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56 Ionel Oprea 8. GWP - global warming potential: the refrigerant selection based on a simple approach of ‘zero ODP’ will have to pay high costs to both global warming and energy efficiency. Using this single criterion is no longer environmentally acceptable today. 9. Price per Unit of refrigerant, $. Agent R134a R717 R600 R507 R410a R407c R404a 1 20 1430 1800 2100 0 500 1000 1500 2000 2500 3000 3500 4000 4500 GWP Fig. 4 – Comparative analysis of price. Fig. 5 – Comparative analysis (70°C, 60°C, 52°C, 45°C condensing temperature and 0°C evaporating temperature). 3900 4000
Bul. Inst. Polit. Iaşi, t. LVIII (LXII), f. 4, 2012 57 4. Conclusions 1. The evaporation heat content of R404a is significantly lower (90% less) than the baseline R717 value, while that of R410a is slightly higher. 2. The COP cycle of R134a is about 17% lower than the baseline value, indicating that this refrigerant does not match the baseline R407c cycle performance. These characteristics imply that both R404a and R410a refrigerants have weaker heat transfer ability and lower cooling capacity on equal heat pump load base, as compared to R717. 3. Increased vapor density for R507, R410a and R404a may also lead to the use of a smaller compressor and coil tubing that could result in less system power consumption and more efficient component design. 4. Overall, however, a comparable COP system is possible for R404a, and even a moderate system efficiency improvement might be expected for R410a for a certain heat pump load. 5. The COP system is also influenced by compressor volumetric efficiency, which is a function of compression ratio H (pcond/pevap) and compressor isentropic efficiency, which could be affected by other transport properties, as well as system design. REFERENCES *** Report of the Refrigeration, Air Conditioning and Heat Pumps. UNEP, Technical Options Committee, Nairobi, 1998. *** Livre blanc sur les fluides frigorigènes. Conseil National du Froid, Paris, AFF, 2001, 51 pages. *** Report of the Technology and Economic Assessment Panel April 2000. UNEP. 2000, UNEP, Nairobi, 193 pages. Harnisch J., Hendriks C., Economic Evaluation of Emission Reductions of HFCs. PFCs and SF in Europe, Ecofys Energy and Environment, 2001. Chang Y.S., Kim M.S., Ro S.T., Performance and Heat Transfer Characteristics of Hydrocarbon Refrigerants in a Heat Pump System. International Journal of Refrigeration, 23 (3), 232-242 (2000). Pelletier O., Propaneas Refrigerant in Residential Heat Pumps. Licentiate thesis. Royal Institute of Technology, Stockholm, Sweden, 1998. METODA MULTICRITERIALĂ DE ALEGERE A AGENŢILOR FRIGORIFICI PENTRU POMPELE TERMICE Lucrarea propune o evaluare multicriterială pentru pompele termice care lucrează cu agenţi frigorifici cu ODP zero (R600, R404a, R407c, R410a, R134a, R507, R134a şi R717). Proprietăţilor termo-fizice ale agenţilor nu sunt suficiente pentru o evaluare completă, iar o abordare multicriterială permite o apreciere completă. Parametrii
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