加熱瓦數對R134a冷凍系統流量分佈之影響

Effect of Heat Load on the Flow Distribution of R134a Refrigeration System applicable to Electronic Cooling

田政蔚(Cheng-Wei Tien)

指導教授 ： 許文震

國立清華大學/工學院/動力機械工程學系/碩士(2007年)

https://doi.org/10.6843/NTHU.2007.00531

摘要

本文中以實驗之方式研究加熱瓦數與冷凍系統應用在電子冷卻中流量分佈之影響。在一般情況下，實驗結果顯示加熱瓦數對於流量分佈有顯著而重要的影響。當瓦數增加時，其總流量將會隨之線性增加;而當瓦數遞減時，其總流量也會隨之減少。在此實驗尚做了在不同流道型式及不同入口乾度對於整體流量分佈的影響。在Diverge流道中，對於加熱瓦數相同之情形下，其流量分佈處為平均分配至兩平行且相同之蒸發器中，而當其一瓦數開始變化，即可從實驗結果中發現，流量對於有瓦數變化蒸發器之影響較另一蒸發器為大;對於其他兩種reverse及parallel型流動方向，其流量趨勢為相反且皆與diverge有相同之流量變化。
在乾度的影響下，其流量分佈在從高降至低瓦數時較無明顯的趨勢走向，然而對於由低瓦數往上加之實驗中，可發現其流量分佈極為類似，此現象可能是因為其經過歧管流入蒸發器之壓升不足以使流量產生明顯的變化所致。

關鍵字

流量分佈 ； 加熱瓦數 ； R134a ； 電子冷卻

並列摘要

The present study experimentally investigates mass flow rate distribution among symmetric heat sinks in conventional channel under a variety of test conditions. The test section consists of adjustable inlet and outlet headers with an inner diameter 4.35 mm which own three fundamental flow directions. The key experimental parameters are flow direction of refrigerant passing through the test section (diverge, reverse and parallel), inlet quality (0.1 and 0.01) and heat load. Different flow direction results in apparent contrast of mass flow rate in reverse and parallel flow schemes. The effect of inlet quality plays an important role in flow distribution and total mass flow rate. The effect of heat load on mass flow rate distribution results in apparent influence on flow distribution. Diverge flow direction initially shows good symmetry in flow distribution due to its arrangement of piping. Both reverse and parallel flow conditions show contrary flow distributions of heat sinks.

並列關鍵字

flow distribution ； heat load ； R134a ； electronic cooling

參考文獻

[2]Lixin C. and Dieter M., “Review of two-phase flow and flow boiling of mixtures in small and mini channels,” International Journal of Multiphase Flow, 32, 183-207, 2006.

[3]Mehendala S.S., Jacobi A.M. and Shan R.K., “Fluid flow and heat transfer at micro- and meso-scales with application to heat exchanger design,” Applied Mechanics Review, 35, 175-193, 2000.

[4]Kandlikar S.G., “Fundamental issues related to flow boiling in minichannels and microchannels,” Experimental Thermal and Fluid Science, 26, 38-47, 2001.

[5]Ghiaasiaan S.M. and Abdel S.I., “Two-phase flow in micro-channels,” Advanced Heat Transfer, 34, 145-254, 2001.

[6]Ross H., Radermacher R., Di Marzo M. and Didino D., “Horizontal flow boiling of pure and mixed refrigerants,” International Journal Heat Mass Transfer, 30, 979-992, 1987.