Numerical Simulation of Lubrication System in a Hermetic Reciprocating Compressor

Abstract

The aim of this numerical study is to investigate the lubrication system of a household hermetic reciprocating compressor. The effects of the rotational speed, oil viscosity and crankshaft-to-oil sump bottom distance on the oil-air two phase flows are investigated in detail. Necessary oil to lubricate the components of the compressor is sucked from the oil sump through an asymmetrically opened suction hole of the crankshaft by its rotational movement and climbs as an oil film on the helical channel carved on the shaft wall. This oil film is directed to crankshaft outlet. The oil forms an immiscible mixture with air, thus a two phase flow model should be analyzed using Volume of Fluid (VoF) method in the flow solver. Main findings related to the oil mass flow rate released from the crankshaft outlet reveal that with increasing rotational speed, the mass flow rate from the crankshaft outlet also increases, but with increasing viscosity and decreasing crankshaft-to-oil sump bottom distance, the oil mass flow rate decreases.