Search results for " Heat transfer"
showing 10 items of 63 documents
Characterization of membrane-spacer industrial distillers using thermochromic liquid crystals
2011
Experimental Analysis via Thermochromic Liquid Crystals of the Temperature Local Distribution in Membrane Distillation Modules
2013
A reliable and optimized design of channels for Membrane Distillation (MD) requires knowledge of local temperature distributions within the module. This information is essential to measure the temperature polarization, choice the module configuration (net spacer features, channel size, etc) providing the best process performance. Notwithstanding such crucial aspects, only few studies have been devoted to the experimental characterization of MD channels and none of them includes data on the local temperature distribution. In the present work, an experimental technique based on the use of Thermochromic Liquid Crystals (TLCs) and digital image processing, previously proposed by the authors (Pi…
Application of Mathematical Models in Analysis of Heat Losses in the Buildings
2006
Physical model of heat balance for separate living room is discussed, which allows to analyse the distributions of the flow of air and temperature depending on the physical conditions and geometry. The model enables to choose the optimal surface area of building elements and their properties in order to decrease the heat losses and improve the conditions of thermal comfort. Room with bounding constructions and real dimensions is modelled that helps to understand the peculiarities of heat transfer process in the room as well as distribution of various characteristic quantities and their dependence on the different conditions. Multiple parameters are varied in 2D calculations and their influe…
Thermodynamic approach to vortex production and diffusion in inhomogeneous superfluid turbulence
2014
In this paper, we use a non-equilibrium thermodynamic framework to generalize a previous nonlocal model of counterflow superfluid turbulence to incorporate some new coupled terms which may be relevant in the evolution of inhomogeneous vortex tangles. The theory chooses as fundamental fields the energy density, the heat flux, and the averaged vortex line length per unit volume. The constitutive quantities are assumed to depend on the fundamental fields and on their first spatial derivatives, allowing us to describe thermal dissipation, vortex diffusion and a new contribution to vortex formation. The restrictions on the constitutive relations are deduced from the entropy principle, using the …
On the thermomechanical behavior of the European target assembly design of IFMIF-EVEDA lithium test loop under start-up transient scenarios
2013
Uncoupled thermomechanical transient analyses have been carried out to investigate the behavior of IFMIF-EVEDA lithium test loop bayonet backplate target assembly under two selected start-up transient operational scenarios. The first transient scenario considered foresees that the target assembly, starting from the initial uniform temperature of 50 C, is heated up uniquely by convective heat transfer with lithium, flowing from inlet to outlet nozzle at its reference nominal temperature and pressure, until its nominal steady state thermal field distribution is reached. The second transient scenario foresees, more realistically, that the target assembly, starting from the uniform temperature …
Inhomogeneous vortex tangles in counterflow superfluid turbulence: flow in convergent channels
2016
Abstract We investigate the evolution equation for the average vortex length per unit volume L of superfluid turbulence in inhomogeneous flows. Inhomogeneities in line density L andincounterflowvelocity V may contribute to vortex diffusion, vortex formation and vortex destruction. We explore two different families of contributions: those arising from asecondorder expansionofthe Vinenequationitself, andthose whichare notrelated to the original Vinen equation but must be stated by adding to it second-order terms obtained from dimensional analysis or other physical arguments.
Stationary heat flux profile in turbulent helium II in a semi-infinite cylindrical channel
2012
In this paper we determine a set of solutions for a system of partial dif- ferential equations describing stationary heat flux in a semi-infinite cylindrical channel filled with turbulent superfluid helium. This study uses a continuous model for liquid helium II, derived from Extended Thermodynamics, in which the heat flux q is a fundamental variable. The influence of the vortex line den- sity on the radial distribution of the heat flux is especially discussed.
Investigation of Effective Thermal Conductivity Aluminum Foams
2012
Abstract The study on the heat transfer mechanisms through the aluminium foam with a fluid in void cells of that foam was reported in this paper. Based on laboratory experiments, the effective thermal conductivity coefficient values were found for various type aluminum foams which had been filled up with a gas or a liquid. The significant effects were observed from porosity as well as from metal and fluid properties on the heat transfer capacity in a foam-fluid system. The convective heat transfer phenomenon was identified to occur in the foam cellular space. That phenomenon affected the effective thermal conductivity much more for liquid-filled foams than for gas-filled foams.
Thermal conductivity of disperse insulation materials and their mixtures
2017
Development of new, more efficient thermal insulation materials is a key to reduction of heat losses and contribution to greenhouse gas emissions. Two innovative materials developed at Thermeko LLC are Izoprok and Izopearl. This research is devoted to experimental study of thermal insulation properties of both materials as well as their mixture. Results show that mixture of 40% Izoprok and 60% of Izopearl has lower thermal conductivity than pure materials. In this work, material thermal conductivity dependence temperature is also measured. Novel modelling approach is used to model spatial distribution of disperse insulation material. Computational fluid dynamics approach is also used to est…
Effect of material and geometric parameters on natural convection heat transfer over an eccentric annular-finned tube
2019
In this work, the performance of an eccentric annular finned tube heat exchanger under natural convection conditions has been investigated numerically. The objective of the study is to analyse the ...