Search results for "Thermal"

Soret coefficient of nanoparticles in ferrofluids in the presence of a magnetic field

1998

Experiments on a nonstationary separation of nanometer-sized Mn0.5Zn0.5Fe2O particles of hydrocarbon-based ferrocolloids in a flat vertical thermal diffusion column are performed. By using a modified separation theory which accounts for a one-dimensional mixed (thermal and concentration) convection in the column, the Soret coefficient of lyophilized nanoparticles from the separation curves are calculated. It is shown that in a zero magnetic field particles are transferring toward decreasing temperatures. The thermal diffusion ratio αT reaches a value αT≈+20. A significant influence of a uniform magnetic field B on particle separation is observed. If B is oriented along the temperature gradi…

A mathematical simulation of high temperature induction heating of electroconductive solids

2007

The mathematical model of non-stationary coupled electromagnetic and thermal processes in polarizable and magnetizable axisymmetric electroconductive solids subjected to electromagnetic field generated by external currents is proposed. The processes parameters are connected through heat sources and temperature dependence of material characteristics. The problem is solved by finite element method. The process of induction heating of a finite steel cylinder is considered.

An MAS-based subjective model for indoor adaptive thermal comfort

2015

The achievement of high level personalized sets of comfort parameters is contemplated within the more general context of the so-called smart buildings, where people, by means of the new communication technologies, become active actors to the process of the singling out and control of the best indoor conditions. This Dynamic Intelligence approach would usefully contribute to a better energy efficient and environmental friendly management of buildings. Multi-Agent schemes are suitable tools in this aim, since they are able to manage the user-building-plant system where the adaptivity of people to the indoor conditions is suitably achieved. In this paper a contribution to a development of the …

A Constructal Law optimization of a boiler inspired by Life Cycle thinking

2018

Abstract The aim of the paper is to explore how design optimization contributes to a technology's ecological evolution. The article develops this concept through an application of Constructal Law, used to account for the “evolution” of technologies design (configuration, shape, structure, pattern, rhythm), and Life Cycle Assessment (LCA), used for quantifying the environmental impacts of the design choices. The combination of both methods assesses how technology evolution affects the environment during its life, extending the concept of evolution of design. The study is applied to a case study of a real biomass boiler. The study analyses basic case and a series of alternative scenarios opti…

Natural convection heat transfer in a partially—or completely—partitioned vertical rectangular enclosure

1991

Abstract The effect of symmetric partitions protruding centrally from the end walls of a rectangular vertical enclosure on heat transfer rates is investigated numerically. The enclosure has opposite isothermal walls at different temperatures. The Rayleigh number is varied from 10 4 to 10 7 and the aspect ratio from 0.5 to 10. The thickness of the partitions is fixed and equal to one tenth of the width of the enclosure. Their non-dimensional length ( L / H ) is varied from 0 (non-partitioned enclosure) to 0.5 (two separate enclosures). The effect of different thermal boundary conditions at the end walls and at the partitions is included in the investigation.

Effect of laser radiation upon heat and mass transfer in two-component elastic semitransparent layer

2004

Abstract In present paper the effect of the correlation between spectral radiative characteristics of different lasers and absorptive characteristics of laser irradiated two-component elastic semitransparent material upon coupled thermal, diffusive and elastic processes in the layer is examined. Irradiated material is supposed to consist of elastic matrix and gaseous admixture. Investigations are carried out within the model applied early to the study of mentioned coupled processes in the layer subjected to thermal infrared radiation. Calculations were carried out for four different infrared lasers. Peculiarities of heat and admixture mass transfer caused by laser irradiation are establishe…

Optofluidic microconvection with magnetic nanoparticles: Novel interaction of thermal diffusion and magnetic field

2021

Abstract Light-matter interactions are exploited in many applications, whereas superparamagnetic nanoparticles allow to introduce magnetic field control in diverse fluid environments. We study the structure of laser-induced thermal lens in thin layers of ferromagnetic colloid and predict significant magnetoconvective motion around the beam spot. It was found that localized heating depletes/accumulates magnetic nanoparticles in the beam-spot by thermal diffusion and collective magnetic interactions of nanoparticles produce strong microconvective currents. This mode of mass transport can be controlled by magnetic field. We expect the novel magnetosolutal microconvective coupling, which we des…

Thermal and Hydrodynamic Analysis of the Melting Process in the Cold Crucible Using 3D Modeling

2008

On natural convection in a single and two zone rectangular enclosure

1992

Abstract Convective heat transfer was investigated numerically for rectangular enclosures both undivided and divided in two zones by a vertical partition, and having opposite isothermal walls at different temperatures. The aspect ratio was varied from 0.1 to 16 and the Rayleigh number from 3.5 ∗ 10 3 to ∗ 10 7 (non-partitioned enclosures) and from 1.0 ∗ 10 5 to 1.6 ∗ 10 8 (partitioned enclosures). The thickness and conductivity of the partition were varied. The end wall thermal boundary conditions were adiabatic or LTP (Linear Temperature Profile). The continuity, momentum and energy equations for a 2-D laminar steady flow were solved under the Boussinesq approximation by using a finite-dif…

A Solar Pond for Feeding a Thermoelectric Generator or an Organic Rankine Cycle System

2017

The world energy demand is continuously growing, which means an increase in consumption for all modern fuels or stronger effort on the development and improvement of renewable technologies. Moreover, Developing Countries claims more energy and they have often wide unutilized or unusable lands. The solar energy represents a useful opportunity for these Countries. The Solar Pond is both a solar collector and a thermal storage for long period and is suitable to use in wide sunny areas. Solar pond technology is able to supply heat for several applications requiring low-grade thermal energy or for electrical power production. In order to produce electrical energy from solar ponds it is necessary…