Search results for " heat"
showing 10 items of 830 documents
Numerical investigation of thermomagnetic convection in a heated cylinder under the magnetic field of a solenoid
2011
The main objective of this paper is the numerical investigation of the process of thermomagnetic convection of a special temperature sensitive ferrofluid. The fluid is studied in a cylindrical domain, with constant temperatures on the top and bottom ends and adiabatic boundary conditions on the sidewalls. The thermomagnetic convection is generated by a non-uniform constant magnetic field of a solenoid, which is placed in a hollow area inside the domain. It has been found that the efficiency of convective heat transfer in such a set-up can be increased up to sevenfold by magnetic field within the studied range of parameters.
Non-dimensional groups for air solar collectors
2003
Abstract The radiant heat captured by a passive air solar collector during a day divides itself into three fractions, of which one is transmitted by conduction to the backside, one is collected by the convective air flow, and the last one is lost through glazing. Some calculations of heat transfer taking place in a collector in 24-h periodic regime have been done with different combinations of the values of the relevant thermo-physical variables. Calculation results were the fractions of energy transmitted to the internal room through the wall by conduction and with the air flow by convection, and lost through the glazing. The results give rise to a correlation among non-dimensional variabl…
Influence of Skin Depth on Convective Heat Transfer in Induction Heating
2017
International audience; We investigate convection driven by induction heating of a horizontal fluid layer using direct numerical simulations (DNS). This problem is of particular interest in the context of nuclear severe accident mastering. In a real severe accident, the molten core is subjected to homogeneous internal sources resulting from nuclear disintegrations. This situation is mimicked in the laboratory using induction heating as the internal source. In induction heating, however, heat sources are localized in the skin layer. Consequently, this concentration of heat may modify the flow and wall heat transfer compared to the case of homogeneous internal sources. DNS are carried out for…
Controlling melt convection—an innovation potential for concerted microstructure evolution of Nd-Fe-B alloys
2005
The solidification process and the resulting microstructure of Nd-Fe-B alloys in consideration of melt convection has been investigated experimentally with a specially designed forced crucible rotation technique. Samples were subjected to well-defined forced rotation and vibration, respectively, during induction heating and solidification. A concerted microstructure evolution is possible by enhancement or suppression of the melt convection. As a result, the microstructure pattern, mainly the volume fraction of the soft magnetic a-Fe phase, vary strongly with the strength of the internal flow motion. A distinct reduction of the a-Fe volume fraction in samples with strong melt rotation was ob…
Heat transfer calculation in a free convection air solar collector
1998
This paper deals with the free convective air flow developing in a vertical channel with a rectangular cross-section heated on one side. The channel geometric and physical properties are such as to simulate an air solar collector suitable for building heating. A calculation method that can be applied to the transient combined heat transfer by conduction through the wall and by convection from the wall to the air stream is presented. The conduction across the wall is computed with a one-dimensional, time-dependent finite difference scheme, with convective boundary conditions at both wall surfaces. For the free convective flow along the channel, the air flow rate and the mean convective coeff…
Study of a water-cooled convective divertor prototype for the DEMO fusion reactor
2000
The plasma facing components of a fusion power reactor have a large impact on the overall plant design, its performance and availability and on the cost of electricity. The present work concerns a study of feasibility for a water-cooled prototype of the convective divertor component of the DEMO fusion reactor. The study has been carried out in two steps. In the first one thermal-hydraulic and neutronic parametric analyses have been performed to find out the prototype optimized configuration. In the second step thermo-mechanical analyses have been carried out on the obtained configuration to investigate the potential and limits of the proposed prototype, with a particular reference to the ma…
Modeling of Melt Flow and Heat Transfer in Stationary Gas Tungsten Arc Welding with Vertical and Tilted Torches
2021
A 3D numerical simulation was conducted to study the transient development of temperature distribution in stationary gas tungsten arc welding with filler wire. Heat transfer to the filler wire and the workpiece was investigated with vertical (90°) and titled (70°) torches. Heat flux, current flux, and gas drag force were calculated from the steady-state simulation of the arc. The temperature in the filler wire was determined at three different time intervals: 0.12 s, 0.24 s, and 0.36 s. The filler wire was assumed not to deform during this short time, and was therefore simulated as solid. The temperature in the workpiece was calculated at the same intervals using heat flux, current flux, ga…
Analysis of variability in divergence and turn-over induced by three idealized convective systems with a 3D cloud resolving model
2020
Abstract. The sensitivity of upper tropospheric and lower stratospheric convective outflows and related divergence fields is analysed using an ensemble of cloud resolving model (CM1) simulations in LES-mode including various physically manipulated simulations for three different convective systems initialized with an idealized trigger. The main goal of this study is to assess to what extend the divergence field depends on cloud microphysical processes, the mode of convection and on the processes of convective momentum transport and moist static energy redistribution. We find that latent heat release (representing the microphysical uncertainty) plays an essential role by explaining much of m…
A self-consistent 2-D model for the dip angle ofmantle downflow beneath an overriding continent
1999
Abstract We demonstrate how the inclination of descending mantle flow is affected by thepresence of a continent overriding the downwelling zone. The mantle is modelled by a fluidhaving a temperature- and pressure-dependent viscosity which describes a low viscosityasthenosphere and a higher viscosity lower mantle. The fluid occupies a square x:y=10:1 boxheated from below. In the absence of overlying continents thermal convection sets in with colddownwellings being nearly vertical. A continent is placed on the convecting mantle and starts todrift. The continent is assumed to be a thick rigid plate. We consider models of two types. Model1 involves a free-floating continent. The continent is pu…
Onset of Convection in an Inclined Anisotropic Porous Layer with Internal Heat Generation
2019
The onset of convection in an inclined porous layer which is heated internally by a uniform distribution of heat sources is considered. We investigate the combined effects of inclination, anisotropy and internal heat generation on the linear instability of the basic parallel flow. When the Rayleigh number is sufficiently large, instability occurs and a convective motion is set up. It turns out that the preferred motion at convection onset depends quite strongly on the anisotropy ratio, &xi