Fatih ÜNAL, Derya Burcu ÖZKAN, Ahmet Erhan AKAN

INVESTIGATION OF EFFICIENCY OF R717 REFRIGERANT SINGLE STAGE COOLING SYSTEM AND R717/R744 REFRIGERANT CASCADE COOLING SYSTEM

This study is an adaptation of ammonia cascade cooling systems using carbon dioxide on ice cream production machines and includes thermodynamic analysis of R717/R744 cascade refrigeration system with R717 refrigerant single-stage refrigeration system and investigation of its efficiency. As a result of the analyses, the COP value of the single-stage system was 3.67, the Carnot efficiency was 0.57, the second law efficiency was 0.19 and the power required to operate the compressor was 27.55 kW. In the cascade cooling system, the COP value was 4.46, the Carnot efficiency 0.59 and the compressor power 22.7 kW in the high-temperature part, while the COP value was measured as 14.65, the Carnot efficiency 0.58 and the compressor power 6.4 kW in the low-temperature part. For the whole cascade system, the COP 3.24 and the second law efficiency were found to be 0.43. When the results were compared, it was concluded that although the COP value of the cascade cooling system was 0.43 points lower than the single-stage ammonia system, when our country's climate conditions and the thermophysical properties carbon dioxide gas were considered together, one of the most suitable designs was the cascade cooling system.

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Alan, A. (2011). The effect of expansion turbine usage on energy potential in dual stage CO2 cooling systems, MSc Thesis, University of Süleyman Demirel, Isparta, Turkey.
Bingming, W., Huagen, W., Jianfeng, L., Ziwen, X. (2009). “Experimental investigation on the performance of NH3/CO2 cascade refrigeration system with twinscrew compressor.” International Journal of Refrigeration, Vol. 32, No. 6, pp. 1358–1365.
Çerkezoğlu, B. (2010). Analysis of Cascade Cooling System Using Co2, MSc Thesis, Istanbul Technical University, Istanbul, Turkey.
Dopazo, J. A., Fernández-Seara, J., Sieres, J., Uhía, F. J. (2009). “Theoretical analysis of a CO– NH cascade refrigeration system for cooling applications at low temperatures.” Applied Thermal Engineering, Vol. 29, No. 8-9, pp. 1577–1583.
Dopazo, J. A., Fernández-Seara, J. (2011). “Experimental evaluation of a cascade refrigeration system prototype with CO2 and NH3 for freezing process applications.” International Journal of Refrigeration, Vol. 34, No. 1, pp. 257–267.
Getu, H. M., Bansal, P. K. (2007). “Modeling and performance analysis of evaporators in frozen food supermarket display cabinets at low temperatures.” International Journal of Refrigeration, Vol. 30, No. 7, pp. 1227-1243.
Kasap, F., Acül, H., Canbaz, H., Erbil, S. (2011). “R744 (CO2) Refrigerant cooling systems, finned tube R744 (CO2) evaporator and gas cooler design principles.” X. National Installation Engineering Congress, İzmir, Turkey, pp. 391-410.
Onbaşıoğlu, H. (2010). “An Overview of Vapour Compression System Using Natural Refrigerant CO2”. İSKİD ACV&R Journal of Turkey, Vol.2, pp.48-64.
Özyurt, A., Erdönmez, N., Yilmaz, B., Yilmaz, D., Sevindir, M. K., Mançuhan, E. (2014). “Thermodynamic Analysis and Performance Evaluation of CO2 / NH3 Cascade Cooling System.” 15th International Refrigeration And Air Conditioning Conference, Plant Egineering, Purdue, Indiana pp. 2598-2608.
Rezayan, O., Behbahaninia, A. (2011). “Thermoeconomic optimization and exergy analysis of CO2/NH3 cascade refrigeration systems.” Energy, Vol. 36, No. 2, pp. 888–895.
Vestergaard, N. P. (2007). “Danfoss Refrigeration and Air Conditioning Division, CO2 Refrigerant for Industrial Refrigeration”. Danfoss A/S (RA Marketing/MWA), DKRCI.PZ.000.C1.02 / 520H2242.