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Thermal conductivity of binary and ternary refrigerant mixtures’ experimental results and correlations
Klaus Spindler, Nico Hoffmann, Jochen Sohns, Erich Hahne

Thermal conductivity measurements of saturated liquid and vapour are presented here for three binary mixtures of the refrigerants R32 and R125, including the commercially available mixture R410A, for the binary mixture of R125 and R143a which is almost R507, and for the ternary mixture R407C, which consists of 23% R32, 25% R125, and 52% R134a. The experimental results for the mixtures are compared with the sum of the molar weighted values of the pure components and with calculated values from existing correlations. The thermal conductivity of the mixture in the saturated vapour phase, lm, can be calculated by molar weighting of the values of the pure components: lm = Syili, where yiis the molar fraction of the component i. The thermal conductivity of the mixture in the saturated liquid state, lm, is lower than the sum of the molar weighted value of the pure components. The values calculated by the correlation of Wassiljewa (ltrm = Sziltri, zi is the mass fraction of the component i) agree best with the experimental results. The fit parameter was determined to be r = -0.65.

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