R-22與二元近共沸混合冷媒R-410A於水平圓管內的蒸發熱流分析

Abstract

賑膍s以實驗方法分別探討R-22及二元近共沸混合冷媒R-401A(R-32/R-125， 50%/150%，重量比)於內徑6.54mm的水平平滑管及6.48mm水平 微鰭管中的對流蒸發熱傳性能及兩相流動壓降。質量速度範圍為100∼ 400kg/m2sec，飽和汽泡點溫度為2℃與10℃。實驗結果顯示R-410A在 平滑管及微鰭管內之熱傳係數均高於R-22，但在高質量速度及高乾度 區時，熱傳係數會有低落的現象。與平滑管相較，R-22於微鰭管的熱 傳係數提昇1.5∼2.4倍， R-410A則提昇1.5∼2.1倍。 本研究之實驗數據與前人之熱傳經驗式及壓降經驗式比對的結果， Wattelet之經驗式能預測R-22於平滑管內之熱傳係數在±30%之內； Souza之經驗式則能預測壓降在±30%之內。

The characteristics of convection evaporation heat transfer coefficients and two-phase flow pressure drops were measured for R-22 and binary near-azeotropic refrigerant mixture R-410A (R32/R125, 50%/50%, by weight) flowing in smooth tube with inner diameter of 6l.54 mm and micro-fin tubes with inner diameter of 6.48mm. The range of mass flux is between 100 to 400 kg/m2 sec, and data were taken at two evaporation temperature (2℃ and 10℃ respectively). The experimental results show that the heat transfer coefficient of R-410A is higher than R-22 in both smooth and micro-fin tubes, but it will be dacaied at high amss flux and high vapor quality region. Compare with smooth tubes, the heat transfer coefficients of R-22 in the micro-fin tubes increase by 150% 240% and the heat transfer coefficient of R-410A in the micro-fin tubes increase by 150% to 210%. Between experimental data and correlations proposed for the heat transfer coefficients, Wattlet's correlation can predict R-22 datain smooth tube within ±30%. For the pressure drops, Souza's correlaiton can predict the data within ±30%.