Experimental investigation on cold startup characteristics of a rotary compressor in the R290 air-conditioning system under cooling condition

• Cold startup characteristics of a rotary compressor in the R290 air-conditioning system were experimentally investigated.
• Pressures and temperatures in the R290 air-conditioning system during startup process were measured.
• Temperatures in the rotary compressor shell and the pressure in cylinder during cold startup process were measured.
• The oil viscosity and oil level of the oil sump in the rotary compressor during cold startup process were also considered.
• The solubility of R290 in the oil during cold startup was discussed.

R290 is one of the most alternative refrigerants for the air-conditionings for its negligible environmental impact and high efficiency. This experimental study investigated the cold startup characteristics of the rotary compressor in a R290 air-conditioning system under cooling condition. The characteristics include the pressures and temperatures in the system and the rotary compressor respectively, the mixture of oil and refrigerant viscosity and oil level of the oil sump. The measurements showed that the startup time for the pressures and the temperatures were much longer than that of R410A and R22 systems. A slight liquid slugging happened in the cylinder at the initial time of startup for the pressure during the later exhaust process increasing rapidly to 2.21 MPa in 1.3 seconds. After startup of the system, both the mixture of oil and refrigerant viscosity and oil level of the oil sump in the compressor were within a proper range to guarantee a steady startup of the air-conditioning system.