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Constant Wall Temperature (constant + wall_temperature)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

Thermal-fluid transport phenomena in an axially rotating flow passage with twin concentric orifices of different radii

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2006
Shuichi Torii
Abstract This paper investigates the thermal fluid-flow transport phenomena in an axially rotating passage in which twin concentric orifices of different radii are installed. Emphasis is placed on the effects of pipe rotation and orifice configuration on the flow and thermal fields, i.e. both the formation of vena contracta and the heat-transfer performance behind each orifice. The governing equations are discretized by means of a finite-difference technique and numerically solved for the distributions of velocity vector and fluid temperature subject to constant wall temperature and uniform inlet velocity and fluid temperature. It is found that: (i) for a laminar flow through twin concentric orifices in a pipe, axial pipe rotation causes the vena contracta in the orifice to stretch, resulting in an amplification of heat-transfer performance in the downstream region behind the rear orifice, (ii) simultaneously the heat transfer rate in the area between twin orifice is intensified by pipe rotation, (iii) the amplification of heat transfer performance is affected by the front and rear orifice heights. Results may find applications in automotive and rotating hydraulic transmission lines and in aircraft gas turbine engines. Copyright © 2005 John Wiley & Sons, Ltd. [source]

CFD simulations of hydrodynamic/thermal coupling phenomena in a bubble column with internals

AICHE JOURNAL, Issue 9 2010
Cédric Laborde-Boutet
Abstract CFD simulations have been carried out in a full three-dimensional, unsteady, Eulerian framework to simulate hydrodynamic/thermal coupling in a bubble column with internals. A first part of the study, dedicated to the hydrodynamic/thermal coupling in liquid single-phase flows, showed that assuming constant wall temperature on the internals constitutes a reasonable approximation in lieu of comprehensive simulations encompassing shell flow and coolant flow together. A second part dealing with the hydrodynamics of gas,liquid flows in a bubble column with internals showed that a RNG k,, turbulence model formulation accounting for gas-induced turbulence was a relevant choice. The last part used these conclusions to build a hydrodynamic/thermal coupling model of a gas,liquid flow in a bubble column with internals. With a per-phase RNG k,, turbulence model and assuming constant wall temperature, it was possible to simulate heat transfer phenomena consistent with experimentally measured heat transfer coefficients. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source]

Influence of the cooling conditions on the temperature and crystallinity profiles generated in a sisal fiber reinforced-polycaprolactone/starch molded part

POLYMER COMPOSITES, Issue 5 2004
V. P. Cyras
In this work, we performed the simulation of the temperature and relative degree of crystallinity developed across the thickness of a sisal fiber reinforced-polycaprolactone/starch (30%SF-PCL/S) molded part under different cooling conditions. The non-isothermal kinetic model of Kamal and Chu (13) was used to predict the degree of crystallinity profiles. In order to obtain the temperature profiles, the energy equation was solved by treating the composite as a continuum using mass averaged physical properties. The results indicated that for cooling at a constant wall temperature, gradient-less crystallinity profiles for a wall temperature of 283 K and thicknesses lower than 10 mm are obtained. On the other hand, when cooling at a constant cooling rate, paired degree of crystallinity pieces can be obtained only for thicknesses lower than 2 mm. The continuum numerical approach used herein has the ability of predicting the optimal cooling cycle for manufacturing thick and crystallinity gradient-less SF-PCL/S parts. Polym. Compos. 25:461,469, 2004. © 2004 Society of Plastics Engineers. [source]

CFD Study of Effects of Module Geometry on Forced Convection in a Channel with Non-Conducting Fins and Flow Pulsation

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 10 2010
B. O. Olayiwola
Abstract CFD simulations were carried out to investigate the effects of the module geometry on forced convection in a rectangular channel containing series of regularly spaced non-conducting baffles with flow oscillation. The simulations were performed at constant wall temperature. Steady-flow Reynolds numbers Re in the range of 200 and 600 were studied. The results of the CFD simulations show that, for the effect fin spacing to be significant on heat transfer enhancement in finned system with oscillating flow, the oscillating flow velocity must be higher than the mean flow velocity. Superposition of oscillation yields increasing heat transfer performance with increasing fin height. Fin geometry with pyramidal shape yields highest performance in terms of the heat transfer effectiveness. [source]