Study of Lubricant Compatibility with a Low-GWP Refrigerant as an Alternative to R410A in a Compressor Test Loop

Due to large concerns over global warming, many countries signed and ratified the Kigali Amendment. The amendment is an international agreement to gradually exclude HFCs that have zero ODP but thousands of GWP. R410A which has 2088 GWP is a representative HFC and common refrigerant in air-conditioning systems. To replace the fluid with a low-GWP one, R466A is considered a promising substitutional one because R466A obtained class A1 from ASHRAE. Until now, the compatibility test for R466A with lubricant and materials has been only done by sealed tube with copper, iron, and aluminum coupons. In this study, oil compatibility characteristics of R466A with oil and materials are assessed in real operating conditions of a compressor. For this, a simple heat pump cycle test loop is designed and tested under an accelerated test protocol. To confirm how R466A is compatible with oil and materials, the oil is periodically sampled after regular operation time. As decision factors, the viscosity of oil and decomposed ions in oil are selected, and they are measured by a rotational rheometer and ion chromatography, respectively.