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Drop-in assessment of plug-in R404A refrigeration equipment using low-global warming potential mixtures
(Oxford University Press, 2022) Devecioğlu, Atilla G.; Oruç, Vedat
This study analyzes 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 < 150 such as R454C, R455A, R457A and R465A. In the study, four cases of evaporation temperatures (−25°C, −15°C, −5°C and 0°C) and two cases of condenser temperatures (30°C and 40°C) were considered for freezer and chiller modes of the equipment. According to the obtained results, the power consumption of R404A is determined to be higher than other refrigerants for both studied condenser temperatures. The mass flow rate circulating in the system decreases using R404A’s alternatives. Furthermore, the highest coefficient of performance (COP) is reached with R457A, which has a greater COP than R404A about by 8.5%. The compressor discharge pressures of alternative refrigerants are smaller compared with R404A as well. The reduction in CO2 emission is also presented in terms of total equivalent warming impact (TEWI) computations. The conducted analysis points out that it will be possible to use directly the investigated mixtures (especially R457A and R455A are most promising ones) in plug-in refrigeration devices as alternatives to R404A without performing any constructional modification in the system.
Experimental assessment of the retrofit of an internal heat exchanger in refrigeration systems: The effect on energy performance and system operation
(Pergamon-Elsevier Science LTD, 2020) Oruç, Vedat; Devecioğlu, Atilla G.
The aim of this experimental study is to retrofit a refrigeration system with an internal heat exchanger (IHX) and to assess its effect on the energy performance of the system. The separate IHX cases in the investigation are tube-in-tube type and plate type and these are also compared with the system without any IHX. R404A and R442A refrigerants are tested in a single stage vapour compression refrigeration system. In the experimental work evaporation temperatures of −5°C and 0°C are considered while the condenser temperatures are 30°C and 50°C. The results indicated that both utilised types of IHX elements improved the energy performance of the system while the benefit with the tested plate type IHX case was better. Also, the alternative refrigerant R442A can be preferred as a substitute for R404A due to the enhanced energy performance of the system. The thermal effectiveness of IHX devices and the volumetric efficiency of the compressor are considered as well for the evaporation and condenser temperatures covered.
Experimental comparison of R404A and R452A in refrigeration systems
(Taylor & Francis, 2021) Devecioğlu, Atilla G.; Oruç, Vedat
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 temperatures (−5, 0, +5 °C) and condenser temperatures (25, 35, 45 °C). It was seen that COP was higher but power consumption of system was lower using R452A as a substitute for R404A. When R452A was used, COP was improved about by 3% to 8% compared to R404A. Furthermore, cooling capacity decreased about by 2% for condenser temperatures of 25 and 35 °C while it increased at condenser temperature of 45 °C. Power consumption of system was also reduced nearly by 5%. Mass flow rate of refrigerant was lower when the system was operated with R452A. In the middle term, R452A could be a suitable alternative refrigerant for commercial refrigeration applications due to its low GWP value and better energy performance compared to R404A.
Experimental investigation of a solar air heater with copper wool on the absorber plate
(Taylor & Francis, 2020) Biçer, Ayşe; Devecioğlu, Atilla G.; Oruç, Vedat; Tuncer, Zafer
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 selective surface. Hence, the area of absorber plate was enhanced to absorb much amount of heat energy. The experimental study was conducted for both cases (presence and absence of copper wool on the absorber plate) to determine the effect of copper wool on the thermal efficiency of the collector. The mass flow rate values of the study were 0.035 and 0.044 kg/s. The results pointed out that fluid temperature at outlet of collector with copper wool was increased by about 8 to14%. Therefore, these collectors may be suitable for space heating and drying of food applications. However, copper wool caused more pressure loss through the collector by 40% compared to simple case of collector. The thermal efficiency of the collectors was obtained as 34 to 83% depending on experimental variable parameters. Similarly, effective efficiency of collectors was computed to be 24 to 70%. It is found that efficiency of the collector was improved when using copper wool on the absorber plate as well as increasing mass flow rate of air.
Experimental investigation of thermal performance of a new solar air collector with porous surface
(Elsevier Ltd, 2017) Devecioğlu, Atilla G.; Oruç, Vedat
In this study, thermal performance of a new solar air collector with porous absorber plate was investigated. The porous surface was accomplished by laying out the copper meshing on the absorbing plate. Hence, it was aimed that the plate could absorb more heat and the thermal boundary layer of the flow would be disturbed. The experimental data was acquired for mass flow rates of 0.031 and 0.038 kg/s. The thermal efficiency was determined as 25 to 57% while the thermal-hydraulic efficiency of the collector was calculated as 14 to 44% depending on the experimental case. It was seen that temperature of the fluid at outlet of the collector, useful heat amount and pressure loss were increased as mass flow rate was increased. The results presented that the increasing the mass flow rate and establishing the surface of collector as porous would improve the thermal efficiency of the collector.
Experimental investigation on the low-GWP HFC/HFO blends R454A and R454C in a R404A refrigeration system
(Elsevier SCI LTD., 2021) Oruç, Vedat; Devecioğlu, Atilla G.
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.
Genleştirilmiş kil agregalı betonların ısıl özelliklerinin incelenmesi
(Dicle Üniversitesi Mühendislik Fakültesi, 2012) Devecioğlu, Atilla G.; Biçer, Yaşar
Tüketilen enerjinin büyük bölümü yapıların ısıtılması için harcanmaktadır. Bu nedenle yapı bileşenlerinin düşük ısıl iletkenliğe sahip malzemelerden üretilmesi son derece önemlidir. Yapılardaki ısı kayıplarını azaltmak için, yapı bileşenlerini, ısıl iletkenliği çok düşük malzemelerle kaplamak bir yöntem olarak uygulanmaktadır. Diğer bir yöntem de yapı elemanlarının ısıl iletkenliğini düşürmektir. Bu çalışmada yapı elamanı olarak kullanılabilecek betonarme malzemelerde, agrega olarak genleştirilmiş kil (GK) kullanılmış ve üretilen betonların ısıl özellikleri araştırılmıştır. Hazırlanan numunelere, 0-2 mm, 2-4 mm ve 4-8 mm tane çaplarında GK, ağırlıkça %20, %40, %60 ve %80 oranında eklenmiştir. Farklı tane çap değerleri ve oranları içeren 12 çeşit numune, ölçüm cihazı problarına uygun şekilde hazırlanan kalıplara dökülmüştür. Çalışmada CEM IV/B (P) 32.5 R tipi puzolanik çimento kullanılmıştır. Numuneler 28 gün kurumaya bırakılarak, bekletilmiştir. Yoğunlukları tespit edilen numunelerin, ısıl iletkenlik katsayıları ve özgül ısı değerleri ölçülmüştür. Ölçülen bu sonuçlardan ısıl yayınım katsayısı hesaplanmıştır. Ölçüm cihazı, DIN 51046 normuna göre sıcak tel metodunu kullanarak ölçüm yapmaktadır. Elde edilen bulgularda, tane çapı ve ağırlıkça GK agregasının artması sonucu, numune yoğunluğu ve ısıl iletkenliğinin azaldığı, özgül ısının ise arttığı görülmüştür. Sonuçlar, birçok yapı malzemesiyle mukayese edilmiştir. 4-8 mm tane çaplı ve %80 GK içeren numunenin ısıl iletkenlik değerinin çimento harcının ısıl iletkenlik değerinden %69 daha düşük olduğu belirlenmiştir.
İklimlendirme sistemlerinde R22 yerine R442A kullanılmasının enerji parametrelerine etkisinin incelenmesi
(Dicle Üniversitesi Mühendislik Fakültesi, 2016) Devecioğlu, Atilla G.; Oruç, Vedat; Berk, Uğur; Ender, Sertaç
Bu çalışmada buhar sıkıştırmalı iklimlendirme cihazında R22 soğutucu akışkanı yerine R442A kullanılması deneysel olarak incelenmiştir. Sistemde sadece kompresör yağı değiştirilmiştir. R22 ile çalışırken mineral yağ kullanılırken R442A ile yapılan çalışmalarda sentetik polyol ester (POE) yağ kullanılmıştır. Deneyler aynı çalışma şartları altında üç farklı çevre sıcaklığı (25°C, 30°C, 35°C) için tekrarlanmıştır. Deneyler sonucunda soğutucu akışkanlara ait kütlesel debi, soğutma kapasitesi, COP ve sıkıştırma oranı tespit edilmiştir. Tespit edilen bu enerji parametrelerinin mukayesesi yapılmıştır. Sonuçlarda R22’nin soğutma kapasitesi ve soğutma performans katsayısı R442A’ya göre bir miktar yüksek tespit edilmiştir. R22’nin elektrik tüketimi ise R442A’dan düşük tespit edilmiştir. Ozon yok etme potansiyeli sıfır olan ve R22’nin enerji parametrelerine yakın değerlere sahip R442A’nın orta vadede R22 yerine iklimlendirme sistemlerinde kullanılabilecek uygun bir soğutucu akışkan olduğu söylenebilir.
On the satisfaction of EU F-Gas regulation using R455A as an alternative to R404A in refrigeration systems
(Elsevier, 2022) Devecioğlu, Atilla G.; Oruç, Vedat
The aim of this study is to investigate the possibilities for satisfying F-Gas regulation of European Union (EU) using R455A with low-global warming potential (GWP) in refrigeration systems. Hence an experimental work was conducted for energy analysis of a refrigeration system constructed to operate with R404A. The studied evaporation temperatures were -5 and + 5 degrees C while the condenser temperatures were 35 and 55 degrees C. It was determined that COP values of R455A were higher about by 13.7% compared to R404A. The results of the present investigation point out that R455A is suitable to use in refrigeration systems due to better energy performance. It is possible to use R455A in refrigeration systems after 2022 with respect to the EU regulation 517/2014. (C) 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Smart and Sustainable Developments in Materials, Manufacturing and Energy Engineering.
Retrofitting of R-22 Air-conditioning system with R1234ze(E)
(Springer International Publishing Ag, 2020) Devecioğlu, Atilla G.; Oruç, Vedat
In this study, the effect on energy parameters and total equivalent warming impact (TEWI) using R1234ze(E) as a substitute for R22 in an air-conditioning device was investigated. The R22 system was retrofitted with R1234ze(E) changing compressor oil. The experimental data was obtained for three different ambient temperatures (30, 35 and 40 degrees C). It was seen that the power consumption of R1234ze(E) was smaller than that of R22 about by 41%. Although the cooling capacity of R1234ze(E) was 50% lower, its coefficient of performance (COP) was reduced only by 5% compared to R22. Furthermore, refrigerant charging amount of R1234ze(E) was smaller by 16% than R22. The results indicated that TEWI value of R1234ze(E) was lower than that of R22 by 65% due to small GWP (global warming potential) value and proper COP of the alternative refrigerant tested in the study. Hence, it can be expressed that R1234ze(E) can be used in air-conditioners of small capacity as an alternative to R22.
Soğutma sistemlerinde R454C kullanılmasının deneysel incelenmesi
(Gazi Üniversitesi, 2023) Devecioğlu, Atilla G.; Oruç, Vedat
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.
Thermodynamic analysis of a refrigeration system operating with R1234yf refrigerant
(Springer, 2018) Oruç, Vedat; Devecioğlu, Atilla G.
[Abstract Not Available]

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