İklimlendirme sistemlerinde R22 yerine R442A kullanılmasının enerji parametrelerine etkisinin incelenmesi

Abstract

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.

Keywords

• İklimlendirme sistemleri, R22, R442A, COP

The investigation of the effect on the energy parameters using R442A instead of R22 in air-conditioning systems

Abstract

The refrigerant of R22 is widely used in the airconditioning systems. However this refrigerant would be gradually removed to use as per Montreal protocol since it has a serious potential of ozone depletion. According to EU regulations, refrigerants, which do not deplete the ozone layer, having low global warming potential (GWP) should be preferred in both air-conditioning and refrigeration systems. Obviously, the gas leakages may occur from the available devices operating with R22 as a result of their maintenance and installation elsewhere. Hence, R22 currently utilized in the refrigeration systems should be replaced with refrigerants having ozone depletion potential (ODP) of zero in order to protect the ozone layer. Although the air-conditioners of small capacity are widely used, the effect of different alternative refrigerants (especially R442A) on the energy parameters such as COP, cooling capacity, and power consumption etc. is not well known. Some studies can be found in the literature on refrigerants, which are not ozone-depleting, as alternatives for R22 in the air-conditioning systems. The refrigerants such as R407C and R410A that do not deplete the ozone layer are used as an alternative for R22 in the air-conditioners by implementing some modifications in the system. It was remarked in the previous studies that the refrigerants should be preferred as alternatives to HCFC-22. The related investigations are still continuing due to the significance of the topic. The literature survey has pointed out that there are two possible methods to use the alternative refrigerants in air-conditioning or refrigeration systems. In the first one, the new refrigerant is directly charged into the system instead of R22 without making any constructional modification which is called as “drop-in” process. On the other hand, the second method known as “retrofitting” in which changing compressor oil and/or modifying some elements of the system depending on the refrigerant type would be necessary. In this study, an experimental investigation was carried out using R442A as a substitute for R22 in a vapour compression air-conditioning system. A split-type air-conditioning device with a cooling capacity of 2.05 kW and operating with R22 was used as the experimental test unit. Although GWP values of R22 and R442A are similar, their ODP values are 0.05 and zero, respectively. Both refrigerants have been classified as non-flammable class by ASHRAE. Moreover, the thermodynamic properties of the tested refrigerants were seen to be in the similar range of magnitude. The compressor oil has only been changed in the experimental system such that while mineral oil was used for R22, synthetic Polyolester oil (POE) was utilized for the case of R442A. The experiments were conducted under the same conditions for each refrigerant at three different ambient temperatures, Ta (25°C, 30°C, 35°C). Basically, measurements of mass flow rate, pressure and temperatures in the system were accomplished for the experimental work. The enthalpy values of the refrigerants have been subsequently determined according to the measured data through Refprop software. The compression ratio, cooling capacity, power consumption of the compressor, and coefficient of performance (COP) were evaluated in the investigation. Then the comparison of these determined energy parameters for both refrigerants were performed. It was seen that mass flow rate of R442A was smaller than that of R22 at the considered ambient temperatures. The evaporation temperature, Te had greater values for higher Ta cases regardless of refrigerant type while Te for R22 was lower compared to R442A. The compression ratio, PH/PL increased with Ta and it was larger for R442A case. The experimental results demonstrated that the cooling capacity and COP values of R22 were somewhat greater in comparison with R442A. Furthermore, the power consumption of the compressor was lower in the case of using R22. In addition, the COP was considerably reduced as a result of increasing Ta for both refrigerants. According to the experimental results of the present investigation R442A should be a suitable refrigerant in the medium term that can be alternatively utilized in the air-conditioning systems considering its zero ozone depletion potential and similar energy parameters of R22.

Keywords

• Air-conditioning systems, R22, R442A, COP