Analysis Of Magnetic Field Effects Research Articles

Computational Fluid Dynamics-Based Analysis of Magnetic Field Effect on Improvement the Performance of Stepped Solar Still

Computational Fluid Dynamics-Based Analysis of Magnetic Field Effect on Improvement the Performance of Stepped Solar Still

Numerical Analysis of Magnetic Field Effect on Ferro Particle Suspended Nanofluid Filled Square Enclosure Consist of Heat Generating Body

In presents of a magnetic field, an enclosure filled with ferro-particle suspended nanofluid is subjected to a numerical analysis to investigate natural convective heat transfer. At the center of the enclosure is a heat conducting and generating solid body, and the enclosure is influenced by four different thermal boundary conditions. To solve the governing equation, a Fortran algorithm based on the finite volume approach was created. The numerical approach used in this study produces consistent results for a variety of non-dimensional parameters like Rayleigh number (104 ≤ Ra ≤ 106), Hartmann number (0 ≤ Ha ≤ 100), solid volume fraction (0 ≤ φ ≤ 0.2) and distributed wall temperature. Streamlines, isotherms, and the Nusselt number graph are used to describe the flow and heat transfer properties. Based on this study, It has been noted that improved heat transfer for lower Hartmann number with higher Rayleigh number particularly along sinusoidal wall. For the low Hartmann number, the fluid flow enhances for higher Rayleigh number. In particular, the presence of ferro-particle suspended nanofluid enhances the heat transfer rate. Moreover, this study has found that the inclusion of magnetic fields and nanoparticles can increase heat transfer by up to 60%. The suggested methods in this research can assist manufacturers improve efficiency without increasing heat generator space in industrial applications for cooling or heating.

Sensitivity of endogenous autofluorescence in HeLa cells to the application of external magnetic fields

Dramatically increased levels of electromagnetic radiation in the environment have raised concerns over the potential health hazards of electromagnetic fields. Various biological effects of magnetic fields have been proposed. Despite decades of intensive research, the molecular mechanisms procuring cellular responses remain largely unknown. The current literature is conflicting with regards to evidence that magnetic fields affect functionality directly at the cellular level. Therefore, a search for potential direct cellular effects of magnetic fields represents a cornerstone that may propose an explanation for potential health hazards associated with magnetic fields. It has been proposed that autofluorescence of HeLa cells is magnetic field sensitive, relying on single-cell imaging kinetic measurements. Here, we investigate the magnetic field sensitivity of an endogenous autofluorescence in HeLa cells. Under the experimental conditions used, magnetic field sensitivity of an endogenous autofluorescence was not observed in HeLa cells. We present a number of arguments indicating why this is the case in the analysis of magnetic field effects based on the imaging of cellular autofluorescence decay. Our work indicates that new methods are required to elucidate the effects of magnetic fields at the cellular level.

Analysis of magnetic field effect in micro-beam resonators at distinct boundary conditions

The present study is concerned with the analysis of the existence of magnetic field in micro-beam resonators in the context of generalized thermoelasticity with single relaxation time. MEMS are mostly set in permanent magnetic fields. Two dissimilar cases, with different boundary conditions (First: simply supported and isothermal, Second: clamped and isothermal) of micro-beam resonators, have been discussed. In the first case, magneto-thermoelastic damping has been analyzed by the vibration responses of deflection and thermal moment, which are obtained by the Laplace transform method along with the finite Fourier sine transform method, while in the second case, the magneto-thermoelastic damping has been characterized by the vibration frequency through normal mode analysis. Therefore, the present study highlights the influence of magnetic field in the vibration responses of deflection as well as thermal moment of the micro-beam resonators in both cases separately. Size dependency of micro-beam resonators has been observed. The analytic result shows that the amplitude of deflection and thermal moment is attenuated for the coupled magneto-thermoelasticity.

Experimental analysis of magnetic field effects on compressor energy saving cooling system

A research on different refrigerants with and without influence of the magnetic field is provided in this paper. The magnetic field degree viz is four gauss. The condenser exit row was 3000, 6000, 9000 and 12000 gauss. Magnetic fields at condenser exit lines are found to reduce the consumption of the compressor energy. Through applying magnet fields on R134a, compressor energy savings was observed up to 1.35%, 6.23%, 5.40% and 4.19%, respectively, in gauss levels of 3000, 6000, 9000 and 12000, while R152a savings in energy levels were up 13.10%, 15.59% and 25.86% and R407a saving in power up to 7.3%, 9.19%, 13.05% and 12.40%. The coolant R152a saves energy in contrast to other coolant compressors. As the magnetic field strength increases, a vapor refrigeration system decreases the energy consumption of the compressor.

Numerical analysis of magnetic field effects on the heat transfer enhancement in ferrofluids for a parabolic trough solar collector

A parabolic trough is defined as a type of solar thermal collector that is straight in one dimension and curved as a parabola in the other two, lined with a polished metal mirror. Enhancing the thermal efficiency of this collectors is one of the major challenges of developing and growing of parabolic trough solar thermal power plants. Ferrofluids were proposed as a novel working fluid for industrial applications, due to their thermal performances. In this study, the convective heat transfer of Fe3O4-Therminol 66 ferrofluid under magnetic field (0–500 G) is evaluated using computational fluid dynamics. The ferrofluid with different volume fraction (1–4%) and the Therminol 66 (as the base fluid) are considered as the working fluids for a parabolic trough solar collector. Numerical analysis first validated using theoretical results, and then a detailed study is conducted in order to analyze the effect of the magnetic field on different parameters. The result demonstrated that using magnetic field can increase the local heat transfer coefficient of the collector tube, thermal efficiency as well as output temperature of the collector. In addition, increasing the volume fraction of nanoparticle in the base fluid and intensity of magnetic field increased the collector performance.

Structure and dynamics of triplet-exciton pairs generated from singlet fission studied via magnetic field effects

Singlet fission is the conversion of a singlet exciton to a pair of triplet excitons followed by a diffusion process to form two free triplet excitons. The quantum yield of singlet fission per photon can exceed 100%. Singlet fission is thus an attractive way to enhance solar-cell performance. However, singlet fission events are not well characterized. In particular, the structure and diffusion pathways of triplet-exciton pairs, which strongly affect the efficiency of the singlet fission event, are unclear. Here we study the magnetic field effects (MFEs) on the singlet fission of diphenylhexatriene (DPH) and fluorinated DPHs crystals. Their fluorescence intensities show clear MFEs and the shape of the MFE curve depends on the crystal structure. Analysis of MFEs with the stochastic Liouville equation reproduces the MFE curve well. This use of MFEs allows one to determine the structure and diffusion pathways of triplet-exciton pairs, and to predict the efficiency of singlet fission events.

Experimental analysis of magnetic field effect on the pool boiling heat transfer of a ferrofluid

In this research, an experimental study was conducted to investigate the pool boiling heat transfer of Fe3O4/water nanofluid (ferrofluid) in the atmospheric pressure. This study also investigated the influence of the magnetic field on the rate of boiling heat transfer of nanofluid. Deionized (DI) water was used to examine the repeatability, integrity and precision of the experimental apparatus where a well agreement with the existing correlations was observed. The investigation of various volume concentrations of nanofluid revealed that boiling heat transfer in high concentrations decreases with an increase of concentration while it rises with the increase of concentration in low concentrations. The boiling heat transfer coefficient at 0.1% volume concentration nanofluid was evaluated as optimal (increasing up to 43%). In addition, experimental studies showed that the presence of positive and negative magnetic field gradients decrease and increase the boiling heat transfer, respectively. The findings of this study showed that at higher concentrations of nanofluid, the effect of the magnetic field on nanoparticles is boosted. The results of the experiments indicated that adding nanoparticles would not necessarily increase the boiling heat transfer coefficient. In fact, the surface roughness and the magnetic field gradient on the boiling surface were the main factors that could affect the boiling heat transfer coefficient, significantly.

Analysis of Magnetic Field Effects on Distributed Heat Sources in a Nanofluid-Filled Enclosure by Natural Convection

Analysis of Magnetic Field Effects on Distributed Heat Sources in a Nanofluid-Filled Enclosure by Natural Convection

Numerical analysis of magnetic field effects on hydro-thermal behavior of a magnetic nanofluid in a double pipe heat exchanger

This study attempts to numerically investigate the hydro-thermal characteristics of a ferrofluid (water and 4vol% Fe3O4) in a counter-current horizontal double pipe heat exchanger, which is exposed to a non-uniform transverse magnetic field with different intensities. The magnetic field is generated by an electric current going through a wire located parallel to the inner tube and between two pipes. The single phase model and the control volume technique have been used to study the flow. The effects of magnetic field have been added to momentum equation by applying C++ codes in Ansys Fluent 14. The results show that applying this kind of magnetic field causes kelvin force to be produced perpendicular to the ferrofluid flow, changing axial velocity profile and creating a pair of vortices which leads to an increase in Nusselt number, friction factor and pressure drop. Comparing the enhancement percentage of Nusselt number, friction factor and pressure drop demonstrates that the optimum value of magnetic number for Reff=50 is between Mn=1.33×106 and Mn=2.37×106. So applying non-uniform transverse magnetic field can control the flow of ferrofluid and improve heat transfer process of double pipe heat exchanger.

Numerical analysis of magnetic field effects on Eyring-Powell fluid flow towards a stretching sheet

In the present article, we have examined the two dimensional MHD flow of Eyring–Powell fluid model towards a stretching sheet. The governing equations of Eyring–Powell fluid are modeled and then simplified by using boundary layer approach and similarity transformations and then solved numerically using implicit finite difference method. It was found that the increase in the intensity of the magnetic field as well as Eyring–Powell fluid parameter γ shows resistance to the flow.

Long-Distance Sequential Charge Separation at Micellar Interface Mediated by Dynamic Charge Transporter: A Magnetic Field Effect Study.

Construction of photogenerated long-lived charge-separated states is crucial for light-energy conversion using organic molecules. For realization of cheap and easy-to-make long-distance electron transfer (ET) systems, we have developed a supramolecular donor(D)-chromophore(C)-acceptor(A) triad utilizing a micellar interface. Alkyl viologen (A(2+)) is adsorbed on the hydrophilic interface of Triton X-100 micelle, which bears D units in the hydrophobic core. Excited triplet state of a hydrophobic flavin C entrapped in the supercage gives rise to primary ET from D, which is followed by the secondary ET from C(-•) to A(2+) to give the long-lived (>10 μs) charge-separated state with negligible yield of escaped C(-•). Analysis of magnetic field effect reveals that diffusion of C(-•) from the core to the hydrophilic interface leads to long-distance ET with a low charge recombination yield of ∼20%. This novel concept of "dynamic charge transporter" has important implications for development of photon-energy conversion systems in solution phase.

Lie symmetry group analysis of magnetic field effects on free convective flow of a nanofluid over a semi-infinite stretching sheet

Abstract We investigate the steady two-dimensional flow of an incompressible water based nanofluid over a linearly semi-infinite stretching sheet in the presence of magnetic field numerically. The basic boundary layer equations for momentum and heat transfer are non-linear partial differential equations. Lie symmetry group transformations are used to convert the boundary layer equations into non-linear ordinary differential equations. The dimensionless governing equations for this investigation are solved numerically using Nachtsheim–Swigert shooting iteration technique together with fourth order Runge–Kutta integration scheme. Effects of the nanoparticle volume fraction ϕ , magnetic parameter M , Prandtl number Pr on the velocity and the temperature profiles are presented graphically and examined for different metallic and non-metallic nanoparticles. The skin friction coefficient and the local Nusselt number are also discussed for different nanoparticles.

Three dimensional numerical analysis of magnetic field effect on Convective heat transfer during the MHD steady state laminar flow of liquid lithium in a cylindrical pipe

In this study, effect of perpendicularly applied magnetic field on steady state laminar liquid lithium flow in a horizontal circular pipe was theoretically analysed with 3D computer base programme. Convective heat transfer behaviour has been examined. Liquid lithium flow was observed for two different conditions as cooling and heating with constant wall temperature. Analyse was proceeded for thermal fully developed but hydro-dynamically transient region of flow. Calculation was carried out with ANSYS Fluent software. As a result, by the increase of magnetic field induction, the local flow velocity was decreased, but the Nusselt number, skin friction coefficient and pressure was increased for the heating and cooling conditions of liquid lithium through the pipe length. Additionally, while the liquid lithium was heating the fluid temperature was decreased and also while the liquid lithium was cooling the fluid temperature was increased by the increase of magnetic field induction through the pipe length. Increase of magnetic field induction enhanced the convective heat transfer and so, indirectly improved the cooling and heating of liquid lithium.

Analysis of magnetic field effect on 3D melt flow in CZ Si growth

Three-dimensional turbulent melt convection in an industrial Czochralski Si-crystal growth system subjected to action of an axial stationary magnetic field is numerically simulated using a hybridization of the Reynolds-averaged Navier-Stokes approach and large-eddy simulation. The proposed RANS/LES model is based on a differential model of turbulence. The results obtained with three computational models differing in the number of considered hot-zone components are presented and compared with the experimental data for temperature in the melt and along the melt-crucible surface. The influence of electrical currents in the crystal on melt motion reorganization is studied.

Magnetic field effects upon photochemistry of bifuctional chain molecules

AbstractExternal magnetic field effects are discussed for three typical examples of photoreactions involving biradical intermediates: photo‐induced intramolecular electron transfer in chain molecules D(CH2)nA consisting of an electron donor (D) and an acceptor (A), intramolecular hydrogen abstraction in bifunctional species :X(CH2)nYH containing a hydrogen donor (YH) and an acceptor (:X in the excited triplet state) and photochemical homolytic ring opening of a cyclic ketone which yields a biradical consisting of an acyl and an alkyl group. There has been progress in the elucidation of reaction mechanisms through the analysis of magnetic field effects on lifetimes of reaction intermediates and product yields in radical reactions involving biradicals. Extremely small interactions such as the Zeeman energy and hyperfine interaction may give rise to a large change in the distribution of photo‐products derived from bifunctional chain molecules.

Dynamical analysis of magnetic field effects on a cholesteric cano wedge

Dynamical analysis of magnetic field effects on a cholesteric cano wedge

Quantum theory of static shielding II: Intermediate magnetic field strength

A theoretical analysis of magnetic field effects on the Friedel-Kohn “wiggle” contribution to shielding by a quantum plasma is carried out here for conditions of intermediate magnetic field strength ( E F > ω c > kT). In this case, magnetic field quantum corrections to the Friedel-Kohn “wiggl” may be expected to be of two types: (1) monotonic magnetic field corrections associated with an expansion in powers of ω c E F and (2) DHVA-type oscillatory magnetic field corrections associated with oscillatory terms involving the DHVA oscillation frequency E F ω c . The analysis of the monotonic magnetic field corrections is carried out with an expansion in powers of ω c E F , and we find that the actual expansion parameter involved is not ω c E F which is small; but rather it is [ ω c E F ) · p Fr] which may be either small or large since p F r is large. For distances from the shielded impurity such that [( ω c E F ) · p Fr] ⪡ 1 , the power expansion is valid and the zero-field Friedel-Kohn “wiggle” is the dominant high-wavenumber shielding phenomenon, with monotonic and anisotropic magnetic field corrections given by the power series. However, for distances from the impurity such that [( ω c E F ) · p Fr] ⪢ 1 the power expansion is invalid, and we estimate the monotonic magnetic field corrections from a nonperturbative integral representation. The resulting estimate obtained shows that when [( ω c E F ) · p Fr ⪢ 1 the Friedel-Kohn “wiggle” no longer retains its zero-field form, but instead it takes on the properties of its counter-part in the quantum strong field limit, which has a rather different character in that the long range of the “wiggle” is destroyed by a decaying exponential envelope factor exp(−2p F| r|) , while the “wiggle” is still discernable through an anisotropic oscillatory factor cos(2 p F r z ). This is not very surprising since the effective magnetic field “mixed” parameter [( ω c E F ) · p Fr] ⪢ 1 is large enough to be associated with the quantum strong field limit, in spite of the fact that ω c E F ⪡ 1 is small in the intermediate field case under consideration. The analysis of DHVA-type oscillatory magnetic field corrections is of special physical interest, since the occurrence of such terms in conjunction with the Friedel-Kohn “wiggle” would suggest the observation of two of the most interesting specifically quantum phenomena of the quantum plasma in a single experiment. However, our investigation of the only mechanisms which could give rise to such DHVA terms shows that the Friedel-Kohn “wiggle” is in fact devoid of DHVA oscillatory effects at large distances from the shielded impurity [ p F r ⪢ 1 and ( ω c E F )p Fr ⪢ 1 ]. This analysis should serve to provide some insight into questions arising in connection with the recent work of M.E. Rensink [5] and M. L. Glasser [6].