Masters Theses

An Yan

Date of Award

8-1992

Degree Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Major Professor

Edward G. Keshock

Committee Members

J. W. Hodgson

Abstract

Experimental studies of flow pattern and pressure drop for air-water and R113 liquid/vapor flow in helical and spiral coils were conducted. Five test sections, namely, helical coils having a circular cross-section and three rectangular cross-sections of different aspect ratios, along with a circular cross-section spiral tube, were utilized in the study. Five sets of the flow pattern test data — helical coil vertical upflows for both air-water and R-113 in a circular cross-section tube, R-113 in a near-square cross-section tube, and spiral horizontal outward flow of both air-water and R-113 in a circular cross-section tube — are analyzed and compared with a modified Baker map, the Taitel & Dukler map, the Choe, Weinberg, & Weisman map, and the Uddin map. None of the maps are able to adequately predict both the helical and spiral coil test data. An empirical correlation of the slug-annular transition was developed for both helical vertical-up flow and spiral horizontal outward flow which gives good agreement with the test data. Three sets of the pressure drop test data — helical coil vertical upflows for both air-water and R-113 in a circular cross-section tube, and R-113 in a near-square cross-section tube — are analyzed and compared with homogenous and Lock hart-Martinelli models. All of them predict pressure drops only approximately in the slug and developing-annular flow regions. Empirical correlations were developed to calculate the critical Reynolds number and friction factors for R-113 helical coil vertical up-flow in both circular and near-square cross-section tubes.

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