Abstract
Leakage flow through a narrow clearance in refrigerant compressors is a flow of refrigeration oil mixed with refrigerant. Its characteristics are very complicated because there is a possibility of a separation of vapor refrigerant from the oil according to a change of refrigerant solubility with pressure drop in the clearance. In this study, we studied the flow characteristics of refrigerant-oil miture through the narrow clearance experimentally and theoreticalIy. At first we investigated the characteristics of the two-phase flow through the narrow clearance by using a two-phase analytical model. The characteristics were also analyzed by a single phase model and the limitation of the homogeneous model was discussed by comparing results of the both models. On the other hand, the flow characteristics were measured by using an experimental channel having the narrow clearance. The followings were clarified. (1) The separation of vapor refrigerant from the liquid mixture in the channel does not progress according to the change of saturation solubility and the condition of the flowing liquid is in a super saturated condition. (2) The diverging shape of the channel induces the vapor separation. (3) The vapor separation decreases flow rate of the liquid mixture through the clearance, and the flow rate can be estimated by the analysis with an appropriate separation ratio.
