Date of Award

Fall 2001

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Advisor

Park, Hyunjae

Second Advisor

Gaggioli, Richard A.

Third Advisor

Paulus, David M.

Abstract

This thesis investigates a set of correlations for pressure drop and heat transfer for turbulent fluid flow in a coiled tube system. Most of the existing correlations for single-phase pressure drop and heat transfer in the coiled tube have been developed based on the results of straight tube correlations. These correlations include different application ranges for parameters such as Reynolds number, Dean number, coil pitch and Prandtl number among others. Depending upon the experimental methods and the theoretical and/or numerical approach, the results obtained by using the (existing) correlations show some degrees of inconsistency over the ranges of parameters. A literature search revealed no existing correlations for two-phase flow in a coiled tube system. Existing correlations for condensation heat transfer in a straight tube were found to be based on a variety of dependent and independent parameters and yielded inconsistent results. Thus, it is not a simple matter to select proper correlations for analyzing the coiled tube system performance. Therefore, it is the author's intention to investigate the existing correlations by introducing Coiling Influence Factors (CIFs) for both Nusselt number and friction factor in the single-phase turbulent flow regime. These factors are defined as the ratio of the correlations for the coiled tube over those for straight tube. In order to compare and evaluate, the effects of individual parameters on the CIFs were explicitly investigated in each correlation. Furthermore, employing the method of least-squared curve fit and integrating the individual parametric effects, new proposed correlations for turbulent flow in the helically coiled tube are developed. Reducing the number of independent variables and standardizing the dependent variable for condensation heat transfer in a straight tube, the effects of individual parametric effects were explicitly investigated. Employing the method of least-squared curve fit, new proposed correlations for turbulent condensation heat transfer are proposed. Methods of utilizing the developed single-phase coiling influence factor to find a two-phase coiling influence factor were explored. The two-phase coiling influence factor can then be applied to the developed condensation heat transfer correlations for a straight tube to yield correlations for a coiled tube. Noting the empirical nature of this work, an experimental apparatus is designed that is capable of gathering data on fluid flow characteristics in a coiled tube system. It is expected that data to be obtained from this apparatus can be analyzed to verify or modify the proposed correlations.

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