Mechanical Engineering ETDs

Publication Date

11-9-1973

Abstract

An analysis was made to determine a surface which has potential use in a high-heat-flux, low-temperature-drop water heat pipe evaporator. A comprehensive survey of the literature was made to determine those surfaces which had high-heat-flux potential under evaporation. A circumferentially grooved surface was selected as the surface to be analyzed. Two groove geometries were selected for analysis, rectangular and triangular. A mathematical model of the grooves was constructed in order to predict the maximum surface heat flux capability. In addition, a model of the heat transfer within the fluted surface was proposed which postulated that conduction through the wall and liquid to the liquid-vapor interface is the mechanism of heat transfer. A numerical analysis of the heat transfer in the groove was made based on the proposed model to predict evaporator film coefficients. The numerical heat transfer models were two-dimensional which used average meniscus profiles obtained from simpler, three-dimensional models. The results of the analyses were compared with experimental data and sufficient agreement was obtained to establish their validity. The computer models showed that the film coefficient of a circumferentially grooved surface non-linearly increases with increasing surface heat flux and asymptotically approaches a maximum value. In addition, it was determined that the film coefficient of rectangular grooves is independent of groove depth while that for triangular grooves decreases with increasing depth. Design equations are proposed for predicting the maximum film coefficient for a grooved surface. It was determined that deep, narrow rectangular grooves with small land widths have the largest heat flux capability for a given temperature difference; however, to attain these heat fluxes without boiling would require impractically large film coefficients. It was also shown that triangular grooves, due to their larger film coefficients, may make a more practical surface for many applications.

Degree Name

Mechanical Engineering

Level of Degree

Doctoral

Department Name

Mechanical Engineering

First Committee Member (Chair)

Karl Thomas Feldman Jr.

Second Committee Member

Glenn Frank Cochrane, Jr.

Third Committee Member

Arthur Vincent Houghton III

Fourth Committee Member

Steven Arthur Pruess

Sponsors

The Office of Naval Research Contract Number N00014-68-A-0155-0002

Document Type

Dissertation

Language

English

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