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논문 기본 정보
- 자료유형
- 학술대회자료
- 저자정보
- 발행연도
- 2011.11
- 수록면
- 1,478 - 1,482 (5page)
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The effects on boiling performance of heating tubes coated with Carbon Nanotubes (CNT) composites were studied.
The method used in this experiment is sintering. And two test set-ups are employed. The first set-up is to test for boiling heat transfer in which optimum Cu/CNT composition will be used for the next set-up on shell and tube heat exchanger to minimize cost and time of testing and to test whether it can surpass commercially used heating tubes. During the first test different composition of Cu/CNT is tested. CNT used is based on vol. % in the following composition, 5, 10, 20 and 30 vol. % CNT. In this experiment, it was observed that the optimum composition is at 20 vol. % CNT to achieve good result because when increasing to 30 vol. % CNT the heat transfer begins to go down. This is due to the powder size getting smaller and during sintering it will coagulate resulting in cracks and the diminishing of the heat transfer performance. The increase of vol. % CNT in the composition results in the reduction of size of the powder composite. In the second test set-up for heating tubes different tubes are used including plain copper tube as base result, conventional, commercial and coated tubes with ridge and no ridge inside tube surface. It was found out that the coated tube with ridge inside is higher compared to that of commercially available tubes. This can be due to the surface modification that alters the flow inside the tube.
The raw materials for surface coatings were fabricated my mechanical alloying through use of attrition ball mill. Then after fabrication it’"s being coated on tubes by use of electrostatic spraying and then sintering.
The refrigerant used in this process is R134a. It is known that CNT has a remarkably high thermal conductivity so it is expected that using CNT as a coating material will show an enhancement on boiling performance.
The effects of CNT composition and having an inside surface ridge for sintering is being investigated and thus a conclusion has been made. Too much CNT affects the heat transfer performance of the surface and having surface modifications that alters the flow inside the tube greatly enhances overall heat transfer coefficient even up to 60%.
Scanning Electron Microscopy is being done to investigate the surface morphology, characteristics and microstructure in relation to boiling performance of the heating tubes.
The method used in this experiment is sintering. And two test set-ups are employed. The first set-up is to test for boiling heat transfer in which optimum Cu/CNT composition will be used for the next set-up on shell and tube heat exchanger to minimize cost and time of testing and to test whether it can surpass commercially used heating tubes. During the first test different composition of Cu/CNT is tested. CNT used is based on vol. % in the following composition, 5, 10, 20 and 30 vol. % CNT. In this experiment, it was observed that the optimum composition is at 20 vol. % CNT to achieve good result because when increasing to 30 vol. % CNT the heat transfer begins to go down. This is due to the powder size getting smaller and during sintering it will coagulate resulting in cracks and the diminishing of the heat transfer performance. The increase of vol. % CNT in the composition results in the reduction of size of the powder composite. In the second test set-up for heating tubes different tubes are used including plain copper tube as base result, conventional, commercial and coated tubes with ridge and no ridge inside tube surface. It was found out that the coated tube with ridge inside is higher compared to that of commercially available tubes. This can be due to the surface modification that alters the flow inside the tube.
The raw materials for surface coatings were fabricated my mechanical alloying through use of attrition ball mill. Then after fabrication it’"s being coated on tubes by use of electrostatic spraying and then sintering.
The refrigerant used in this process is R134a. It is known that CNT has a remarkably high thermal conductivity so it is expected that using CNT as a coating material will show an enhancement on boiling performance.
The effects of CNT composition and having an inside surface ridge for sintering is being investigated and thus a conclusion has been made. Too much CNT affects the heat transfer performance of the surface and having surface modifications that alters the flow inside the tube greatly enhances overall heat transfer coefficient even up to 60%.
Scanning Electron Microscopy is being done to investigate the surface morphology, characteristics and microstructure in relation to boiling performance of the heating tubes.
목차
Abstract
1. Introduction
2. Experimental Procedure
3.0 Results and Discussion
4.0 Conclusion
References
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