噴柱沸騰之熱傳研究

Abstract

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。

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.