Investigation of ejector entrainment ratio and condenser temperature effect on performance parameters of the experimental refrigeration system using dual evaporators and a single compressor with R515A refrigerant

Abstract

In this paper, the effects of ejector entrainment ratio (ER) and condenser temperature on performance parameters such as COP, cooling capacity, etc. were investigated in an experimental refrigeration system using a single compressor with R515A refrigerant and two evaporators that can operate at different temperatures. An extra expansion valve and mixing chamber are necessary to ensure pressure balance in the two evaporator refrigeration systems. Alternatively, the ejector can be utilized instead of these two pieces of equipment and can provide the required cooling capacity. The experimental test system has two evaporators at two different evaporation temperatures and an expansion valve before each evaporator. First tests were carried out by altering the ER and it was observed that when ER increased from 0.2 to 0.8, the total cooling capacity and COP values dropped by 18% and 15%, respectively. When ER value was adjusted to range of 0.5-0.6, the cooling capacities of the two evaporators were closest to each other. Second tests were carried out by changing the condenser temperature but with a constant ER value (between 0.5-06); the results showed that as the condenser temperature increased from 28 °C to 43 °C, the total cooling capacity increased by 11% and the COP value dropped by 23%.

Keywords

• R515A
• COP
• Ejector
• Evaporator
• Condenser

R515A soğutucu akışkanlı tek kompresör ve iki buharlaştırıcılı deneysel soğutma sisteminde ejektör sürüklenme oranının ve yoğuşma sıcaklığının performans parametrelerine etkisinin incelenmesi

Abstract

Bu çalışmada, R515A soğutucu akışkanlı, tek kompresör ve farklı sıcaklıklarda çalışabilen iki buharlaştırıcı kullanılan deneysel soğutma sisteminde ejektör sürüklenme oranının (ER) ve kondenser sıcaklığının performans parametrelerine etkisi araştırılmıştır. İki evaporatörle çalışan sistemlerde, basınç dengesini sağlamak için sisteme bir genleşme cihazı ve bir karışım odasının eklenmesi gerekmektedir. Ejektör bu iki ekipman yerine tercih edilebilir ve ihtiyaç duyulan soğutma kapasitesini sağlayabilir. Laboratuvar ölçeğinde kurulan deneysel soğutma sistemi ejektörlü ve iki evaporatörlü olarak tasarlanmıştır. Ayrıca her evaporatör öncesinde, gerektiğinde by-pass olabilecek şekilde termostatik genleşme vanaları (TXV) konulmuştur. Sürüklenme oranına göre yapılan deneylerde; sürüklenme oranının 0,2’de 0,8’e artmasıyla toplam soğutma kapasitesinin ve COP değerinin sırasıyla %18 ve %15 azaldığı görülmüştür. Evaporaytör#1 ve evaporatör#2’nin soğutma kapasitesinin birbirine en yakın olduğu sürüklenme oranı, 0,5-0,6 aralığı olduğu tespit edilmiştir. Bu aralığın sabit olarak alındığı ve kondenser sıcaklığının değişimiyle yapılan deneylerde; kondenser sıcaklığı 28 °C’ den 43 °C’ ye yükseldiğinde toplam soğutma kapasitesinin %11 arttığı, COP değerinin ise %23 azaldığı belirlenmiştir. Sonuç olarak ejektörün iki evaporatörlü sistemlerde kullanılmasıyla klasik iki evaporatörlü sistemlere göre performansının iyileştiği görülmüştür.

Keywords

• R515A
• COP
• Ejektör
• Evaporatör
• Kondenser

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