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전기도금계를 활용한 수직관내 혼합대류 열전달에 관한 연구

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Alternative Title
A Study on the Mixed Convection Heat Transfer in a Vertical Cylinder Using Electroplating System
Abstract
Hydrogen economy has drawn public attentions as a promising future energy source. Hydrogen is a non-petroleum-based, non-toxic, renewable and clean burning energy source. Hydrogen is the secondary energy, which means that it is produced by consuming the first energy such as coal, gas, petroleum etc. This again means that it is clean so long as it is produced by clean methods.
One of the promising production methods of hydrogen is to use the heat from an HTGR(High Temperature Gas-cooled Reactor), a next generation nuclear reactor for a safe and reliable operation as well as for efficient and economic generation of energy.
The knowledge of detailed heat transfer phenomena in gaseous phase emerges as an important factor for HTGR, where buoyancy effect plays a significant role. Large and expensive test facilities are to be constructed to assess the detailed mixed convection phenomena.
However, using analogy concept, heat transfer system can be transformed to mass transfer system and vice versa. If a simple mass transfer system could be devised, and the experimental solution from that system could be obtained, then this could theoretically lead to a solution for a similar heat transfer system.
In this study, a copper electroplating system was selected as the mass transfer system. A copper electroplating system with limiting current technique has a good advantage to simulate heat transfer system as mass transfer coefficient, analogous with heat transfer coefficient, can be directly obtained from the information of the bulk concentration and electric current between electrodes.
This study simulated the mixed convective heat transfer phenomena in a vertical cylinder using copper electroplating system. The mixed convection phenomenon is observed when the forced and natural convections are of comparable magnitudes in one system. The mixed convection is classified as laminar and turbulent flows depending on the exchange mechanism and also as buoyancy aided and buoyancy opposed flows depending on the directions of forced flows with respect to the buoyance forces.
For a laminar flow, the heat transfer rate of buoyancy aided flow is larger than the corresponding forced convection heat transfer due to the increased flow velocity while the heat transfer rate of buoyancy opposed flow is smaller. However for a turbulent flow, the buoyancy opposed flow shows higher heat transfer rates than corresponding forced convective flow due to the increased turbulent production and the buoyancy aided flow shower lower heat transfer rates due to laminarization.
Mixed convection heat transfer in a vertical cylinder with aiding flow and opposing flow studied experimentally for Reynolds numbers ranging from 4,000 to 10,000 with a constant Grashof number 6.2X109 and Prandtl number about 2000. The experimental results reproduced the trend of mixed convection heat transfer phenomena in a turbulent situation and agree well with the study performed by Y. Parlatan(1996).
The analogy experimental method successfully simulates the mixed convection heat transfer system and seems to be a useful tool for heat transfer studies for HTGR as well as the systems with high buoyancy condition and high Prandtl number fluid, as the electroplating method not only provides useful information regarding heat transfer but also has a cost-effective advantage over any other comparable experimental method.
Author(s)
高鳳振
Issued Date
2008
Awarded Date
2008. 8
Type
Dissertation
URI
http://dcoll.jejunu.ac.kr/jsp/common/DcLoOrgPer.jsp?sItemId=000000004425
Alternative Author(s)
Ko, Bong-Jin
Department
대학원 에너지공학과
Advisor
鄭釩津
Table Of Contents
I. 서 론 1

II. 이론적 배경 4
1. 수직관내에서의 혼합대류 4
1) 수직관 내에서의 대류 개념(Mechanism) 4
1.1) 강제대류 4
1.2) 자연대류 5
1.3) 혼합대류 6
2) 수직관 내 층류 혼합대류 9
2.1) 기존연구(Previous studies) 10
3) 수직관 내 난류 혼합대류 11
3.1) 순부력유동(Aiding flow) 11
3.2) 역부력유동(Opposing flow) 12
3.3) 부력효과에 따른 전단응력과 속도성분 15
3.4) 입구효과 16
3.5) 난류 운동에너지 17
4) 기존연구 19
5) 상관식(Correlations) 22
5.1) 강제대류 22
5.2) 혼합대류 22
6) 부력계수(Bouyancy coefficient) 24
2. 열전달과 물질전달의 상사성 27
1) 상사성 27
2) 열전달과 물질전달의 상사성 27
3. 전기도금계 30
1) 물질전달 구조 30
2) 한계전류 기법 34
3) 주요 무차원수 및 물성치 37

III. 실험장치 및 방법 40
1. 예비실험 40
1) 강제대류 실험배경 및 개요 40
2) 강제대류 실험장치 구성 41
3) 실험범위행렬(Test matrix) 42
4) 실험방법 43
5) 실험결과 및 고찰 44
2. 실험장치 구성 47
3. 실험방법 53
1) 실험조건 53
2) 실험절차 53
3) 전압인가방법 54

IV. 실험결과 및 고찰 56
1. 실험범위와 실험범위행렬(Test matrix) 56
2. 순부력유동 (Aiding flow) 58
1) Re 수에 따른 비교 58
2) Bo 수에 따른 비교 59
3. 역부력유동 (Opposing flow) 63
1) Re 수에 따른 비교 63
2) Bo 수에 따른 비교 64
4. 기존 데이터와의 비교 66

V. 결 론 68

참 고 문 헌 70
Degree
Master
Publisher
제주대학교 대학원
Citation
高鳳振. (2008). 전기도금계를 활용한 수직관내 혼합대류 열전달에 관한 연구
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Faculty of Applied Energy System > Energy and Chemical Engineering
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