engleski

Heat Transfer Comparison in Coaxial Tube in Tube Heat Exchanger Operating with Refrigerants R407C and R22

Due to hazardous environmental impact of the CFC and HCFC refrigerants that are currently used in R&AC systems, in accordance with the Montreal Protocol, actual is exchange of those by new, ecologically acceptable, HFC refrigerants. Therefore system performance analysis was made where the single component R22 refrigerant was replaced by zeotropic mixture R407C. In the system operating at the same conditions, a comparison of heat transfer in coaxial exchanger for R22 and R407C is performed. Experimental data are presented in the form of average heat transfer coefficients as a function of heat flux and mass velocity. Results have showed that in the heat exchange process with R407C refrigerant heat transfer coefficient is lower (10-35%) than for R22. As R407C is a blend of three pure refrigerants (R32, R125 and R134a) with temperature glide of 5-7°C, the concentration shift occurs during two-phase flow in the condenser and evaporator.

zeotropic mixtures; Lorenz process; thermodynamic efficiency

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