由於全球暖化已經成為全球越來越重要的議題，在車用空調中所使用的傳統HCFC和HFC冷媒很快會在未來被淘汰掉，近來有一種新型冷媒R-1234yf出現，其GWP值僅只有4遠低於R-134a的GWP值1430，除此之外R-1234yf的熱力性質與R-134a非常相似，使它非常適合用來取代R-134a。 本實驗以實驗方法來測試冷媒R-134a以及低GWP冷媒R-1234yf在板式熱交換器中流動沸騰、冷凝之熱傳係數、壓降的表現以及兩種冷媒之間的差異，其中在實驗中所使用的板式熱交換器長194mm、寬154mm、高80mm並且由6個版片組合而成，實驗中的飽和溫度為30°C，流量分別為 G=10, 20, 30 and 40 kg/m2s，冷媒在板式熱交換器入出口之間的乾度變化量為0.2。實驗結果顯示在高流量時兩種冷媒的熱傳係數會因為性質相似的原因而非常相近；R-1234yf的摩擦壓降均比R-134a來的低這是因為在R-1234yf的動黏滯係數比R-134a來的低所造成的。 ;Due to the effect of the global warming has become more and more important, the conventional refrigerants like HCFC and HFC will be phased out for the application on automobile air-condition systems in the near future. Recently a new refrigerant, R-1234yf has been developed with GWP as low as 4, which is much lower than the GWP value of 1430 of the R-134a. Moreover, R-1234yf has similar thermodynamic properties compare to R-134a, which makes it a good candidate for replacing the R-134a. This study provides an experimental investigation on two-phase flow boiling and condensation heat transfer and pressure drop of refrigerants R-134a and low GWP refrigerant R-1234yf in 6 plates brazed plate heat exchangers with length 194mm, width 154mm and height of 80mm. The experiment is done under saturation temperature of 30°C and mass flux of G=10, 20, 30 and 40 kg/m2s, the vapor quality change from the inlet to the outlet of the test section is 0.2. The result shows that the heat transfer coefficient of both refrigerants will be similar in plate heat exchanger due to the similarity of their properties, the pressure drop of R-1234yf is slightly lower compare to R-134a because of the lower viscosity of R-1234yf.
