A new methodology for the determination of transport properties of refrigerants

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Lin, Jian-Yuan
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Michael B. Pate
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Mechanical Engineering
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R-22, R-502, and R-114 have been widely used as working fluids in refrigeration units for the past several decades. However, all of the above refrigerants have been classified as phase-out refrigerants because they are detrimental to the ozone layer. Presently, one of the leading candidates to replace R-114 is HFC-236ea (hexafluoropropane), while several potential refrigerant mixtures are being considered to replace R-22 and R-502. These refrigerant mixtures to replace R-22 and R-502 are primarily composed of R-32, R-125, R-134a, and R-143a. Two ternary blends reported to have potential to replace R-22 and R-502 are blend A: R-32 (23%)/R-125 (25%)/R-134a (52%) and blend B: R-125 (44%)/R-134a (4%)/R-143a (52%);Before these refrigerants can be used as working fluids in real systems, a complete property evaluation must be performed. As a result, this study focuses on developing a new methodology for simultaneously measuring all of the important transport properties. After developing the method, transport properties of above potential alternative refrigerants were measured. Liquid viscosity and thermal conductivity were the two main transport properties of interest in this study. In addition, a special interest was focused on the lubricant effects on the properties of blend A. Properties of lubricant-blend A mixtures with various lubricant concentrations were also investigated by this method;In the present approach, the thermal conductivity was measured from the knowledge of single-phase heat transfer characteristics of a heated test-section, while viscosity was measured with an inline torsional oscillation viscometer. The methodology was verified with R-114 by comparing experimental data with ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) data. The results show deviations within ±5% in thermal conductivity and ±2% in viscosity.

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Sat Jan 01 00:00:00 UTC 1994