Analysis on the reliability of R290 rotary compressor in the high ambient temperature.

• The reliability of R290 rotary compressor experimentally and numerically studied. • Study was conducted at ambient temperature (t a) 35°C, 46°C, 55°C, with SO, MO oil. • Oil sump viscosity decreases with the increase of t a , and solubility varies little. • Oil film thicknesses of bearings were analyzed at different t a. • The motor still works normally with condensing temperature 70°C. The R290 rotary compressor is suggested to use in split room air conditioners in hot climate areas for its higher efficiency, environmental-friendly, and lower discharge temperature. However the higher condensing temperature and pressure would result in reliability problems. In this paper the reliability of rotary compressor with R290&MO and R290&SO (mainly including the motor reliability; the oil sump viscosity, temperature and solubility; the oil film thickness of bearings) under the ambient temperature of 35 °C,46 °C,55 °C were studied experimentally and numerically. The results show that the motor temperature in R290 rotary compressor is lower than the allowable maximum temperature even under the condition of EXT/8 (condensing temperature = 70 °C). In addition, the oil sump viscosity of either synthetic oil (SO) or mineral oil (MO) decrease with the increase of ambient temperature (SO: from 4.7cp to 3.1cp; MO: from 2.2cp to 1.6cp), while under any condition, the solubility of SO (15%–16%) or MO (22%–25%) varies little. Besides, in the high ambient temperature (46 °Cand 55 °C), it is feasible to increase suction superheat to satisfy the proper viscosity when MO is used, while it is infeasible to SO. Influenced by oil viscosity and load, the oil film thickness of main bearing, sub bearing and eccentric bearing decrease with the increase of ambient temperature. [ABSTRACT FROM AUTHOR]