隨著全球環境意識提升與法規的限制，用於汽車空調機的R-134a因為高GWP而必須面臨汰換。本研究採用R-600a與HR-12作為R-134a汽車空調機直接換裝的替代冷媒，以不同充填量之下的相關性能進行比較以決定最佳替代R-134a的冷媒以及充填量。此外，本研究進一步開發蒸發冷卻性能提升裝置去強化汽車空調機冷凝器的散熱能力，以提升汽車空調機的性能與效率。冷媒換裝的研究結果顯示，R-600a在飽和溫度及壓力與現有的R-134a熱力膨脹閥無法匹配會使得送風溫度升高，導致冷氣能力下降而不適合直接替代R-134a。HR-12則是在冷媒充填量247.5g時，其COP、冷氣能力及EER分別比R-134a高22.18%、5.44%以及72.17%。蒸發冷卻性能提升裝置的研究結果顯示，在E1（30℃）條件時，原機本身即可使冷凝器達到足夠的熱交換能力，因此在各個厚度的冷卻板，COP與EER並沒有明顯提升。在E2（35℃）條件時，愈厚的冷卻板因為可吸附之水量較高而能提升冷凝器散熱能力，故裝設THK3（7 cm）的COP與EER分別比原機提升3.58%與6.66%。THK3（7 cm）在E3（40℃）條件下，環境溫度的升高使得蒸發冷卻性能提升裝置的效益進一步地增加，因此COP與EER分別比原機提升7.76%與13.09%。

R-134a used in automobile air conditioners (MACs) has to face replacement due to its high global warming potential (GWP) with global environmental awareness and regulatory constraints. In this study, R-600a and HR-12 were used as replacement refrigerants for direct replacement of R-134a-MACs, and the relative performances under different charging amounts of refrigerant were compared to determine the optimal refrigerant and charging amounts of refrigerant to replace R-134a. In addition, the evaporative cooling performance enhancer (ECPE) was also developed to enhance the heat dissipation capacity of the condenser and improve the performance and efficiency of the MAC. The results of the refrigerant replacement show that the inability of R-600a to match the existing R-134a thermal expansion valve in saturation temperature and pressure will increase the supply air temperature, resulting in a decrease in cooling capacity, which is not suitable for direct replacement of R-134a. The coefficient of performance (COP), cooling capacity, and energy efficiency ratio (EER) of HR-12 with a refrigerant charging amount of 247.5g were 22.18%, 5.44%, and 72.17% higher than R-134a, respectively. The research results of the ECPE show that under the condition of E1 (30°C), the condenser of the original machine could achieve sufficient heat exchange capacity. Therefore, the COP and EER were not significantly improved with the cooling plate of various thicknesses. The thicker cooling plate could improve the heat dissipation capacity of the condenser because of the higher amount of water that could be adsorbed under the condition of E2 (35℃). Therefore, the COP and EER of the THK3 (7 cm) were 3.58% and 6.66% higher than the original machine, respectively. Under the condition of E3 (40°C) for THK3 (7 cm), the increase in the ambient temperature further increased the benefit of the ECPE. Therefore, the COP and EER were 7.76% and 13.09% higher than the original machine, respectively.

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