Effects of electric field on internal convective two-phase flow heat transfer and pressure drop /
Electrohydrodynamic (EHD) phenomena take place when the imposed electric fields are coupled with the fluid flow fields. The EHD phenomena can be used to significantly enhance the internal two-phase flow heat transfer. The EHD technique features several distinct advantages over conventional methods,...
| Main Author: | |
|---|---|
| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
2002.
|
| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=764789641&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Electrohydrodynamic (EHD) phenomena take place when the imposed electric fields are coupled with the fluid flow fields. The EHD phenomena can be used to significantly enhance the internal two-phase flow heat transfer. The EHD technique features several distinct advantages over conventional methods, such as the ability to be controlled, significant heat transfer enhancement, no moving parts, and low energy consumption. However, the literature review shows that only a few researchers have investigated the effects of the electric fields on the internal convective two-phase flow in the past. Many questions are still remaining due to the complex interactions of the interdependent variables. The purpose of this research is to obtain further fundamental understanding of the internal convective two-phase flow in the presence of the radial electric field. Efforts have been made to re-evaluate the existing Helmholtz and Kelvin EHD force expressions, to experimentally investigate the EHD-enhanced internal convective condensation, to qualitatively understand the cause and conditions of the EHD heat transfer suppression during the convective boiling using the linear instability theory, and to develop an analytical model to properly predict the magnitude of the EHD heat transfer enhancement and pressure drop penalty based on the turbulence analysis. Limited efforts have also been made to investigate the effects of electric fields on the film condensation, which can not be explained by the turbulence analysis. The re-evaluation of the existing EHD force expressions indicated that the Kelvin equation represented the exact electric force density. The Helmholtz and Kelvin equations can become identical if combined with their associated pressure terms. The linear instability analysis qualitatively showed that the EHD heat transfer suppression was due to the flow regime transition and the EHD extraction force at the liquid/vapor interface tended to destabilize the liquid film. The experimental data further verified that the EHD technique could significantly enhance the internal convective condensation. The predictions of the theoretical model based on the turbulence analysis were in agreement with the experimental data from this research and the other sources. |
|---|---|
| Item Description: | Vita. "Major Subject: Mechanical Engineering". |
| Physical Description: | xxii, 221 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 182-197). |