Measurements of Transport Properties of the Environmentally Acceptable Alternatives to Fully Halogenated Chlorofluorocarbons

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Fluorocarbons and their mixtures have been used extensively in refrigeration, air conditioning, plastic foam blowing, cleaning, and fire extinguishing applications. However, serious problems have arisen, as well known, for the release of fluorocarbons in connection with the new environmental consequences, such as the greenhouse effect in the troposphere and the ozone depletion in the stratosphere. It is, therefore, an urgent need to search appropriate alternatives to fluorocarbons employed so far. The accumulation of reliable numerical data and knowledge on the thermophysical properties of these fluids is desired.The present investigation has been undertaken to obtain accurate transport property data of new environmentally acceptable alternative refrigerants to fully halogenated chlorofluorocarbons. The alternative refrigerants investigated are HCFC-22 (CHClF_2), HFC-134a (CH_2F-CF_3), HFC-143a (CH_3-CF_3), HCFC-123 (CHCl_2-CF_3), HCFC-123a (CHClF-CCIF_2), HCFC-141b (CH_3-CCl_2F), HCFC-142b (CH_3-CClF_2), and their non-azeotropic binary mixtures which are potential replacements of CFC-11 (CCl_3F) and CFC-12 (CCl_2F_2). The viscosity measurements were performed with a rolling-ball viscometer in the gas phase and with a falling-cylinder viscometer in the liquid phase in a temperature range from 283 to 343 K under pressures up to 120 MPa. The thermal conductivity has been measured with a coaxial-cylinder cell on a relative basis in the gas phase and with a transient hot-wire apparatus in the liquid phase at temperatures from 293-353 K and pressures up to 100 MPa. The experimental data obtained have been correlated with temperature, pressure and density by several empirical methods. The author hopes that the present experimental results may contribute to the selection and utilization of alternative refrigerants.