汽車空調系統換裝環保冷媒與運轉性能最佳化評估之研究

Abstract

本研究選擇兩種低全球暖化潛勢（GWP）冷媒（R-152a、R-1234yf）作為R-134a汽車空調系統（MACS）的直接替代品，以R-134a原機充填量75%的 R-152a與110%的 R-1234yf 直接進行冷媒換裝。實驗時的環境溫度與壓縮機轉速均參考中華民國國家標準汽車空調檢驗法CNS 7897 - D3079所訂定之規範，並增設40 ℃與30 ℃的高、低溫室外條件，針對三種冷媒的系統性能指標進行分析與評估。研究結果顯示，在所有測試條件下，MACS使用 R-152a 時的能源效率比（EER）與性能係數（COP）相較於原機皆有顯著提升，且消耗電功率（W ̇_total）與壓縮比（CR）大幅降低。在環境溫度35 ℃且壓縮機轉速1800 rpm進行性能測試時，R-152a與R-1234yf的W ̇_total分別比原機低5.96%與5.04%，且EER分別比原機高11.26%與1.45%。此外，R-152a與R-1234yf的COP與原機的差異百分比分別為15.05%與-14.95%。換裝R-1234yf導致冷氣能力與COP下降的主要是因為相變熱與熱傳係數（thermal conductivity, k）較低所致。再者，R-152a在每日行駛里程超過4.9 hr以上時，其總當量暖化影響（TEWI）即可優於R-1234yf，顯示R-152a應用在長時間行駛的MACS更能達到節能與環保兼具的需求。

This study selects two low Global Warming Potential （GWP） refrigerants （R-152a, R-1234yf） as direct substitutes for R-134a mobile air conditioning systems （MACS）, with R-152a filled at 75% and R-1234yf at 110% of the original R-134a charge. The experimental conditions, including ambient temperature and compressor speed, follow the specifications set forth by the national standard of the Republic of China for automotive air conditioning inspection, CNS 7897 - D3079, with additional conditions set at 40 °C and 30 °C for high and low outdoor temperatures, respectively. System performance indicators for the three refrigerants are analyzed and evaluated. The results show that under all test conditions, the energy efficiency ratio （EER） and coefficient of performance （COP） of mobile air conditioning systems using R-152a exhibit significant improvements compared to the original system, with reduced total power consumption （W ̇_total） and compression ratio （CR）. During performance testing at an ambient temperature of 35 °C and compressor speed of 1800 rpm, W ̇_total for R-152a and R-1234yf is respectively 5.96% and 5.04% lower than the original system, with EER respectively 11.26% and 1.45% higher. Additionally, the percentage differences in COP between R-152a and R-1234yf compared to the original system are 15.05% and -14.95%, respectively. The decrease in cooling capacity and COP when switching to R-1234yf is primarily attributed to its lower latent heat and thermal conductivity （k）.Furthermore, when the daily driving mileage exceeds 4.9 hours, the Total Equivalent Warming Impact （TEWI） of R-152a is superior to that of R-1234yf, indicating that R-152a is more energy-efficient and environmentally friendly for mobile air conditioning systems requiring long-term driving.