Numerical and Experimental Investigations of Momentum and Heat Transfer in Microchannels

2008 ◽  
Author(s):  
M. Favre-Marinet ◽  
S. Drobniak ◽  
D. Asendrych ◽  
G. Gamrat ◽  
M. Niklas
Keyword(s):  
Heat Transfer ◽  
Hydraulic Properties ◽  
Flow Model ◽  
Experimental Investigations ◽  
Microchannel Flow ◽  
The Third ◽  
Numerical Studies ◽  
Continuum Flow ◽  
Momentum And Heat Transfer

The paper presents the results of a research performed during recent years at LEGI Grenoble with joint participation of CzUT researchers. The special attention is devoted to experimental and numerical studies devoted to three cases involving various aspects of microchannel flow physics (range of microchannel sizes corresponds to the classification of Kandlikar [19]). The first aspect is related to hydraulic properties of a network of parallel triangular microchannels, where experimental investigations revealed the rapid increase of pressure drop for Re exceeding value of 10. The second aspect of the research was the influence of surface roughness, which was investigated both experimentally and numerically for periodically and randomly distributed surface elements. The third research case was devoted to the numerical modelling of heat transfer. As a result, experimental and numerical analyses showed that there was no scale effect for the microchannels considered, i.e. the relevance of the classical continuum flow model was confirmed.

Experimental investigations of momentum and heat transfer in pulse detonation engines

2002 ◽  
Vol 29 (2) ◽  
pp. 2847-2854 ◽  
Author(s):  
Jiro Kasahara ◽  
Kouki Takazawa ◽  
Takakage Arai ◽  
Yu Tanahashi ◽  
Shingo Chiba ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Investigations ◽  
Pulse Detonation Engines ◽  
Pulse Detonation ◽  
Momentum And Heat Transfer

Eddie Leonardi Memorial Lecture: “Natural Convection From Earth to Space”

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Victoria Timchenko
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Solutions ◽  
Numerical Study ◽  
Three Dimensional ◽  
Experimental Investigations ◽  
Memorial Lecture ◽  
Numerical Studies ◽  
Fluid Properties ◽  
Microgravity Conditions

This lecture is dedicated to the memory of Professor Eddie Leonardi, formerly International Heat Transfer Conference (IHTC-13) Secretary, who tragically died at an early age on December 14, 2008. Eddie Leonardi had a large range of research interests: he worked in both computational fluid dynamics/heat transfer and refrigeration and air-conditioning for over 25 years. However starting from his Ph.D. ‘A numerical study of the effects of fluid properties on natural convection’ awarded in 1984, one of his main passions has been natural convection and therefore the focus of this lecture will be on what Eddie Leonardi has achieved in numerical and experimental investigations of laminar natural convective flows. A number of examples will be presented which illustrate important difficulties of numerical calculations and experimental comparisons. Eddie Leonardi demonstrated that variable properties have important effects and significant differences occur when different fluids are used, so that dimensionless formulation is not appropriate when dealing with flows of fluids with significant changes in transport properties. Difficulties in comparing numerical solutions with either numerically generated data or experimental results will be discussed with reference to two-dimensional natural convection and three-dimensional Rayleigh–Bénard convection. For a number of years Eddie Leonardi was involved in a joint US-French-Australian research program—the MEPHISTO experiment on crystal growth—and studied the effects of convection on solidification and melting under microgravity conditions. Some results of this research will be described. Finally, some results of experimental and numerical studies of natural convection for building integrated photovoltaic (BIPV) applications in which Eddie Leonardi had been working in the last few years will be also presented.

Molecular-to-Large-Scale Heat Transfer With Multiphase Interfaces: Current Status and New Directions

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Raj M. Manglik ◽  
Milind A. Jog
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Film Coating ◽  
Spray Cooling ◽  
Current Status ◽  
Experimental Investigations ◽  
Interfacial Behavior ◽  
Two Phase ◽  
New Directions ◽  
Momentum And Heat Transfer

The scientific understanding of multiphase interfaces and the associated convective mass, momentum, and heat transport across and along their boundaries, provide the fundamental underpinnings of the advancement of boiling heat transfer, two-phase flows, heat pipes, spray cooling, and droplet-film coating, among many other engineering applications. Numerous studies have tried to characterize the interfacial behavior and model their mechanistic influences either directly or implicitly via parametric experimental investigations and/or simulations. The goal of advancing our understanding as well as developing generalized, perhaps “universal,” and more accurate phenomenological or mechanistic correlations, for predicting mass, momentum, and heat transfer, continues to engage the worldwide research community. A collection of some such current investigations that are representative of both basic and applied issues in the field is presented in this special issue of the Journal of Heat Transfer.

Modeling of Intensified Heat Exchangers with Different Fluid Viscosities

2021 ◽  
Vol 628 (6) ◽  
pp. 44-50
Author(s):  
A. G. Laptev ◽  
◽  
E. A. Lapteva ◽  
A. A. Akhmitshin ◽  
◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Mathematical Model ◽  
Heat Exchangers ◽  
Transformer Oil ◽  
Design Parameters ◽  
Experimental Investigations ◽  
Industrial Enterprises ◽  
Wide Range ◽  
Momentum And Heat Transfer

Equations are derived for mean friction and heat transfer coefficients to solve problems of updating industrial plants for getting oil fractions based on application of approximate method of modeling momentum and heat transfer in heat exchangers with surface intensifiers. The Dyssler and Van-Driest turbulent boundary-layer model is used for the turbulent viscosity function for a flat smooth wall. An equation for the Stanton number is written using Chilton-Colborne hydrodynamic analogy and agreement with the known analogy is shown. Identical local properties of turbulent motion in a boundary layer on a plate and in a near-wall layer of a tube and the conservative properties of the laws of friction and heat transfer to turbulences, which are taken account of parametrically, are used for modeling momentum and heat transfer in channels with surface intensifiers. An equation for mean tangential stress in channels with intensifiers and, further, an equation for the Nusselt number is derived using a dissipative model. The results of calculations and comparison with the known experimental investigations are given for tubes with surface wire inserts, with spiral finning and rectangular projections for transformer oil at Reynolds numbers 200 < Re <2000. Thus, the adequacy of the developed mathematical model is proved in a wide range of operating and design parameters and thermophysical properties of fluids and gases. Further, the hydraulic resistance of the channel is the key experimental information about the object of modeling. Examples of use of mathematical model for designing and commissioning heat exchangers in petroleum fuels fractionating plants at industrial enterprises in the Russian Federation and abroad are given.

scholarly journals Unsteady natural convection in micropolar nanofluids

2014 ◽  
Vol 35 (3) ◽  
pp. 155-170 ◽  
Author(s):  
Kazimierz Rup ◽  
Konrad Nering
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Single Phase ◽  
Volume Fraction ◽  
Cu Nanoparticles ◽  
Small Particles ◽  
The Third ◽  
Water Based ◽  
Momentum And Heat Transfer ◽  
Unsteady Natural Convection

Abstract This paper presents the analysis of momentum, angular momentum and heat transfer during unsteady natural convection in micropolar nanofluids. Selected nanofluids treated as single phase fluids contain small particles with diameter size 10-38.4 nm. In particular three water-based nanofluids were analyzed. Volume fraction of these solutions was 6%. The first of the analyzed nanofluids contained TiO2 nanoparticles, the second one contained Al2O3 nanoparticles, and the third one the Cu nanoparticles.

ABOUT THE PROBLEM OF CLASSIFICATION OF THE CONCEPTS OF INFORMATICS STUDIED AT SECONDARY SCHOOL

2018 ◽  
pp. 4-7
Author(s):  
S. I. Zenko
Keyword(s):  
Secondary School ◽  
Foreign Language ◽  
Computer Science ◽  
Parts Of Speech ◽  
The Third ◽  
The Cross ◽  
Definition Of

The article raises the problem of classification of the concepts of computer science and informatics studied at secondary school. The efficiency of creation of techniques of training of pupils in these concepts depends on its solution. The author proposes to consider classifications of the concepts of school informatics from four positions: on the cross-subject basis, the content lines of the educational subject "Informatics", the logical and structural interrelations and interactions of the studied concepts, the etymology of foreign-language and translated words in the definition of the concepts of informatics. As a result of the first classification general and special concepts are allocated; the second classification — inter-content and intra-content concepts; the third classification — stable (steady), expanding, key and auxiliary concepts; the fourth classification — concepts-nouns, conceptsverbs, concepts-adjectives and concepts — combinations of parts of speech.

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