Hedef Sıcaklığa Ulaşma Sürecinde R600a, R134a ve R1234yf’nin Dinamik Enerji, Ekserji ve Çevresel Analizi

Abstract

Soğutma sistemleri için iş akışkanı (soğutucu akışkan) seçimi birçok faktöre bağlıdır. Bu faktörler arasında soğutucu akışkanın küresel ısınma potansiyeli, ozon inceltme potansiyeli, yanıcılık özellikleri, enerji ve ekserji verimliliği ile çevresel etki performansı yer almaktadır. Dolayısıyla, uygun soğutucu akışkan seçimi bu kriterlerin bütüncül bir yaklaşımla birlikte değerlendirilmesini gerektirmektedir. Bu çalışmada ev tipi bir buzdolabının teorik modeli oluşturulmuş; R600a, R134a ve R1234yf soğutucu akışkanlarının performansları dinamik olarak ele alınmış ve karşılaştırılmıştır. R600a’nın soğutma kapasitesinin R134a ve R1234yf’ye kıyasla daha düşük olması, pull-down sürecinde sistemin hedef sıcaklığa ulaşma süresini uzatmış ve bu parametre açısından daha sınırlı bir performans ortaya koymasına neden olmuştur. Yüksek soğutma kapasitesi, hedef sıcaklığa daha kısa sürede ulaşma açısından önemli bir avantaj sağlasa da, performans değerlendirmesi mutlaka enerji tüketimi ile birlikte ele alınmalıdır. Yüksek kapasiteye karşılık artan güç tüketimi, bu avantajı azaltarak sistemin toplam verimliliğini düşürebilir. Benzer şekilde, enerji verimliliği yüksek ancak soğutma kapasitesi düşük olan bir akışkan, hedef sıcaklığa ulaşma süresini uzatarak sistemin belirlenen zaman aralığındaki etkinliğini sınırlandırabilir. Enerji, ekserji ve çevresel performans kriterleri birlikte değerlendirildiğinde R600a en avantajlı seçenek olarak öne çıkmaktadır. Bununla birlikte, hedef sıcaklığa ulaşma konusundaki dezavantajının, R600a’nın termofiziksel özelliklerine uygun daha yüksek süpürme hacmine sahip bir kompresör seçimi ile önemli ölçüde giderilebileceği öngörülmektedir.

Keywords

• Enerji
• Ekserji
• Soğutma sistemleri
• Çevresel etki
• Sera gazları
• Yaşam döngüsü iklim performansı

Dynamic Energy, Exergy, and Environmental Analysis of R600a, R134a, and R1234yf During the Pull-Down Process

Abstract

The selection of a working fluid (refrigerant) for cooling systems depends on many factors. These factors include the refrigerant's global warming potential, ozone-depletion potential, flammability characteristics, energy and exergy efficiency, and environmental impact. Therefore, selecting the appropriate refrigerant requires a comprehensive evaluation of all these criteria. In this paper, a theoretical model of a household refrigerator was developed; the performance of R600a, R134a, and R1234yf refrigerants was dynamically analyzed and compared. The lower cooling capacity of R600a compared to R134a and R1234yf has prolonged the system's time to reach the target temperature during the pull-down process, resulting in reduced performance on this parameter. While high cooling capacity provides a significant advantage in terms of reaching the target temperature in a shorter time, performance evaluation must always be considered in conjunction with energy consumption. Increased power consumption corresponding to high capacity can reduce this advantage and decrease the overall efficiency of the system. Similarly, a fluid with high energy efficiency but low cooling capacity can limit the system's effectiveness within the specified time frame by extending the time required to reach the target temperature. When energy, exergy, and environmental performance criteria are evaluated together, R600a emerges as the most advantageous option. However, it is anticipated that the disadvantage in reaching the target temperature can be significantly mitigated by selecting a compressor with a higher sweep volume suitable for the thermophysical properties of R600a.

Keywords

• Energy
• Exergy
• Cooling systems
• Environmental impact
• Greenhouse gases
• Life cycle climate performance

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