R-134a與R-32/R-134a之池沸騰加強熱傳分析

Abstract

本論文係探討R-134a與混合冷媒R-32/R-134a在不同的飽和狀態 下，分別以平滑管、16FPI、21FPI、26FPI微鰭管，以控制電流、電 壓方式加熱，進行核沸騰實驗與熱傳增強效果差異。實驗結果顯示， 熱傳係數皆隨者熱通量增加而增加，而熱傳效果隨者不同鰭片幾何尺 寸大小而明顯不同，在本實驗中以16FPI微鰭管增強效果最佳。本論 文所推導之平滑管、微鰭管關係式，對於冷媒R-134a和R-32核沸騰熱 傳係數預測性良好，預測值與實驗值誤差在±25％以內。對雙成份混 合冷媒R-32/R-134a平滑管熱傳係數關係式中，以Inoue ane Monde[1.25] 、Thome and Shakir[.30]、Bier [4.4]等人所提這關係式均能準確的預 測本系統之實驗值，有95%以上的預測值與本實驗之誤差在±20%以內： 而對於微鰭管，Stephan and Korner[1.23]、Inoue and Monde[1.25]、 Thome and Shakir[1.30]等人所提出之關係式有90%以上的預測值落在 ±35%誤差以內。

The heat transfer characteristics of R-134a and refrigerant mixture R-32/R-134a in pool boiling were investigated, experimentally using a smooth tube and three integral-fin tubes of 16FPI, 21FPI, 26FPI at different saturated states. The experimental results showed that the heat transfer coefficients increase with heat flux. However, it was observed that the 16FPI integral-fin tube can enhance the heat transfer coefficients to the greatest extent. The analysis for both smooth and integral-fin tube correlations inthis study could predict the heat transfer coefficients of nucleate pool boiling for refrigerant R-134a and R-32 successfully with erros of ±25%. For predictions of the pool boiling heat transfer coefficients of the binary mixture R-32/R-134a for the smooth tube, the correlations of Inoue, Monde [1.25], Thome, Shakir [1.30] and Bier [4.4] are able to predict the experimental data quite accurately with over 95% data lie the band of ±20% errors and for the integral-fin tubes, the correlations of Stephan, Korner [1.23], Inoue, Monde [1.25], Thome and Shakir [1.30] can also predict the experimental data with over 90% data in the band of ±35% errors.