Search

The article presents an analysis of the heat transfer process during the heat transfer boiling in pipes and channels of small diameter. The authors gave an overview of the main calculation methods for determining the boiling heat transfer coefficient. When analyzing the main calculation methods, two common ones were identified: considering convective and nucleate boiling. The specificity of the heat transfer mechanisms for these two types of boiling has been determined. The authors of this article presented a method for calculating the parameters of heat transfer during boiling, taking into account the combined effect of convective and incipient boiling processes. This method will allow you to enter the calculation of the boiling process along the length of the channel, considering the change in the dryness degree. The structure of a two-phase flow is also presented, taking into account the gradual transition from nucleate boiling to convective boiling with an increase in the dryness degree. The technique presented in the work can be used to calculate the boiling process in pipes and channels of small diameter that occurs in various power plants and heat exchangers.

Fluidization-bed columns are widely used in the electrical industry, particularly in the insulation of busbars by epoxy coating. Control of the hydrodynamic parameters of the fluidized bed and the loading rate and distribution of solid particles are essential factors in the coating processes of the busbars. Successful control of the fluidized bed hydrodynamic parameters and solid particles loading rate reduces the waste in the manufacturing of the busbars. The objective of the present work is to investigate and improve the effect of solid loading and the properties, of both single and binary mixtures, on the hydrodynamic parameters of the fluidized bed to standardize the epoxy coating process of the busbars. All data acquisition and measurements have been carried out at the production facility of a leading busduct manufacturer. The investigation included compressed air holdup and bubble dynamics of a fluidized–bed bubble column and its influence on the coating performance of the busbars with different compositions of solid particles. The methodology of the study is based on experimental investigation, measurement of the hydrodynamic parameters and analysis of the quality of coating of the manufactured busbars. It was observed that for specified operating conditions, there is a proportional relationship between gas holdup, superficial gas velocity and solid particle diameter, while an inverse relationship exists between the gas holdup and solid concentration versus particles density. Bubble mean diameter and bubble rise velocity are directly proportional to solid concentration and particle diameter.

Our work is a review of algebraic and geometric constructions appearing in some problems of Quantum Information Theory.

In this work, numerical studies are conducted for a supersonic M = 2.0 steady flow over a flat plate with a suction through single circular hole of variating intensity. The computed flow fields near the suction hole are estimated to build special boundary condition of Dirichlet type. Such a simulated suction can be used in DNS of disturbances propagation over walls with multiple suction holes.

In this paper, we will discuss the possibility of increasing the Holevo value when measuring with post-selection. By measurement with post-selection we mean that some of the outcomes of the measurement are discarded, and then we work with the resulting states. Using the example of two mixed states, it will be shown that mutual information after performing post-selection is greater than their initial Holevo value. An increase in the Holevo value follows from the monotonicity property of the quantum relative entropy.

This paper presents an observation of the performance of a solar PV system under high temperature in a hot climate area. The main objective of this work is to observe the effect of high temperature on the efficiency of a 13.2 kW rooftop system and to analyze the relative technical parameters with and without a direct current optimizer (DC Optimizer). In such climates, the impact of high temperatures on the performance of solar system should be taken into consideration to get the intended output power. The average amount of solar radiation falls in this area is around 2200 kWh/m2. The simulation results are done using PVsyst software which shows the amount of energy produced yearly, the amount of loss of energy, the carbon emissions that have been reduced and the performance categories. The 13.2 kW system without DC optimizers can produce 24190 kWh/ year at performance ratio of 77.66 and a tilt angle of 25°, latitude of 24.70°, longitude of 46.68° and altitude of 450m. The system with DC optimizer produces 24640 kWh/ year at performance ratio of 79.06. In this case, it is obvious that optimizers can increase the output power up to 1.83% and can be higher in other cases. The effect of temperature cause both systems to have 14.21 % of loss per system which shows that optimizer is also affected by the increase in temperature.

In this work, deformation of micro fin machined by wire electrical discharge machining (WEDM) was studied. Firstly, transient temperature change on a workpiece caused by WEDM discharges was calculated using finite element method (FEM). Then, the result was used to calculate the residual stress. It was found that the residual stress in the radial direction, δr (z) along the centre axis of each discharge crater was distributed non-linearly in thickness direction from the workpiece top surface. Then, based on structural analysis, the δr (z) was imposed within the micro fin model. Here, thermal stress field caused by series of sequential discharges was considered. The summation of calculated deflection after three sequential discharges was approximately equal to the measuring result. As a result, the non-linear distribution of δr (z) was found to be the main reason that cause the non-uniform bending of the micro fin.

At present, the development of laser technology and high-speed optical cameras suggests that the necessary experimental information can be obtained by optical methods. Therefore, the work is aimed at developing optical method for measuring structures in hypersonic boundary layers as applied to the study of the mechanisms of laminar-turbulent transition. The proposed method is based on the laser knife method improved by the PIV system

Analysis of temperature distribution within a nuclear fuel rod is needed to be performed for safety purpose. The maximum fuel temperature must be ensured to be not exceeding the fuel integrity limit to prevent the release of hazardous fission products to the environment. The fuel temperature distribution is obtained through the calculation of the heat transfer process within the fuel rod. The multiple heat transfer processes with various heat transfer modes involved in transporting the fission heat generation in the fuel meat to the coolant are interesting and important to be studied in detail to verify the safety aspect of nuclear fuel. This paper aims to show the applicability of CFD FLUENT and analytical solution in calculating the temperature distribution within a nuclear fuel rod. The CFD FLUENT simulation was performed using the two-dimensional axisymmetric model and the three-dimensional model, while the analytical solution was performed using the one-dimensional heat conduction equation and an energy balance equation. The calculations were performed in both laminar and turbulent coolant flow regime cases. A sensitivity analysis was also conducted to investigate the fuel properties which has a significant contribution to the fuel meat temperature. The results show that the two-dimensional and three-dimensional CFD FLUENT simulations and the analytical solution give similar results in calculating the fuel rod temperature distribution in laminar and turbulent coolant flow cases. Both CFD FLUENT and analytical solution can show the distribution profiles of coolant average temperature, cladding outer surface temperature, cladding inner surface temperature, fuel meat surface temperature, and fuel meat centerline temperature. The distribution of coolant temperature near the cladding surface was only provided by CFD calculation. Unfortunately, the results of CFD FLUENT simulation and analytical solution do not agree with the experimental result available in the literature due to the limitation of CFD FLUENT. Another result of this work reveals that fuel meat conductivity, gap conductivity and heat generation distribution have a significant role in predicting the fuel rod temperature accurately. Finally, this work concludes that the CFD FLUENT simulation and a simple analytical solution are capable in predicting the fuel temperature distribution by calculating the heat transfer within a fuel rod and the heat removal from the fuel to the coolant. Further work is still needed to conduct the verification and validation of the CFD FLUENT and analytical solution results.

Electromagnetic forming has gradually become one of the most effective methods to overcome the existing problems in the processing of aircraft alloys. According to various types of metal processing in the production of aircraft parts, electromagnetic forming can be divided into sheet and tubular metal forming. Based on the requirements for metal processing, electromagnetic forming of a hollow tubular billet involves expansion and compression of the metal. The aim of this work is to determine the stresses and strains that can arise during the electromagnetic formation of two convex rift elements on a hollow tube. The calculation of numerical simulation during expansion in the radial direction of a D16AM tube covers all the nodes of the finite element grid from the beginning to the end of its deformation. From the Lagrangian formulation, the two tubular rifts are assembled into the geometric configuration of the current increment, and the results calculated at the end of the increment (stresses, strains, and nodal displacements) are associated with the nodal geometry by the calculated displacements. This formulation is the most appropriate one available for modeling this deformational process of two convex rift elements, characterized by constantly changing geometry and large displacements of individual elements.

The need for using sustainable green energy to fulfill the more and more energy demands is essential because of many problems like changes in climate, environmental pollution, and global warming and their effects on the health of humans. A process of closed-loop pressure retarded osmosis (CL-PRO) is a renewable technology producing green energy with no deleterious impacts on nature. For the first time, Ethylene-diamine tetra-acetic acid disodium (EDTA-2Na) salt is estimated for its possibility as a draw solution in the PRO process, while its performance is put to comparison with inorganic sodium chloride (NaCl) draw solution. The impact of various operational variables including the concentration of draw solution (0.1M-0.5M) and applied pressure difference (0-8bar) was estimated via laboratory-based investigation related to the CL-PRO. The impact of such operational parameters was examined on power density, reverse salt flux, water flux, and specific salt flux. Based on the experimental results, the EDTA-2Na salt is showing as an effective draw solution in CL-PRO as a result of its elevated osmotic pressure and reduced reverse salt flux. With regard to the same molar concentrations, the EDTA-2Na draw solution created high water flux and significantly less reverse salt flux in comparison with NaCl. Furthermore, the maximum power density which is reached for EDTA-2Na draw solution is 1.6 W/m2, while the corresponding water flux is 7.209 LMH at an applied pressure of 8 bars. According to the results of this work, elevated production of power and low reversal salt flux made EDTA-2Na salt as possible draw solution for future studies in CL-PRO.

Coal transport by sea transportation method including inter-islands barge system remains important means of bulk material transportation method. Depend upon the distance between the coal mine sites to the power plant sited, the coal transportation could take days or weeks. Prolonged transportation time could lead to self-heating leading to spontaneous combustion of lower rank coal. To prevent this, a heat exchanger submersion method is proposed to reduce the potentials of self-heating problem by means increasing the heat loss from the coal piles. This experiment work was conducted to determine the effect of cooling water flow rate on decreasing temperature of coal. Laboratory-scale experiments were performed using a stainless steel cylinder that opens at the top and insulated by rockwool to reduce heat loss. The heat source comes from the bottom which is heated by a hot plate heater. A U-shaped heat exchanger of laboratory-scale experiments was prepared. In this experiment, subbituminous coal was used. The effect of flow rate on the prevention of spontaneous combustion was studied by providing variations of the flow rates, thus the amount of heat taken from the heated coal bed. In this experiment the greater flow rate is accompanied by a higher decrease in coal temperature. Therefore, this heat exchanger effective for taking heat from the coal bed.

Levitation of two-dimensional (2D) ordered arrays of microdroplets over hot liquid surfaces has been studied in several previous papers. This phenomenon is relevant for many practical applications, such as spray cooling or synthesis of chemical components by containerless process. However, the mechanism of interaction of drops with each other in the 2D array has not yet been clarified. In this connection, the aim of this work is to determine the dependence of the distance between microdroplets on their size and on the number of drops in the array. It was found that the average distance between the drops grows with increasing diameter of the drops. According to the results of the experiment, for the number of droplets N less than about 7, the average distance between the drops practically does not change, however for N>7 the distance between the drops starts to decrease with N.

The foam injection molding process provides a multitude of advantages both during production and throughout the life cycle of foamed components. Yet still there are many uncertainties concerning the conditions inside the cylinder during gas injection. For a better understanding of these processes, the solubility of gases in polymers is crucial. In current literature, almost exclusively static solubility is investigated. It is questionable whether results from static solubility measurements are relevant for highly dynamic processes like injection molding. Additionally, it is unknown whether the limits detected in static measurements also count for dynamic systems. In this work, a novel measurement method based on the bulk modulus of gas containing polymer melts, which provides in-line determination of dynamic solubility limits, was applied. Using a talc filled polypropylene in a MuCell®-process the question was whether the solvable amount of gas can be influenced and increased by a larger gas injection time to dosing time ratio (Rt=ti/td). Starting at a gas concentration that was initially beyond the solubility limit the ratio Rt was increased stepwise, while process pressure and gas content were kept constant. The bulk modulus method in combination with transmissive ultrasonic measurements proves that the dynamic solubility can be increased above 1.6 wt% nitrogen at 140 bar. In addition, compression work and injection work were monitored and compared to the respective states of solution. These findings show that the influence of material on solubility limits might only be relevant at long dosing and gas injection times as an equilibrium cannot develop in short times typical for injection molding. This approach is useful when large amounts of gas should be dissolved in the melt in order to achieve high density reductions. It opens new perspectives for injection foam molding.The foam injection molding process provides a multitude of advantages both during production and throughout the life cycle of foamed components. Yet still there are many uncertainties concerning the conditions inside the cylinder during gas injection. For a better understanding of these processes, the solubility of gases in polymers is crucial. In current literature, almost exclusively static solubility is investigated. It is questionable whether results from static solubility measurements are relevant for highly dynamic processes like injection molding. Additionally, it is unknown whether the limits detected in static measurements also count for dynamic systems. In this work, a novel measurement method based on the bulk modulus of gas containing polymer melts, which provides in-line determination of dynamic solubility limits, was applied. Using a talc filled polypropylene in a MuCell®-process the question was whether the solvable amount of gas can be influenced and increased by a larger gas injection tim...

The present article evaluates coupled response of magneto-electro-hygrothermo-elastic (MEHTE) beam under framework of finite element methods. Through principle of total potential energy, equations of motions are derived. Solutions are obtained by incorporating the condensation procedure. Credibility of proposed formulation is validated by comparing the outcomes with previously published literature. Results reveal that with higher magnitude of hygrothermal loads, the static parameters of MEHTE beam significantly increases. Further, a comparative study between the thermal load alone and combined hygrothermal load reveals that the moisture effect plays a significant role in coupled response. The present work also attempts to evaluate the effects of various in-plane hygro-thermal loading profiles. Among the various hygrothermal loads considered, uniform hygrothermal load is found to have a predominant effect. Numerical examples are offered to assess individual effect of moisture as well.The present article evaluates coupled response of magneto-electro-hygrothermo-elastic (MEHTE) beam under framework of finite element methods. Through principle of total potential energy, equations of motions are derived. Solutions are obtained by incorporating the condensation procedure. Credibility of proposed formulation is validated by comparing the outcomes with previously published literature. Results reveal that with higher magnitude of hygrothermal loads, the static parameters of MEHTE beam significantly increases. Further, a comparative study between the thermal load alone and combined hygrothermal load reveals that the moisture effect plays a significant role in coupled response. The present work also attempts to evaluate the effects of various in-plane hygro-thermal loading profiles. Among the various hygrothermal loads considered, uniform hygrothermal load is found to have a predominant effect. Numerical examples are offered to assess individual effect of moisture as well.

Taking into account the effects of unperturbed electrons, harmonic phonons, anharmonicities, electron-phonon coupling, and impurities, the electron energy spectrum has been obtained for the representative high temperature cuprate superconductor YBa2Cu3O7-δ, with the help of double-time temperature-dependent thermodynamic many-body Green’s function theory of electrons. An exceptional feature of the present work crop up with the evolution of pairons and temperature dependent electron density of states (EDOS).

In this work we study the thermodynamic properties and phase transition of higher dimensional regular Bardeen black hole in AdS spacetime. The black hole thermodynamics is studied using Hawking temperature vs Bekenstein entropy (T - S) plot, which shows a critical behaviour. This is followed by the investigation of the phase transition by observing the divergence of specific heat. The critical behaviour of the blackhole is further analysed in detail via Ruppeiner geometry. The divergence behaviour similar to specific heat is found in Ruppeiner curvature scalar confirms a second order phase transition.

The aim of this research work is to find the numerical solutions of incompressible, viscous and electrically conducting Casson fluid flow past a vertical plate in presence of heat and mass transfer, transverse magnetic field. In energy equation, the influence of heat absorption is considered. The fundamental equations of the flow field are converted into linear partial differential equations, are solved using an efficient and versatile finite element method. After finding the solutions, we discussed the velocity, temperature and concentration profiles with the help of graphs by variation of engineering parameters for discussing the flow field. Also, with the variation of same parameters, we compared the present numerical values of Skin-friction coefficient, rate of heat and mass transfer coefficients with the available results in literature.

In this work, 3D simulation of an air flow inside the Ranque-Hilsch vortex tube was carried out in an unsteady statement for the laminar flow using the OpenFOAM software package. A qualitative possibility of energy separation in the laminar flow in a vortex tube is shown.

In this work, new generalized correlations for predicting the friction factor and heat transfer for the flow in pipes with inner helical finning are presented. The given correlations could be applied for the single-phase Newtonian fluid flow in a wide range of Reynolds and Prandtl numbers and a broad range of geometrical parameters of inner helical finning: number of starts, fin height, relative fin spacing, and helix angle.

In this work, we systematically investigate the effect of biaxial strain on the electronic transport coefficients of monolayer MoSe2 (n-type and p-type) by using the DFT formalism. The application of strain modifies the electronic band structure by changing the energy band gap and also makes the transition from direct to indirect, which in turn directly modulates the transport coefficients of the material i.e. Seebeck coefficients and electrical conductivity. The compressive strain is found to enhance the power factor of n-type MoSe2 monolayer and in case of p-type tensile strain improves power factor but only slightly. In particular, the application of strain enhances the various transport parameters which further help in increasing the efficiency of monolayer MoSe2 as a thermoelectric material.

Global environmental problems lead to the development of new technologies with lower carbon print, and selection of materials incorporating various waste materials. This trend in in the building industry reflected by the replacement of Portland cement by binding systems demanding lower amount of energy and non-renewable resources. The aim of this work is an experimental study dealing with the resistance of non-cement concrete to the action of deicers and cycle freezing-thawing in terms of determination of surface scaling resistance and ingress of chloride ion into concrete mass. Used binder was based on the activated energy by products. The conducted program confirmed good resistance to scaling of this mixtures, which could be additionally increased by the addition of fly ash. Although good scaling resistance studied mixtures exhibited increased ingress of chloride ions, which exceeded critical concentration in the surface layer.

Motivated from a recent theoretical work [1] on efficient storage of terahertz frequency signals in ultracold Rydberg atoms, I have studied the above mentioned storage process in the case when Doppler effect is present. It is present when the atoms are moving with a velocity which is coming from the thermal effect. Here, I have shown that this effect has made a prominent change in susceptibility and relative difference of the slope of dispersion which is the key factor of group index and group velocity [2].

In recent years, exponential growth has been observed in renewable energy sources, especially solar power, while the total capacity in the world has increased tenfold. In order to predict their work, it’s necessary to use an accurate mathematical photovoltaic (PV) cell model and adequately simulate the processes occurring in it. This article considers the partial shading effect on a PV module, using Matlab. Modeling impact of bypass diodes on modules output characteristics is also presented. The results can be used to assess the PV module efficiency and determine the optimal operation mode.

Micro polishing is a process used when a fine surface quality is desired. In optics, it represents the key process to achieve low surface roughness and form error required for optics application. Automated micro polishing with polymer-based tools requires a better understanding of the interaction between tool and workpiece than conventional polishing, and an important phenomenon that has to be taken into account is polymer relaxation. Stress relaxation is due to the non-linear viscoelastic behaviour of polymers. This relaxation is a time-dependent phenomenon that causes a decrease in stress, although the strain is kept constant. In this work, the effect of polymer stress relaxation on polishing is studied. While this effect can be neglected in conventional polishing, it becomes an essential and dominant factor in micro polishing. Characterization tests are conducted on a very common extruded polyurethane (LP-66) used in polishing. Subsequently, bonnet polishing using a spherical tool with a diameter of 1 mm is performed for 8 minutes on a nickel sample. Due to relaxation, the induced stress on the tool decreases during polishing, causing a reduction in the polishing pressure. This implies a reduction in the material removal rate in accordance with Preston’s law. Experimental results are in accordance with the physical phenomenon. The polymer relaxation characteristics can be used to compensate the tool path to achieve uniform removal along the polished surface.

Heat flow is one of the most common phenomena occurring in the surrounding reality. Despite this, many problems associated with it, such as finding the explicit analytical solution of the unsteady heat equation with spatially variable thermal properties, remain unsolved. It is the driving force of research like this. The purpose of this work was to model one-dimensional heat flow in a thermal metamaterial with spatially variable thermophysical parameters using the heat equation in conjunction with the unsymmetric Kansa method. Particular emphasis was placed on the problem of selecting the quasi-optimal value of shape parameter e which is of fundamental importance in the Kansa method. Empirical studies have shown that for the considered class of problem there is a relationship between the quasi-optimal value of the shape parameter e and the oscillatory behaviour in the graph of the function L (e ) where L is the condition number of matrix found in the system of equations whose solution approximates the solution of a problem. Importantly, the proposed method is computationally inexpensive because it does not require performing simulations.

In this article, the analysis of heat transfer of convected Maxwell fluid with slip boundary conditions, viscous dissipation and chemical reaction is investigated. The similarity transformation is utilized to change the governing partial differential equations (PDEs) to the system of nonlinear ordinary differential equations (ODEs). The resulting system of ODEs is sorted out mathematically by utilizing the shooting technique along with Adams-Bashforth Moulton method and the obtained mathematical outcomes are compared with those obtained using the MATLAB built-in function bvp4c. Numerical values of the physical quantities like, the Nusselt number and the Sherwood number and for the emerging parameters are also computed and discussed in this work.

The present study analyze the thermosolutal convection analysis in an inclined porous bed. It is also extended to investigate the influence of heat source. This work is analyzed by using linear stability analysis to examine the Hadley flow in an inclined porous body. The thermal stability of small-amplitude distributions is analyzed with corresponded to longitudinal rolls by using normal modes analysis. By applying the Runge Kutta method the eigenvalue problem is solved. The problem is studied for different flow parameters.

In the present work, the results of a research of a gas ejector with a nozzle with a partial swirl of the active flow at the outlet and a velocity distribution according to the law of the free vortex are presented. The determining criterion for the efficiency of the studied gas ejector is the level of the temperature field at its outlet. A technique for calculating the ejector, taking into account the geometry of the nozzle of the active stream with a velocity distribution according to the law of the free vortex has been developed.

The work is devoted to the study of the effect of rotation of a stationary fullerene molecule on interaction with a moving atom. To determine the precession characteristics of the C60 fullerene molecule, the pairwise interaction model of nonpolar Lennard-Jones molecules was used. The influence of the precession motion of a rotating fullerene molecule on the deviation from the initial position is investigated.

The rotational band structure of the neutron deficient even mass Cerium isotopes with neutron numbers 74 and 76 is investigated using the Projected Shell Model. For these isotopes, the band structures have been analyzed in terms of quasi-particles configurations. The yrast states are found to arise not only from single quasi-particle states but from multi quasi-particle states also. The phenomenon of back-bending in moment of inertia is also studied in the present work. The results obtained from the PSM calculations are also compared with the available experimental data and an excellent agreement is obtained between them.

Recently, study of physical properties of the liquid mixtures, their nature and behavior with change in frequency, temperature or concentration has gained interest. In the present work, ultrasonic velocity and attenuation measurements have been carried out in the binary mixture of nitrobenzene and ethanol using pulse echo technique in the temperature range of 274.15K-308.15K maintaining the temperature of the sample with an accuracy of ±0.1°C. It is observed that the mixture of nitrobenzene and ethanol shows maximum absorption at 277.15K at 0.27 moles of Nitrobenzene in the binary mixture. Critical nature of the mixture revealed by ultrasonic absorption indicates the molecular interaction between two liquids and attributes due to the fluctuation in the concentration.

In this present work, the influence of sintering temperature (1250 °C and 1275 °C) on the structural and electrical properties of the layered perovskite structured Ruddlesen-Popper class of material SmSrNiO4+δ is studied. The samples are synthesized in single-phase, and tetragonal phase with I4/mmm symmetry is suggested through Rietveld refinement. The microstructural studies reveal the increase in grain size with sintering temperature. The optical studies reveal that the bandgap of the material increases with the increase in sintering temperature.

In this work we proposed a mathematical model of ecological interactions among three species with a prey, predator and competitor. Distributed type of delay is incorporated in the interaction of prey and competitor species is taken for investigation. The system dynamics is studied at its interior equilibrium point with exponential type of delay kernels. The effect of Time delay on the dynamical behavior of the system is studied using Numerical simulation. It is observed that Hopf bifurcation exist for the system for different kernel strengths.

The hydrokinetic turbine is one of the renewable energy without generating emission impacted on environmental. In this work, the numerical simulation is used to investigate the influence of discretization along the blade surface towards the amount of the torque coefficient and power coefficient. This work will be done on Savonius hydrokinetic turbine numerically by using the Myring formula for n equal with 1 having the performance better than the conventional blade. This work will compare the performance among the blade discretization. Firstly, the numerical will be validated with experimental results at TSR of 0.8 and velocity of fluid kept constant at 0.22 m/s. Problem-solving uses Unsteady RANS with moving mesh for the rotating body. The turbulence model uses the Realizable k-epsilon (RKE) enhanced wall treatment with the discretization varied 200, 400, 800 and 1,600. The first layer number is 20 layers on the blade surface. This work obtains the torque coefficient and power coefficient. The results indicate that the increase of discretization on the surface of the blade has improved the accuracy results of the turbine performance by seeing the stability of graphic at 800 and 1,600. This Savonius model of Myring formula can use the number of the layer around 800 towards time efficiency.

Energy conservation is one of the recent fields which demands more technological upgradations. It is necessary to utilize the available source of energy effectively and efficiently such that we would obtain greater results with lesser energy consumption. Shell and Tube heat exchanger is one of widely used heat exchanger in process industries. Normally, in a shell and tube exchanger, as per TEMA recommendations, the hot fluid flows through the shell side and the cold fluid flows through the tubes. Due to the larger shell diameter, and greater temperature difference between the shell fluid and the exposed atmosphere, a larger amount of heat is radiated to the surrounding. This heat is actually wasted and the main objective of the present work is to effectively utilize this heat. The Hybrid Heat Exchanger is a technological modification which is brought on to a conventional used shell and tube heat exchanger. Here, a larger diameter shell is placed over an existing shell and tube exchanger; therefore, this would produce the combined effect of a shell and tube exchanger and double pipe heat exchanger within the same confined area. The objective of this heat exchange design is to reuse the waste heat radiated on the large surface of the shell of a shell and tube exchanger. This modification enhanced the rate of heat transfer which in turn improve the effectiveness of the heat transfer equipment. This design is created in such a way that, the up gradation would require very less additional area, but produce greater result, compared to the conventional shell and tube heat exchanger.

In this research work, various conventional and computational algorithms for designing a PI controller is studied. The lab scale non interacting liquid tank system is considered for this study and simulation purposes. The mathematical model of system is identified and various conventional methods for design a PI controller is implemented. The simulation results of the conventional algorithms is compared with various computational algorithms and the effectiveness is demonstrated both in simulation and real time environment using Simulink software. Also, the closed loop performance indices are tabulated and compared

This work deals with the formation of mesoscopic porous materials on chemically active surfaces. The theoretical studies are performed using Monte Carlo simulation program. The computer program has been developed by the author to demonstrate the formation of nano-scale liquid columns in extremely narrow geometries. The Lenard-Jones fluid is placed in a confined geometry with circularly patterned surfaces with affinity; ew = 4.0, 8.0, 12.0 and 16.0 and is studied at temperatures T=0.50, 0.60, 0.70 and 0.80 are studied. Four column liquid structures emerge out after completion of 5×105 Monte Carlo cycles. The initial configuration system is taken as a random distribution of molecules; obtained by annealing the initial regular systems at high temperatures as T=10.0. The obtained density profile data confirm for the same, though of initial nature. Wetting at the chemically active areas shows strong dependence on surface affinity and temperature.

The analytical description of the melt flow within the co-rotating twin screw extruder has been issued in various publications and it is an integral part of calculation models, software solutions for simulating polymer compounding processes such as SIGMA. Nevertheless, the accuracy of an analytical model depends on the defined simplifications. The more simplifications within the analytical description, the more deviation between the technical system and the calculation model. Analytical models for twin screw processes are no exception and are subject to simplifications and adaptations due to the complex geometry and the transient flow field. Therefore, the use of the kinematical inversion principle, the exchange of the original screw channel geometry and the consideration of an evenly distributed pressure gradient are commonly used simplifications for calculations models. In this paper a new analytical approach to calculate the melt flow is presented. The model is based on numerical simulations and with the use of the performance mapping method an analytical calculation method is derived. The advantage of the performance mapping method is that the original channel geometry and kinematical behavior of the twin screws are considered and the transient flow field in the system is used to generate a wide range of performance maps. Within the scope of this work, the performance maps of the melt conveyance and the pressure gradient in the fully filled screw channel are quantitatively examined with the aid of specially defined evaluation routines. Characteristic operating points are identified by the conveying characteristics of the melt which are displayed in the performance maps. The validation of this new analytical approach by using the performance mapping method with numerical data demonstrated that the two-dimensional description of the melt flow within the screw channel flow has a deviation of less than 10 % for varying flow law exponents geometry and process parameters.The analytical description of the melt flow within the co-rotating twin screw extruder has been issued in various publications and it is an integral part of calculation models, software solutions for simulating polymer compounding processes such as SIGMA. Nevertheless, the accuracy of an analytical model depends on the defined simplifications. The more simplifications within the analytical description, the more deviation between the technical system and the calculation model. Analytical models for twin screw processes are no exception and are subject to simplifications and adaptations due to the complex geometry and the transient flow field. Therefore, the use of the kinematical inversion principle, the exchange of the original screw channel geometry and the consideration of an evenly distributed pressure gradient are commonly used simplifications for calculations models. In this paper a new analytical approach to calculate the melt flow is presented. The model is based on numerical simulations and with t...

The authors wish to acknowledge the financial support given by FCT/MEC through Projects: UNIDEMI UID/EMS/00667/2019 and CEMAPRE UID/MULTI/00491/2019. The first author also wishes to thank the support of Project IPL/2019/MOCHVar/ISEL. The increasing complexity associated to both structures and materials have been posing a continuous demand for numerical tools that allow predicting their behavior and simultaneously consider the influence of the uncertainty associated to multiple parameters. This work presents a Bayesian approach to characterize the influence of each material phase's properties and the volume fraction parameters in the behavior of biphasic functionally graded plates. publishersversion published

In the present work temperature profile measurement of lighter flame has been performed using digital holographic interferometry. The experimental set up used here is cost effective and simpler than the set up used earlier. The temperature profile of lighter flame has been calculated without rotation and with rotation of flame by 180° around vertical axis of flame.

The present work involves the study of radial quantum confinement of two-dimensional hydrogen atom in the presence of a magnetic field. The corresponding Schrodinger equation has been solved numerically. Both radial confinement and magnetic field are found to significantly alter the energy spectrum.

Thermoelectric materials have been studied vastly in the past decades due their high potential for generating a useful amount of power from waste heat. The reverse process, electricity to heat effect and cooling effect, is also implemented using thermoelectric modules (TEM). The efficiency of TEM in both the processes has a direct proportional dependence upon a performance parameter (ZT) of the material which is also called figure of merit (FOM). ZT is inversely linked to thermal conductivity of the material used for the fabrication of the TEM. Hence determination of ZT value requires accurate measurement of magnitude of thermal conductivity. Out of various methods employed for measurement, 3ω method is one of the most trustworthy methods which is transient in methodology. In present work, we have set up a custom made three omega set up for the measurement of thermal conductivity of bulk samples. For the validation of the set up, we have measured thermal conductivity of the glass substrate and have obtained a value of ~ 1.30 W/mK.

The present work was to investigated the effects of trapezoidal and elliptical shape on stenosis artery. The variation of outlet velocity, pressure and wall shear stress has been investigated in a patient specific artery under pulsatile condition using open foam. Newtonian and Non-Newtonian model has been implemented in order to find out the variation in flow parameters. The trapezoidal model was found to be showing higher value of wall shear stress and velocity as compared to elliptical model. Higher wall shear stress was found in the region of maximum velocity. Non- Newtonian model showing higher value of wall shear stress than Newtonian model. This Problem has significant importance in the field of medical application.

This work considers discrete fractional nonlinear equations with Riemann-Liouville (R-L) type difference operator of the form Δβ[v(l)−p(l,v(l))]=f(l+β,v(l+β)),l∈N0,0

In this work, second law analysis of MHD Jeffrey fluid through asymmetric channel with peristalsis is investigated. For the governing equations, exact solutions are obtained by employing a low Reynolds number and long wavelength assumptions. The channel walls are maintained at constant temperature. The solutions of temperature distribution and stream function are used to compute the entropy generation and the Bejan number. The influence on peristaltic flow, of all physical parameters heat, transmit characteristics, entropy generation and Bejan number are demonstrated precisely and graphically.

In general, one of the main components used in electric power systems is a transformer. In principles, this equipment uses a magnetic process through the pairing winding where a cooling system is also applied to maintain the expected operational performance and to maintain heat transfer during the power delivery. In fact, load demand changes fluctuate depending on the behavior of energy users. This research is conducted to evaluate heat transfer in a three-phase transformer. This work also takes into the flowing current gradually based on the heat generated in the transformer. To cover these objectives, the analysis is directed to the power transformer optimization using the Artificial Salmon Tracking Algorithm (ASTA) for performing heat flow rates on-demand changes. The results obtained indicate that ASTA has a potential implementation for determining the optimal heat transfer. The demand changes have affected the power loss detected in both windings which are migrated out of heat through the cooling and fluid systems.

Electric Submersible Pumps (ESP) are widely used in agriculture and petroleum industries. These pumps are designed to work under wide range of flowrates and heads. To achieve the desired flow rate, various methods are employed. One of the methods widely used in industries to control the flow rate is varying the operating speed of the pump. Speed regulation of the pump with variable duty requirements leads to reliable operation of the pump. To access the performance characteristics of the pump at speeds other than the designed speed the affinity law of pumps is used. This paper investigates the application of the affinity law when a multistage electric submersible pump is operated at variable speeds. A five stage ESP was selected to conduct the performance test at various speeds. A Variable Frequency Drive (VFD) was employed to operate the ESP at five different speed settings from 40 to 60 Hz. Results have shown that there is a deviation between the performance characteristics obtained from the test and the one which was calculated using affinity law when the pump was operated at various speeds, which indicated the necessity of conducting experiments when a VFD is to be employed to vary the flow rate.

In processing metals by pressure like cold-drawing reduction, face broaching, extrusion forging, cold rolling, etc., it is observed that the work of external forces at various ways of complex strain is of less than at simple loading ones. These effects were established in experimental studies and can be explained by Ilyushin’s theory of elastoplastic processes and the so-called “damping memory” principle or the principle of delay of vector and scalar properties of material. Here described so effects in theoretical calculation by Ilyushin’s approach.

In this work, the process parameters of friction stir welded dissimilar joints of aluminium alloys were analysed. The experimental investigations are carried out by the various researchers are evaluated and tabulated. Friction Stir Welding (FSW) is a solid-state metal joining process. Solid state metal joining means, the metal is not melted during the welding process and also original metal characteristics remain unchanged. Selection of material with specific properties is the key parameter in many industrial applications, especially in the aircraft and automotive industries. However, processing of such alloys with specific properties, like high strength, suffer from certain limitations in terms of cost and time of production, apart from the reduction in ductility. High strength accompanied by high ductility is possible with materials having fine and homogenous grain structures. Hence there arises a necessity to develop a processing technique that would produce a material with small grain size that satisfies the requirements of strength and ductility as well as the cost and time of production. FSP expands the innovation of friction stir welding (FSW) developed by The Welding Institute (TWI) of United Kingdom in 1991 to develop local and surface properties at selected locations. FSP is a new and unique thermo mechanical processing technique that alters the microstructural and mechanical properties of the material in a single pass to achieve maximum performance with low production cost in less time. In the present work, FSP is investigated as a potential processing technique for aluminum alloys because of various advantages it offers over other processes as mentioned above. This FSW process mostly implemented on aluminium alloys. FSW of dissimilar alloys are controlled by various process parameters, in this paper, the effect of FSW tool geometry is analyzed and tabulated. From this brief discussion, we can improve the quality of FSW process.