A One-Dimensional Model for Cooling of Optical Fibers

2003 ◽  
Author(s):  
M. Usman Ghani ◽  
Ovidiu Marin ◽  
Martin Theriault
Keyword(s):  
Heat Transfer ◽  
Flow Regime ◽  
Forced Convection ◽  
Optical Fibers ◽  
Gas Flow ◽  
Gas Temperature ◽  
Dimensional Model ◽  
Operational Parameters ◽  
One Dimensional ◽  
Improved Design

This paper presents a one-dimensional model for the cooling of optical fibers. Heat transfer between the fiber, gas and wall, by conduction, convection, and radiation, are taken into account. The model offers advanced features such as multiple inlets and outlets. Six different pure gases or their mixtures may be used to study the effect of gas composition. The forced convection heat transfer coefficient is computed using the correlation for the forced convection in tubes and conduits. This correlation is then corrected to account for the enhanced heat transfer due to the motion of the fiber. This factor is determined from the limited experimental data available in the literature. The mathematical model consists of a system of ordinary differential equations and is solved using the LSODE solver. The model was used to study the effect of various operational parameters. The results show that at the typical conditions used in a commercial draw tower, Helium is the most effective cooling medium. A smaller diameter exchanger is more effective in cooling the fiber. More cooling is achieved if the incoming gas temperature is lower as well as if the cooler wall is kept at a lower temperature. The most critical factor is the fiber draw speed. At higher draw speeds, the residence time is low, which leads to shorter contact time for the fiber and gas to exchange heat. The effect of gas flow rate is not very significant, provided the flow regime is laminar. The turbulence flow regime is, in general, not desirable as it may cause vibrations, which is detrimental to fiber properties such as diameter and strength. Comparisons of the one-dimensional model results with the results of a two-dimensional model as well as simulations using Fluent, a commercial CFD package, are also presented. The results of these simulations may be used for an improved design of an exchanger, providing more efficient cooling of optical fiber. An improved design of exchanger will be the focus of future work in this area.

One-dimensional model for the Rijke tube

1989 ◽  
Vol 202 ◽  
pp. 83-96 ◽  
Author(s):  
C. Nicoli ◽  
P. Pelcé
Keyword(s):  
Heat Transfer ◽  
Transfer Function ◽  
Dimensional Model ◽  
Unsteady Heat Transfer ◽  
Order Unity ◽  
Rijke Tube ◽  
Thermoacoustic Instability ◽  
One Dimensional ◽  
The Stability ◽  
Stability Limits

We develop a simple model in which longitudinal, compressible, unsteady heat transfer between heater and gas is computed in the small-Mach-number limit. This calculation is used to determine the transfer function of the heater, which plays an important role in the stability limits of the thermoacoustic instability of the Rijke tube. The transfer function is determined analytically in the limit of small expansion parameter γ, and numerically for γ of order unity. In the case ρμ/cp = constant, an analytical solution can be found.

The Mechanics and Thermodynamics of Steady One-Dimensional Gas Flow

1947 ◽  
Vol 14 (4) ◽  
pp. A317-A336 ◽  
Author(s):  
Ascher H. Shapiro ◽  
W. R. Hawthorne
Keyword(s):  
Heat Transfer ◽  
Dimensional Analysis ◽  
High Speed ◽  
Gas Flow ◽  
Gas Injection ◽  
Wall Friction ◽  
Analytical Treatment ◽  
Area Change ◽  
One Dimensional ◽  
Recent Developments

Abstract Recent developments in the fields of propulsion, flow machinery, and high-speed flight have emphasized the need for an improved understanding of the characteristics of compressible flow. A one-dimensional analysis for flow without shocks is presented which takes into account the simultaneous effects of area change, wall friction, drag of internal bodies, external heat exchange, chemical reaction, change of phase, injection of gases, and changes in molecular weight and specific heat. The method of selecting independent and dependent variables, and the organization of the working equations, leads, it is believed, to a better understanding of the influence of the foregoing effects, and also simplifies greatly the analytical treatment of particular problems. Examples are given first of several simple types of flow, including (a) area change only; (b) heat transfer only; (c) wall friction only; and (d) gas injection only. In addition, examples of flow with combined effects are given, including (a) simultaneous friction and area change; (b) simultaneous friction and heat transfer; and (c) simultaneous liquid injection and evaporation. A one-dimensional analysis for flow through a discontinuity is presented, allowing for energy, shock, drag, and gas-injection effects, and for changes in gas properties. This analysis is applicable to such processes as: (a) the adiabatic normal shock; (b) combustion; (c) moisture condensation shocks; and (d) steady explosion waves.

One Dimensional Model for Rotating Channels in the Turbine System: Part 2 — Formulation and Validation for Film Condensation

2013 ◽  
Author(s):  
Murali Krishnan R. ◽  
Zain Dweik ◽  
Deoras Prabhudharwadkar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Steam Turbine ◽  
Compressible Flow ◽  
Saturation Temperature ◽  
Film Condensation ◽  
Bulk Temperature ◽  
Dimensional Model ◽  
One Dimensional

This paper provides an extension of the previously described [1] formulation of a one-dimensional model for steady, compressible flow inside a channel, to the steam turbine application. The major challenge faced in the network simulation of the steam turbine secondary system is the prediction of the condensation that occurs during the engine start-up on the cold parts that are below the saturation temperature. Neglecting condensation effects may result in large errors in the engine temperatures since they are calculated based on the boundary conditions (heat transfer coefficient and bulk temperature) which depend on the solution of the network analysis. This paper provides a detailed formulation of a one-dimensional model for steady, compressible flow inside a channel which is based on the solution of two equations for a coupled system of mass, momentum and energy equations with wall condensation. The model also accounts for channel area variation, inclination with respect to the engine axis, rotation, wall friction and external heating. The formulation was first validated against existing 1D correlation for an idealized case. The wall condensation is modeled using the best-suited film condensation models for pressure and heat transfer coefficient available in the literature and has been validated against the experimental data with satisfactory predictions.

Experimental studies of the propagation of combustion in solids

1992 ◽  
Vol 339 (1654) ◽  
pp. 387-394 ◽  
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Steady State ◽  
Chemical Kinetics ◽  
Profile Analysis ◽  
Numerical Models ◽  
Experimental Studies ◽  
Dimensional Model ◽  
Thermal Methods ◽  
One Dimensional

The application of thermal methods to the study of steady-state combustion is described. Such methods provide a route to information on heat transfer and chemical kinetics which forms a basis for the implementation of numerical models. The experimental results from thermal analysis and temperature profile analysis have been examined within the context of a simple pseudo one-dimensional model of propagation offering some confirmation of the validity of the approach.

A One-Dimensional Model for Heat Transfer in Engine Exhaust Systems

2005 ◽  
Author(s):  
Huiyu Fu ◽  
Xiangdong Chen ◽  
Ian Shilling ◽  
Steve Richardson
Keyword(s):  
Heat Transfer ◽  
Dimensional Model ◽  
Engine Exhaust ◽  
One Dimensional ◽  
Exhaust Systems

One-dimensional model on fuel penetration in diesel sprays with gas flow

2016 ◽  
Vol 17 (1) ◽  
pp. 109-118 ◽  
Author(s):  
M. Xu ◽  
Y. C. Sun ◽  
Y. Cui ◽  
K. Y. Deng ◽  
L. Shi
Keyword(s):  
Gas Flow ◽  
Dimensional Model ◽  
Diesel Sprays ◽  
One Dimensional
Sign in / Sign up

Export Citation Format

Share Document