence in this model, a comparison between the values predicted, and experimental results taken from literature for almost the same case, was done. Moreover, a holistic numerical study for sinusoidal and square channels together with global comparisons with triangular corrugation under the same condition, were handled. Later, a comparison between electric, and fluid cooling through varying the boundary condition was achieved. The constant wall temperature and constant wall heat flux boundary conditions were employed, and the different resulted Nusselt numbers as a consequence were justified. The results obtained can be used to come up with an optimal design, a 'compromise' between heat transfer and pressure drop.

Keywords: Corrugated Channel, CFD, Heat Exchanger, Heat Enhancement.

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Authors: Sam Rasoulzadeh, Atefeh Mousavi

Abstract:

Fluidized bed reactors are known as highly exothermic and endothermic according to uniformity in temperature as a safe and effective mean for catalytic reactors. In these reactors, a wide range of catalyst particles can be used and by using a continuous operation proceed to produce in succession. Providing optimal conditions for the operation of these types of reactors will prevent the exorbitant costs necessary to carry out laboratory work. In this regard, a hydrodynamic analysis was carried out with heat transfer in the solid-gas fluidized bed reactor for solar thermal applications. The results showed that in the fluid flow the input of the reactor has a lower temperature than the outlet, and when the fluid is passing from the reactor, the heat transfer happens between cylinder and solar panel and fluid. It increases the fluid temperature in the outlet pump and also the kinetic energy of the fluid has been raised in the outlet areas.

Keywords: Heat transfer, solar reactor, fluidized bed reactor, CFD.

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Authors: Sameena Tarannum, S. Pranesh

Abstract:

A nonlinear study of triple diffusive convection in a rotating couple stress liquid has been analysed. It is performed to study the effect of heat and mass transfer by deriving Ginzburg-Landau equation. Heat and mass transfer are quantified in terms of Nusselt number and Sherwood numbers, which are obtained as a function of thermal and solute Rayleigh numbers. The obtained Ginzburg-Landau equation is Bernoulli equation, and it has been elucidated numerically by using Mathematica. The effects of couple stress parameter, solute Rayleigh numbers, and Taylor number on the onset of convection and heat and mass transfer have been examined. It is found that the effects of couple stress parameter and Taylor number are to stabilize the system and to increase the heat and mass transfer.

Keywords: Couple stress liquid, Ginzburg-Landau model, rotation, triple diffusive convection.

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Authors: E. T. L. Cöuras Ford, V. A. C. Vale, J. U. L. Mendes, R. M. Nascimento

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The great majority of the applications of thermal isolation in the strip of drops and averages temperatures (up to 200ºC), it is made of materials aggressive nature, such an as glass wool, rock wool, polystyrene, EPS among others. Such materials, in spite of the effectiveness in the retention of the flow of heat, possess considerable cost and when discarded they are long years to be to decompose. In that context, trying to adapt the world politics the about of the preservation of the environment, a study began with intention of developing a material composite, with properties of thermal, originating from insulating industrial residues. In this research, the behavior of the composite was analyzed, as submitted the fire. For this, the reaction rehearsals were accomplished to the fire for the composites 2:1; 1:1; 1:2 and for the Latex, based in the "con" experiment in agreement with the norm ASTM - E 1334 - 90. As consequence, in function of the answers of the system was possible to be observed to the acting of each mixture proportion.

Keywords: Composite, Latex, Reaction to the fire.

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Authors: Esam M. Alawadhi, Raed I. Bourisli

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Periodic vortex shedding in pulsating flow inside wavy channel and the effect it has on heat transfer are studied using the finite volume method. A sinusoidally-varying component is superimposed on a uniform flow inside a sinusoidal wavy channel and the effects on the Nusselt number is analyzed. It was found that a unique optimum value of the pulsation frequency, represented by the Strouhal number, exists for Reynolds numbers ranging from 125 to 1000. Results suggest that the gain in heat transfer is related to the process of vortex formation, movement about the troughs of the wavy channel, and subsequent ejection/destruction through the converging section. Heat transfer is the highest when the frequencies of the pulsation and vortex formation approach being in-phase. Analysis of Strouhal number effect on Nu over a period of pulsation substantiates the proposed physical mechanism for enhancement. The effect of changing the amplitude of pulsation is also presented over a period of pulsation, showing a monotonic increase in heat transfer with increasing amplitude. The 60% increase in Nusselt number suggests that sinusoidal fluid pulsation can an effective method for enhancing heat transfer in laminar, wavy-channel flows.

Keywords: Vortex shedding, pulsating flow, wavy channel, CFD.

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Authors: Saktioto, F.D Ismail, P.P. Yupapin, J. Ali

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The equilibrium process of plasma nitrogen species by chemical kinetic reactions along various pressures is successfully investigated. The equilibrium process is required in industrial application to obtain the stable condition when heating up the material for having homogenous reaction. Nitrogen species densities is modeled by a continuity equation and extended Arrhenius form. These equations are used to integrate the change of density over the time. The integration is to acquire density and the reaction rate of each reaction where temperature and time dependence are imposed. A comparison is made with global model within pressure range of 1- 100mTorr and the temperature of electron is set to be higher than other nitrogen species. The results shows that the chemical kinetic model only agrees for high pressure because of no power imposed; while the global model considers the external power along the pressure range then the electron and nitrogen species give highly quantity densities by factor of 3 to 5.

Keywords: chemical kinetic model, Arrhenius equation, nitrogen plasma, low pressure discharge

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