本論文以實驗方法探討介電液HFE-7100 於多管式微通道內，單 向對流以及兩相沸騰熱傳的性能與兩相流動壓降特性。散熱冷板上微 通道的水利直徑為435µm，介電液質通量的範圍為200、300、400 kg/m2s，測試段熱通量範圍為10、25、37.5 kW/m2，分別探討在不同 乾度下之熱傳特性與壓降分析。其結果歸納如下：
1. 單相流動的實驗結果主要在探討紐賽爾數和表面摩擦因子。結果指 出在微通道中，熱傳性能與摩擦因子皆高於完全發展流。本實驗 所得的熱傳係數在不考慮流動不均勻與突縮、突擴的影響之下，
與發展中流動的結果相仿。相反的，突縮、突擴與流動不均勻的 影響卻會導致相當程度的壓降。
2. 在兩相沸騰熱傳方面，在質通量200 kg/m2s時，當熱通量由10 kW/m2增加至25 kW/m2時，冷媒HFE-7100的對流沸騰熱傳係數會 隨著乾度的增加而明顯下降的趨勢。這是因為在鄰近的流道中因 受到爆發性沸騰的影響而產生迴流現象。然而，在較高質通量400 kg/m2s時，可以發現熱傳係數幾乎不隨乾度變化而增減，這是因為 迴流現象的影響會隨著流體慣性的增加而減少所造成的結果。
3. 在兩相流動壓降上，吾人得知無論是使用Muller and Heck經驗式或 是均質模式來預測本實驗之壓降皆顯示出兩個趨勢，一為在乾度 越大時兩者之預測性皆越差；二為當質通量G值越小時預測性也越 佳。與Muller之經驗式比較時，G=400、300、200 kg/m2s最大誤差 為70%、37.5%、25%。如此，吾人推論以Muller and Heck之經驗 式對本實驗散熱冷板之壓降預測質通量的影響較經驗式中的2次
方為小，而乾度項的影響也較3次方小。
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Classification Range of hydraulic diameter
Convectional channels Dh > 3mm
Mini-channels 3mm > Dh > 200µm Micro-channels 200µm> Dh > 10µm Transitional Micro-channels 10µm >Dh > 1µm
Transitional Nano-channels 1µm >Dh > 0.1µm Molecular nano-channels 0.1µm> Dh
表 1 水力直徑範圍之流道分類
物理性質 HFE-7100 Water 單位
飽和溫度(1atm) 61 100 oC
凝固點 -135 0 oC
分子量 250 18 g / mol
液體密度 1510 1000 Kg / m3
氣體密度 9.87 1.673 Kg / m3
液體黏滯係數 3.70×10-4 2.81×10-4 Kg / m.s
液體表面張力 1.019×10-2 58.92 N / m
介電常數 7.4 80 1 KHz
潛熱 111.6 2272 KJ / Kg
液體比熱 1183 1450 J / Kg.K
液體熱傳導係數 0.062 0.6 W / m.K
溫室效應 (GWP) 320 None
大氣週期 (ALT) 4.1 None year
表2 介電液 HFE-7100 與水在一大氣壓之性質比較
參數 範圍 單位
熱通量 10~37.5 kW/m2
飽和壓力 1.3~1.85 bar
質量通率 100~400 kg/m2sec
乾度 0.1~0.9
表 3 控制參數範圍
圖 1 系統設備圖
HFE-7100與不凝結氣體蒸發向上 蛇形冷卻管
不凝結氣體逸出
液體HFE-7100回流
冷卻水出口
冷卻水進口
加熱面 HFE-7100
溫度計
圖 2 介電液 HFE-7100 之除氣過程示意圖
散熱冷板
圖 3 測試段設計示意圖
電木
壓力扣具施固定壓力 加熱片
熱電偶
熱電偶 空氣隔熱層
熱電偶
熱電偶
圖 4 熱電偶之量測位置示意圖
Deep=0.5 Deep=0.5
Deep=0.5
(a) (b)
圖 5 微流道散熱冷板示意圖 (a) 上板 (b) 底板
圖 6 散熱冷板外觀圖
do
di
HFE-7100
Water
Di
Do
(a)
HEF-7100 出口
冷卻水進口
HEF-7100 進口
冷卻水出口
(b)
圖 7 反向流動式熱交換器-雙套管(a)雙套管截面圖 (b)外觀
圖
圖 8 壓力扣具
T
∞T
wTtop
T
b圖 9 測試段熱散失狀況示意圖
Quality, x
0.1 0.2 0.3 0.4 0.5 0.6
Pressure Drop, ∆P [Pa]
0 5000 10000 15000 20000 25000 30000 35000 40000
∆P,Exp
∆P,Muller and Heck ∆P,homogeneous theory
(a)
Quality, x
0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55
Pressure Drop, ∆P [Pa]
0 5000 10000 15000 20000 25000 30000
∆P,Exp
∆P,Muller and Heck ∆P,homogeneous theory
(b)
圖 10 質通量G = 402.7 kg/m
2s在不同熱通量(a) q” = 37.5
kW/m
2(b) q” = 25 kW/m
2時，壓降實驗值與經驗式之比較
Quality, x
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Pressure Drop, ∆P [Pa]
0 5000 10000 15000 20000 25000 30000
∆P,Exp
∆P,Muller and Heck ∆P,homogeneous theory
(a)
Quality, x
0.1 0.2 0.3 0.4 0.5 0.6 0.7
Pressure Drop, ∆P [Pa]
0 5000 10000 15000 20000 25000 30000
∆P,Exp
∆P,Muller and Heck ∆P,homogeneous theory
(b)
圖 11 質通量G = 295.6 kg/m
2s在不同熱通量(a) q” = 37.5
kW/m
2(b) q” = 25 kW/m
2時，壓降實驗值與經驗式之比較
Quality, x
0.2 0.3 0.4 0.5 0.6 0.7
Pressure Drop, ∆P [Pa]
0 2000 4000 6000 8000 10000
∆P,Exp
∆P,Muller and Heck ∆P,homogeneous theory
(a)
Quality, x
0.0 0.1 0.2 0.3 0.4 0.5 0.6
Pressure Drop, ∆P [Pa]
0 2000 4000 6000 8000 10000
∆P,Exp
∆P,Muller and Heck ∆P,homogeneous theory
(b)
圖 12 質通量G = 201.9 kg/m
2s在不同熱通量(a) q” = 25
kW/m
2(b) q” = 10 kW/m
2時，壓降實驗值與經驗式之比較
Mass flux, G [kg/m
2s]
150 200 250 300 350 400 450
Percentage of all pressure drop terms
0.0 0.2 0.4 0.6 0.8
∆Pf / ∆Ptotal
∆Pa / ∆Ptotal
∆Pc / ∆Ptotal
∆Pe / ∆Ptotal
圖 13 不同質通量時各項壓降所占總壓降之值
(a)
(b)
圖14 單相實驗結果與經驗式和完全發展流之比較(a)表面摩
擦因子 (b)紐塞爾數
Quality, x
0.1 0.2 0.3 0.4 0.5 0.6
Heat Transfer Coefficient, htp [W/m2 K]
0 500 1000 1500 2000 2500 3000 3500
q" = 37.5 kW/m2 q" = 25 kW/m2
(a)
Quality, x
0.1 0.2 0.3 0.4 0.5 0.6
Pressure Drop, ∆P [Pa]
5000 10000 15000 20000 25000 30000 35000 40000
q" = 37.5 kW/m2 q" = 25 kW/m2
(b)
圖15 質通量G = 402.7 kg/m
2s，熱通量對(a)兩相對流熱傳係
數 (b)壓降與蒸氣乾度之影響
Quality, x
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Heat Transfer Coefficient, htp [W/m2 K]
0 500 1000 1500 2000 2500 3000 3500
q" = 25 kW/m2 q" = 10 kW/m2
(a)
Quality, x
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Pressure Drop, ∆P [Pa]
0 2000 4000 6000 8000 10000