This research project determined the solubility of water in HFC refrigerants R-134a, R-32, R-143a, R-125, and R-152a and HFC refrigerant blends R-410A, R-407C, R-507A, and R-404A from –100°F (–73°C)to 160°F (71°C)(or within 15°F [8.3°C ] of critical temperature)in liquid refrigerant and in the presence of refrigerant clathrate hydrate below 60°F (16°C). Water solubility curves were constructed for each refrigerant and blend by measuring water content at 20°F (11°C) increments over the entire temperature range. In this study, all refrigerants in the presence of 1%w/w water were confirmed to form stable solid clathrate hydrates between 50°F (10°C) and 60°F (16°C), with R-32 and blends containing R-32 demonstrating stable clathrate hydrates up to 80°F (27°C).

Evaluation of water solubility in HFC refrigerants and blends was performed using a small, bench-top unit constructed of type 316 stainless steel that was temperature controlled, inexpensive to build, and easy to operate. The test cell/unit controlled the temperature of both the liquid and vapor refrigerant phases. This instrument and a Karl Fischer coulometer were used to measure the water equilibrium in solution of the aforementioned HFC refrigerants and blends at the specified temperatures, as well as water equilibrium between clathrate hydrate and liquid refrigerant. Data from this project determined the maximum amount of water permissible for operating systems down to –40°F (–40°C).

Units: Dual