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Bu çalışmanın amacı, yüksek GWP değerine sahip R404A soğutucu akışkanı yerine hidrofloroolefin/hidroflorokarbon (HFO/HFC) karışımı düşük GWP değerine sahip R454C soğutucu akışkanın kullanılmasının incelenmesidir. Deneysel çalışmada iki farklı buharlaşma sıcaklığı (4°C ve +4°C) ve iki farklı yoğuşma sıcaklığı (30°C ve 50°C) kullanılmıştır. Her iki kondenser sıcaklığında R404A’nın elektrik tüketimi R454C’den yüksek tespit edilmiştir. Ayrıca R454C’nin COP değeri R404A’dan ortalama %10 fazla tespit edilmiştir. R454C’nin kullanılmasıyla, sistemde dolaşan kütlesel debi değerinde azalma olmuştur. R454C’nin güç tüketimi R404A’dan ortalama %15 daha düşüktür. Alternatif karışımın kompresör çıkış sıcaklıkları R404A’dan yüksek olmakla birlikte R454C’nin çalışma koşulları için uygun olduğu görülmüştür. Hesaplanan TEWI değeriyle, R454C kullanılmasıyla CO2 emisyonlarında önemli azalmalar olmuştur. R454C’nin ekserji verimi R404A’dan yaklaşık %10-%15 daha yüksek bulunmuştur. Sistemde hiçbir değişiklik yapılmadan R404A’ya alternatif olarak R454C kullanılması mümkün olabilecektir.

This study analyses the performance of plug-in refrigeration equipment, which has the condenser on the system and delivers heat to the indoor medium, using mixtures with low-global warming potential (GWP). The theoretical drop-in replacement of R404A that is widely used in the plug-in refrigeration equipment, is investigated utilizing refrigerants with GWP

The thermal performance of a novel solar air heater was experimentally studied in this paper. For this aim, a new solar air collector was designed using copper wool on its absorber plate to be a se...

In this study, R404A and R452A refrigerants used in refrigeration systems were compared experimentally. The energy performance of the system was investigated for widely used evaporation temperature...

This study experimentally compares the high-GWP R404A with two low-GWP HFC/HFO blends, R454A (35% R32 + 65% R1234yf) and R454C (21.5% R32 + 78.5% R1234yf). Three evaporation temperatures ( -5, 0 and + 5 degrees C) and three condenser temperatures (30, 40, 50 degrees C) were studied. For all covered cases of condenser temperatures, the measured compressor power consumption was reduced by about 6% and 15% for R454A and R454C, respectively compared to R404A. The cooling capacity of R454A was higher than R404A by 11%, approximately, although the mass flow rate values have been reduced using the studied alternative refrigerants. As a result, the COP values of R454A and R454C were greater than R404A by about 14% and 10%, respectively. Although the discharge temperatures of the alternative blends were determined to be higher than that obtained for R404A, they are suitable for the tested operating conditions. The proposed alternative refrigerants could be used directly in available R404A systems without any constructional modification requirement if safety concerns can be solved. Moreover, it is possible to have higher cooling capacity and COP values as well as reduced environmental impacts. (c) 2021 Elsevier Ltd and IIR. All rights reserved.

Bu çalışmada, Diyarbakır ili iklim koşullarında güneşi iki eksende takip eden parabolik çanak kolektörden sıcak su elde edilmesi amaçlanmıştır. Sistemin odak noktasında bakır spiral elemanlı ısı eşanjörü soğurucu olarak tasarlanmıştır. Şebekeden gelen su, absorbırde ısıtılarak sistemden çıkar. Deneysel veriler saat 10: 00'dan 16: 30'a kadar alınmıştır. Kütlesel debinin verimlilik üzerindeki etkisi 0,00187, 0,00217 ve 0,00345 kg/s'lik üç durum dikkate alınarak incelenmiştir. Sonuçlar, en yüksek faydalı ısı miktarının ve termal verimin 0,00345 kg/s'de elde edildiğini gösterdi. Isıl verim değerleri %32-39 olarak belirlenmiştir. Sistemin ekserji verimi de deneysel verilere göre % 5,7 ile 6,3 olarak tespit edilmiştir., In this study, it is aimed to obtain hot water through a parabolic dish mirror tracking the sun in two axes in climatic conditions of Diyarbakır, Turkey. A heat exchanger of copper spiral element was designed as an absorber on the focus point of the system. Water coming from network exits from the system by heated in the absorber. The experimental data was acquired from 10:00 to 16:30 o’clock. The effect of mass flow rate on efficiency was studied considering three cases of 0.00187, 0.00217 and 0.00345 kg/s. The results indicated that the highest useful heat amount and thermal efficiency were obtained at 0.00345 kg/s. The thermal efficiency values were determined as 32 to 39%. The exergy efficiency of the system was also evaluated as 5.7 to 6.3% according to the experimental data.

This study is directed to propose a method for enhancing the energy parameters of the refrigeration systems operating with R134a which generally presents low performance of the units. Hence, R134a was experimentally compared with HFO-based refrigerants of R1234yf and R1234ze(E) having low-GWP. Additionally, plate-type liquid to suction heat exchanger (LSHX) was utilized in order to determine its effect on the system's energy performances. The evaporation temperatures were −9, −4.5 and 0 °C while the condenser temperatures were 40, 45, and 50 °C in the experimental work. The cooling capacity and power consumption of R1234ze(E) were noticed lower, however its COP was higher compared to R1234yf. It was also figured out that COP of the system with LSHX using R1234ze(E) was better about by 3% than that without LSHX which operated with R134a. The results of the present study indicated that the presence of LSHX caused improved COP and lower power consumption of the refrigeration system.