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In this paper are presented desing, testing and numerical analysis for two manufactured control valve trims. Valve trim is consisted of cage or dick stack, plug, stem and seat. Size from app. 15.88 mm (0.625 in) up to 101.6 mm (4 in) is suitable for 3-D metal and plastic print, what is presented in this paper. Selective laser melting 3-D metal printing is applied on the disc presented in this paper. Even better material properties from rest of the valve parts could be obtained. This is of great importance for valve retrofitting. In this paper is presented, also, new developed channel geometry, what is followed by various fluid-flow phenomena. Measurement results for second prototype manufactured by 3-D printing using plastics are presented in details. Here is shown, in short, procedure for determination of KV values of the test valves according to the EN 60534-2-3, Industrial-process control valves - Part 2-3: Flow capacity - Test procedures. In addition, some aspects of CFD calculations are presented. [ABSTRACT FROM AUTHOR]

The current flat-plate solar collectors perform best when their absorbers rotate around their axis. However, with their concentrators, reflectors, and tracking mechanisms, they take up a lot of space and are thus commercially speaking, not the best solutions. This paper proposes a novel solar collector design which employs the (relative) rotation of absorbers, but strives to combine the benefits of fixed and (absolute) tracking solar systems, i.e. volume occupancy from the former and thermal performance from the latter. The findings of our numerical analysis show that, the solar irradiance efficiency of this novel design is 20% higher than that of a fixed flat-plate collector during clear-sky days, and it is equally lower than that of an absolute tracking collector. This paper also introduces a new criterion for describing single-axis tracking solar collectors which should be included in the classifications of solar collectors. Finally, the article, which represents a continuation of our research in the field of solar energy utilization, can contribute to the future development of solar technologies and solve some of the current challenges. [ABSTRACT FROM AUTHOR]

Ultrasonic plastic welding is widely used in the bonding process of medical device accessories. In this paper, a thermo-force indirect coupling finite element analysis model was established in the ultrasonic plastic welding process between the blood cap and the shell of polypropylene (PP) dialyzer. The temperature field distribution between the blood cap and the shell was simulated and analyzed by using finite element analysis software, and the influence of welding process parameters on the temperature field was studied. The results show that: by changing the ultrasonic amplitude parameters, welding time parameters, initial pressure, etc., the longer the ultrasonic welding time, the temperature of the welding area will increase. In order to ensure the quality of the dialyzer, it should be controlled within 0.8-1 seconds. The increase of ultrasonic amplitude will make the welding temperature continue to rise, and in order to avoid poor welding, the amplitude should not exceed 120 μm. The initial pressure has little effect on the temperature field. [ABSTRACT FROM AUTHOR]

In order to study the heat dissipation characteristics of lithium batteries, a staggered bi-directional flow cooling method is designed and numerical simulations are established using CFD in this paper with a circular battery as the research object. Since the optimal operating range of Li-ion battery is 293.15-313.15 K and the maximum temperature difference is not higher than 5 K, the maximum temperature and maximum temperature difference are selected as the optimized design objectives. Firstly, the temperature field of the round lithium battery with discharge multiplier 3C working at ambient temperature 308.15 K is studied, and an orthogonal test design is carried out for three factors: battery pack embedding distance, coolant flow rate and coolant temperature, and the best combination of orthogonal test is selected by extreme difference analysis and analysis of variance. Secondly, in order to further verify the heat dissipation efficiency of the battery pack, a back propagation neural network with multi-objective optimization algorithm is proposed, and the optimal heat dissipation method of the numerical simulation is obtained by parameter solution and simulation analysis using the parameter range of the orthogonal test as the constraints of the multi-objective optimization. The results show that this optimized way of battery pack heat dissipation has a significant improvement for the maximum temperature, and non-e of them will exceed its working range; compared with the 3.39 K obtained from the orthogonal test design, the maximum temperature difference of the battery pack calculated by the multi-objective optimization is 3.15 K, which is reduced by 7.08%. [ABSTRACT FROM AUTHOR]

Wastewaters from power plants is a major concern for environmental protection. After the water is used in thermal power plant, the heated effluent is again discharged in the same water body from where it is taken. This not only disturbs the aquatic life but also affects the balance of the ecosystem. This paper presents the background of the thermal pollution, modelling approach and analysis methods for prediction of thermal pollution. A 2-D model of Sava River is discussed. The thermal power plant Nikola Tesla B was considered. Analysis of thermal discharge into the Sava River for the twelve-year period has been carried out. It was done a comparative analysis of the results obtained using mathematical (Electricity of France - EDF) method and numerical analysis using the CFD software package ANSYS FLUENT. A comparison of these two methods was made in order to show that it is possible to predict thermal pollution precisely and that it is possible to apply these methods in the design of industrial plants and not only in large thermal power plants. Finally, the results showed the matching of the obtained values at greater distances from the water outlet of the thermal power plant. [ABSTRACT FROM AUTHOR]

This paper presents two methods (theoretical and numerical) for the thermal analysis of the previously experimentally installed solar collector construction at the Faculty of Engineering in Kragujevac -- a fixed flat-plate solar collector with Sn-Al2O3 selective absorber and gravity water flow. The theoretical research was based on the application of a specific calculation algorithm with a triple iterative procedure, i.e. with a three-stage check of all important performance indicators of the fixed flat-plate solar collector. In the numerical phase of the research, simple linear regression was applied to experimentally measured values of solar radiation intensity and experimentally determine values of heat power to form simple equations that could be used to predict the thermal performance of similar solar structures in the future. The results of theoretical and numerical studies showed agreement with experimental studies, because in the first case, the absolute measurement error was less than 10%, while in the second case, the determination coefficient was greater than 90%, so the authors hope that this work will be useful to the wider scientific community. [ABSTRACT FROM AUTHOR]

Shell and tube heat exchangers have great thermal stress due to the different fluid temperature and instability of the flow field. In this paper, based on the fluid physical model of shell and tube heat exchanger, the velocity field, pressure field and temperature field inside the heat exchanger are simulated and analyzed on Workbench platform. The numerical simulation shows that the baffle plate has a great influence on the internal flow field of the heat exchanger. [ABSTRACT FROM AUTHOR]

The rural household biogas digesters are studied in this paper, and numerical analysis is used to simulate the effects of light climates in the cold season and the heat of sunlight on the temperature distribution in the pool. The numerical results show that the uneven distributions of light intensity and temperature in the biogas digester have a great influence on its cumulative gas production. The central area has a significant heat collection effect, the inner wall is weaker, and the temperature near the top is slightly higher than that in the lower area, and the vertical temperature changes in a decreasing trend. Aiming at the different photoclimatic conditions of the household biogas digester and the uneven heat collection and temperature distribution in different periods, the traditional slag pumping work is cumbersome, and the utilization rate of the biogas residue is low, so a new household with pretreatment is proposed. An intelligent temperature control system is designed for the biogas tank to analyze the adverse effects of straw fermentation at low temperature, insufficient gas production and low resource utilization. [ABSTRACT FROM AUTHOR]

This paper proposes a numerical approach based on the fractional complex transform and the homotopy perturbation method to solving the space-time fractional Benjamin-Bona-Mahony (mBBM) equation with Caputo fractional derivative. Approximated solutions with high accuracy are provided without linearization or complicated computation. Numerical examples are given to illustrate the efficiency of this method. [ABSTRACT FROM AUTHOR]

Cold regional tunnels have been encountering numerous frost damages as a result of dynamic changes in hydrothermal conditions of tunnel structural layers. The climate change is recognized as a major contributor for the problems. In this study, the hydrothermal conditions of a high speed railway tunnel are evaluated under different climate scenarios based on in-situ data and numerical analysis. Subsequently, the effect of different thicknesses of insulation board on hydrothermal conditions inside the tunnel is compared and the reasonable thickness is obtained. The main findings are: The temperature and unfrozen water content gradually decreased and the ice content gradually increased with the service time of the tunnel in the early 15 years; the maximum frozen depth occurs at the tunnel sidewall and it with a depth of 1.64 m within 30 years after the construction. The hydrothermal conditions inside the tunnel are significantly affected by annual mean air temperature (AMAT) and annual range of air temperature (ARAT); the maximum frozen depth decreases with AMAT, but increases with ARAT. After the XPS board with a thickness of 5 cm is laid in tunnel structural layers, the temperature at the most unfavorable position is 0.55 °C in the cold season, which suggests that frost damages disappeared and this method can be used to protect the tunnel against the frost damages. This paper can provide a basis for heat insulation design of the cold regional tunnels. [ABSTRACT FROM AUTHOR]

Serious accidents of gas explosion always result in massive casualties, however the propagation law of flame during gas explosion is not clear yet, though it is important for prevention and control of such accidents. This paper designs a piping gas explosion system for numerical revealing the propagation law, which is then verified experimentally. [ABSTRACT FROM AUTHOR]

An effective and robust thermal management system can control the temperature of lithium batteries and maintain the long service life and high performance of the module. In this work, the thermal design and optimization of cylindrical battery packs based on air-cooled thermal management strategies are studied. Lumped model is implemented to investigate the thermophysical characteristics of single cell, and the experimental measurements is used to determine the transient heat generation of cylindrical lithium batteries under different discharge rates. On this basis, the CFD method is used to analyze the temperature of the battery pack, and the heat dissipation performance of the air-cooled heat management system is explored. Finally, different air cooling strategies are investigated by changing the area and position of inlet and outlet to obtain the best cooling scheme. The results indicate that the multi-inlet and multi-outlet structure in this paper can significantly lower the temperature and improve the temperature uniformity in the battery pack. A better air-cooling performance can be obtained under the optimal parameter configuration, which will help the design of the air-cooled battery thermal management system. [ABSTRACT FROM AUTHOR]

The braking system is one of the most important elements in vehicle systems from the aspect of vehicle safety, besides the steering system and the internal combustion engine. During the braking process, the disc and pads absorb a large amount of kinetic energy that converted to heat. Owing to this frictional heating, it is necessary to compute the temperature distribution that will be appeared during the braking process, which is the main goal of this research paper. There are many factors that can be influenced to the distribution of frictional heat generated. One of the significant factors is the applied pressure by the brake pad on the braking disc. The results proved that when increased the applied pressure then the frictional heat generated increased too. It was developed a new finite element model based on observed data from real vehicle. It was used ANSYS/WORKBENCH 14.5 software to perform the numerical analysis, module Transient Structural. Parts that are the most disposed to the thermal stress are braking pads. Also, it was found time period from 0 to 0.1 second is the most critical period during the whole braking period, because in this period, temperature rises rapidly, the maximum temperature occurred at 1.338 seconds, and after that it falls. [ABSTRACT FROM AUTHOR]

Blade is one of the core components of turbine machinery. The reliability of blade is directly related to the normal operation of plant unit. However, with the increase of blade length and flow rate, non-linear effects such as finite deformation must be considered in strength computation to guarantee enough accuracy. Parallel computation is adopted to improve the efficiency of classical nonlinear finite element method and shorten the blade design period. So it is of extraordinary importance for engineering practice. In this paper, the dynamic partial differential equations and the finite element method forms for turbine blades under centrifugal load and flow load are given firstly. Then, according to the characteristics of turbine blade model, the classical method is optimized based on central processing unit + graphics processing unit heterogeneous parallel computation. Finally, the numerical experiment validations are performed. The computation speed of the algorithm proposed in this paper is compared with the speed of ANSYS. For the rectangle plate model with mesh number of 10 k to 4000 k, a maximum speed-up of 4.31 can be obtained. For the real blade-rim model with mesh number of 500 k, the speed-up of 4.54 times can be obtained. [ABSTRACT FROM AUTHOR]

Porous foam is an ideal material for enhancing radiative heat transfer in numerous thermal equipment. The solid skeletons of porous foams can absorb/release radiative energy and transfer convective energy with the surrounding fluid in the pores. In this paper, the conduction-convection-radiation coupling heat transfer in a porous cavity is investigated. A local thermal non-equilibrium model is used to represent the energy transport during the solid and fluid phases. The heat flux caused by thermal radiation is obtained by solving the radiation transfer equation. The thermal and fluid fields are studied to discern various parameters, including the Planck numbers, the modified Rayleigh numbers, and the interphase heat transfer coefficients, H. Our study indicates the following: the effect of radiation can be neglected when Pl > 20, the modified Rayleigh numbers have little influence on the solid temperature when the radiative heat transfer is dominant and the convective heat transfer between the two-phases is weak, and the local thermal-equilibrium can be formed when H exhibits high values. [ABSTRACT FROM AUTHOR]

A conventional axial turbine drived by a pulse detonation combustor heavily challenges the turbine cooling and hot gas sealing. In order to fully understand the physical behavior of ingress and egress effect with the pulse inlet mainstream, a study is carried out to investigate the unsteady flow field and sealing efficiency inside the cavity using the method of unsteady, 3-D CFD simulation. The pulse detonation inflow boundary condition simplified using simple exponential decay formulas are applied to the inlet of mainstream passage. The results reveal that the magnitude of sealing gas pressure does affect the pressure and sealing efficiency distribution inside cavity. The sealing efficiency inside the cavity goes through three sub-stages, respectively, "the decline stage", "the plateau stage", and "the recovery stage". when the sealing gas pressure increases, the sealing efficiency of these three sub-stages will increase, and the duration of "the plateau stage" and "the recovery stage" will decrease. As a result, the ability of turbine cavity that resist the ingress of pulse detonation inflow can be augmented with the sealing gas pressure increases. [ABSTRACT FROM AUTHOR]

In this paper we present a second order numerical scheme for the Cahn-Hilliard equation, with a Fourier pseudo-spectral approximation in space. An additional Douglas-Dupont regularization term is introduced, which ensures the energy stability. The bound of numerical solution inH²h and ℓ∞norms are obtained at a theoretical level. Moreover, for the global nature of the pseudo-spectral method, we propose a linear iteration algorithm to solve the non-linear system, due to the implicit treatment for the non-linear term. Some numerical simulations verify the efficiency of iteration algorithm. [ABSTRACT FROM AUTHOR]

In order to further improve the crack resistance of concrete engineering, a numerical simulation method is constructed to study the effect of temperature on the fission of concrete. Based on the finite element method, the mathematical model is constructed, and the numerical calculation and image display are used to simulate and analyze the engineering problems. The temperature sensor is used to observe the whole variation law of typical temperature field, and the temperature of concrete entering and pouring is obtained. Thus, the temperature control real-time automatic acquisition system is set up. According to the temperature field and temperature stress distribution rules, the ideal temperature control curve model of concrete is proposed. Finally, the numerical calculation and experiment of the model are carried out. The results show that the maximum surface stress level decreases in varying degrees after different surface insulation measures are taken, and if the thermal insulation material's β = 10 kJ/m²h °C, the maximum surface stress of concrete can be reduced to 0.06~0.14 MPa. In this paper, it is shown that the negative effect of the large diurnal temperature difference on concrete surface insulation can be controlled. [ABSTRACT FROM AUTHOR]

Accurately obtaining the temperature distribution of the medium in the shutdown pipe-line of waxy crude-oil has important guiding significance for making maintenance plan and restart plan. The phase transition process of waxy crude-oil involves complex problems such as natural-convection heat transfer, latent heat release, and difficulty in tracing liquid-solid interface. In this paper, the concept and significance of breaking point were proposed. Taking the breaking point and the freezing point as dividing point, a new zonal partition model was established based on the influence of phase change of crude-oil wax crystal on heat transfer mode, with the corresponding governing equations being established for different regions. With the proposed model, the effects of natural-convection on heat transfer, latent heat release, location change of condensate reservoir, heat transfer mechanism, and other key issues in the process of oil phase transition were analyzed. [ABSTRACT FROM AUTHOR]

In this paper, an application of the Picard's iterative method for finding the solution of two phase Stefan problem is presented. In the proposed method an iterative connection is formulated, which allows to determine the temperature distribution in considered domain. Another unknown function, describing position of the moving interface, is approximated with the aid of linear combination of some base functions. Coefficients of this combination are determined by minimizing a properly constructed functional. [ABSTRACT FROM AUTHOR]

Cavitation is a common phenomenon in components of fluid machinery and it may induce material damage and vibration. A more accurate and commercial turbulence model is required to predict cavitation. In this paper, we make a combination of filter-based model (FBM) and density correction method (DCM) to propose a new DCM FBM. Firstly, the new DCM FBM and the homogeneous cavitation model are validated by comparing the simulation result with the experiment of cavitation shedding flow around the Clark-y hydrofoil and the filter size is determined as well. Then, the cavitation pattern cycle and shedding vortex structure of the twist hydrofoil experimented by Delft University of Technology were predicted using the DCM FBM . The predicted 3-D cavitation structures and development cycle of twist hydrofoil as well as the collapsing features show a good qualitative agreement with the high speed photography results. Numerical results show that the improved turbulence model could predict the cloud cavity evolution well, including the cloud cavity generation, shedding and dissipation. It is found that the re-entrant jet induced by the by adverse pressure gradient is the main reason to generate the cloud cavity shedding. The secondary shedding is also observed which is result from the combination of the radially advancing reentrant jet and side-entrant jet simulated by the DCM FBM turbulence method. [ABSTRACT FROM AUTHOR]

In this paper we discuss parameter estimation in black scholes model. A non-parametric estimation method and well known maximum likelihood estimator are considered. Our aim is to estimate the unknown parameters for stochastic differential equation with discrete time observation data. In simulation study we compare the non-parametric method with maximum likelihood method using stochastic numerical scheme named with Euler Maruyama. [ABSTRACT FROM AUTHOR]

In order to improve the dynamic control ability of multiphase flow in heavy oil reservoir by steam injection, he put forward the sequential solution method of multiphase flow in heavy oil reservoir by steam injection based on numerical oscillation, established saturation equation and dynamic equation of multiphase flow in heavy oil reservoir by steam injection, solved the output pressure of multiphase flow in heavy oil reservoir by pressure equation based on volume conservation, and established the sequential solution model of all-component model of multiphase flow in heavy oil reservoir by steam injection. The output pressure of multiphase seepage in steam injection-production heavy oil reservoir is transformed into parabolic variable, and the saturation and composition are hyperbolic variable models. Through the analysis method of saturation and composition characteristics of all-component model, combined with the pressure signal analysis of numerical oscillation, empirical mode decomposition and spectrum analysis methods are adopted to realize the velocity parameter analysis and multiphase seepage sequence analysis of steam injection-production heavy oil reservoir, and the numerical oscillation analysis and parameter estimation of multiphase seepage in steam injection-production heavy oil reservoir are realized by establishing the sequential solution algorithm of steam injection-production heavy oil reservoir. The simulation results show that this method is used to solve the multiphase seepage sequence of heavy oil reservoir by steam injection, and the parameter estimation accuracy is high, which improves the calculation efficiency of numerical simulation of steam injection and production. The calculation efficiency and accuracy of this algorithm in 2-D and 3-D examples with gravity are verified by examples. [ABSTRACT FROM AUTHOR]

Most thermal problems can be modeled by nonlinear equations, fractional calculus and fractal geometry, and can be effectively solved by various analytical methods and numerical methods. Analytical technology is a promising tool to outlining various features of thermal problems. [ABSTRACT FROM AUTHOR]

Soil-to-air heat exchanger concept is one of the efficient methods to reduce the cooling effort required for any air conditioning system. In this paper, a theoretical model of soil-to-air heat exchanger has been developed to predict the air temperature in the outlet of the system during a hot atmospheric condition. This theoretical model is used to predict the sub-soil temperature for a specific ambient condition in a southern part of India and also compared with the measured sub-soil temperature. Performance of the soil-to-air heat exchanger system has been calculated during peak hours in summer and found to have the potential to reduce the energy required to cool the building. [ABSTRACT FROM AUTHOR]

Water scarcity, energy scarcity, and demographic difficulties are all real concerns for many countries throughout the world. Due to the high solar intensities and long sunshine duration in Saudi Arabia, solar water desalination can be effectively utilized for obtaining fresh water. The aim of this paper is explore the potential of simple-design and plentiful rectangular trough in desalination under vacuum condition. Numerical analysis of the heat and mass transfer of tubular solar still containing rectangular trough was performed. A 2-D code that solves the systems of equations for mass, momentum, concentration, and energy was developed and validated. The effect of the rib and the vertical elevation of the trough on heat and mass transfer were investigated. The numerical results showed that the distillation rate is significantly increased with the increase of the rib of the trough at a minimum of 19.78%. In addition, the distillation rate is increased at a minimum of 12.88% when the trough moves towards the upper side of the glass cover where the condensation takes place. [ABSTRACT FROM AUTHOR]

Thermal protective garment has been deemed as an important shielding against fire hazard and inflammable gas leakage. The coupling model of thermal protective garment, air-gap, and human body has been widely established, but the heat transfer in air-gap was commonly simplified, resulting in inaccurate results. This paper suggests a coupling heat transfer model of the microsystem consisting of thermal protective garment, air-gap, and human body, taking into account the heat transfer of air-gap, and human skin, its numerical solution is obtained by the finite element method. The degree of skin burn could be extracted and determined from the model, and the effect of heat source, fabric thickness, and air-gap thickness on the degree of skin burn are investigated. [ABSTRACT FROM AUTHOR]

This paper establishes a 3-D numerical model for inter-fiber flows in non-woven materials composed of super absorbent fibers. The velocity distribution of the inter- fiber flow is obtained. The effects of absorbent fibers and geometrical structure of non-woven fabrics on flow properties are analyzed. [ABSTRACT FROM AUTHOR]

In the present paper, along with experimental study, CFD analysis of forced convection in a twisted tube is performed, using the transition SST model which can predict the change of flow regime from laminar through transition to turbulent. The differential governing equations are discretized by the finite volume method. The investigations are conducted for Reynolds numbers ranging from 100 to 50000 covering laminar, transitional and turbulent regimes, and for three length and three pitch ratios. The predictions are observed to show a good agreement with the measurements and published correlations of other authors. The analysis indicates that the large length ratio and small pitch ratio yields a higher heat transfer rate with relatively low performance penalty. The transition from laminar to turbulent regime is observed between Reynolds numbers of 2500 to 3500 for all cases. For almost all investigated cases the performance factors are greater than unity. [ABSTRACT FROM AUTHOR]

Paper presents the problem of heating the damaged insulation of an orbiter. Changes of the insulation's thermal properties, made by adding conductive material of high value of specific heat in a form of a dope to the protective layer, were examined. An iterative algorithm determining a variable of dope concentration in the material was developed. Insulating material LI900 was used for calculations. Determination of distribution of conductive material concentration was made for materials which, after verification, demonstrated the most beneficial effect on protective properties of the modified insulation layer. Change of properties was to enable time extension of the LI900 insulation tile heating up to the maximal temperature and, additionally, to lowering this temperature. [ABSTRACT FROM AUTHOR]

This paper presents the solution of the initial boundary-value problem for the system of 1-D thermoelasticity using a new modified decomposition method that takes into accounts both initial and boundary conditions. The obtained solution is based on the generalized form of the inverse operator and is given in the form of a finite series. Also, some numerical experiments were presented to the both the effectiveness and the accuracy of the presented method. [ABSTRACT FROM AUTHOR]

This paper combines thermal-structure coupling technique and pattern search optimization algorithm to establish an optimization system for the start-up process of a turbine unit. Firstly, a finite element model for thermal-structure coupling calculation is established to accurately analyze the transient temperature field and thermal stress field, which can obtain the thermal stress distribution during start-up process. Afterwards, a program of optimization on rotor start-up process is exploited to improve the time allocation in each operating stage of start-up process, which minimizes the maximum equivalent stress of rotor. The maximum equivalent stress has reduced 25.7% after the optimization, which reveals obvious effect. [ABSTRACT FROM AUTHOR]

In this paper, numerical solutions for the generalized Rosenau-KdV equation are considered via the energy and momentum conservative non-linear implicit finite difference scheme. Unique existence of the conservative properties of the solutions for the difference scheme is shown. Numerical results demonstrate that the scheme is efficient and reliable. [ABSTRACT FROM AUTHOR]

In this paper, we combine the variational iteration method and perturbation theory to solve a time-dependent singularly perturbed reaction-diffusion problem. The problem is considered in the boundary layers and outer region. In the boundary layers, the problem is transformed by the variable substitution, and then the variational iteration method is employed to solve the transformed equation. In the outer region, we use the perturbation theory to obtain the approximation equation and the approximation solution. The final numerical experiments show that this method is accurate. [ABSTRACT FROM AUTHOR]

The paper presents results of experimental and numerical investigation addressing combustion of baled agricultural biomass in a 50 kW experimental furnace equipped with cigar burners. Experiments performed included measurements of all parameters deemed important for mass and energy balance, as well as parameters defining quality of the combustion process. Experimental results were compared with results of numerical simulations performed with previously developed CFD model. The model takes into account complex thermo mechanical combustion processes occurring in a porous layer of biomass bales and the surrounding fluid. The combustion process and the corresponding model were deemed stationary. Comparison of experimental and numerical results obtained through research presented in this paper showed satisfactory correspondence, leading to the conclusion that the model developed could be used for analysis of different effects associated with variations in process parameters and/or structural modifications in industrial biomass facilities. Mathematical model developed was also utilized to examine the impact of flue gas re-circulation on maximum temperatures in the combustion chamber. Gas re-circulation was found to have positive effect on the reduction of maximum temperature in the combustion chamber, as well as on the reduction of maximum temperature zone in the chamber. The conclusions made provided valuable inputs towards prevention of biomass ash sintering, which occurs at higher temperatures and negatively affects biomass combustion process. [ABSTRACT FROM AUTHOR]

The paper deals with the heat input and maximum temperature developed during friction stir welding with different parameters. Aluminum alloy (AA 6061-T6) has been used for experimental and numerical analysis. Experimental analysis is based on temperature measurements by using infrared camera, whereas numerical analysis was based on empirical expressions and finite element method. Different types of defects have been observed in respect to different levels of heat input. [ABSTRACT FROM AUTHOR]

The aim of the research described in this paper, is to make a virtual thermal manikin that would be simple, but also robust and reliable. The virtual thermal manikin was made in order to investigate thermal conditions inside vehicle cabins. The main parameters of the presented numerical model that were investigated in this paper are mesh characteristics and turbulence models. Heat fluxes on the manikin's body segments obtained from the simulations were compared with published results, from three different experiments done on physical thermal manikins. The presented virtual thermal manikin, meshed with surface elements of 0.035 m in nominal size (around 13,600 surface elements) and in conjunction with the two-layer RANS Realizable k-e turbulence model, had generally good agreement with experimental data in both forced and natural flow conditions. [ABSTRACT FROM AUTHOR]

In this paper, we introduced a numerical analysis for the effect of a magnetic field on the mixed convection and heat transfer inside a two-sided lid-driven cavity with convective boundary conditions on its adjacent walls under the effects of the presence of thermal dispersion and partial slip. A single-phase model in which the water is the base fluid and a copper is nanoparticles is assumed to represent the nanofluid. The bottom and top walls of the cavity move in the horizontal direction with constant speed, while the vertical walls of the cavity are stationary. The right wall is mentioned at relatively low temperature and the top wall is thermally insulated. Convective boundary conditions are imposed to the left and bottom walls of the cavity and the thermal dispersion effects are considered. The finite volume method is used to solve the governing equations and comparisons with previously published results are performed. It is observed that the increase in the Hartmann number causes that the shear friction near the moving walls is enhanced and consequently the horizontal velocity component decreases. [ABSTRACT FROM AUTHOR]

The unsymmetrical air flow of the dual slot die in the melt blowing process is simulated. The diameter and transverse displacement of the threadline are obtained numerically. The result shows that the threadline diameter in the unsymmetrical air flow is larger than that in the symmetrical one. This paper helps to point out the research direction for producing finer melt blown fibers. [ABSTRACT FROM AUTHOR]

This paper describes a numerical analysis of a heat transfer enhancement technique that introduces fractal-shaped design for impingement cooling. Based on the gas turbine combustion chamber cooling, a fractal-shaped nozzle is designed for the constant flow area in a single impingement cooling model. The incompressible Reynolds-averaged Navier-Stokes equations are applied to the system using CFD software. The numerical results are compared with the experiment results for array impingement cooling [ABSTRACT FROM AUTHOR]

The paper presents an analytic method applied for finding the approximate solution of Stefan problem reduced to the one-phase solidification problem of a plate with the a priori unknown, and varying in time, boundary of the region in which the solution is sought. Proposed method is based on the known formalism of initial extension of a sought function describing the temperature field into the power series, some coefficients of which can be determined with the aid of boundary conditions, and also based on the approximation of a function defining the freezing front location with the broken line, parameters of which can be obtained by solving the appropriate differential equations. Results received by applying the proposed procedure are compared with the results obtained using a classical numerical method for solving the Stefan problem. [ABSTRACT FROM AUTHOR]

This paper studies the linear stability and dynamic structure for a generalized non-linear heat equation, and obtains novel analytic solutions such as homoclinc orbit and breather solitary solutions for the first time based on Hirota method. [ABSTRACT FROM AUTHOR]

Solar energy may be practically utilized directly through transformation into heat, electrical or chemical energy. A physical and mathematical model is presented, as well as a numerical procedure for predicting thermal performances of the P2CC solar concentrator. The demonstrated prototype has the reception angle of 110° at concentration ratio CR = 1.38, with the significant reception of diffuse radiation. The solar collector P2CC is designed for the area of middle temperature conversion of solar radiation into heat. The working fluid is water with laminar flow through a copper pipe surrounded by an evacuated glass layer. Based on the physical model, a mathematical model is introduced, which consists of energy balance equations for four collector components. In this paper, water temperatures in flow directions are numerically predicted, as well as temperatures of relevant P2CC collector components for various values of input temperatures and mass flow rates of the working fluid, and also for various values of direct sunlight radiation and for different collector lengths. The device which is used to transform solar energy to heat is referred to as solar collector. This paper gives numerical estimated changes of temperature in the direction of fluid flow for different flow rates, different solar radiation intensity and different inlet fluid temperatures. The increase in fluid flow reduces output temperature, while the increase in solar radiation intensity and inlet water temperature increases output temperature of water. Furthermore, the dependence on fluid output temperature is determined, along with the current efficiency by the number of nodes in the numerical calculation. [ABSTRACT FROM AUTHOR]

A new kind of louvered fin structures with staggered holes is proposed, numerical simulation is carried out to study the heat transfer factor and the friction factor, and an experiment is designed to verify the simulation results at different Reynolds numbers, a good agreement is observed. Comparison with the traditional louver structure reveals that when the Reynolds number is between 150 and 400, the heat transfer factor increases by 10~24%, the friction factor increases by 1~2%, and the comprehensive evaluation factor increases by 9~23%. These results can be used for optimization of louver finned heat exchangers. [ABSTRACT FROM AUTHOR]

The present work deals with a numerical investigation on an experimental single cylinder direct injection Diesel engine. Calculations are carried out with Kiva3v2 code using multidimensional detailed chemistry. The study was carried out on predicted CO, and NOx emission levels by the engine cylinder before exhaust valve opening. Correlations proposed for predicted NO, CO, and NOx levels function of fuel, O2, N2 concentrations and the maximum in-cylinder pressure rather than temperature. Predicted values of averaged pressures, O2, CO, and CO2 levels in the exhaust manifold were validated by the measured ones for a set of five loads at 1500 rpm. CO, NO, and NOx concentrations at the exhaust obtained by calculations lies perfectly with measured values. Otherwise, numerical simulations lead us to analyze injection timing, duration and fuel amount injected effect on the engine performances, ignition delay, combustion duration as well as CO and NOx emission levels. [ABSTRACT FROM AUTHOR]

The Tickhonov based well-condition asymptotic waveform evaluation is presented here to study the non-Fourier heat conduction problems with various boundary conditions. In this paper, a novel Tickhonov based well-condition asymptotic waveform evaluation method is proposed to overwhelm ill-conditioning of the asymptotic waveform evaluation technique for thermal analysis and also presented for time-reliant problems. The Tickhonov based well-condition asymptotic waveform evaluation method is capable to evade the instability of asymptotic waveform evaluation and also efficaciously approximates the initial high frequency and delay similar as well-established numerical method, such as Runge-Kutta. Furthermore, Tickhonov based well-condition asymptotic waveform evaluation method is found 1.2 times faster than the asymptotic waveform evaluation and also 4 times faster than the traditional Runge-Kutta method. [ABSTRACT FROM AUTHOR]

Numerical study of combined laminar natural convection and surface radiation with internal heat generation is presented in this paper and computations are performed for an air-filled square cavity whose four walls have the same emissivity. Finite volume method through the concepts of staggered grid and SIMPLER algorithm has been applied, and the view factors are determined by analytical formula. A power scheme is also used in approximating advection-diffusion terms. Representative results illustrating the effects of emissivity and the internal heat generation on the streamlines and temperature contours within the enclosure are reported. In addition, obtained results for local and average convective and radiative Nusselt number, for various parametric conditions, show that internal heat generation modifies significantly the flow and temperature fields. [ABSTRACT FROM AUTHOR]

The novelty and innovativeness of this paper are the combination of reproducing kernel theory and spline, this leads to a new simple but effective numerical method for solving variable-order anomalous sub-diffusion equation successfully. This combination overcomes the weaknesses of piecewise polynomials that can not be used to solve differential equations directly because of lack of the smoothness. Moreover, new bases of reproducing kernel spaces are constructed. On the other hand, the existence of any ε-approximate solution is proved and an effective method for obtaining the ε-approximate solution is established. A numerical example is given to show the accuracy and effectiveness of theoretical results. [ABSTRACT FROM AUTHOR]

In this paper we present numerical study, using software named Calculation FDS, of thermal plume that evolve from the source at the entrance of a vertical channel. In the literature, there are researchers who are interested in the interaction of plume with confined medium. These studies are based on the determination of the global structure of plume confined. It is found that this plume consists of three distinct zones. First zone near source (instability zone), followed by a second zone, the plume development, and third zone which is the zone of turbulence, Comparing the overall structure of the plume confined to that of the free plume, one can identify the presence of a third zone (zone of instability). The aim is firstly to determine the height of the instability zone located above of source, and secondly, to make a spectral study frequencies exhaust. Thus, effects of geometrical parameters on frequencies of these escapements and height an instability zone can be shown. The final aim is to establish correlations between the dimensionless Strouhal and Grashof numbers. [ABSTRACT FROM AUTHOR]

In this paper, a numerical simulation has been performed to study the fluid flow and heat transfer around a square cylinder utilizing AL2O3-H2O nanofluid over low Reynolds numbers. Here, the Reynolds number is varied within the range of 1 to 40 and the volume fraction of nanoparticles (φ) is varied within the range of 0 < φ < 0.05. Two-dimensional and steady mass continuity, momentum, and energy equations have been discretized using finite volume method. SIMPLE algorithm has been applied for solving the pressure linked equations. The effect of volume fraction of nanoparticles on fluid flow and heat transfer were investigated numerically. It was found that at a given Reynolds number, the Nusselt number, drag coefficient, re-circulation length, and pressure coefficient increases by increasing the volume fraction of nanoparticles. [ABSTRACT FROM AUTHOR]