漸縮漸擴微流道沸騰熱傳研究｜國立清華大學博碩士論文庫

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研究生：	盧俊庭 Chun-Ting Lu
論文名稱：	漸縮漸擴微流道沸騰熱傳研究 A Study of Boiling Heat Transfer in Converging and Diverging microchannels
指導教授：	潘欽 Chin Pan
口試委員:
學位類別：	碩士 Master
系所名稱：	原子科學院 - 工程與系統科學系 Department of Engineering and System Science
論文出版年：	2005
畢業學年度：	93
語文別：	英文
論文頁數：	134
中文關鍵詞：	沸騰熱傳、雙相流譜、氣泡動力學、壓降、氣泡脫離半徑、氣泡成長速率、氣泡脫離頻率
外文關鍵詞：	Boiling heat transfer, two-phase flow, bubble dynamics, pressure drop, Bubble departure radius, Bubble growth rate, Bubble departure frequency
相關次數：	點閱：2 下載：0
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摘要
本研究主要探討平均水力直徑為70.6μm跟116μm的漸縮漸擴微流道的沸騰熱傳跟雙相流譜。並分析加熱功率、體積流量跟平均水力直徑對於熱傳遞係數、壓降、氣泡動力學和雙相流譜的影響。
研究結果顯示漸縮微流道的氣泡成長速率跟氣泡脫離頻率比漸擴微流道慢，而氣泡脫離半徑則是大於漸擴微流道氣泡脫離半徑。在流譜的觀察上發現相對於漸擴微流道，漸縮微流道有明顯激烈的回流現象並觀察到一個新的流譜，稱之為蛇行流。沸騰發生前，熱通率跟熱傳遞係數會隨著流量的增加而緩慢增加；沸騰發生後，熱通率跟熱傳遞係數會有顯著上升現象。研究結果也顯示在沸騰發生後，流量對於熱通率跟熱傳遞係數沒有明顯的效應。在單相流動下，壓降會隨溫度升高而降低；在雙相流動時，壓降反而會隨溫度升高而快速地增加。研究結果也顯示在雙相流動時，流量對於壓降沒有明顯的效應。本研究最後比較漸縮微流道和漸擴微流道於沸騰熱傳和壓降上有何差異。結果顯示在單相壓降時，兩者並無太大差異，但是雙相流動時，漸擴微流道的壓降會比漸縮微流道的壓降小，且在相同的條件下，漸擴微流道的沸騰熱傳性能比漸縮微流道好，也就是說漸擴微流道有比較高的熱通率跟熱傳遞係數。

Abstract
The present study focuses on two-phase flow visualization and boiling heat transfer for deionized water flowing in the converging and diverging microchannel with a mean hydraulic diameter of 70.6μm and 116μm, respectively. The effects of the imposed wall heat flux, volume flow rate and mean hydraulic diameter on the boiling heat transfer coefficient, pressure drop, bubble dynamics and two-phase flow pattern are analyzed in detail.
Experimental results indicate that the bubble growth rate and the bubble departure frequency in the converging microchannels are smaller than that in the diverging microchannels. On the other hand, the bubble departure radius in the converging microchannels is bigger than that in the diverging microchannels. Observation of two-phase flow pattern indicates that the flow reversal in the converging microchannels is more violent than that in the diverging microchannels. The new flow pattern is found, called snake flow in the diverging microchannel with a mean hydraulic diameter of 70.6μm and under certain conditions. For single-phase flow, the heat flux and the heat transfer coefficient increase slowly with the flow rate. After boiling begins, heat flux and the heat transfer coefficient are elevated significantly. The mass flow rate has little effect in boiling heat transfer. For single-phase flow, the pressure drop decreases with increasing the wall temperature (or heat flux) increases with the wall temperature. On the other hand, the two-phase pressure drop increases rapidly with the wall temperature (or heat flux). The effect of flow rates does not affect in two-phase is found to be insignificant. Comparison of the heat fluxes and heat transfer coefficients between converging and diverging microchannels with DH=116μm and 70.6μm, respectively, show that the diverging microchannel presents better performance in boiling heat transfer than that of converging microchannels. Comparison of the pressure drop between the converging and diverging microchannel with DH=116μm and 70.6μm, respectively, indicates that there is little different in single-phase pressure drop. On the other hand, the two-phase pressure drop after boiling begins in the converging microchannel is higher than that in the diverging microchannel. It is demonstrated that boiling heat transfer performance of the diverging microchannel is better than that of the converging microchannel with the same mean hydraulic diameter and under similar operating conditions.

Table of Contents
Abstract    Ⅰ
Table of Contents    Ⅲ
List of Tables    Ⅵ
List of Figures    Ⅷ
1    Introduction    1
    1.1    Background    1
    1.2     Literature Review    3
        1.2.1 Rectangle Microchannels    3
        1.2.2 Trapezoid Microchannels    7
        1.2.3 Triangle Microchannels    9
        1.2.4 Circular Microchannels    12
    1.3    Objectives    14
    1.4    Thesis Scope    15
2    Experimental Apparatus, Procedures and the Fabrication of Microchannels    16
    2.1    Experimental Apparatus    16
    2.2    Measurement and Acquisition Systems    19
            2.2.1 Measurement System    19
            2.2.2 Acquisition System    20
    2.3    Experimental Procedures    21
    2.4    The Fabrication of Microchannels    23
            2.4.1 The Principles of the Fabrication Processes    26
    2.5    Surface Roughness of Microchannel Walls    27
    2.6    SEM pictures    30
3    Heat transfer and Uncertainty Analysis    32
    3.1    Heat transfer Analysis    32
    3.2    Uncertainty Analysis    42
4    Results and Discussion    53
    4.1    Bubble Dynamics    53
            4.1.1 Bubble Growth Process    53
            4.1.2 Bubble Growth Rate    55
            4.1.3 Bubble Departure Size    74
            4.1.4 Bubble Departure Frequency    79
    4.2    Two-Phase Flow Patterns    83
            4.2.1 Bubbly Flow    83
            4.2.2 Slug Flow    88
            4.2.3 Annular Flow    91
            4.2.4 Snake Flow    93
            4.2.5 Reversal Flow    99
    4.3    The Boiling Heat Transfer Analysis    102
    4.4    The Pressure Drop Analysis    113
5    Conclusion    121
Reference    124
Appendix A: Mettler Toledo    131
Appendix B: Zoom Microlens Systems    132
Appendix C: The amplification factor of Zoom Microlens Systems    134

                                

Reference
[1] Intel product information, http://www.intel.com/.
[2] I. Mudawar, “Assessment of High-Heat-Flux Thermal Management Schemes”, IEEE Transactions on Components and Packaging Technologies”, vol. 24, 2001, 122-141.
[3] M.J. Ellsworth, “Chip power density and Module cooling technology projections for the current decade”, inter Society Conference on Thermal Phenomena”, 2004, 707-708.
[4] X.F. Peng, H. Y. Hu and B.X. Wang, “Boiling nucleation during liquid flow in microchannels”, International Journal of heat and mass Transfer, vol. 41, 1997, 101-106.
[5] L. Zhang, J.M. Koo, L. Jiang, K.E. Goodson, J.G. Santiago and T.W. Kenny, “Study of Boiling Regimes and Transient Signal Measurements”, Transduces’01, 2001, 1514-1517.
[6] L. Zhang, E.N. Wang, J.M. Koo, L. Jiang, K.E. Goodson, J.G. Santiago and T.W. Kenny, “Enhanced Nucleate Boiling in Microchannels”, IEEE, 2002, 89-92.
[7] L. Zhang, J.M. Koo, L. Jiang, M. Asheghi, K.E. Goodson, Associate, J.G. Santiago and T.W. Kenny, “Measurements and Modeling of Two-Phase Flow in Microchannels With Nearly Constant Heat Flux Boundary Conditions”, Journal of Microelectromechanical Systems, vol. 11, 2002, 12-19.
[8] W. Qu and I. Mudawar, “Experimental and numerical study of pressure drop and heat transfer in a single-phase microchannel heat sink”, International Journal of heat and mass Transfer, vol. 45, 2002, 2549-2565.
[9] W. Qu and I. Mudawar, “Prediction and measurement of incipient boiling heat flux in microchannel heat sinks”, International Journal of heat and mass Transfer, vol. 45, 2002, 3933-3945.
[10] W. Qu and I. Mudawar, “Measurement and prediction of press drop in two-phase microchannel heat sinks”, International Journal of heat and mass Transfer, vol. 46, 2003, 2737-2753.
[11] W. Qu and I. Mudawar, “Flow boiling heat transfer in two-phase micro-channel heat sinks-I: Experimental investigation and assessment of correlation methods”, International Journal of heat and mass Transfer, vol. 46, 2003, 2755-2771.
[12] W. Qu and I. Mudawar, “Flow boiling heat transfer in two-phase micro-channel heat sinks-II: Annular two-phase flow model”, International Journal of heat and mass Transfer, vol. 46, 2003, 2773-2784.
[13] W. Qu and I. Mudawar, “Measurement and correlation of critical heat flux in two-phase micro-channel heat sinks”, International Journal of heat and mass Transfer, vol. 47, 2004, 2045-2059.
[14] D. Brutin , F. Topin and L. Tadrist, “Experimental study of unsteady convective boiling in heated minichannels”, International Journal of heat and mass Transfer, vol. 46, 2003, 2957-2965.
[15] S.G. Kandlikar, “Heat Transfer Mechanisms During Flow Boiling in Microchannels”, Journal of Heat Transfer, vol. 126, 2004, 8-16.
[16] J. Lee and I. Mudawar, “Two-phase flow in high-heat-flux micro-channel heat sink for refrigeration cooling applications: Part I-pressure drop characteristics”, International Journal of heat and mass Transfer, vol. 48, 2005, 928-940.
[17] J. Lee and I. Mudawar, “Two-phase flow in high-heat-flux micro-channel heat sink for refrigeration cooling applications: Part II-heat transfer characteristics”, International Journal of heat and mass Transfer, vol. 48, 2005, 941-955.
[18] L. Zhang, E.N. Wang, K.E. Goodson and T.W. Kenny, “Phase change phenomena in silicon microchannels”, International Journal of heat and mass Transfer, vol. 48, 2005, 1572-1582.
[19] W. Qu, G.M. Mala, L. Dongqing, “Pressure-driven water flows in trapezoidal silicon microchannels”, International Journal of heat and mass Transfer, vol. 43, 2000, 353-364.
[20] W. Qu, G.M. Mala, L. Dongqing, “Heat transfer for water flow in trapezoidal silicon microchannels”, International Journal of heat and mass Transfer, vol. 43, 2000, 3925-3936.
[21] H.Y. Wu, P. Cheng, “Friction factors in smooth trapezoidal silicon microchannels with different aspect ratios”, International Journal of heat and mass Transfer, vol. 46, 2003, 2519-2525.
[22] H.Y. Wu, P. Cheng, “An experimental study of convective heat transfer in silicon microchannels with different surface conditions”, International Journal of heat and mass Transfer, vol. 46, 2003, 2547-2556.
[23] H.Y. Wu, P. Cheng, “Visualization and measurements of periodic boiling in silicon microchannels”, International Journal of heat and mass Transfer, vol. 46, 2003, 2603-2614.
[24] H.Y. Wu, P. Cheng, “Boiling instability in parallel silicon microchannels at different heat flux”, International Journal of heat and mass Transfer, vol. 47, 2004, 3631-3641.
[25] M. Lee, Y.W. Yiu, W. Man and Y. Zohar, “Size and shape effects on two-phase flow patterns in microchannel forced convection boiling”, Journal of Micromechanics and Micorengineering, vol. 13, 2003, 155-164.
[26] P. C. Lee, F. G. Tseng and C. Pan, “Bubble dynamics in microchannels. Part Ⅰ: single microchannel”, International Journal of heat and mass Transfer, vol. 47, 2004, 5575-5589.
[27] H. Y. Li, F. G. Tseng and C. Pan, “Bubble dynamics in microchannels. Part Ⅱ: two parallel microchannels”, International Journal of heat and mass Transfer, vol. 47, 2004, 5591-5601.
[28] L. Jiang, M. Wong, Member, IEEE, and Y. Zohar, “Forced Convection Boiling in a Microchannel Heat Sink”, Journal of Microelectromechanical Systems, vol. 10, 2001, 80-87.
[29] G. Hetsroni, A. Mosyak, and Z. Segal, “Nonuniform Temperature Distribution in Electronic Devices Cooled by Flow in Parallel Microchannels”, IEEE Transactions on Components and Packaging Technologies, vol. 24, 2001, 16-23.
[30] G. Hetsroni, A. Mosyak, Z. Segal and E. Pogrebnyak, “ Two-phase flow patterns in parallel microchannels”, International Journal of Multiphase Flow, vol. 29 ,2003, 341-360.
[31] I. Tiselj, G. Hetsroni, B. Mavko, A. Mosyak, E. Pogrebnyak, and Z. Segal, “Effect of axial conduction on the heat transfer in microchannels”, International Journal of heat and mass Transfer, vol. 47, 2004, 2551-2565.
[32] M. Lee, L.S. L. Cheung, Y.K. Lee, M. Wong and Y. Zohar, “Height Effect on Nucleation-Site Activity in Microchannel Convective Boiling”, IEEE, 2004, 300-303.
[33] Y.T. Chen, S.W. Kang, W.C. Tuh and T.H. Hsiao, “Experimental Investigation of Fluid Flow and Heat Transfer in Microchannels”, Journal of Science and Engineering, vol. 7, 2004, 11-16
[34] J. Xu, Y. Gan1, D. Zhang and X. Li, “Microscale boiling heat transfer in a micro-timescale at high heat fluxes”, Journal of Micromechanics and Microengineering, vol. 15, 2005, 362-376.
[35] T.N. Tran, M.W. Wambsganss and D.M. France, “Small circular- and rectangular-channel boiling with two refrigerants”, International Journal of Multiphase Flow, vol. 22, 1996, 485-498.
[36] P.A. Kew and K. Cornwell, “Correlations for the prediction of boiling heat transfer in small-diameter channels”, Applied Thermal Engineering, vol. 17, 1997, 705-715.
[37] W. Tong, A.E. Bergles and M.K. Jensen, “Pressure Drop with Highly Subcooled Flow Boiling in Small-Diameter Tubes”, Experimental Thermal and Fluid Science, vol. 15, 1997, 202-212.
[38] Y.Y. Yan and T.F. Lin, “Evaporation heat transfer and pressure drop of refrigerant R-134a in a small pipe”, International Journal of Heat and Mass Transfer, vol. 30, 1998, 3072-3083.
[39] W. Yu , D.M. France, M.W. Wambsganss and J.R. Hull, “Two-phase pressure drop, boiling heat transfer, and critical heat flux to water in a small-diameter horizontal tube”, International Journal of Multiphase Flow, vol. 28, 2002, 927-941.
[40] T.H. Yen, N. Kasagi and Y. Suzuki, “Forced convective boiling heat transfer in microtubes at low mass and heat fluxes”, International Journal of Multiphase Flow, vol. 29, 2002, 1771-1792.
[41] H.Y. Wu and P. Cheng, “Boiling instability in parallel silicon microchannels at different heat flux”, International Journal of Heat and Mass Transfer, vol. 47, 2004, 3631-3641.
[42] J.J. Hwang, F.G. Tseng, and C. Pan, “Ethanol-CO2 two-phase flow in diverging and converging microchannels”, International Journal of Multiphase Flow, Vol. 31, pp. 548-570, 2005.
[43] S. Levy, Forced convection subcooled boiling prediction of vapor volumetric fraction, Int. J. Heat Mass Transfer, vol. 10, 1967, 951-965.

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