Kemal ATİK, Abdurrazzak AKTAŞ

An experimental investigation of refrigerant charge effects on mobile air conditioning system performance

Çevreyi tehdit eden küresel ısınmayı azaltmak amacıyla araştırmacı ve endüstri kuruluşları tarafından son 25 yılda otomotiv klima sistemlerinde (AAC) önemli gelişmeler sağlanmıştır. Bu çalışmanın amacı, kompresör hızı ve soğutucu akışkan kaybının bir AAC sistemi performansına etkisini incelemektir. Bunun için bir deney düzeneği kurulmuştur. Deney düzeneği için üretici firma 750 g soğutucu akışkan tavsiye etmesine rağmen kompresör hızına göre performans-katsayısı (COP), soğutma kapasitesi ve kompresör gücü değişimini analiz etmek için aynı soğutucu akışkanın farklı miktarları ile de deneyler gerçekleştirilmiştir. Yapılan deneysel gözlemler sistem için en iyi soğutma kapasitesinin 500 g soğutucu akışkan durumunda (optimum değer) elde edildiğini ve soğutucu akışkan miktarı 500 g’dan %40 oranında düşük veya %20 oranında yüksek tutulduğunda ise soğutma kapasitesinin %25’e kadar azaldığını göstermiştir. Test sonuçları ayrıca, soğutucu akışkan seviyesinin belirli bir miktarı için kompresör hızı arttıkça soğutma sistemi performans-katsayısının etkili bir şekilde azaldığını göstermiştir.

Soğutucu akışkan miktarının otomotiv AC sistemi performansına etkisinin deneysel araştırılması

During the last 25 years automotive air conditioning (AAC) systems have significant development introduced by the industry and research institutes in the world to minimize the global warming threat to the environment. This paper reports the results of a study on the performance of an AAC system with measuring the compressor driving speed and the refrigerant leakage. For this purpose an experimental set up is designed and constructed to investigate the system performance. Although, the manufacturer’s recommended amount for the tests with R-134a as refrigerant was 750 g, the experiments were also carried out by selecting different amount of the same refrigerant charges to analyse the coefficient of performance (COP), the cooling capacity and the compressor power change with respect to the rotating speed of the compressor. The evaluation of experimental data revealed that the best cooling capacity was achieved at 500 g refrigerant charge. Although, while the charge level decreased 40% below or increased 20% above the 500g of the charge amount, cooling capacity loss increased up to 25% when optimum value of 500 g of the cooling refrigerant was utilized. The test results proved in each case that increasing the compressor driving speed cause almost a linear change in the corresponding power level. The test results also shown that COP of the cooling system was decreased effectively when the revolution speed increased for any specified charge amount of the refrigerant.

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