噴柱沸騰之熱傳研究

Investigation of the Impinging Jet Boiling Heat Transfer

葉芳伸(Fang-Shen Yeh)

指導教授 ： 陳瑤明

國立臺灣大學/工學院/機械工程學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.00249

摘要

本文建立一套噴柱面積與發熱面積比例等於1的實驗系統，討論噴柱在停滯區的熱傳現象，並以實驗數據導得臨界熱通量預測式。本實驗以控制熱通量的方式做穩態量測，變化參數有：發熱直徑尺寸（4mm、6mm、8mm）；過冷度（20℃、30℃）；噴柱速度（0.5m/s、1.0m/s、2.0m/s）。藉由各參數變化，瞭解噴柱沸騰在不同沸騰區域的熱傳機制。另外，本實驗於發熱尺寸8mm、過冷度30℃、噴柱速度2.0m/s下測得最大臨界熱通量測得值為522W/cm2相對表面過熱度37℃。最後，更進一步藉由前人的基礎，並以本文實驗數據導出臨界熱通量的預測式，誤差在±15％以內。

關鍵字

噴柱 ； 臨界熱通量 ； 沸騰熱傳 ； 停滯區對流

並列摘要

We construct an experiment system to investigate the heat transfer phenomenon at the stagnation region of an impinging jet with a unitary ratio of jet cross section and heat transfer area. Thereafter, a critical heat flux equations deduced from the experimental results was obtained. All experiment data was measured in steady state. Experiments were carried out at heat transfer surface diameters of 4~8mm, jet velocities of 0.5~2.0m/s and liquid subcooling of 20℃ and 30℃. With the parameter varying, we can interpret the heat transfer mechanism in each boiling region. Besides, the maximum CHF and wall superheat were 522W/cm2 and 37℃, recorded at heat transfer surface diameter of 8mm,jet velocity of 2.0m/s and liquid subcooling of 30℃. Finally, we deduce an equation to forecast the critical heat flux in jet stagnation region within a 15% error.

並列關鍵字

Jet ； Critical heat flux ； boiling heat transfer ； stagnation zone force convection

參考文獻

1. Ahuja, A. S., “Augmentation of Heat Transfer in Laminar Flow of Polystyrene Suspensions,” J. Appl. Phys., Vol.46, pp.3408-3425, 1975.

3. Wang, B. X., Zhou, L. P., and Peng, X. F., “A Fractal Model for Predicting the Effective Thermal Conductivity of Liquid with Suspension of Nanoparticles,” Int. J. Heat Mass Transfer, Vol.46, pp.2665-2672, 2003.

4. Das, S. K., Putra, N., and Roetzel, W., “Pool Boiling Characteristics of Nano–Fluids,” Int. J. Heat and Mass Transfer, Vol.46, pp.851-862, 2003A.

5. Das, S. K., Putra, N., Thiesen, P., and Roetzel, W., “Temperature Dependence of Thermal Conductivity Enhancement for Nanofluids,” J. Heat Transfer, Trans. ASME, Vol.125, pp.567-574, 2003B.

6. Ding, Y., and Wen, D., “Particle Migration in a Flow of Nanoparticle Suspensions,” Powder Technology, Vol.149, pp.84-92, 2005.